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(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - November 16, 2009 Category: Radiology Source Type: journals

Editorial BoardEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - November 16, 2009 Category: Radiology Source Type: journals

ContentsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - October 15, 2009 Category: Radiology Source Type: journals

Editorial BoardEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - October 15, 2009 Category: Radiology Source Type: journals

3D sensitivity encoded ellipsoidal MR spectroscopic imaging of gliomas at 3TEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Purpose: The goal of this study was to implement time efficient data acquisition and reconstruction methods for 3D magnetic resonance spectroscopic imaging (MRSI) of gliomas at a field strength of 3T using parallel imaging techniques.Methods: The point spread functions, signal to noise ratio (SNR), spatial resolution, metabolite intensity distributions and Cho:NAA ratio of 3D ellipsoidal, 3D sensitivity encoding (SENSE) and 3D combined ellipsoidal and SENSE (e-SENSE) k-space sampling schemes were compared with conventional k-space data acquisition methods.Results: The 3D SENSE and e-SENSE methods resulted in simi...
Source: Magnetic Resonance Imaging - September 21, 2009 Category: Radiology Authors: Esin Ozturk-Isik, Albert P. Chen, Jason C. Crane, Wei Bian, Duan Xu, Eric T. Han, Susan M. Chang, Daniel B. Vigneron, Sarah J. Nelson Tags: Original Contributions Source Type: journals

Feasibility of post-gadolinium three-dimensional gradient-echo sequence to evaluate the pulmonary arterial vasculatureEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusion: Post-gadolinium 3D-GE sequence may be an alternative technique for the visualization of central, lobar and segmental arteries, and may diagnose PE and other pathologies involving the chest in different patient populations. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - September 21, 2009 Category: Radiology Authors: Ersan Altun, Vasco Heredia, Ertan Pamuklar, Mauricio Zapparoli, Richard C. Semelka Tags: Original Contributions Source Type: journals

Neural activity-induced modulation of BOLD poststimulus undershoot independent of the positive signalEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, it was investigated whether the so-called poststimulus BOLD signal undershoot is solely a passive vascular effect or actively induced by neural responses. Prolonged static and flickering black-white checkerboard stimulation with isoluminant grey screen as baseline condition were employed on eight human subjects. Within the same region of interest, the positive BOLD time courses for static and flickering stimuli were identical over the entire stimulus duration. In contrast, the static stimuli exhibited no poststimulus BOLD signal undershoot, whereas the flickering stimuli caused a strong BOLD poststimulus und...
Source: Magnetic Resonance Imaging - September 16, 2009 Category: Radiology Authors: Sepideh Sadaghiani, Kâmil Uğurbil, Kâmil Uludağ Tags: Research Articles Source Type: journals

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(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - September 16, 2009 Category: Radiology Source Type: journals

Topics/Lecturers pageEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - September 16, 2009 Category: Radiology Source Type: journals

Special issue title pageEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - September 16, 2009 Category: Radiology Source Type: journals

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(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - September 16, 2009 Category: Radiology Source Type: journals

PrefaceEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Each meeting in Erice is a step forward on the way to a full comprehension of the functional organization of the human brain. Fundamental advancements in brain investigation depend on the discovery of new physical ways and on the invention of new modalities which will allow the observation of the physiological and metabolic processes occurring during brain activity. Such processes have time scales which range from milliseconds to several seconds, while some of the most successful modalities, such as fMRI or MRS, are rather slow. It is then more and more important on one hand to find new and efficient techniques, and on the...
Source: Magnetic Resonance Imaging - August 24, 2009 Category: Radiology Authors: Bruno Maraviglia Tags: Preface Source Type: journals

Quantitative permeability magnetic resonance imaging in acute ischemic stroke: how long do we need to scan?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Blood–brain barrier (BBB) permeability estimation with dynamic contrast-enhanced MRI (DCE-MRI) has shown significant potential for predicting hemorrhagic transformation (HT) in patients presenting with acute ischemic stroke (AIS). In this work, the effects of scan duration on quantitative BBB permeability estimates (KPS) were investigated. Data from eight patients (three with HT) aged 37–93 years old were retrospectively studied by directly calculating the standard deviation of KPS as a function of scan time. The uncertainty in KPS was reduced only slightly for a scan time of 3 min and 30 s (4% reduction in P...
Source: Magnetic Resonance Imaging - August 19, 2009 Category: Radiology Authors: Logi Vidarsson, Rebecca E. Thornhill, Fang Liu, David J. Mikulis, Andrea Kassner Tags: Original Contributions Source Type: journals

