Ultrasound in Medicine and Biology via MedWorm.com

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Ultrasound in Medicine and Biology — Thu, 09 Feb 2012 08:13:48 +0100

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Effect of Surface Architecture on In Vivo Ultrasound Contrast Persistence of Targeted Size-Selected Microbubbles

Ultrasound in Medicine and Biology — Thu, 09 Feb 2012 08:13:48 +0100

Abstract: Ultrasound molecular imaging is a powerful diagnostic modality using microbubbles coated with targeting ligands specific for endothelial biomarkers. The circulation persistence of ligand-bearing contrast agents is a key determinant in their contrast enhancement and targeting capability. Prior studies have shown that targeted microbubbles with ligands attached to the shell using the conventional exposed-ligand architecture (ELA) could trigger undesired ligand-induced complement activation and decreased circulation time. Microbubbles with the buried-ligand architecture (BLA), however, were found to inhibit complement activation and prolong circulation time. In the present study, we extended the stealth BLA microbubble design to size-selected (4 to 5-μm diameter) microbubbles targe...

New Microembolus Size Estimator for Peripheral Blood Vessels

Ultrasound in Medicine and Biology — Thu, 09 Feb 2012 08:13:48 +0100

Abstract: Several factors affecting the power of Doppler scattered signal and, consequently, microembolus size estimation, may be eliminated when assessing the microembolus size via multiple measurements. A new microembolus size estimator is proposed based on the ratio of microembolus scattering cross-section in two directions and for two emission frequencies. Theoretical considerations indicate that the estimation of size of microembolic elements should be independent of the spatial distribution of the wave intensity, tissue attenuation and hardware factors. The simulation results indicate that this estimation only slightly depends on the material of the microembolus and acoustic properties of blood. The experimental results indicate that the accuracy of median size estimation increases w...

High-Frequency Ultrasound in the Evaluation of Cerebral Intraventricular Haemorrhage in Preterm Rabbit Pups

Ultrasound in Medicine and Biology — Thu, 09 Feb 2012 08:13:48 +0100

Abstract: Cerebral intraventricular haemorrhage (IVH) is the most common cause of severe neurologic impairment following preterm birth in human infants. Ideally, an animal model for cerebral IVH should allow for reliable noninvasive evaluation of haemorrhagic extension and of subsequent development of posthaemorrhagic ventricular dilatation (PHVD). The aim of this study was to evaluate the use of high-frequency ultrasound (HFU) in premature rabbit pups with cerebral IVH induced by IP glycerol injection. Serial examinations using HFU enabled an accurate description of haemorrhagic extension and measurement of progressive PHVD over 72 h. The coefficient of variation for inter- and intraobserver variability in two measurements of ventricular size was less than 8.8% and 9.3%, respectively. Rep...

Ultrasound in Medicine and Biology — Thu, 09 Feb 2012 08:13:48 +0100

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Ultrasound in Medicine and Biology — Thu, 09 Feb 2012 08:13:48 +0100

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Ultrasound in Medicine and Biology — Thu, 09 Feb 2012 08:13:48 +0100

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A Texture Matching Method Considering Geometric Transformations in Noninvasive Ultrasonic Measurement of Arterial Elasticity

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

This article proposes a novel texture matching method based on ultrasonic B-mode image considering geometric transformations to accurately measure arterial displacement and acquire arterial elasticity noninvasively. The method was validated by simulated images with rotation and deformation and further by measurements in vitro arterial phantom and in vivo common carotid arteries of 20 healthy volunteers. Simulation results demonstrate that the method can improve the accuracy of measurement of arterial displacement. Experimental results show that the elastic modulus of the arterial phantom agrees well with the results obtained from mechanical tests, deviating only 4.1%. The mean elastic modulus of the common carotid arteries is 361.7 ± 93.5 kPa. The texture matching method was shown to b...

A New Nonlinear Parameter in the Developed Strain-to-Applied Strain of the Soft Tissues and Its Application in Ultrasound Elasticity Imaging

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

In this study, a new nonlinear elastic parameter of the soft tissues is proposed to overcome this limit. The purpose of this study is to evaluate the newly proposed method and demonstrate its feasibility in the UEI. A nonlinear characteristic of soft tissues over a relatively large dynamic range of strain was investigated. A simplified tissue model based on a finite element (FE) analysis was integrated with a laboratory developed ultrasound radio-frequency (RF) signal synthesis program. Two-dimensional speckle tracking was applied to this model to simulate the nonlinear behavior of the strain developed in a target inclusion over the applied average strain to the surrounding tissues. A nonlinear empirical equation was formulated and optimized to best match the developed strain-to-applied st...

Microbubble Contrast Imaging of the Cardiovascular System of the Chick Embyro

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

This study demonstrates microbubble contrast imaging of the embryonic cardiovascular anatomy and physiology. Day 8–19 (Hamburger & Hamilton Stage 34–43) chick embryos are examined in ovo using high-frequency ultrasound imaging through an opening in the blunt end (air cell) of the egg. A chorioallantoic vein is cannulated, and small boluses of octofluoropropane lipid microspheres (Definity®) are injected to visualize the chick embryo cardiovascular system. The entire chick embryo cardiovascular system including the two embryologic arteriovenous (AV) shunts can be visualized. More accurate physiologic measurements of ejection fractions and cardiac output measurements can be obtained using this technology. Microbubble contrast ultrasound imaging in the chick embryo greatly expands the ab...

Effect of Ultrasound Parameters on the Release of Liposomal Calcein

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

Abstract: The ultrasound exposure parameters that maximize drug release from dierucoyl-phosphatidylcholine (DEPC)-based liposomes were studied using two transducers operating at 300 kHz and 1 MHz. Fluorescent calcein was used as a model drug, and the release from liposomes in solution was measured using a spectrophotometer. The release of calcein was more efficient at 300 kHz than at 1 MHz, with thresholds of peak negative pressures of 0.9 MPa and 1.9 MPa, respectively. Above this threshold, the release increased with increasing peak negative pressure, mechanical index (MI), and duty cycle. The amount of drug released followed first-order kinetics and increased with exposure time to a maximal release. To increase the release further, the MI had to be increased. The results demonstrate that...

Simultaneous Measurement of Red Blood Cell Aggregation and Whole Blood Coagulation Using High-Frequency Ultrasound

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

This study aims to investigate the feasibility of using high-frequency ultrasound (HFUS) for simultaneous monitoring of blood coagulation and red blood cell (RBC) aggregation. Using a 35-MHz ultrasound scanner, ultrasound speckle data were acquired from whole blood samples of three experimental groups of rats, including 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS)-treated, noncoagulation and normal control groups. The variations of blood echogenicity, the shape parameters of probability distribution of speckle intensity (skewness and kurtosis) and the correlation coefficient between two consecutive speckle data were calculated as a function of time starting from immediately after taking blood. The blood echogenicity increases rapidly to plateaus at the early stage of measu...

Differentiation of Benign Periablational Enhancement from Residual Tumor Following Radio-Frequency Ablation Using Contrast-Enhanced Ultrasonography in a Rat Subcutaneous Colon Cancer Model

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

The objective of this study was to evaluate the role of quantitative of contrast-enhanced ultrasound (CEUS) in early differentiation of BPE from residual tumor in a BD-IX rat subcutaneous colon cancer model. A phantom study was first performed to test the validity of the perfusion parameters in predicting blood flow of two US contrast imaging modes—contrast harmonic imaging (CHI) and microflow imaging (MFI). To create a simple model of BPE, a peripheral portion of the tumor was ablated along with surrounding normal tissue, leaving part of the tumor untreated. First-pass dynamic enhancement (FPDE) and MFI scans of CEUS were performed before ablation and immediately, 1, 4 and 7 days after ablation. Time-intensity-curves in regions of BPE and residual tumor were fitted to the function , in ...

High-Frequency Ultrasound for In Vivo Measurement of Colon Wall Thickness in Mice

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

In conclusion, HF-US provides an easy to use and noninvasive method to perform anatomical investigations of mouse colon and to monitor changes in CWT. (Source: Ultrasound in Medicine and Biology)

Real-Time Tissue Elastography for the Diagnosis of Lymph Node Metastasis in Oral Squamous Cell Carcinoma

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

Abstract: We compared conventional ultrasound (US) B-mode, color Doppler and elastographic assessment of lymph node (LN) stiffness against pathological findings from surgical samples, to determine the most useful factors for identifying LN metastases. Seventy-one LNs in 19 patients with oral squamous cell carcinoma (OSCC) were examined. Using our new system, elastography images were scored from 1–5. The score 1–4 were correlated with the blue area of each LN, which indicated increased stiffness: (1) none; (2) 50%. A score 5 indicated central necrosis and did not correlate with the blue area. We found significant differences in minimal diameter, shape index, margin, internal structure, hilus presence or absence, elastography score and percentage of blue area between metastatic and nonme...

Ultrasound Is a Reliable Measure of Muscle Thickness in Acute Stroke Patients, for Some, but Not All Anatomical Sites: A Study of the Intra-Rater Reliability of Muscle Thickness Measures in Acute Stroke Patients

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

Abstract: This prospective, blinded study investigates the test retest reliability of measures of muscle thickness made by one sonographer across two cohort groups (n = 29) of people hospitalised with acute stroke. Reliability was assessed in cohort one (n = 14) for measurements made bilaterally at the anterior and posterior upper arms, the anterior and posterior thighs (total of eight measurements) and in cohort two (n = 15), for measurements made bilaterally at the lateral forearms, the anterior abdominal wall and the anterior and lower legs (total of eight measurements). Reliability estimates varied between measurement sites; intraclass correlation coefficients (ICCs) ranged from –0.26 (lateral forearm, paretic side) to 0.95 (anterior thigh, nonparetic side), percent mean differenc...

The Effect of Vasospasm on Cerebral Perfusion: A Colour Duplex Study of the Extra- and Intracranial Cerebral Arteries

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

Abstract: To assess whether middle cerebral artery (MCA) vasospasm reduces the flow volume in the corresponding extracranial internal carotid artery (ICA) or global cerebral blood flow volume (CBFV) in subarachnoid haemorrhage (SAH) patients, a colour duplex ultrasound study of the intra- and extracranial cerebral arteries was performed. MCA vasospasm was defined as a time-averaged maximum flow velocity (TAMX) exceeding 120 cm/s. ICA flow volumes and CBFV, were compared in each patient at maximum TAMX recorded in one MCA (“maximum-vasospasm”) and when TAMX in the same vessel was closest to mean reference values (“no-vasospasm”). Additionally, the CBFV course during the first 3 weeks after SAH was evaluated longitudinally. Data from age- and gender-matched healthy test persons serve...

Clinical Integrated Ultrasound of the Thorax Including Causes of Shock in Nontraumatic Critically Ill Patients. A Practical Approach

Ultrasound in Medicine and Biology — Tue, 24 Jan 2012 05:00:00 +0100

Abstract: A rapid identification of the causes of hemodynamic instability or cardiac arrest is crucial for correct treatment. In a critical care setting, ultrasound seems to be an ideal tool for a rapid diagnosis. A multiple-goal problem-based approach represents the main peculiarity of emergency ultrasound and may be considered an extension of physical examination. The integration of data that can rapidly be obtained from the heart, lung, inferior vena cava, abdomen and leg vein examination are often essential for the diagnosis and treatment in critically ill patients. The role and potentiality of integrated ultrasound in cardiac arrest, shock/hypotension and severe dyspnea are considered in this article. (Source: Ultrasound in Medicine and Biology)

Fetal Echocardiography, 2nd Edition

Ultrasound in Medicine and Biology — Fri, 20 Jan 2012 05:00:00 +0100

The second edition of the textbook Fetal Echocardiography, by Julia Drose, includes many of the same contributors as the first edition, published in 1998, but represents a substantial improvement as it has been brought up to date with many expanded features. The new text is well-organized, with chapters dedicated to defining normal anatomy, as well as chapters dedicated to every type of major fetal heart malformation. Each chapter has been updated and many images that were in gray-scale in the first edition have been changed to color with enhanced resolution. Additionally, the line art has been redrawn in full color. (Source: Ultrasound in Medicine and Biology)

The Relation Between Carotid Plaque Echogenicity and Oxidative Stress Marker 8-iso-Prostaglandin F2α

Ultrasound in Medicine and Biology — Fri, 20 Jan 2012 05:00:00 +0100

Abstract: Echolucent plaques are associated with high risk of ischemic cerebrovascular events. Oxidative stress has been implicated in the process of atherosclerotic plaque development from initiation to progression. We assessed the relation between carotid plaque echogenicity and urinary 8-iso-prostaglandin F2α, as an index of oxidative stress. This cross-sectional study was conducted prospectively on 290 consecutive outpatients. Each patient was evaluated for carotid plaque echogenicity using the gray-scale median at the maximal thickness plaque and urinary 8-iso-prostaglandin F2α using enzyme linked immunosorbent assay. By Pearson correlation analysis, we found significant negative linear relation between gray-scale median values and the urinary 8-iso-prostaglandin F2α levels (r = �...

Ultrasound Markers that Describe Plaques Are More Sensitive than Mean Intima-Media Thickness in Patients with Familial Hypercholesterolemia

Ultrasound in Medicine and Biology — Fri, 20 Jan 2012 05:00:00 +0100

Abstract: A widely adopted ultrasound surrogate marker for predicting cardiovascular risk is mean intima-medial thickness (mean-IMT). There are, however, certain limitations to this methodology. We compared the severity of carotid atherosclerosis in adult patients with high cardiovascular risk (patients with familial hypercholesterolemia [FH] and without previous statin treatment) and in their adult FH-free first-degree relatives using not only mean-IMT, but also maximum-IMT, plaque number, plaque score and percent area stenosis. Mean-IMT has not differed in both groups (0.64 ± 0.18 mm vs. 0.58 ± 0.13 mm in the control group, p = 0.349). Maximum-IMT (0.99 ± 0.35 vs. 0.76 ± 0.19, p = 0.0057), plaque number (3 ± 3 vs. 1 ± 2, p = 0.0009), plaque score (5.14 ± 4.97 mm vs. 1.58 ± 3.0...