Images-based suppression of unwanted global signals in resting-state functional connectivity studiesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Correlated fluctuations of low-frequency fMRI signal have been suggested to reflect functional connectivity among the involved regions. However, large-scale correlations are especially prone to spurious global modulations induced by coherent physiological noise. Cardiac and respiratory rhythms are the most offending component, and a tailored preprocessing is needed in order to reduce their impact. Several approaches have been proposed in the literature, generally based on the use of physiological recordings acquired during the functional scans, or on the extraction of the relevant information directly from the im...
Source: Magnetic Resonance Imaging - August 19, 2009 Category: Radiology Authors: Federico Giove, Tommaso Gili, Vittorio Iacovella, Emiliano Macaluso, Bruno Maraviglia Tags: Research Articles Source Type: journals

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(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - August 18, 2009 Category: Radiology Source Type: journals

Editorial BoardEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - August 18, 2009 Category: Radiology Source Type: journals

Steady-state activation in somatosensory cortex after changes in stimulus rate during median nerve stimulationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Passive electrical stimulation activates various human somatosensory cortical systems including the contralateral primary somatosensory area (SI), bilateral secondary somatosensory area (SII) and bilateral insula. The effect of stimulation frequency on blood oxygenation level-dependent (BOLD) activity remains unclear. We acquired 3-T functional magnetic resonance imaging (fMRI) in eight healthy volunteers during electrical median nerve stimulation at frequencies of 1, 3 and 10 Hz. During stimulation BOLD signal changes showed activation in the contralateral SI, bilateral SII and bilateral insula. Results of fMRI ...
Source: Magnetic Resonance Imaging - July 22, 2009 Category: Radiology Authors: Paolo Manganotti, Emanuela Formaggio, Silvia Francesca Storti, Mirko Avesani, Michele Acler, Francesco Sala, Stefano Magon, Giada Zoccatelli, Francesca Pizzini, Franco Alessandrini, Antonio Fiaschi, Alberto Beltramello Tags: Original Contributions Source Type: journals

Functional magnetic resonance imaging brain activation directly from k-spaceEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: In functional magnetic resonance imaging (fMRI), the process of determining statistically significant brain activation is commonly performed in terms of voxel time series measurements after image reconstruction and magnitude-only time series formation. The image reconstruction and statistical activation processes are treated separately. In this manuscript, a framework is developed so that statistical analysis is performed in terms of the original, prereconstruction, complex-valued k-space measurements. First, the relationship between complex-valued (Fourier) encoded k-space measurements and complex-valued image m...
Source: Magnetic Resonance Imaging - July 16, 2009 Category: Radiology Authors: Daniel B. Rowe, Andrew D. Hahn, Andrew S. Nencka Tags: Original Contributions Source Type: journals

Neurophysiological and functional MRI evidence of reorganization of cortical motor areas in cerebral arteriovenous malformationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Functional magnetic resonance imaging (fMRI) research has shown that brain arteriovenous malformations (AVMs) lead to reorganization of cortical motor areas. Since it is known that blood oxygenation level-dependent signal in fMRI may be influenced by the hemodynamic perturbation associated with the presence of the AVM, in the present study, a combined exploration with fMRI and transcranial magnetic stimulation was performed in a patient with a right rolandic AVM in order to explore the relationship between neuronal and hemodynamic activity. The combined protocol of investigation adopted in this study was able to ...
Source: Magnetic Resonance Imaging - July 16, 2009 Category: Radiology Authors: Francesca Caramia, Ada Francia, Caterina Mainero, Emanuele Tinelli, Maria Giuseppina Palmieri, Claudio Colonnese, Luigi Bozzao, Maria Donatella Caramia Tags: Original Contributions Source Type: journals

Estimation of mutual information objective function based on Fourier shift theorem: an application to eddy current distortion correction in diffusion tensor imagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Diffusion tensor imaging requires correction of eddy current distortion in diffusion-weighted images. An effective retrospective correction approach is to transform a diffusion-weighted image to maximize the mutual information (MI) between the transformed diffusion-weighted image and the corresponding T2-weighted image. In the literature, either linear interpolation or partial volume interpolation is applied to estimate the MI objective function. However, these interpolation methods induce artifacts to the MI objective function, thus compromising correction results. In this work, the MI objective function is esti...
Source: Magnetic Resonance Imaging - July 15, 2009 Category: Radiology Authors: Udomchai Techavipoo, John Lackey, Jianrong Shi, Xin Guan, Song Lai Tags: Original Contributions Source Type: journals