Ultrasonographic Evidence of Intra-Abdominal Umbilical Vein Dilatation: Is It a True Varix?

Ultrasound in Medicine and Biology — Fri, 20 Jan 2012 05:00:00 +0100

This article describes FIUV tortuosity in cases with suspected varix and provides ultrasonographic criteria for its diagnosis. Cases of suspected FIUV varix referred to our unit for final diagnosis and follow-up were studied. Each woman underwent comprehensive US evaluations that included basic grayscale scan and color Doppler scan. In 12 singleton pregnancies, primary grayscale scan confirmed FIUV dilatation. Supplementary color Doppler scans, however, revealed linear bidirectional blood flow and FIUV tortuosity in all cases. Color Doppler scans did not depict true FIUV dilatations or varix but rather a tortuous course of the vein. A normal pregnancy outcome can be expected in these cases. (Source: Ultrasound in Medicine and Biology)

Measurement of Articular Cartilage Thickness Using a Three-Dimensional Image Reconstructed from B-Mode Ultrasonography Mechanical Scans Feasibility Study by Comparison with MRI-Derived Data

Ultrasound in Medicine and Biology — Fri, 20 Jan 2012 05:00:00 +0100

Abstract: The present study aimed to develop a method to measure three-dimensional (3-D) thickness of cartilage (Tc) at the femoral condyle using B-mode ultrasonography (US) and to clarify the feasibility of US in clinical evaluations of articular cartilage by comparing the results with 3-D measurement values using magnetic resonance imaging (MRI) and assessing repeatability. The medial surface of the right knees of two healthy male volunteers (age, 37 and 59 years) and the knees on affected side of three male patients with osteoarthritis (OA) (age, 73, 81 and 83 years) were scanned using B-mode US with the knee flexed at 120°. The range of the angle of probe rotation for the arm was 0-80° and B-mode images (total, 101 images) were acquired every 0.8°. MRI of the knees was also performe...

Transvaginal 3-D Power Doppler Ultrasound Evaluation of the Fetal Brain at 10–13 Weeks’ Gestation

Ultrasound in Medicine and Biology — Fri, 20 Jan 2012 05:00:00 +0100

The objective of this study was to measure the fetal brain volume (FBV) and vascularization and blood flow using transvaginal 3-D power Doppler (3DPD) ultrasound late in the first trimester of pregnancy. 3DPD ultrasound examinations with the VOCAL imaging analysis program were performed on 36 normal fetuses from 10–13 weeks’ gestation. FBV and 3DPD indices related to the fetal brain vascularization (vascularization index [VI], flow index [FI] and vascularization flow index [VFI]) were calculated in each fetus. Intra- and interclass correlation coefficients and intra- and interobserver agreements of measurements were assessed. FBV was curvilinearly correlated well with the gestational age (R2 = 0.861, p < 0.0001). All 3-D power Doppler indices (VI, FI and VFI) showed no change at 10�...

Heterogeneity of Microbubble Accumulation: A Novel Approach to Discriminate Between Well-Differentiated Hepatocellular Carcinomas and Regenerative Nodules

Ultrasound in Medicine and Biology — Fri, 20 Jan 2012 05:00:00 +0100

Abstract: This prospective study aimed to elucidate the possibility of differentiating well-differentiated hepatocellular carcinoma (wHCC) from regenerative nodule (RN) on the basis of the heterogeneity of microbubble accumulation. Intensity analysis was conducted on early-phase and late-phase (60 s and 900 s post-injection; perflubutane microbubble) harmonic sonograms in 33 focal hepatic lesions (≤15 mm; 30 patients with chronic liver disease) that were histologically proven as wHCC or RN. Heterogeneity of enhancement, an average of standard deviation of late-phase enhancement in three different sections in the lesions with late-phase iso-enhancement, was examined with respect to the histologic findings. Heterogeneity of enhancement was higher in wHCC (28.7 ± 3.8) than RN (19.8 ± 2.1,...

Detection of Hepatocellular Carcinoma and Liver Metastases with BR14: A Multicenter Phase IIA Study

Ultrasound in Medicine and Biology — Fri, 20 Jan 2012 05:00:00 +0100

Abstract: The study was designed primarily to find the optimal dosage range of BR14 contrast-enhanced ultrasonography (CEUS) to detect malignant focal liver lesions. Secondary objectives were the evaluation of the safety profile and comparison with contrast-enhanced MRI (CE MRI). We studied 25 patients (9 females, 16 males, mean age, 66 years) with known hepatocellular carcinoma or liver metastases at 3 centers over a 3-month period. Each patient underwent a baseline examination and at least 3 CEUS examinations with ascending dose levels (0.25 mL; 1.0 mL; 4.0 mL) of BR14. CE MRI was performed 4 weeks before or after the CEUS examination. Dedicated liver maps were used to record the location, size, and type of detected lesions. Examination quality was documented and safety parameters were a...

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Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:41 +0100

(Source: Ultrasound in Medicine and Biology)

Left Ventricular Assist Devices: Physiologic Assessment using Echocardiography for Management and Optimization

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:41 +0100

We present a pragmatic and systematic echocardiographic approach that serves as a guide for the management of left ventricular assist devices. (Source: Ultrasound in Medicine and Biology)

Evaluation of the Accuracy of Articular Cartilage Thickness Measurement by B-Mode Ultrasonography with Conventional Imaging and Real-Time Spatial Compound Ultrasonography Imaging

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:41 +0100

Abstract: The present study aimed to quantify the thickness of articular cartilage (Tc) in vitro using both conventional and real-time spatial compound B-mode ultrasonography (US) with a clinically used transducer and to evaluate the accuracy of measurement by comparing the results with values obtained microscopically. Femoral condyle samples were obtained from a 6-month-old pig and a 3-year-old pig. B-mode US images with conventional imaging and real-time spatial compound imaging (RTSCI) of osteochondral blocks were acquired. Tc determined using US (Tc-US) was measured from line data parallel to US beam direction acquired from B-mode images with an objective method for determining cartilage surface and bone-cartilage interfaces at the peak brightness values. Tc was also determined under ...

Speckle Noise Reduction in Ultrasound Biomedical B-Scan Images Using Discrete Topological Derivative

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:41 +0100

Abstract: Over three decades, several despeckling techniques have been developed by researchers to reduce the speckle noise inherently present in ultrasound B-scan images without losing the diagnostic information. The topological derivative (TD) is the recently adopted technique in the area of biomedical image processing. In this work, we computed the topological derivative for an appropriate function associated to the ultrasound B-scan image gradient by assigning a diffusion factor k, which indicates the cost endowed to that particular image. In this article, a novel image denoising approach, called discrete topological derivative (DTD) has been implemented. The algorithm has been developed in MATLAB7.1 and tested over 200 ultrasound B-scan images of several organs such as the liver, kidn...

Completely Automated Segmentation Approach for Breast Ultrasound Images Using Multiple-Domain Features

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:41 +0100

Abstract: Lesion segmentation is a challenging task for computer aided diagnosis systems. In this article, we propose a novel and fully automated segmentation approach for breast ultrasound (BUS) images. The major contributions of this work are: an efficient region-of-interest (ROI) generation method is developed and new features to characterize lesion boundaries are proposed. After a ROI is located automatically, two newly proposed lesion features (phase in max-energy orientation and radial distance), combined with a traditional intensity-and-texture feature, are utilized to detect the lesion by a trained artificial neural network. The proposed features are tested on a database of 120 images and the experimental results prove their strong distinguishing ability. Compared with other breast...

Low-Intensity Pulsed Ultrasound (LIPUS) May Prevent Polyethylene Induced Periprosthetic Osteolysis In Vivo

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:41 +0100

Abstract: We investigated the effect of local low-intensity pulsed ultrasound (LIPUS) on polyethylene debris induced periprosthetic osteolysis. The periprosthetic osteolysis model was made by injecting endotoxin-free pure polyethylene particles into the distal part of the femur canal and inserting a stainless steel plug into this femur. The effects of polyethylene and LIPUS were assessed histologically and by the shear strength test and periprosthetic bone mineral density (BMD) test. Sixteen rabbits received a stainless steel plug on one side and both polyethylene and a stainless steel plug on the other side. Three months later, the side that received polyethylene showed periprosthetic osteolysis. Subsequently, another 16 rabbits received polyethylene plus local LIPUS (200 mW/cm2 for 20 mi...

Color Doppler Ultrasonography Evaluation for Chemotherapy Treatment Response of Osteogenic Sarcoma

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:40 +0100

Abstract: The aim of this study was to evaluate the vascular parameters of the proximal peripheral arteries of limbs by color Doppler ultrasonography (CDUS) in individuals with osteogenic sarcoma (OGS) after neoadjuvant chemotherapy and their relation to the tumor necrosis rate. We recruited 50 individuals with osteogenic sarcoma who were scheduled for neoadjuvant chemotherapy before elective surgery from 2003 to 2010. Once enrolled, we evaluated these 50 subjects using color Doppler sonography to identify vascular parameters of tumor vessels before and after neoadjuvant therapy. The vascular parameters of the proximal peripheral arteries of limbs (peak systolic velocity [PSV], end-diastolic velocity [EDV], resistive index [RI]) and tumor neovascularity were compared before and after neoad...

Mapping of Superficial Extremity Veins: Normal Diameters and Trends in a Vascular Patient-Population

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:40 +0100

Abstract: Ultrasonic measurement of superficial extremity veins is a common procedure. To establish normal values for vein-size in a population of vascular patients and to assess if measurements remain unchanged over time, we analyzed a database with results of 28,130 measurements in 2420 separate saphenous and 3206 cephalic veins. Mean size of the great saphenous vein ranges from 2.3 mm to 4.4 mm but did not follow a tapering pattern as is often assumed. The distal calf segment is smaller than the ankle segment. The mean cephalic vein size in the upper arm (2.4 mm) was smaller than at the antecubital level (2.7 mm). A decrease in vein diameter over time was noted in many locations and this reached statistical significance (p < 0.005 for the thigh segment). The clinical significance of thi...

Evaluation of Color Doppler Ultrasonography in Diagnosing Hepatic Alveolar Echinococcosis

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:40 +0100

Abstract: To assess the accuracy of color Doppler ultrasonography in diagnosing hepatic alveolar echinococcosis, 129 patients were examined at the First Affiliated Hospital of Xinjiang Medical University between July 2004 and June 2010. Those patients suspected of having hepatic alveolar echinococcosis were examined and diagnosed by color Doppler ultrasound. All the cases were compared with the gold standard. The findings of their sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio and 95% confidence interval were recorded. Sensitivity: 95% (95% confidence interval: 90.7%–99.3%); specificity: 20.7% (95% confidence interval: 6.0%–35.4%); positive predictive value: 80.5%; negative predictive value: 54.5%; po...

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:40 +0100

(Source: Ultrasound in Medicine and Biology)

Editorial Advisory Board

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:40 +0100

(Source: Ultrasound in Medicine and Biology)

Masthead

Ultrasound in Medicine and Biology — Sat, 14 Jan 2012 19:41:40 +0100

(Source: Ultrasound in Medicine and Biology)

Ultrasonography in Vascular Diagnosis. A Therapy-Oriented Textbook and Atlas

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

This is the English version of the third edition of Wilhelm Schaberle’s book, first published in German. An excellent translation covers major areas of vascular ultrasound, peripheral arteries, peripheral veins, “shunts” - intentional and unintentional A-V communications, extracranial cerebral arteries, visceral and retroperitoneal arteries and penile and scrotal vessels. (Source: Ultrasound in Medicine and Biology)

Integration of Crawling Waves in an Ultrasound Imaging System. Part 2: Signal Processing and Applications

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

Abstract: This paper introduces methods to generate crawling wave interference patterns from the displacement fields generated from radiation force pushes on a GE Logiq 9 scanner. The same transducer and system provides both the pushing pulses to generate the shear waves and the tracking pulses to measure the displacements. Acoustic power and system limitations result in largely impulsive displacement fields. Measured displacements from pushes on either side of a region-of-interest (ROI) are used to calculate continuously varying interference patterns. This technique is explained along with a brief discussion of the conventional mechanical source-driven crawling waves for comparison. We demonstrate the method on three example cases: a gelatin-based phantom with a cylindrical inclusion, an ...

Integration of Crawling Waves in an Ultrasound Imaging System. Part 1: System and Design Considerations

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

Abstract: An ultrasound system (GE Logiq 9) was modified to produce a synthetic crawling wave using shear wave displacements generated by the radiation force of focused beams formed at the left and the right edge of the region of interest (ROI). Two types of focusing, normal and axicon, were implemented. Baseband (IQ) data was collected to determine the left and right displacements, which were then used to calculate an interference pattern. By imposing a variable delay between the two pushes, the interference pattern moves across the ROI to produce crawling waves. Also temperature and pressure measurements were made to assess the safety issues. The temperature profiles measured in a veal liver along the focal line showed the maximum temperature rise less than 0.8°C, and the pressure measu...

Measurement of Mechanical Properties with Respect to Gap Healing in a Rabbit Osteotomy Model Using Echo Tracking

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

Abstract: The most important issue in the assessment of fracture healing is to acquire information about the restoration of the mechanical integrity of bone. Echo tracking (ET) can noninvasively measure the displacement of a certain point on the bone surface under a load. Echo tracking has been used to assess the bone deformation angle of the fracture healing site. Although this method can be used to evaluate bending stiffness, previous studies have not validated the accuracy of bending stiffness. The purpose of the present study is to ensure the accuracy of bending stiffness as measured by ET. A four-point bending test of the gap-healing model in rabbit tibiae was performed to measure bending stiffness. Echo tracking probes were used to measure stiffness, and the results were compared wit...

Disruption of Tumor Neovasculature by Microbubble Enhanced Ultrasound: A Potential New Physical Therapy of Anti-Angiogenesis

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

Abstract: Tumor angiogenesis is of vital importance to the growth and metastasis of solid tumors. The angiogenesis is featured with a defective, leaky and fragile vascular construction. Microbubble enhanced ultrasound (MEUS) cavitation is capable of mechanical disruption of small blood vessels depending on effective acoustic pressure amplitude. We hypothesized that acoustic cavitation combining high-pressure amplitude pulsed ultrasound (US) and circulating microbubble could potentially disrupt tumor vasculature. A high-pressure amplitude, pulsed ultrasound device was developed to induce inertial cavitation of circulating microbubbles. The tumor vasculature of rat Walker 256 was insonated percutaneously with two acoustic pressures, 2.6 MPa and 4.8 MPa, both with intravenous injection of a l...

Ultrasound Enhanced Prehospital Thrombolysis Using Microbubbles Infusion in Patients with Acute ST Elevation Myocardial Infarction: Pilot of the Sonolysis Study

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

Abstract: In animal studies, transthoracic ultrasound and microbubbles have shown to dissolve thrombi in ST elevation myocardial infarction (STEMI). To examine this effect in patients, we have initiated the Sonolysis trial. In this pilot study of 10 patients with a first acute STEMI, we investigated the safety and feasibility of this trial. After pretreatment in the ambulance, five patients were randomized to receive microbubbles with three-dimensional (3-D) guided high mechanical index impulses (1.18) for 15 min, whereas the control group received placebo without ultrasound. Subsequently, primary percutaneous coronary intervention (PPCI) was performed, if indicated. All patients successfully underwent study treatment and PPCI. No significant difference between treatment and control group ...

Changes in Carotid Plaque Echogenicity with Time Since the Stroke Onset: An Early Marker of Plaque Remodeling?

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

In conclusion, carotid plaque echogenicity is increased with time from stroke onset and could be an early marker of plaque remodeling. (Source: Ultrasound in Medicine and Biology)

Assessment of Carotid Elasticity During Exercise: A Reproducibility Study

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

Abstract: The study aimed to evaluate the reproducibility of carotid elasticity during exercise. Eighteen healthy volunteers (nine males, age 34 ± 3 years, BMI 22 ± 6 kg/m2) underwent maximal exercise testing on a graded semi-supine cycle ergometer in two different sessions 3 days apart. Ultrasound B-mode image sequences of the right common carotid were acquired at different steps and analyzed by an automatic system; pressures were estimated by tonometry. Compliance (CC) and distensibility (DC) were significantly decreased at exercise peak and in the first recovery minute (CC from 1.6 ± 0.8 to 1 ± 0.6 mm^2/KPa, DC from 56.2 ± 25.3 to 34.5 ± 20 10^−3/KPa, p < 0.05). For the whole examination, intraclass coefficient was 0.780 for CC and 0.694 for DC. Mean coefficient of variation wa...

In Vivo Time Harmonic Elastography of the Human Heart

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

Abstract: Time harmonic elastography is introduced as a modality for assessing myocardial elasticity changes during the cardiac cycle. It is based on external stimulation and real-time analysis of 30-Hz harmonic shear waves in axial direction of a parasternal line of sight through the lateral heart wall. In 20 healthy volunteers, the externally induced waves showed smaller amplitudes during systole (76.0 ± 30.8 μm) and higher amplitudes during diastole (126.7 ± 52.1 μm). This periodic wave amplitude alteration preceded ventricular contraction and dilation by about 100 ms. The amplitude ratio of 1.75 ± 0.49 indicates a relative change in myocardial shear elasticity on the order of 14 ± 11. These results well agree with observations made by cardiac magnetic resonance elastography for a...

Transvaginal Ultrasound-Guided Embryo Aspiration Plus Local Administration of Low-Dose Methotrexate for Caesarean Scar Pregnancy

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

This study evaluated the effect of transvaginal ultrasound-guided embryo aspiration plus local administration of low-dose methotrexate (MTX) on caesarean scar pregnancy (CSP). Sixty-eight cases of CSP were randomly grouped for (1) systemic administration of MTX plus curettage with hysteroscopy (control group); and (2) transvaginal ultrasound-guided embryo aspiration plus local administration of low-dose MTX (experimental group). Serum β-HCG and transaminase levels, length of hospital stay, occurrence of hypoleukocytosis, vaginal bleeding and genital infection were analyzed. No statistical differences in the duration needed for β-HCG normalization, genital infection and length of hospital stay were observed between the two groups. However, the occurrence of massive vaginal bleeding, hypol...

Shear Wave Elasticity Imaging of Cervical Lymph Nodes

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

Abstract: A pilot study of real-time shear wave ultrasound elastography (SWE) for cervical lymphadenopathy in routine clinical practice was conducted on 55 nodes undergoing conventional ultrasound (US) with US-guided needle aspiration for cytology. Elastic moduli of stiffest regions in nodes were measured on colour-coded elastograms, which were correlated with cytology. Malignant nodes (n = 31, 56.4%) were stiffer (median 25.0 kPa, range 6.9–278.9 kPa) than benign nodes (median 21.4 kPa, range 8.9–30.2 kPa) (p = 0.008, Mann Whitney U test). A cut-off of 30.2 kPa attained highest accuracy of 61.8%, corresponding to 41.9% sensitivity, 100% specificity and 0.77 area under the receiver operating characteristic curve. Qualitatively, elastograms of benign nodes were homogeneously soft; mal...

Shear Wave Dispersion Measures Liver Steatosis

Ultrasound in Medicine and Biology — Mon, 19 Dec 2011 05:00:00 +0100

We report that the dispersion of shear wave velocity and attenuation, that is, the frequency dependence of these parameters, are strongly correlated with the degree of steatosis in a mouse liver model, ex vivo. The results demonstrate the possibility of assessing liver steatosis using noninvasive imaging methods that are compatible with color Doppler scanners and, furthermore, suggest that liver steatosis can be separated from fibrosis by assessing the dispersion or frequency dependence of shear wave propagations. (Source: Ultrasound in Medicine and Biology)

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Ultrasound in Medicine and Biology — Sun, 04 Dec 2011 21:03:45 +0100

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Representativeness of Nodal Sampling With Endobronchial Ultrasonography in Non–Small-Cell Lung Cancer Staging

Ultrasound in Medicine and Biology — Sun, 04 Dec 2011 21:03:45 +0100

In conclusion, representative sampling of regions 4R, 4L and 7 is achieved in more than 80% of patients staged using EBUS-TBNA, and in the procedures that attain this requirement a NPV >90% for mediastinal malignancy is reached, a figure equivalent to cervical mediastinoscopy. (Source: Ultrasound in Medicine and Biology)

Real-Time Virtual Sonography, A Coordinated Sonography and MRI System that Uses Magnetic Navigation, Improves the Sonographic Identification of Enhancing Lesions on Breast MRI

Ultrasound in Medicine and Biology — Sun, 04 Dec 2011 21:03:45 +0100

This study verified that recently developed real-time virtual sonography (RVS) to coordinate a sonography image and the magnetic resonance imaging (MRI) multiplanar reconstruction (MPR) with magnetic navigation was useful. The purpose of this study was to evaluate the accuracy of RVS to sonographically identify enhancing lesions by breast MRI. Between December 2008 and May 2009, RVS was performed in 51 consecutive patients with 63 enhancing lesions. MRI was performed with the patients in the supine position using a 1.5-T imager with a body surface coil to achieve the same position as with sonography. To assess the accuracy of the RVS, the following three issues were analyzed: (i) The sonographic detection rate of enhancing lesions, (ii) the comparison of the tumor size measured by sonograp...

Ultrasound in Medicine and Biology — Sun, 04 Dec 2011 21:03:45 +0100

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Editorial Advisory Board

Ultrasound in Medicine and Biology — Sun, 04 Dec 2011 21:03:45 +0100

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Masthead

Ultrasound in Medicine and Biology — Sun, 04 Dec 2011 21:03:45 +0100

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Subject Index to Volume 37

Ultrasound in Medicine and Biology — Tue, 22 Nov 2011 20:38:44 +0100

For a version of the subject index with embedded hyperlinks, please see http://www.umbjournal.org/content/indices 3-D, three dimensional, three-dimensional, 3-dimensional (Source: Ultrasound in Medicine and Biology)

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Ultrasound in Medicine and Biology — Tue, 22 Nov 2011 20:38:44 +0100

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Analysis of Ultrasound Fields in Cell Culture Wells for In Vitro Ultrasound Therapy Experiments

Ultrasound in Medicine and Biology — Tue, 22 Nov 2011 20:38:44 +0100

Abstract: Ultrasound is an established therapy method for bone fracture healing, hyperthermia and the ablation of solid tumors. In this new emerging field, ultrasound is further used for microbubble-enhanced drug delivery, gene therapy, sonoporation and thrombolysis. To study selected therapeutic effects in defined experimental conditions, in vitro setups are designed for cell and tissue therapy. However, in vitro studies often lack reproducibility and the successful transfer to other experimental conditions. This is partly because of the uncertainty of the experimental conditions in vitro. In this paper, the ultrasound wave propagation in the most common in vitro ultrasound therapy setups for cell culture wells is analyzed in simulations and verified by hydrophone measurements. The ac...

Changes in Ultrasonic Properties of Liver Tissue In Vitro During Heating-Cooling Cycle Concomitant with Thermal Coagulation

Ultrasound in Medicine and Biology — Tue, 22 Nov 2011 20:38:44 +0100

Abstract: The present work considers the ultrasonic properties of porcine liver tissue in vitro measured during heating concomitant with thermal coagulation followed by natural cooling, so as to provide information about changes in the ultrasonic properties of the tissue after thermal coagulation. The excised liver samples were heated in a degassed water bath up to 75°C and naturally cooled down to 30°C. The tissue was observed to begin thermally coagulating at temperatures lower than 75°C. The ultrasonic parameters considered include the speed of sound, the attenuation coefficient, the backscatter coefficient and the nonlinear parameter of B/A. They were more sensitive to temperature when heating than during natural cooling. All of the parameters were shown to rise significantly on co...

In Memoriam: Wesley Nyborg (1917–2011)

Ultrasound in Medicine and Biology — Tue, 22 Nov 2011 20:38:44 +0100

Wesley Nyborg, Physics Professor Emeritus at the University of Vermont, passed away on September 24, 2011 after a full and wonderful life of 94 years. Wesley was born in Ruthven, Iowa in 1917 as the youngest of Isaac Nyborg and Leva Larson’s six children. Wesley’s childhood was spent on a rural farm in a time and place before electricity and cars were widely available. In his youth, he attended a one-room schoolhouse, and greatly enjoyed family sing-a-longs at the piano. After high school, he studied at Luther College where he was introduced to physics, which became his lifelong intellectual pursuit. He earned his Ph.D. from Pennsylvania State University in 1947 and served as an Assistant and Associate Professor of Physics at Brown University prior to joining the UVM Physics Department...

Ultrasound in Medicine and Biology — Tue, 22 Nov 2011 20:38:44 +0100

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Editorial Advisory Board

Ultrasound in Medicine and Biology — Tue, 22 Nov 2011 20:38:44 +0100

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Masthead

Ultrasound in Medicine and Biology — Tue, 22 Nov 2011 20:38:44 +0100

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A Pilot Study to Assess Markers of Renal Damage in the Rodent Kidney After Exposure to 7 MHz Ultrasound Pulse Sequences Designed to Cause Microbubble Translation and Disruption

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: Acoustic radiation force has been proposed as a mechanism to enhance microbubble concentration for therapeutic and molecular imaging applications. It is hypothesized that once microbubbles are localized, bursting them with acoustic pressure could result in local drug delivery. It is known that low-frequency, high-amplitude acoustic energy combined with cavitation nuclei can result in bioeffects. However, little is known about the bioeffects potential of acoustic parameters involved in radiation force and microbubble destruction pulse sequences applied at higher frequencies. In this pilot study, rat kidneys are exposed to high-duty cycle, low-amplitude pulse sequences known to cause substantial bubble translation due to radiation force, as well as high-amplitude short pulse seque...

First Application of Axial Speed of Sound to Follow Up Injured Equine Tendons

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: Ultrasonography is an established technique to follow up injured tendons, although the lesions’ echogenicity tends to become normal before the tendon is ready to sustain the stresses imposed by exercise. Normalized axial speed of sound (SOS) has been found to correlate with an injured tendon’s stiffness; therefore, the purpose of this study was to establish whether SOS would be a useful tool in tendon injury follow-up. Axial SOS was measured in 11 equine superficial digital flexor tendons during a 15-week follow-up period and compared with an ultrasonographic grading system. SOS significantly decreased 2 weeks after the surgical induction of a core lesion, showing a minimum between 7 and 10 weeks; ultrasonographic grade showed a minimum at 3 weeks and increased thereafter. T...

Thermally-Mediated Ultrasound-Induced Contraction of Equine Muscular Arteries In Vitro and an Investigation of the Associated Cellular Mechanisms

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: We have previously shown that MHz frequency ultrasound causes contraction of the carotid artery in vitro. We now extend this investigation to equine mesenteric arteries and investigate the cellular mechanisms. In vitro exposure of the large lateral cecal mesenteric artery to 4-min periods of 3.2 MHz continuous wave ultrasound at acoustic powers up to 145 mW induced reversible repeatable contraction. The magnitude of the response was linearly dependent on acoustic power and, at 145 mW, the mean increase in wall stress was 0.020 ± 0.017 mN/mm2 (n = 34). These results are consistent with our previous study and the effect was hypothesised to be thermally mediated. A 2°C temperature rise produced an increase in intracellular calcium, measured by Fluo-4 fluorescence. Inhibition of...