Quantitative assessment of regional systolic and diastolic functions and temporal heterogeneity of myocardial contraction in patients with myocardial infarction using cine magnetic resonance imaging and Fourier fittingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this study is to determine regional left ventricle (LV) function and temporal heterogeneity of LV wall contraction by analyzing regional time–volume curve (TVC) after Fourier fitting and to assess altered systolic and diastolic functions and temporal indices of myocardial contraction in infarcted segments in comparison with noninfarcted myocardium in patients with myocardial infarction (MI).Methods: Steady-state cine magnetic resonance (MR) and late gadolinium-enhanced (LGE) MR images were acquired using a 1.5-T MR system in 60 patients with MI. Regional LV function was determined by analyzing regional T...
Source: Magnetic Resonance Imaging - July 6, 2009 Category: Radiology Authors: Takahiro Natsume, Tomoyasu Amano, Yasuo Takehara, Takashi Ichihara, Kan Takeda, Hajime Sakuma Tags: Original Contributions Source Type: journals

Elliptical magnetic resonance spectroscopic imaging with GRAPPA for imaging brain tumors at 3 TEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Magnetic Resonance Spectroscopic Imaging (MRSI) is a technique for imaging spatial variation of metabolites and has been very useful in characterizing biochemical changes associated with disease as well as response to therapy in malignant pathologies. This work presents a self-calibrated undersampling to accelerate 3D elliptical MRSI and an extrapolation-reconstruction algorithm based on the GRAPPA method. The accelerated MRSI technique was tested in three volunteers and five brain tumor patients. Acceleration allowed larger spatial coverage and consequently, less lipid contamination in spectra, compared to fully...
Source: Magnetic Resonance Imaging - July 6, 2009 Category: Radiology Authors: Suchandrima Banerjee, Esin Ozturk-Isik, Sarah J. Nelson, Sharmila Majumdar Tags: Original Contributions Source Type: journals

Brain networks responsive to aversive visual stimuli in humansEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The neural mechanisms subserving recognition of noxious stimuli and empathy for pain appear to involve at least in part the cortical regions associated with the processing of pain affect. An important issue concerns the specificity of brain networks associated with observing and representing painful conditions, in comparison with other unpleasant stimuli. Recently, we found both similarities and differences between the brain patterns of activity related to the observation of noxious or disgusting stimuli delivered to one hand or foot. Overlap regions included the perigenual anterior cingulate (pACC), whose activi...
Source: Magnetic Resonance Imaging - July 5, 2009 Category: Radiology Authors: Francesca Benuzzi, Fausta Lui, Davide Duzzi, Paolo F. Nichelli, Carlo Adolfo Porro Tags: Research Articles Source Type: journals

A post-processing method for correction and enhancement of chemical shift imagesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Chemical shift imaging (CSI) relies on a strong and homogeneous main field. Field homogeneity ensures adequate coherence between the precessions of individual spins within each voxel. Variation of field strength between different voxels causes geometric distortion and intensity variation in chemical shift images, resulting in errors when analyzing the spatial distribution of specific chemical compounds. A post-processing method, based on detection of the spectral peak of water and baseline subtraction with Lorentzian functions, was developed in this study to automatically correct spectra offsets caused by field i...
Source: Magnetic Resonance Imaging - July 2, 2009 Category: Radiology Authors: Yu-Che Cheng, Jyh-Horng Chen, Tsu-Tsuen Wang, Ta-Te Lin Tags: Original Contributions Source Type: journals

Noise estimation in single- and multiple-coil magnetic resonance data based on statistical modelsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Noise estimation is a challenging task in magnetic resonance imaging (MRI), with applications in quality assessment, filtering or diffusion tensor estimation. Main noise estimators based on the Rician model are revisited and classified in this article, and new useful methods are proposed. Additionally, all the surveyed estimators are extended to the noncentral chi model, which applies to multiple-coil MRI and some important parallel imaging algorithms for accelerated acquisitions. The proposed new noise estimation procedures, based on the distribution of local moments, show better performance in terms of smaller ...
Source: Magnetic Resonance Imaging - July 2, 2009 Category: Radiology Authors: Santiago Aja-Fernández, Antonio Tristán-Vega, Carlos Alberola-López Tags: Original Contributions Source Type: journals

Bootstrap generation and evaluation of an fMRI simulation databaseEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Computer simulations have played a critical role in functional magnetic resonance imaging (fMRI) research, notably in the validation of new data analysis methods. Many approaches have been used to generate fMRI simulations, but there is currently no generic framework to assess how realistic each one of these approaches may be. In this article, a statistical technique called parametric bootstrap was used to generate a simulation database that mimicked the parameters found in a real database, which comprised 40 subjects and five tasks. The simulations were evaluated by comparing the distributions of a battery of st...
Source: Magnetic Resonance Imaging - July 2, 2009 Category: Radiology Authors: Pierre Bellec, Vincent Perlbarg, Alan C. Evans Tags: Original Contributions Source Type: journals