Comparison of Real-Time In Vivo Spectral and Vector Velocity Estimation

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: The purpose of this study is to show whether a newly introduced vector flow method is equal to conventional spectral estimation. Thirty-two common carotid arteries of 16 healthy volunteers were scanned using a BK Medical ProFocus scanner (DK-2730, Herlev, Denmark) and a linear transducer at 5 MHz. A triplex imaging sequence yields both the conventional velocity spectrum and a two-dimensional vector velocity image. Several clinical parameters were estimated and compared for the two methods: Flow angle, peak systole velocity (PS), end diastole velocity (ED) and resistive index (RI). With a paired t-test, the spectral and vector angles did not differ significantly (p = 0.658), whereas PS (p = 0.034), ED (p = 0.004) and RI (p < 0.0001) differed significantly. Vector flow can measu...

Automatic Bone Localization and Fracture Detection from Volumetric Ultrasound Images Using 3-D Local Phase Features

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

This article presents a novel method for bone segmentation from three-dimensional (3-D) ultrasound images that derives intensity-invariant 3-D local image phase measures that are then employed for extracting ridge-like features similar to those that occur at soft tissue/bone interfaces. The main contributions in this article include: (1) the extension of our previously proposed phase-symmetry-based bone surface extraction from two-dimensional (2-D) to 3-D images using 3-D Log-Gabor filters; (2) the design of a new framework for accuracy evaluation based on using computed tomography as a gold standard that allows the assessment of surface localization accuracy across the entire 3-D surface; (3) the quantitative validation of accuracy of our 3-D phase-processing approach on both intact and f...

Effect of a Novel Segmentation Algorithm on Radiologists’ Diagnosis of Breast Masses Using Ultrasound Imaging

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: We investigated the effect of using a novel segmentation algorithm on radiologists’ sensitivity and specificity for discriminating malignant masses from benign masses using ultrasound. Five-hundred ten conventional ultrasound images were processed by a novel segmentation algorithm. Five radiologists were invited to analyze the original and computerized images independently. Performances of radiologists with or without computer aid were evaluated by receiver operating characteristic (ROC) curve analysis. The masses became more obvious after being processed by the segmentation algorithm. Without using the algorithm, the areas under the ROC curve (Az) of the five radiologists ranged from 0.70∼0.84. Using the algorithm, the Az increased significantly (range, 0.79∼0.88; p < 0.0...

Activation of Microbubbles by Short-Pulsed Ultrasound Enhances the Cytotoxic Effect of Cis-Diamminedichloroplatinum (II) in a Canine Thyroid Adenocarcinoma Cell Line In Vitro

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

This study was designed to explore characteristics of ultrasound targeted microbubble destruction using short-pulsed diagnostic ultrasound. Canine thyroid adenocarcinoma cells were exposed to short-pulsed diagnostic ultrasound in the presence of cis-diamminedichloroplatinum (II) (cisplatin) and ultrasound contrast agent Sonazoid® microbubbles. The cytotoxic effect of cisplatin was enhanced by short-pulsed diagnostic ultrasound and microbubbles. Incubation time with microbubbles influenced the cytotoxic effect of cisplatin. However, exposure duration did not affect the cytotoxic effect of cisplatin. Therefore, short-pulsed diagnostic ultrasound may activate microbubbles near cells and deliver cisplatin into cells. In addition, activation of microbubbles may be concluded in a short time. Ou...

Impact of Propagating and Standing Waves on Cavitation Appearance

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: Standing waves play a significant role in the appearance of cavitation phenomena. The goal of this study was to investigate the effect that the relation between standing and propagating waves in a focused field has on acoustic bubble cloud formation. Measurements of the cavitation signals were performed on five different configurations of a hemispheric phased array transducer (230 kHz) representing a wide range of relations between propagating and standing waves. The results show that configurations with a larger propagating component induce bubble clouds at lower pressures than configurations with a larger standing component. (Source: Ultrasound in Medicine and Biology)

Vascular Effects of Microbubble-Enhanced, Pulsed, Focused Ultrasound on Liver Blood Perfusion

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: The purpose of this study was to investigate the vascular effects of microbubble-enhanced pulsed high-pressure ultrasound on liver blood perfusion. In the presence of circulating lipid-shell microbubbles, a focused ultrasound transducer was used to transcutaneously treat eight livers of healthy rabbits for perfusion analysis and to treat three livers with the abdomen open for histologic analysis. Twenty-two livers treated with the ultrasound only (n = 11) or microbubbles only (n = 11) served as the controls. The focused ultrasound was operated at a frequency of 1.22 MHz with a peak negative pressure of 4.6 MPa. The liver blood perfusion was estimated by performing contrast-enhanced ultrasound and gray-scale quantification on the livers before and after treatment. A temporary, n...

Intense Focused Ultrasound Can Reliably Induce Sensations in Human Test Subjects in a Manner Correlated With the Density of Their Mechanoreceptors

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: Sensations generated by intense focused ultrasound (iFU) can occur cutaneously and/or at depth, in contrast to other forms of stimulation (e.g., heat, electricity), whose action usually occurs only at the skin surface, or mechanical stimulation (e.g., von Frey hairs, calibrated forceps, tourniquets) that compress and thus stimulate all tissue. Previous work on iFU stimulation has led to the hypothesis that the tactile basis of iFU stimulation should correlate with the density of mechanoreceptors at the site of iFU stimulation. Here we tested that hypothesis, correlating a “two-point” neurological examination—a standard measure of superficial mechanoreceptor density—with the intensity of superficially applied iFU necessary to generate sensations with high sensitivity and s...

Propagation Characteristics of Photomechanical Waves and Their Application to Gene Delivery into Deep Tissue

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: Targeted gene transfection can be achieved by the use of photomechanical waves (PMWs) generated by irradiating a solid material with high-power nanosecond laser pulses. To examine the treatable tissue depth, we investigated propagation characteristics of PMWs and depth-dependent properties of gene transfection with different laser fluences and spot diameters. Pressure characteristics of PMWs were measured at different propagation distances using tissue phantoms and their propagation was imaged by shadowgraphing. Phantoms with various thicknesses were placed on rat dorsal skin that had been injected with plasmid DNA coding for a reporter gene and three pulses of PMWs were applied from the top of each phantom. Significant gene expression was observed in the skin even under a 15-mm-...

Would Gestational Age and Presence of Brain Anomalies Affect Interobserver Reliability of Fetal Head Biometry? Using Off-Line Analysis of 3-D Dataset

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

The objective was to assess interobserver reliability of fetal head biometry using archived three-dimensional (3-D) volumes and the impact of gestational age and presence of brain anomalies on examiners’ performance. Seventy nine 3-D volume datasets of fetal head were examined: 27 were normal and 52 had brain abnormalities. Off-line analysis was done by three fetal medicine experts (E1, E2 and E2), all were blinded to history and patient details. Measurements of the biparietal diameter (BPD), head circumference (HC), lateral ventricle (Vp) and transcerebellar diameter (TCD) were compared between examiners and to two-dimensional (2-D) measurements. Comparisons were made at two gestational age groups (≤22 and >22 weeks) and in presence and absence of brain anomalies. The intraclass coeff...

Acoustic Radiation Force Impulse Imaging of Human Prostates: Initial In Vivo Demonstration

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: Reliably detecting prostate cancer (PCa) has been a challenge for current imaging modalities. Acoustic radiation force impulse (ARFI) imaging is an elasticity imaging method that uses remotely generated, focused acoustic beams to probe tissue stiffness. A previous study on excised human prostates demonstrated ARFI images portray various prostatic structures and has the potential to guide prostate needle biopsy with improved sampling accuracy. The goal of this study is to demonstrate the feasibility of ARFI imaging to portray internal structures and PCa in the human prostate in vivo. Custom ARFI imaging sequences were designed and implemented using a modified Siemens Antares™ scanner with a three-dimensional (3-D) wobbler, end-firing, trans-cavity transducer, EV9F4. Nineteen pa...

Ultrasound Assessment of the Rotator Cuff Cable: Comparison Between Young and Elderly Asymptomatic Volunteers and Interobserver Reproducibility

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: Our aim was to characterize rotator cable ultrasound appearance in shoulders of different-aged asymptomatic volunteers, also estimating interobserver reproducibility. We studied 83 shoulders in 42 young volunteers (mean age 26 ± 7.0 years, range 21–35 years) and 66 shoulders in 36 elderly volunteers (65–81 years, 73 ± 4.9 years), noting rotator cable visibility and its minimum thickness and width. Interobserver reproducibility was tested in elderly volunteers by two blinded observers. χ2, U Mann-Whitney, t-test, Bland-Altman, and κ statistics were used. Rotator cable was less frequently detected in younger than elderly volunteers (25/83 vs. 36/66 shoulders; p = 0.002). Young subjects had thicker (1.5 ± 0.2 mm, range 1.3–1.8 mm vs. 1.1 ± 0.1 mm, 0.9–1.3 mm; p (Sou...

Ultrasound Measurement of Subcutaneous Adipose Tissue Thickness Accurately Predicts Total and Segmental Body Fat of Young Adults

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

This study evaluated the ability of ultrasound measurement of subcutaneous adiposity to accurately determine whole body and segmental body fat in young adults aged 18–29 years. Subcutaneous adipose tissue (SAT) thickness was measured by ultrasound at five body sites in 135 subjects (83 men, 52 women) and compared with the corresponding segmental fat mass measured by dual energy X-ray absorptiometry (DXA). Ultrasound measures of SAT thickness were strongly correlated to segmental fat mass and total percentage (%) body fat (r = 0.697–0.907, p < 0.01). Prediction equations generated using quantile regression found SAT thickness at the abdomen and thigh to accurately predict % body fat in men (standard error of the estimate, SEE = 1.9%, 95% limits of agreement (LoA); −3.6% to +3.8%) a...

Splenic Doppler Impedance Indices Estimate Splenic Congestion in Patients With Right-Sided or Congestive Heart Failure

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

In conclusion, splenic PI is a measurement of splenic congestion caused by an increase in venous outflow resistance. It can estimate splenic congestion in patients with right-sided or congestive heart failure. (Source: Ultrasound in Medicine and Biology)

The Effect of the Cold Pressor Test on a Visually Evoked Cerebral Blood Flow Velocity Response

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: We investigated the hypothesis that during tonic pain stimulus, neurovascular coupling (NVC) decreases, measuring visually evoked cerebral blood flow velocity response (VEFR) during cold pressor test (CPT) in healthy human subjects as a test. VEFR was calculated as a relative increase in blood flow velocity in the posterior cerebral artery from average values during the last 5 s of the stimulus-OFF period to average values during the last 10 s of the stimulus-ON period. Three consecutive experimental phases were compared: basal, CPT and recovery. During CPT, end-diastolic and mean VEFR increased from 20.2 to 23.6% (p < 0.05) and from 17.5 to 20.0% (p < 0.05), respectively. In recovery phase, end-diastolic and mean VEFR decreased to 17.7% and 15.5%, respectively. Both values were...

Ultrasound for High Altitude Research

Ultrasound in Medicine and Biology — Mon, 21 Nov 2011 05:00:00 +0100

Abstract: This review describes ultrasound techniques of potential use to high altitude researchers and discusses technical issues related to using ultrasound for high altitude research. Ultrasound allows portable, noninvasive evaluation of many physiologic parameters of interest to high altitude researchers. We discuss techniques that have been extensively used and emerging techniques that can be used to assess parameters of particular interest to high altitude researchers. We do not provide a definitive description of all ultrasound scanning methods but references to instructive sources are included. Potential drawbacks of ultrasound use, such as the need for sometimes extensive training and the potential for interobserver variation, are discussed and strategies for mitigating these are ...

Observations of Translation and Jetting of Ultrasound-Activated Microbubbles in Mesenteric Microvessels

Ultrasound in Medicine and Biology — Mon, 31 Oct 2011 04:00:00 +0100

Abstract: High-speed photomicrography was used to study the translational dynamics of single microbubbles in microvessels of ex vivo rat mesenteries. The microbubbles were insonated by a single 2 μs ultrasound pulse with a center frequency of 1 MHz and peak negative pressures spanning the range of 0.8–4 MPa. The microvessel diameters ranged from 10–80 μm. The high-speed image sequences show evidence of ultrasound-activated microbubble translation away from the nearest vessel wall; no microbubble showed a net translation toward the nearest vessel wall. Microbubble maximum translation displacements exceeded 20 μm. Microjets with the direction of the jets identifiable were also observed; all microjets appear to have been directed away from the nearest vessel wall. These observations a...

Effect of Ultrasonic Excitation on the Microtensile Bond Strength of Glass Ionomer Cements to Dentin After Different Water Storage Times

Ultrasound in Medicine and Biology — Mon, 31 Oct 2011 04:00:00 +0100

In conclusion, ultrasound application to Ketac Molar improved its adhesion to dentin, particularly within the first 24 h after setting. Clinically, it seems that ultrasonic excitation can contribute to prevent retention loss of restoration at early stages of GIC setting reaction. (Source: Ultrasound in Medicine and Biology)

Performance Assessment of HIFU Lesion Detection by Harmonic Motion Imaging for Focused Ultrasound (HMIFU): A 3-D Finite-Element-Based Framework with Experimental Validation

Ultrasound in Medicine and Biology — Mon, 31 Oct 2011 04:00:00 +0100

In this study, a theoretical framework of HMIFU is presented, comprising a customized nonlinear wave propagation model, a finite-element (FE) analysis module and an image-formation model. The objective of this study is to develop such a framework to (1) assess the fundamental performance of HMIFU in detecting HIFU lesions based on the change in tissue apparent elasticity, i.e., the increasing Young’s modulus, and the HIFU lesion size with respect to the HIFU exposure time and (2) validate the simulation findings ex vivo. The same HMI and HMIFU parameters as in the experimental studies were used, i.e., 4.5-MHz HIFU frequency and 25 Hz AM frequency. For a lesion-to-background Young’s modulus ratio of 3, 6 and 9, the FE and estimated HMI displacement ratios were equal to 1.83, 3.69 and 5...

Follow-Up of High-Intensity Focused Ultrasound Treatment for Patients with Hepatocellular Carcinoma

Ultrasound in Medicine and Biology — Mon, 31 Oct 2011 04:00:00 +0100

In conclusion, HIFU is safe and effective for patients with hepatocellular carcinoma; HIFU can improve the survival quality of patients with HCC. (Source: Ultrasound in Medicine and Biology)

Impact of Age, Anthropometric Data and Body Composition on Calcaneal Bone Characteristics, as Measured by Quantitative Ultrasound (QUS) in an Older German Population

Ultrasound in Medicine and Biology — Mon, 31 Oct 2011 04:00:00 +0100

Abstract: The impact of fat-free mass (FFM), fat mass (FM), body mass index (BMI), body mass and body height on calcaneal bone characteristics as measured with quantitative ultrasound (QUS) was investigated in 137 women and 85 men aged 62–92 years, considering age, smoking, waist-to-hip ratio (WHR) and physical activity level (PAL). In regression analyses using various models, in women, age was a negative predictor of speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness index (SI) and smoking was a negative predictor of SOS; positive predictors of SOS, BUA, and SI were BMI, body mass and FFM. In men, smoking was a negative predictor and BMI, body mass and FFM were positive predictors of BUA and SI. In both sexes, PAL, body height, WHR and FM had no effect on QUS pa...

Validity of Preoperative Ultrasound-Guided Aspiration in the Revision of Hip Prosthesis

Ultrasound in Medicine and Biology — Mon, 31 Oct 2011 04:00:00 +0100

Abstract: Preoperative diagnosis of septic loosening hip prosthesis is often challenging. Culture test on joint samples obtained during revision surgery is the diagnostic gold standard while the role of preoperative hip aspiration is still controversial. The aims of this prospective randomized study were to compare the sensitivity, specificity and accuracy of preoperative ultrasound-guided and fluoroscopic-guided aspiration, and to identify associated laboratory parameters or scintigraphy that could help in predicting septic loosing hip prosthesis. Sixty patients affected by persistent pain after hip prosthesis randomly received fluoroscopic-guided or ultrasound-guided hip aspiration before revision surgery. The results of culture tests of joint fluid presurgically and at surgery were comp...

Sonoporation Induces Apoptosis and Cell Cycle Arrest in Human Promyelocytic Leukemia Cells

Ultrasound in Medicine and Biology — Fri, 28 Oct 2011 04:00:00 +0100

Abstract: Despite being a transient biophysical phenomenon, sonoporation is known to disturb the homeostasis of living cells. This work presents new evidence on how sonoporation may lead to antiproliferation effects including cell-cycle arrest and apoptosis through disrupting various cell signaling pathways. Our findings were obtained from sonoporation experiments conducted on HL-60 human promyelocytic leukemia cells (with 1% v/v microbubbles; 1 MHz ultrasound; 0.3 or 0.5MPa peak negative pressure; 10% duty cycle; 1 kHz pulse repetition frequency; 1 min exposure period). Membrane resealing in these sonoporated cells was first verified using scanning electron microscopy. Time-lapse flow cytometry analysis of cellular deoxyribonucleic acid (DNA) contents was then performed at four post-sonop...

ARFI Ultrasound Monitoring of Hemorrhage and Hemostasis In Vivo in Canine Von Willebrand Disease and Hemophilia

Ultrasound in Medicine and Biology — Fri, 28 Oct 2011 04:00:00 +0100

Abstract: A validated method for assessing hemostasis in vivo is critical for testing the hemostatic efficacy of therapeutic agents designed for patients with bleeding disorders such as von Willebrand disease (VWD) and hemophilia A. We hypothesize that rate of bleeding and time to hemostasis can be monitored in vivo by acoustic radiation force impulse (ARFI) ultrasound. We performed ARFI imaging following 12-gauge needle puncture of hind limb muscle encompassing an ∼2 mm vein in six normal, eight naïve hemophilia A before and after infusing canine factor VIII, three hemophilia A expressing canine factor VIIa following gene transfer, and two naïve VWD dogs. Serial data sets were processed with custom software to (1) estimate the rate of hemorrhage and (2) estimate the time of hemostas...

Effects of Phase Cancellation and Receiver Aperture Size on Broadband Ultrasonic Attenuation for Trabecular Bone In Vitro

Ultrasound in Medicine and Biology — Fri, 28 Oct 2011 04:00:00 +0100

This study uses an ultra small receiver (aperture size: 0.2 mm) in conjunction with a newly developed two-dimensional (2-D) synthetic array system to investigate the effects of phase cancellation and receiver aperture size on BUA estimations of bone tissue. In vitro ultrasound measurements were conducted on 54 trabecular bone samples (harvested from sheep femurs) in a confocal configuration with a focused transmitter and synthesized focused receivers of different aperture sizes. Phase sensitive (PS) and phase insensitive (PI) detections were performed. The results show that phase cancellation does have a significant effect on BUA. The normalized BUA (nBUA) with PS is 8.1% higher than PI nBUA while PI BUA is well correlated with PS BUA. Receiver aperture size also influences the BUA readi...

Features of In Vitro Ultrasound Biomicroscopic Imaging and Colonoscopy for Detection of Colon Tumor in Mice

Ultrasound in Medicine and Biology — Fri, 28 Oct 2011 04:00:00 +0100

Abstract: The present work tested the capability of ultrasound biomicroscopy (UBM), at 45 MHz, to provide cross-sectional images with appropriate resolution and contrast to detect tumors and determine their penetration depths on the colon of mice, Mus musculus (Linnaeus 1758), treated with carcinogen for colon tumor induction. B-mode images were obtained, in vitro, from each animal (13 treated and 4 untreated) colon opened longitudinally and immersed in saline solution at room temperature. Prior to UBM inspection, all animals were also examined by colonoscopy. The layers of normal colon identified by UBM are: mucosa (hyperechoic), muscularis mucosae (hypoechoic), submucosa (hyperechoic) and muscularis externa (hypoechoic). UBM images of colon lesions presented structures corresponding to ...

The Feasibility of Hybrid Automatic Segmentation of Axillary Lymph Nodes from a 3-D Sonogram

Ultrasound in Medicine and Biology — Fri, 28 Oct 2011 04:00:00 +0100

Abstract: The use of manual segmentation of lymph nodes, within an ultrasound image, is challenging due to operator dependency and speckle. A group of 23 healthy female volunteers consented to a short imaging session to capture a maximum of three axillary lymph nodes. A feasibility study was completed using both automatic and manual segmentation techniques to analyze a sample of 45, three-dimensional (3-D) nodal volume sets. Level-set segmentation based on geodesic active contours and shape-space learning based on a level-set segmentation approach was used to capture global node shapes. Most of the image feature based segmentation methods failed; however, a more precise automatic segmentation algorithm was obtained using a superimposed shape model. Shape model based segmentation significan...

Improving the Statistics of Quantitative Ultrasound Techniques with Deformation Compounding: An Experimental Study

Ultrasound in Medicine and Biology — Fri, 28 Oct 2011 04:00:00 +0100

Abstract: Many quantitative ultrasound (QUS) techniques are based on estimates of the radio-frequency (RF) echo signal power spectrum. Historically, reliable spectral estimates required spatial averaging over large regions-of-interest (ROIs). Spatial compounding techniques have been used to obtain robust spectral estimates for data acquired over small regions of interest. A new technique referred to as “deformation compounding” is another method for providing robust spectral estimates over smaller regions of interest. Motion tracking software is used to follow an ROI while the tissue is deformed (typically by pressing with the transducer). The deformation spatially reorganizes the scatterers so that the resulting echo signal is decorrelated. The RF echo signal power spectrum for the RO...

Active Ellipse Model and Automatic Chamber Detection in Apical Views of Echocardiography Images

Ultrasound in Medicine and Biology — Fri, 28 Oct 2011 04:00:00 +0100

Abstract: In this article, an automatic method for detection of all chambers in apical two- and four-chamber views is proposed. The method is based on four evolving ellipses with their sizes and alignments (centre point) gradually changing through iterations until they reach to the point that approximates the chamber boundaries. The interaction between the internal, external and inter-elliptic forces controls the simultaneous evolution of ellipses. Since no prior assumption of the approximate location is required with our approach, the specialists are not required to locate the centre points of chambers in apical images, making the overall segmentation fully automated. Moreover, the resultant ellipse inside a chamber could be used as the initial contour in segmentation techniques such as a...

Comparison of Echotracking and Magnetic Resonance Assessment of Abdominal Aorta Distensibility and Relationships with Pulse Wave Velocity

Ultrasound in Medicine and Biology — Fri, 28 Oct 2011 04:00:00 +0100

Abstract: Arterial distensibility can be measured either by echotracking or by nuclear magnetic resonance (MRI). Little information, however, is available on the comparison between the two methods and on the relationships between the results obtained with the two approaches and the arterial stiffness gold standard measurement, i.e., pulse wave velocity (PWV). In 28 normotensive subjects (age 33.0 ± 10.4 years, mean ± SD) we measured aortic diameter 1 cm above iliac bifurcation, aortic pulse pressure by tonometry and calculated arterial distensibility via the Reneman formulae for both methods. Aortic diameter and aortic distensibility were not superimposable and higher values were systematically detected with the MRI approach than with the ultrasound one. However, PWV showed a significan...

Does Hepatic Vein Transit Time Performed with Contrast-Enhanced Ultrasound Predict the Severity of Hepatic Fibrosis?

Ultrasound in Medicine and Biology — Fri, 28 Oct 2011 04:00:00 +0100

In this study, we attempted to validate HVTT as a noninvasive index of hepatic fibrosis. Patients were scanned using real-time, pulse-inversion mode following bolus injections of the contrast agent Definity. HVTT was correlated with the degree of fibrosis obtained from contemporaneous liver biopsy. The study population included 40 patients with chronic liver disease and five healthy volunteers. Mean HVTT correlated with histologic grade as follows: absence/minimal fibrosis (n = 18), 25.6 ± 11.8 s; moderate fibrosis (n = 17), 21.5 ± 5.9 s; and severe fibrosis (n = 8), 20.9 ± 5.5 s, (p = .615). Poor sensitivity (57%) and specificity (43%) prevent validation of the previously published HVTT threshold as a surrogate marker of hepatic fibrosis. Further work investigating the different in...

A Fast Slam Approach to Freehand 3-D Ultrasound Reconstruction for Catheter Ablation Guidance in the Left Atrium

Ultrasound in Medicine and Biology — Mon, 24 Oct 2011 04:00:00 +0100

We present a method for real-time, freehand 3D ultrasound (3D-US) reconstruction of moving anatomy, with specific application towards guiding the catheter ablation procedure in the left atrium. Using an intracardiac echo (ICE) catheter with a pose (position/orientation) sensor mounted to its tip, we continually mosaic 2D-ICE images of a left atrium phantom model to form a 3D-US volume. Our mosaicing strategy employs a probabilistic framework based on simultaneous localization and mapping (SLAM), a technique commonly used in mobile robotics for creating maps of unexplored environments. The measured ICE catheter tip pose provides an initial estimate for compounding 2D-ICE image data into the 3D-US volume. However, we simultaneously consider the overlap-consistency shared between 2D-ICE image...

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Ultrasound in Medicine and Biology — Sun, 23 Oct 2011 09:29:17 +0100

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Echoic Features as Predictors of Diagnostic Yield of Endobronchial Ultrasound-Guided Transbronchial Lung Biopsy in Peripheral Pulmonary Lesions

Ultrasound in Medicine and Biology — Sun, 23 Oct 2011 09:29:17 +0100

This study aimed to assess the feasibility of EBUS echoic features as predictors of diagnostic yield of TBLB. Four hundred and eight patients with PPLs underwent TBLB. The yields of TBLB in lesions with characteristic EBUS features were compared with those without such features. The overall diagnostic yield of TBLB was 64.2%. Lesion diameter (≥3 cm vs. (Source: Ultrasound in Medicine and Biology)

Ultrasound in Medicine and Biology — Sun, 23 Oct 2011 09:29:17 +0100

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Editorial Advisory Board

Ultrasound in Medicine and Biology — Sun, 23 Oct 2011 09:29:17 +0100

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Masthead

Ultrasound in Medicine and Biology — Sun, 23 Oct 2011 09:29:17 +0100

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The “Volumetric” Pulsatility Index as Evaluated by Spatiotemporal Imaging Correlation (STIC): A Preliminary Description of a Novel Technique, Its Application to the Endometrium and an Evaluation of Its Reproducibility

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

In this study, we describe these indices and evaluate their interobserver reliability: two static-3-D and two STIC PD datasets were acquired from 60 women and two observers (blinded analysis) evaluated vascularization index (VI), the flow index (FI) and the vascularization flow index (VFI) of standardized spherical samples of endometrium. Three new indices were determined based on maximum, minimum and mean values (vPI, vRImax-min, vS/Dmax-min) and two indices from frames subjectively defined as systole and diastole (vRIsys-dia, vS/Dsys-dia). Highest intraclass coefficient correlations (ICCs) were obtained from vPI derived from VI or VFI (0.77–0.76), followed by vRImax-min (0.72–0.72) and vS/Dmax-min (0.52–0.49). ICCs from indices based on subjectively systole and diastole or FI were ...

Simultaneous Backscatter and Attenuation Estimation Using a Least Squares Method with Constraints

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

We describe a least squares method (LSM) that fits the echo signal power spectra from a ROI to a three-parameter tissue model that simultaneously yields estimates of attenuation losses and backscatter coefficients. To test the method, tissue-mimicking phantoms with backscatter and attenuation contrast as well as uniform phantoms were scanned with linear array transducers on a Siemens S2000. Attenuation and backscatter coefficients estimated by the LSM were compared with those derived using a reference phantom method (). Results show that the LSM yields effective attenuation coefficients for uniform phantoms comparable to values derived using the reference phantom method. For layered phantoms exhibiting nonuniform backscatter, the LSM resulted in smaller attenuation estimation errors than t...