Spinal fMRI investigation of human spinal cord function over a range of innocuous thermal sensory stimuli and study-related emotional influencesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Functional magnetic resonance imaging (fMRI) of the human spinal cord has revealed important details of activity involved with innocuous sensory stimuli, including the primary input to ipsilateral dorsal gray matter and activity in bilateral ventral gray matter regions. The latter is hypothesized to reflect descending modulation from the brainstem and cortex. Here, the functions corresponding to these areas of activity are investigated by varying the temperature of innocuous thermal stimuli, and the order they are presented, across repeated fMRI experiments in the spinal cord and brainstem. Group results and conn...
Source: Magnetic Resonance Imaging - July 2, 2009 Category: Radiology Authors: Patrick W. Stroman Tags: Original Contributions Source Type: journals

Unwrapping magnetic resonance phase maps with Chebyshev polynomialsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: A phase-unwrapping algorithm, based on the method of moments, is introduced in this work. The proposed algorithm expands the phase map in terms of a two-dimensional Chebyshev series. The expansion coefficients are calculated by exploiting the orthogonality of Chebyshev polynomials of the first kind. The performance of the proposed phase-unwrapping algorithm is tested on a synthetic phase map and experimental phase maps of a uniform phantom, a human brain and a mouse torso, all acquired from 3-T magnetic resonance (MR) scanners. To impose additional burdens on the algorithm, we introduced magnetic field inhomogene...
Source: Magnetic Resonance Imaging - July 1, 2009 Category: Radiology Authors: Jason Langley, Qun Zhao Tags: Original Contributions Source Type: journals

The neural correlates of calculation ability in children: an fMRI studyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Most studies investigating mental numerical processing involve adult participants and little is known about the functioning of these systems in children. The current study used functional magnetic resonance imaging (fMRI) to investigate the neural correlates of numeracy and the influence of age on these correlates with a group of adults and a group of third graders who had average to above average mathematical ability. Participants performed simple and complex versions of exact and approximate calculation tasks while in the magnet. Like adults, children activated a network of brain regions in the frontal and pari...
Source: Magnetic Resonance Imaging - July 1, 2009 Category: Radiology Authors: Nicole Davis, Christopher J. Cannistraci, Baxter P. Rogers, J. Christopher Gatenby, Lynn S. Fuchs, Adam W. Anderson, John C. Gore Tags: Original Contributions Source Type: journals

Optimizing ICA in fMRI using information on spatial regularities of the sourcesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Spatial independent component analysis (ICA) is a well-established technique for multivariate analysis of functional magnetic resonance imaging (fMRI) data. It blindly extracts spatiotemporal patterns of neural activity from functional measurements by seeking for sources that are maximally independent. Additional information on one or more sources (e.g., spatial regularity) is often available; however, it is not considered while looking for independent components. In the present work, we propose a new ICA algorithm based on the optimization of an objective function that accounts for both independence and other in...
Source: Magnetic Resonance Imaging - July 1, 2009 Category: Radiology Authors: Giancarlo Valente, Federico De Martino, Giuseppe Filosa, Marco Balsi, Elia Formisano Tags: Research Articles Source Type: journals

Retrospective correction for T1-weighting bias in T2 values obtained with various spectroscopic spin-echo acquisition schemesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Localized tissue transverse relaxation time (T2) is obtained by fitting a decaying exponential to the signals from several spin-echo experiments at different echo times (TE). Unfortunately, time constraints in magnetic resonance spectroscopy (MRS) often mandate in vivo acquisition schemes at short repetition times (TR), that is, comparable with the longitudinal relaxation constant (T1). This leads to different T1-weighting of the signals at each TE. Unaccounted for, this varying weighting causes systematic underestimation of the T2's, sometimes by as mush as 30%. In this article, we (i) analyze the phenomenon for...
Source: Magnetic Resonance Imaging - June 26, 2009 Category: Radiology Authors: Roman Fleysher, Lazar Fleysher, Ivan Kirov, David A. Hess, Songtao Liu, Oded Gonen Tags: Original Contributions Source Type: journals