Is Low-Intensity Pulsed Ultrasound Effective for Revitalizing a Severely Necrotic Small Bone? An Experimental Rabbit Model

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

Abstract: Previously, we successfully applied a new method composed of drilling, bone marrow transplantation (BMT), external fixation and low-intensity pulsed ultrasound (LIPUS) for the clinical treatment of Kienböck’s disease. The purpose of this study was to investigate whether bone regeneration can be induced by LIPUS and/or multiple drilling and/or BMT within a severely necrotic small-bone rabbit model. Eighteen rabbits were divided into three groups (BMT, drilling and control) and LIPUS stimulation was introduced daily for 8 weeks post-transplantation. Next, 12 additional rabbits were produced for the BMT group and LIPUS stimulation was introduced daily for 4 and 12 weeks (n = 6 for each). Histopathologically, new bone formations were rarely observed in the drilling and control gr...

Precision Manufacture of Phase-Change Perfluorocarbon Droplets Using Microfluidics

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

Abstract: Liquid perfluorocarbon droplets have been of interest in the medical acoustics community for use as acoustically activated particles for tissue occlusion, imaging and therapeutics. To date, methods to produce liquid perfluorocarbon droplets typically result in a polydisperse size distribution. Because the threshold of acoustic activation is a function of diameter, there would be benefit from a monodisperse population to preserve uniformity in acoustic activation parameters. Through use of a microfluidic device with flow-focusing technology, the production of droplets of perfluoropentane with a uniform size distribution is demonstrated. Stability studies indicate that these droplets are stable in storage for at least two weeks. Acoustic studies illustrate the thresholds of vaporiz...

Properties of Ultrasonic Waves in Bovine Bone Marrow

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

Abstract: We investigated the properties of ultrasonic waves in bovine bone marrow. Six bone marrow samples were obtained from different parts (proximal, middle and distal) of the shafts of two bovine femora without destruction. The measured frequency range was 3 to 10 MHz, and the temperature range was 15 to 40°C. Both wave velocity and attenuation coefficient in bone marrow always decreased as temperature increased. The velocity ranged from 1400 to 1610 m/s and attenuation coefficient ranged from 4 to 16 dB/cm. Wave velocities in bone marrow were similar to those in water, whereas the temperature dependences were different, and the wave attenuation coefficients were much higher than those in water. The dependence of velocity on temperature changed slightly around 23–24°C, where a tra...

Estimating Axial and Lateral Strain Using a Synthetic Aperture Elastographic Imaging System

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

Abstract: Model-based elastography is an emerging technique with clinical applications in imaging vascular tissues, guiding minimally invasive therapies and diagnosing breast and prostate cancers. Its usage is limited because ultrasound can measure only the axial component of displacement with high precision. The goal of this study was to assess the effect of lateral sampling frequency, lateral beam-width and the number of active transmission elements on the quality of axial and lateral strain elastograms. Elastographic imaging was performed on gelatin-based phantoms with a modified commercial ultrasound scanner. Three groups of radio-frequency (RF) echo frames were reconstructed from fully synthetic aperture data. In the first group, all 128 transmission elements (corresponding to a later...

Impact of Nonlinear Distortion on Acoustic Radiation Force Elastography

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

Abstract: High-intensity focused ultrasound (HIFU) produces an acoustic radiation force that induces tissue displacement, which can be measured by monitoring time shifts in the backscattered signals from interrogation pulses. If the pulse occurs simultaneously with the HIFU, the arrival time of the backscatter will be biased because nonlinearity associated with the HIFU changes the local sound speed. Measurements of the pressure field using 1.1 MHz HIFU and a 7.5 MHz pulse in water exhibited a nonlinearly induced apparent displacement (NIAD) that varied with the HIFU pressure, propagation distance and the timing of the pulse relative to the HIFU. Nonlinear simulations employing the KZK equation predicted NIADs that agreed with measurements. Experiments with chicken breast demonstrated a N...

Experimental Investigation of the Effect of Stiffness, Exposure Time and Scan Direction on the Dimension of Ultrasound Histotripsy Lesions

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

This study experimentally investigated the effects of stiffness, exposure time and scan direction on the size of histotripsy-induced lesions in agar samples. A targeted region 0.45 cm wide (lateral) and 0.6 cm deep (axial) was scanned with the step sizes of 0.075 cm and 0.3 cm, respectively. The single-element spherically focused source (1.1 MHz, 6.34 cm focal length, f/1) had the peak compressional and rarefactional pressures of approximately 102 and 17 MPa. Pulses consisted of 20-cycle sine wave tone bursts with a burst period of 3 ms and exposure time of 15, 30 or 60 s. Also, both inward and outward scan direction were tested along the beam axis. The liquefied lesions generally had a larger size than the initially targeted region with larger sizes corresponding to softer agar and long...

Cavitation-Enhanced Extravasation for Drug Delivery

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

Abstract: A flow-through tissue-mimicking phantom composed of a biocompatible hydro-gel with embedded tumour cells was used to assess and optimize the role of ultrasound-induced cavitation on the extravasation of a macromolecular compound from a channel mimicking vessel in the gel, namely a non-replicating luciferase-expressing adenovirus (Ad-Luc). Using a 500 KHz therapeutic ultrasound transducer confocally aligned with a focussed passive cavitation detector, different exposure conditions and burst mode timings were selected by performing time and frequency domain analysis of passively recorded acoustic emissions, in the absence and in the presence of ultrasound contrast agents acting as cavitation nuclei. In the presence of Sonovue, maximum ultraharmonic emissions were detected for peak ...

In Vivo Gene Transfer into the Ocular Ciliary Muscle Mediated by Ultrasound and Microbubbles

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

This study aimed to assess application of ultrasound (US) combined with microbubbles (MB) to transfect the ciliary muscle of rat eyes. Reporter DNA plasmids encoding for Gaussia luciferase, β-galactosidase or the green fluorescent protein (GFP), alone or mixed with 50% Artison MB, were injected into the ciliary muscle, with or without US exposure (US set at 1 MHz, 2 W/cm2, 50% duty cycle for 2 min). Luciferase activity was measured in ocular fluids at 7 and 30 days after sonoporation. At 1 week, the US+MB treatment showed a significant increase in luminescence compared with control eyes, injected with plasmid only, with or without MB (×2.6), and, reporter proteins were localized in the ciliary muscle by histochemical analysis. At 1 month, a significant decrease in luciferase activity was...

The Feasibility of Low Mechanical Index Contrast Enhanced Ultrasound (CEUS) in Distinguishing Malignant from Benign Thoracic Lesions

Ultrasound in Medicine and Biology — Mon, 03 Oct 2011 04:00:00 +0100

Abstract: We proposed to assess the feasibility of low mechanical index (MI) contrast enhanced ultrasound (CEUS) in the characterisation of thoracic lesions. Fifty patients were prospectively examined by CEUS and images acquired on a low MI (0.17–0.24) setting following injection of SonoVue. From region-of-interest (ROI) generated signal intensity (SI) time curves, the maximum SI, bolus arrival time (BAT), time to peak intensity (TTP), wash-in slope and mean transit time (MTT) were calculated. Using the Wilcoxon rank test; parameters and threshold values for positive differentiation were determined. In addition, for the parameters that allowed positive differentiation between malignant and benign lesions receiver operator curves (ROC) were obtained. The wash-in slope, TTP and MTT (p = 0...

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Ultrasound in Medicine and Biology — Thu, 22 Sep 2011 21:04:41 +0100

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Analysis of Superimposed Ultrasonic Guided Waves in Long Bones by the Joint Approximate Diagonalization of Eigen-matrices Algorithm

Ultrasound in Medicine and Biology — Thu, 22 Sep 2011 21:04:41 +0100

Abstract: The parameters of ultrasonic guided waves (GWs) are very sensitive to mechanical and structural changes in long cortical bones. However, it is a challenge to obtain the group velocity and other parameters of GWs because of the presence of mixed multiple modes. This paper proposes a blind identification algorithm using the joint approximate diagonalization of eigen-matrices (JADE) and applies it to the separation of superimposed GWs in long bones. For the simulation case, the velocity of the single mode was calculated after separation. A strong agreement was obtained between the estimated velocity and the theoretical expectation. For the experiments in bovine long bones, by using the calculated velocity and a theoretical model, the cortical thickness (CTh) was obtained. For compar...

Combined Low-Frequency Ultrasound and Streptokinase Intravascular Destruction of Arterial Thrombi In Vivo

Ultrasound in Medicine and Biology — Thu, 22 Sep 2011 21:04:41 +0100

Abstract: To prevent a distal embolization in the course of ultrasound (US) angioplasty, we combined US thrombus disruption in peripheral artery in vivo with simultaneous administration of streptokinase (SK). Acute thrombosis was induced in the femoral arteries of 23 dogs. Two hours after thrombus formation, thrombus destruction was performed using US (36 kHz) and by a combined US+SK (75,000 U/kg) administration. The results showed that thrombi were disrupted completely by 1.5 ± 0.5 min US. A combined US+SK action resulted in activation of fibrinolysis, as indicated by the increase in the content of fibrinogen and fibrin degradation products and D-dimers by a factor of 1.5–2.0 after 120 min from start of treatment compared with the SK lysis. The duration of clot destruction did not cha...

Advanced Characterization and Refinement of Poly N-Butyl Cyanoacrylate Microbubbles for Ultrasound Imaging

Ultrasound in Medicine and Biology — Thu, 22 Sep 2011 21:04:41 +0100

Abstract: We aimed to develop and characterize poly n-butylcyanoacrylate (PBCA) microbubbles (MBs) with a narrow size distribution. MBs were synthesized by established emulsion polymerization techniques, size-isolated by centrifugation and functionalized for molecular imaging by coating their surface with streptavidin. The physical and acoustic properties of the parent solution, different-size isolated populations and functionalized MBs were measured and compared. As expected from negative zeta potentials at pH 7, cryo scanning electron microscopy showed no aggregates. In phantoms MBs were destructible at high mechanical indices and showed a frequency-dependent attenuation and backscattering. The MBs were stable in solution for more than 14 weeks and could be lyophilized without major dama...

Ultrasound in Medicine and Biology — Thu, 22 Sep 2011 21:04:41 +0100

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Editorial Advisory Board

Ultrasound in Medicine and Biology — Thu, 22 Sep 2011 21:04:41 +0100

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Masthead

Ultrasound in Medicine and Biology — Thu, 22 Sep 2011 21:04:41 +0100

(Source: Ultrasound in Medicine and Biology)

Fetal Reflex Movement in Twin Pregnancies Late in the First Trimester: 4-D Sonographic Study

Ultrasound in Medicine and Biology — Mon, 19 Sep 2011 04:00:00 +0100

The objective of this study was to evaluate reactions to touch in utero between twin fetuses using 4-D sonography late in the first trimester of pregnancy. Six monochorionic diamniotic (MD) and eight dichorionic diamniotic (DD) pregnancies were studied for 30 min with transabdominal 4-D sonography at 12–13 weeks’ gestation. The frequencies of no reaction (twins appear to touch each other but there is no clear reaction) and reaction (twins appear to touch each other and there is a clear reaction by the co-twin) movements were evaluated. There was no significant difference in the rate of reaction movements between MD (median, 33.6%) and DD (median, 33.9%) twins. The median rate of reaction movements in all 14 twins was 33.9% (range, 27 to 64.1%). Our findings suggest that the incidence o...

Ultrasound Insertion Loss of Rat Parietal Bone Appears to Be Proportional to Animal Mass at Submegahertz Frequencies

Ultrasound in Medicine and Biology — Mon, 19 Sep 2011 04:00:00 +0100

Abstract: Transcranial ultrasound therapy is an increasing area of research for noninvasive treatments in the brain including targeted drug delivery. Measurements of ultrasound transmission through rat parietal bone at five frequencies (0.268 MHz, 0.841 MHz, 1.409 MHz, 1.972 MHz and 2.53 MHz) were performed at 88 locations in 22 ex vivo rat skullcaps (Wistar) using a fiber-optic hydrophone system. At submegahertz frequencies, the skull insertion loss was found to be proportional to animal mass, while at higher frequencies this trend was lost. Maps of the transverse pressure profile of the transducer before and after skull insertion showed increased distortion effects at higher frequencies. Parietal bone thickness was measured and was found to increase with increasing body mass. Additional...

Bias Observed in Time-of-Flight Shear Wave Speed Measurements Using Radiation Force of a Focused Ultrasound Beam

Ultrasound in Medicine and Biology — Mon, 19 Sep 2011 04:00:00 +0100

This study shows that shear wave speed measurements with such methods can be transducer, depth and lateral tracking range dependent. Three homogeneous phantoms with different stiffness were studied using curvilinear and linear array transducer. Shear wave speed measurements were made at different depths, using different aperture sizes for push and at different lateral distance ranges from the push beam. The curvilinear transducer shows a relatively large measurement bias that is depth dependent. The possible causes of the bias and options for correction are discussed. These bias errors must be taken into account to provide accurate and precise time-of-flight shear wave speed measurements for clinical use. (Source: Ultrasound in Medicine and Biology)

Vascularization of Three-Dimensional Collagen Hydrogels Using Ultrasound Standing Wave Fields

Ultrasound in Medicine and Biology — Mon, 19 Sep 2011 04:00:00 +0100

In this study, we utilized an application of ultrasound standing wave field (USWF) technology to vascularize 3-D, collagen-based hydrogels in vitro. Acoustic radiation forces associated with USWF were used to noninvasively organize human endothelial cells into distinct, multicellular planar bands within 3-D collagen gels. The formation and maturation of capillary-like endothelial cell sprouts were monitored over time and compared with sham-exposed collagen constructs, which were characterized by a homogeneous cell distribution. USWF-induced cell banding accelerated the formation and elongation of capillary-like sprouts, promoted collagen fiber alignment and resulted in the maturation of endothelial cell sprouts into lumen-containing, anastomosing networks found throughout the entire volu...

The Preparation of a New Self-Made Microbubble-Loading Urokinase and Its Thrombolysis Combined with Low-Frequency Ultrasound In Vitro

Ultrasound in Medicine and Biology — Mon, 19 Sep 2011 04:00:00 +0100

In conclusion, the physiochemical properties of these self-made uPA-MBs are suitable for intravenous administration but 1 uPA-MB and 5 uPA-MBs are better than 10 uPA-MBs. uPA-MBs combined with US can decrease the in vitro dosage of uPA for thrombolysis. (Source: Ultrasound in Medicine and Biology)

Assessment of Skeletal Status by Quantitative Ultrasound at the Hand Phalanges in Children with Bronchial Asthma—A Pilot Study

Ultrasound in Medicine and Biology — Mon, 19 Sep 2011 04:00:00 +0100

In conclusion, the skeletal status in asthmatic children, assessed by quantitative ultrasound, shows no difference in comparison with healthy children. Nonetheless, special caution is necessary in case of long-term corticosteroid therapy, in which a slightly negative influence of treatment on the skeleton cannot be excluded. (Source: Ultrasound in Medicine and Biology)

Comparative Examination of Human Proximal Tibiae In Vitro by Ultrasonic Guided Waves and pQCT

Ultrasound in Medicine and Biology — Mon, 19 Sep 2011 04:00:00 +0100

In this study, six human proximal tibiae in vitro were examined to test the efficacy of an ultrasonic method based on guided waves. Peripheral quantitative computed tomography (pQCT) was used as the comparative reference modality. The guided wave velocity (cF) was derived from two-dimensional (2-D) spatial-temporal waveform profiles formed by multiple ultrasonic signals acquired along the bones at 100 kHz frequency and passed wavelet processing. The ultrasonic profiles from the examined bones were ranged according to pQCT measurements of cortical thickness (CTh), and cortical bone mineral density (CBMD). Strong correlations between cF and CTh (rS = 0.83, p < 0.0001) and CBMD (rS = 0.88, p < 0.0001) resulted. The study confirmed a potential for guided waves to assess atrophic changes of ...

A Novel Three-Dimensional Endoscopic Ultrasound Technique for the Freehand Examination of the Oesophagus

Ultrasound in Medicine and Biology — Mon, 19 Sep 2011 04:00:00 +0100

This study details the development and evaluation of a freehand radial three-dimensional endoscopic ultrasound (3D-EUS) technique for use in the upper gastro-intestinal tract. It comprised of a commercial EUS system, a custom acquisition system to simultaneous acquire radial B-mode images and corresponding incremental changes in position of the scope as it was withdrawn and a custom 3D-EUS package written in Matlab™, to reconstruct and analyse the volume. This technique was evaluated using an EUS phantom with embedded objects of known dimensions and volumes and with clinical images acquired during routine cancer staging. For the phantom measurements, average Z-dimensional error was (Source: Ultrasound in Medicine and Biology)

“Synthetic” Comets: A New Look at Lung Sonography

Ultrasound in Medicine and Biology — Mon, 19 Sep 2011 04:00:00 +0100

Abstract: Ultrasound interstitial syndrome is an echographic pattern of the lung characterized by the presence of multiple acoustic artifacts called “comets” or B-lines. It correlates to increase in extravascular lung water and to interstitial lung disease. From the physical and genetic point of view, the characteristics and the entity of this correlation have not yet been studied. The purpose of this study was to extrapolate past observations and demonstrate how comets or B-lines are artifactual images whose formation is linked to ultrasound interactions on discretely aerated tissues of variable density. Echographic comets were studied by scanning a wet synthetic, partially aerated polyurethane sponge (phantom). Density of the phantom in different drying phases was measured and correl...

Comparison of Scanning Acoustic Microscopy and Histology Images in Characterizing Surface Irregularities Among Engineered Human Oral Mucosal Tissues

Ultrasound in Medicine and Biology — Fri, 26 Aug 2011 04:00:00 +0100

Abstract: Acoustic microscopy was used to monitor an ex vivo produced oral mucosal equivalent (EVPOME) developed on acellular cadaveric dermis (AlloDerm®). As seeded cells adhered and grew, they filled in and smoothed out the surface irregularities, followed by the production of a keratinized protective outermost layer. If noninvasive in vitro ultrasonic monitoring of these cellular changes could be developed, then tissue cultivation could be adjusted in-process to account for biologic variations in the development of these stratified cell layers. Cultured keratinocytes (from freshly obtained oral mucosa) were harvested and seeded onto AlloDerm® coated with human type IV collagen and cultured 11 days. EVPOMEs were imaged on the 11th day post-seeding using a scanning acoustic microscope...

A Single-Ensemble Clutter Rejection Method Based on the Analytic Geometry for Ultrasound Color Flow Imaging

Ultrasound in Medicine and Biology — Mon, 22 Aug 2011 04:00:00 +0100

This article proposes a novel clutter rejection method called the single-ensemble geometry filter (SGF), which is derived from an analytic geometry perspective. If the transmitted pulse number M equals two, the clutter component distribution on a two-dimensional (2-D) plane will be similar to a tilted ellipse. Therefore, the direction of the major axis of the ellipse can be used as the first principal component of the autocorrelation matrix estimated from multiple ensembles. Then the algorithm is generalized from 2-D to a higher dimensional space by using linear algebra representations of the ellipse. Comparisons have been made with the high-pass filter (HPF), the Hankel-singular value decomposition (SVD) filter and the recursive eigen-decomposition (RED) method using both simulated and hu...

Imaging-Histologic Discordance After Sonographically Guided Percutaneous Breast Biopsy: A Prospective Observational Study

Ultrasound in Medicine and Biology — Mon, 22 Aug 2011 04:00:00 +0100

The objective of this study was to determine the frequency of imaging-histologic discordance and to compare the frequency of carcinoma between concordant and discordant lesions in sonographically (US)-guided 14-gauge core needle biopsies (CNBs). From January 2005 to December 2006, we performed US-guided 14-gauge automated CNB on 3339 breast lesions and obtained benign results in 2194 cases. Five radiologists prospectively reviewed the pathologic reports in conjunction with the imaging. We included a total of 1588 lesions that were either excised (n = 658) or followed up for at least 2 years (n = 930) after CNB. We evaluated the rate of discordance and the clinical findings for both discordant and concordant lesions. We also analyzed the clinical and imaging differences between the upgrad...

Dual-Mode IVUS Transducer for Image-Guided Brain Therapy: Preliminary Experiments

Ultrasound in Medicine and Biology — Mon, 22 Aug 2011 04:00:00 +0100

In this study, we investigated the feasibility of using 3.5-Fr intravascular ultrasound (IVUS) catheters for minimally-invasive, image-guided hyperthermia treatment of tumors in the brain. Feasibility was demonstrated by: (1) retro-fitting a commercial 3.5-Fr IVUS catheter with a 5 × 0.5 × 0.22 mm PZT-4 transducer for 9-MHz imaging and (2) testing an identical transducer for therapy potential with 3.3-MHz continuous-wave excitation. The imaging transducer was compared with a 9-Fr, 9-MHz ICE catheter when visualizing the post-mortem ovine brain and was also used to attempt vascular access to an in vivo porcine brain. A net average electrical power input of 700 mW was applied to the therapy transducer, producing a temperature rise of +13.5°C at a depth of 1.5 mm in live brain tumor ti...

A Novel Method for More Accurately Mapping the Surface Temperature of Ultrasonic Transducers

Ultrasound in Medicine and Biology — Mon, 22 Aug 2011 04:00:00 +0100

Abstract: This paper introduces a novel method for measuring the surface temperature of ultrasound transducer membranes and compares it with two standard measurement techniques. The surface temperature rise was measured as defined in the IEC Standard 60601-2-37. The measurement techniques were (i) thermocouple, (ii) thermal camera and (iii) novel infra-red (IR) “micro-sensor.” Peak transducer surface measurements taken with the thermocouple and thermal camera were −3.7 ± 0.7 (95% CI)°C and −4.3 ± 1.8 (95% CI)°C, respectively, within the limits of the IEC Standard. Measurements taken with the novel IR micro-sensor exceeded these limits by 3.3 ± 0.9 (95% CI)°C. The ambiguity between our novel method and the standard techniques could have direct patient safety implications be...

Extracorporeal Shock Wave Therapy in Pillar Pain After Carpal Tunnel Release: A Preliminary Study

Ultrasound in Medicine and Biology — Mon, 22 Aug 2011 04:00:00 +0100

Abstract: “Pillar pain” is a relatively frequent complication after surgical release of the median nerve at the wrist. Its etiology still remains unknown although several studies highlight a neurogenic inflammation as a possible cause. Pillar pain treatment usually includes rest, bracing and physiotherapy, although a significant number of patients still complain of painful symptoms two or even three years after surgery. The aim of this study was to investigate the efficacy of low-energy, flux density–focused extracorporeal shock wave therapy (ESWT) in the treatment of pillar pain. We treated 40 consecutive patients with ESWT who had pillar pain for at least six months after carpal tunnel release surgery, and to our knowledge, this is the first study that describes the use of ESWT for...

Ultrasound-Guided Interventional Therapy for Recurrent Ovarian Chocolate Cysts

Ultrasound in Medicine and Biology — Mon, 22 Aug 2011 04:00:00 +0100

Abstract: The aim of this study was to determine the effectiveness of ultrasound-guided interventional therapy in the treatment of postoperative recurrent chocolate cysts. The 198 patients enrolled in this study were divided into three groups. In group 1, the saline washing group, the cavity of the cyst was washed thoroughly with warm saline. In group 2, the ethanol short-time retention group, after washing with saline, the cyst was injected with 95% ethanol with a volume of half of the fluid aspirated from the cyst. Ten minutes later, the rest of the ethanol was aspirated. In group 3, the ethanol retention group, the procedures were the same as with the ethanol short-time retention group, except that 95% of the ethanol was retained in the cyst. An ultrasound examination was performed in t...

Intravascular Ultrasound Area Strain Imaging Used to Characterize Tissue Components and Assess Vulnerability of Atherosclerotic Plaques in a Rabbit Model

Ultrasound in Medicine and Biology — Mon, 22 Aug 2011 04:00:00 +0100

Abstract: The purpose of this study was to investigate the association of area strain and tissue components and vulnerability of atherosclerotic plaques in a rabbit model. Forty purebred New Zealand rabbits underwent balloon-induced abdominal aorta endothelium injury, then a high-cholesterol diet for 24 weeks. Intravascular ultrasound (IVUS) images of abdominal aortas were acquired in situ and two consecutive frames near the end-diastole were used to construct an IVUS elastogram. Histologic slices matched with corresponding IVUS images were stained for fatty and collagen components, smooth muscle cells (SMCs) and macrophages. Regions-of-interest (ROIs) in plaques were classified as fibrous, fibro-fatty or fatty according to histologic study. Vulnerability indexes of ROIs were calculated as...

The Three-Vessel View in the Fetal Mediastinum in the Diagnosis of Interrupted Aortic Arch

Ultrasound in Medicine and Biology — Tue, 16 Aug 2011 04:00:00 +0100

Abstract: Interruption of the aortic arch (IAA) is difficult to detect and diagnose in utero. However, prenatal diagnosis may be beneficial because IAA is rapidly fatal (median age, 10 d) if left uncorrected. Our objective was to review the direct and indirect echocardiographic markers associated with IAA, focusing on the importance of the three-vessel view (3VV), which is obtained during routine ultrasound examination to rule out malformations. We analyzed the fetal echocardiograms of nine fetuses and compared them with 56 normal controls. In each fetus, there was a large discrepancy between the diameter of the larger, dilated pulmonary artery (PA) and smaller, narrow aortic arch (Ao). The calculated ratio of PA/Ao in fetuses with IAA was 2.6 ± 0.4 compared with 1.1 ± 0.09 in normal con...

Ultrasound-Potentiated Salicylic Acid–Induced Physiological Effects and Production of Taxol in Hazelnut (Corylus Avellana L.) Cell Culture

Ultrasound in Medicine and Biology — Thu, 11 Aug 2011 04:00:00 +0100

Abstract: Effects of ultrasound (US), salicylic acid (SA) and their combined use on the growth and secondary metabolite production of suspension-cultured Corylus avellana cells were investigated. The cultures were treated with US (40 kHz) for short periods of time (2, 3, 5 and 10 min) and SA (25 and 50 mg L−1). Results showed that although phenolic content of the cells was significantly increased under exposure to treatments, flavonoids content significantly decreased. Taxol biosynthesis was improved by all treatments. US exposure increased the extracellular, cell-associated and total taxol yield three-, 1.6-, and two-fold compared with that of the control, respectively. SA at all levels was more effective than US in stimulating cell-associated and total taxol production. Combined treatm...

Assessing the Viscoelastic Properties of Thrombus Using a Solid-Sphere-Based Instantaneous Force Approach

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

This study assessed the feasibility of using a novel acoustic method to assess the viscoelastic properties of blood clots. This method is based on monitoring the motion of a solid sphere in a blood clot induced by an applied instantaneous force. Experiments were performed in which a solid sphere was displaced by a 1 MHz single-element focused transducer, with a 20 MHz single-element focused transducer used to track this displacement. The spatiotemporal behavior of the sphere displacement was used to determine the viscoelastic properties of the clot. The experimental system was calibrated by measuring the viscoelastic modulus of gelatin using different types of solid spheres embedded in the phantoms and, then, the shear modulus and viscosity of porcine blood clots with hematocrits of 0% (pl...

Variance of Speed of Sound and Correlation with Acoustic Impedance in Canine Corneas

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

Abstract: The clinical standard for measuring corneal thickness is ultrasound pachymetry that assumes a constant speed of sound. The purpose of this study was to examine the variance of speed of sound and its relationship with acoustic impedance in healthy eyes of canines with a large age span. Corneal speed of sound and acoustic impedance were measured in 34 canine eyes at room temperature (21 ± 1°C). The mean speed of sound was 1577 ± 10 m/s ranging from 1553 to 1594 m/s. There was a strong correlation between speed of sound and acoustic impedance (R = 0.84, p < 0.001). Corneal speed of sound had a small variance in healthy canines over 1-year-old, but was significantly lower in younger canines suggesting an age effect. The strong correlation between corneal speed of sound and acoust...

Automatic Adaptive Parameterization in Local Phase Feature-Based Bone Segmentation in Ultrasound

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

This article presents a novel method for contextual parameter selection that autonomously adapts to image content. Our technique automatically selects the scale, bandwidth and orientation parameters of Log-Gabor filters for optimizing local phase symmetry. The proposed approach incorporates principle curvature computed from the Hessian matrix and directional filter banks in a phase scale-space framework. Evaluations performed on carefully designed in vitro experiments demonstrate 35% improvement in accuracy of bone surface localization compared with empirically-set parameterization results. Results from a pilot in vivo study on human subjects, scanned in the operating room, show similar improvements. (Source: Ultrasound in Medicine and Biology)

Targeted Long-Term Venous Occlusion Using Pulsed High-Intensity Focused Ultrasound Combined with a Pro-Inflammatory Agent

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

In this study, we investigated a new potential method for inducing long-term vascular occlusion by targeting segments of a rabbit’s auricular vein in vivo with low-duty-cycle, high-peak-rarefaction pressure (9 MPa), pulsed high-intensity focused ultrasound in the presence of intravenously administered ultrasound microbubbles followed by local injection of fibrinogen and a pro-inflammatory agent (ethanol, cyanoacrylate or morrhuate sodium). The novel method introduced in this study resulted in acute and long-term complete vascular occlusions when injecting a pro-inflammatory agent with fibrinogen. Future investigation and translational studies are needed to assess its clinical applicability. (Source: Ultrasound in Medicine and Biology)

Effects of Ultrasound on Osteotomy Healing in a Rabbit Fracture Model

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

This study investigated the effects of ultrasound (US) at different frequencies on fracture healing over a three-week period in a rabbit fibular fracture model. Forty-five adult New Zealand White rabbits were divided into five groups: a control group and four groups treated with US frequencies of 0.5, 1.0, 1.5 and 2.0 MHz (0.5 W/cm2, 200-μs burst, pulsed 1:4). After anesthesia, transverse osteotomy was performed on the fibula bone. This was followed by intravital staining and fluorescence microscopic examination of new bone formation and biomechanical tests of torsional stiffness at the osteotomy site. Results showed that total new bone formation and torsional stiffness of the fibula were greater in all US-treated groups than in the control group. No significant difference was found betwe...

Treatment of Rabbit Liver Cancer In Vivo Using Miniaturized Image-Ablate Ultrasound Arrays

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

Abstract: In the preclinical studies reported here, VX2 cancer within rabbit liver has been treated by bulk ultrasound ablation employing miniaturized image-ablate arrays. Array probes were constructed with 32 elements in a 2.3 × 20 mm2 aperture, packaged within a 3.1 mm stainless steel tube with a cooling and coupling balloon for in vivo use. The probes were measured capable of 50% fractional bandwidth for pulse-echo imaging (center frequency 4.4 MHz) with >110 W/cm2 surface intensity available at sonication frequencies 3.5 and 4.8 MHz. B-scan imaging performance of the arrays was measured to be comparable to larger diagnostic linear arrays, although nearfield image quality was reduced by ringdown artifacts. A series of in vivo ablation procedures was performed using an unfocused 32-e...

Ultrasonographic Assessment of Growth and Estimation of Birthweight in Late Gestation Fetal Sheep

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

In conclusion, AC and RV are parameters of choice for assessment of late-gestation ovine fetal growth and can be used to estimate fetal weight with similar accuracy to human fetuses. (Source: Ultrasound in Medicine and Biology)

The Lognormal Perfusion Model for Disruption Replenishment Measurements of Blood Flow: In Vivo Validation

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

In this study, the lognormal perfusion model was validated using an exposed in vivo rabbit kidney model. Compared against an implanted transit time flow meter, longitudinal relative flow measurement was (×3) less variable and correlated better when quantification was performed with the lognormal perfusion model (Spearman r = 0.90, 95% confidence interval [CI] = 0.05) vs. the prevailing mono-exponential model (Spearman r = 0.54, 95% CI = 0.18). Disruption-replenishment measurements using the lognormal perfusion model were reproducible in vivo to within 12%. (Source: Ultrasound in Medicine and Biology)

Simultaneous Ultrasound Assessment of Brachial Artery Shear Stimulus and Flow-Mediated Dilation During Reactive Hyperemia

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

This article describes an experimental approach to simultaneously measure the wall shear rate (WSR) and the diameter variations, through multigate spectral Doppler and B-mode image processing, respectively. By using an ultrasound advanced open platform (ULA-OP), experimental results from the brachial arteries of 15 presumed healthy volunteers have been obtained. The mean increments during reflow against baseline were 105% ± 22% for the peak WSR and 8% ± 3% for the FMD. The mean time interval between the WSR peak and the beginning of plateau of diameter waveform was 38 ± 8 s. The results confirm that in young healthy subjects the postischemic vasodilation of brachial artery is largely correlated to the WSR increase. (Source: Ultrasound in Medicine and Biology)

Transcranial Doppler Studies on Cerebral Autoregulation Suggest Prolonged Cerebral Vasoconstriction in a Subgroup of Patients with Orthostatic Intolerance

Ultrasound in Medicine and Biology — Mon, 08 Aug 2011 04:00:00 +0100

Abstract: We studied the cerebral autoregulation in a subgroup of patients with orthostatic intolerance, who exhibited excessively decreased middle cerebral artery flow velocity (MCAFV) on transcranial Doppler sonography (TCD) during head-up tilt (HUT) test but without orthostatic hypotension or postural tachycardia. Twenty patients and 20 age- and sex-matched controls underwent Valsalva maneuver (VM) and HUT test with simultaneous monitoring of MCAFV by TCD and blood pressure, heart rate recordings. The pulsatility index (PI), cerebrovascular resistance (CVR) and autoregulatory indices were calculated. During HUT, patients had marked MCAFV reduction (−29.0 ± 5.25% vs. −8.01 ± 4.37%), paradoxically decreased PI (0.68 ± 0.17 vs. 0.96 ± 0.28) but increased CVR (45.7 ± 16.7% vs. 14.3...

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Calendar

Effect of Surface Architecture on In Vivo Ultrasound Contrast Persistence of Targeted Size-Selected Microbubbles

New Microembolus Size Estimator for Peripheral Blood Vessels

High-Frequency Ultrasound in the Evaluation of Cerebral Intraventricular Haemorrhage in Preterm Rabbit Pups

Contents

Editorial Advisory Board

Masthead

A Texture Matching Method Considering Geometric Transformations in Noninvasive Ultrasonic Measurement of Arterial Elasticity

A New Nonlinear Parameter in the Developed Strain-to-Applied Strain of the Soft Tissues and Its Application in Ultrasound Elasticity Imaging

Microbubble Contrast Imaging of the Cardiovascular System of the Chick Embyro

Effect of Ultrasound Parameters on the Release of Liposomal Calcein

Simultaneous Measurement of Red Blood Cell Aggregation and Whole Blood Coagulation Using High-Frequency Ultrasound

Differentiation of Benign Periablational Enhancement from Residual Tumor Following Radio-Frequency Ablation Using Contrast-Enhanced Ultrasonography in a Rat Subcutaneous Colon Cancer Model

High-Frequency Ultrasound for In Vivo Measurement of Colon Wall Thickness in Mice

Real-Time Tissue Elastography for the Diagnosis of Lymph Node Metastasis in Oral Squamous Cell Carcinoma

Ultrasound Is a Reliable Measure of Muscle Thickness in Acute Stroke Patients, for Some, but Not All Anatomical Sites: A Study of the Intra-Rater Reliability of Muscle Thickness Measures in Acute Stroke Patients

The Effect of Vasospasm on Cerebral Perfusion: A Colour Duplex Study of the Extra- and Intracranial Cerebral Arteries

Clinical Integrated Ultrasound of the Thorax Including Causes of Shock in Nontraumatic Critically Ill Patients. A Practical Approach

Fetal Echocardiography, 2nd Edition

The Relation Between Carotid Plaque Echogenicity and Oxidative Stress Marker 8-iso-Prostaglandin F2α

Ultrasound Markers that Describe Plaques Are More Sensitive than Mean Intima-Media Thickness in Patients with Familial Hypercholesterolemia

Ultrasonographic Evidence of Intra-Abdominal Umbilical Vein Dilatation: Is It a True Varix?

Measurement of Articular Cartilage Thickness Using a Three-Dimensional Image Reconstructed from B-Mode Ultrasonography Mechanical Scans Feasibility Study by Comparison with MRI-Derived Data

Transvaginal 3-D Power Doppler Ultrasound Evaluation of the Fetal Brain at 10–13 Weeks’ Gestation

Heterogeneity of Microbubble Accumulation: A Novel Approach to Discriminate Between Well-Differentiated Hepatocellular Carcinomas and Regenerative Nodules

Detection of Hepatocellular Carcinoma and Liver Metastases with BR14: A Multicenter Phase IIA Study

Calendar

Left Ventricular Assist Devices: Physiologic Assessment using Echocardiography for Management and Optimization

Evaluation of the Accuracy of Articular Cartilage Thickness Measurement by B-Mode Ultrasonography with Conventional Imaging and Real-Time Spatial Compound Ultrasonography Imaging

Speckle Noise Reduction in Ultrasound Biomedical B-Scan Images Using Discrete Topological Derivative

Completely Automated Segmentation Approach for Breast Ultrasound Images Using Multiple-Domain Features

Low-Intensity Pulsed Ultrasound (LIPUS) May Prevent Polyethylene Induced Periprosthetic Osteolysis In Vivo

Color Doppler Ultrasonography Evaluation for Chemotherapy Treatment Response of Osteogenic Sarcoma

Mapping of Superficial Extremity Veins: Normal Diameters and Trends in a Vascular Patient-Population

Evaluation of Color Doppler Ultrasonography in Diagnosing Hepatic Alveolar Echinococcosis

Contents

Editorial Advisory Board

Masthead

Ultrasonography in Vascular Diagnosis. A Therapy-Oriented Textbook and Atlas

Integration of Crawling Waves in an Ultrasound Imaging System. Part 2: Signal Processing and Applications

Integration of Crawling Waves in an Ultrasound Imaging System. Part 1: System and Design Considerations

Measurement of Mechanical Properties with Respect to Gap Healing in a Rabbit Osteotomy Model Using Echo Tracking

Disruption of Tumor Neovasculature by Microbubble Enhanced Ultrasound: A Potential New Physical Therapy of Anti-Angiogenesis

Ultrasound Enhanced Prehospital Thrombolysis Using Microbubbles Infusion in Patients with Acute ST Elevation Myocardial Infarction: Pilot of the Sonolysis Study

Changes in Carotid Plaque Echogenicity with Time Since the Stroke Onset: An Early Marker of Plaque Remodeling?

Assessment of Carotid Elasticity During Exercise: A Reproducibility Study

In Vivo Time Harmonic Elastography of the Human Heart

Transvaginal Ultrasound-Guided Embryo Aspiration Plus Local Administration of Low-Dose Methotrexate for Caesarean Scar Pregnancy

Shear Wave Elasticity Imaging of Cervical Lymph Nodes

Shear Wave Dispersion Measures Liver Steatosis

Calendar

Representativeness of Nodal Sampling With Endobronchial Ultrasonography in Non–Small-Cell Lung Cancer Staging

Real-Time Virtual Sonography, A Coordinated Sonography and MRI System that Uses Magnetic Navigation, Improves the Sonographic Identification of Enhancing Lesions on Breast MRI

Contents

Editorial Advisory Board

Masthead

Subject Index to Volume 37

Calendar

Analysis of Ultrasound Fields in Cell Culture Wells for In Vitro Ultrasound Therapy Experiments

Changes in Ultrasonic Properties of Liver Tissue In Vitro During Heating-Cooling Cycle Concomitant with Thermal Coagulation

In Memoriam: Wesley Nyborg (1917–2011)

Contents

Editorial Advisory Board

Masthead

A Pilot Study to Assess Markers of Renal Damage in the Rodent Kidney After Exposure to 7 MHz Ultrasound Pulse Sequences Designed to Cause Microbubble Translation and Disruption

First Application of Axial Speed of Sound to Follow Up Injured Equine Tendons

Thermally-Mediated Ultrasound-Induced Contraction of Equine Muscular Arteries In Vitro and an Investigation of the Associated Cellular Mechanisms

Comparison of Real-Time In Vivo Spectral and Vector Velocity Estimation

Automatic Bone Localization and Fracture Detection from Volumetric Ultrasound Images Using 3-D Local Phase Features

Effect of a Novel Segmentation Algorithm on Radiologists’ Diagnosis of Breast Masses Using Ultrasound Imaging

Activation of Microbubbles by Short-Pulsed Ultrasound Enhances the Cytotoxic Effect of Cis-Diamminedichloroplatinum (II) in a Canine Thyroid Adenocarcinoma Cell Line In Vitro

Impact of Propagating and Standing Waves on Cavitation Appearance

Vascular Effects of Microbubble-Enhanced, Pulsed, Focused Ultrasound on Liver Blood Perfusion

Intense Focused Ultrasound Can Reliably Induce Sensations in Human Test Subjects in a Manner Correlated With the Density of Their Mechanoreceptors

Propagation Characteristics of Photomechanical Waves and Their Application to Gene Delivery into Deep Tissue

Would Gestational Age and Presence of Brain Anomalies Affect Interobserver Reliability of Fetal Head Biometry? Using Off-Line Analysis of 3-D Dataset

Acoustic Radiation Force Impulse Imaging of Human Prostates: Initial In Vivo Demonstration

Ultrasound Assessment of the Rotator Cuff Cable: Comparison Between Young and Elderly Asymptomatic Volunteers and Interobserver Reproducibility

Ultrasound Measurement of Subcutaneous Adipose Tissue Thickness Accurately Predicts Total and Segmental Body Fat of Young Adults