A serial functional connectivity MRI study in healthy individuals assessing the variability of connectivity measures: reduced interhemispheric connectivity in the motor network during continuous performanceEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: To date, little data is available on the reproducibility of functional connectivity MRI (fcMRI) studies. Here, we tested the variability and reproducibility of both the functional connectivity itself and different statistical methods to analyze this phenomenon. In the main part of our study, we repeatedly examined two healthy subjects in 10 sessions over 6 months with fcMRI. Cortical areas involved in motor function were examined under two different cognitive states: during continuous performance (CP) of a flexion/extension task of the fingers of the right hand and while subjects were at rest. Connectivity to lef...
Source: Magnetic Resonance Imaging - June 26, 2009 Category: Radiology Authors: Michael Amann, Jochen G. Hirsch, Achim Gass Tags: Original Contributions Source Type: journals

Contrast-enhanced MR angiography with frequency-dependent mask subtractionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We reported here on a frequency-dependent mask subtraction technique where only low spatial frequency data were subject to mask subtraction to improve image contrast and reduce motion artifact while high spatial frequency data were not subtracted to preserve image noise level. The feasibility of this technique was demonstrated through phantom, animal, and human volunteer studies. The lowest half, quarter, 1/8 and 1/16 of all spatial frequencies were subject to mask subtraction, respectively. These partial subtraction techniques were compared with conventional mask subtraction in terms of SNR and artifact power. An SNR gain...
Source: Magnetic Resonance Imaging - June 26, 2009 Category: Radiology Authors: Jiang Du Tags: Original Contributions Source Type: journals

MRI-based biomechanical imaging: initial study on early plaque progression and vessel remodelingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The goal of the study is to develop a noninvasive magnetic resonance imaging (MRI)-based biomechanical imaging technique to address biomechanical pathways of atherosclerotic progression and regression in vivo using a 3D fluid-structure interaction (FSI) model. Initial in vivo study was carried out in an early plaque model in pigs that underwent balloon-overstretch injury to the left carotid arteries. Consecutive MRI scans were performed while the pigs were maintained on high cholesterol (progression) or normal chow (regression), with an injection of a plaque-targeted contrast agent, Gadofluorine M. At the end of ...
Source: Magnetic Resonance Imaging - June 26, 2009 Category: Radiology Authors: Jie Zheng, Dana R. Abendschein, Ruth J. Okamoto, Deshan Yang, Kyle S. McCommis, Bernd Misselwitz, Robert J. Gropler, Dalin Tang Tags: Original Contributions Source Type: journals

An optimized solenoidal head radiofrequency coil for low-field magnetic resonance imagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Applications of low-field magnetic resonance imaging (MRI) systems ( (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - June 25, 2009 Category: Radiology Authors: Barbara Blasiak, Vyacheslav Volotovskyy, Charlie Deng, Boguslaw Tomanek Tags: Original Contributions Source Type: journals

Detection and grading for esophageal varices in patients with chronic liver damage: comparison of gadolinium-enhanced and unenhanced steady-state coherent MR imagesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The purpose of this study was to compare observer interpreted steady-state coherent coronal images and gadolinium-enhanced axial images in terms of the detection and grading of esophageal varices. Magnetic resonance imaging (MRI) and gastrointestinal endoscopy were performed within 2 weeks in 90 patients with chronic liver damage, including 55 with untreated esophageal varices, for periodic screening purposes. Two blinded readers retrospectively reviewed T1- and T2-weighted images with gadolinium-enhanced (gadolinium image set) and steady-state coherent (coherent image set) images. Sensitivity for the detection o...
Source: Magnetic Resonance Imaging - June 25, 2009 Category: Radiology Authors: Satoshi Goshima, Masayuki Kanematsu, Hiroshi Kondo, Yusuke Tsuge, Haruo Watanabe, Yoshimune Shiratori, Minoru Onozuka, Noriyuki Moriyama Tags: Original Contributions Source Type: journals

Dynamic contrast-enhanced magnetic resonance imaging parameters independent of baseline T10 valuesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: A baseline T10 value is typically needed for dynamic contrast-enhanced (DCE-) MRI studies. However, an assumed baseline T10 has to be used when T10 measurements for patients are not available. In this work, we systematically investigate the dependence on T10 of the commonly used DCE-MRI parameters (Ktrans, kep, ve and IAUC) as well as several newly defined parameters [the normalized ratios (NRs) of kep, Ktrans and ve, which are measures of relative changes in these parameters between two time points] for a spoiled gradient-echo pulse sequence using simulations and in vivo studies. Effects of various factors on th...
Source: Magnetic Resonance Imaging - June 25, 2009 Category: Radiology Authors: Jun-Yu Guo, Wilburn E. Reddick, Mark A. Rosen, Hee Kwon Song Tags: Original Contributions Source Type: journals

Rotating frame relaxation during adiabatic pulses vs. conventional spin lock: simulations and experimental results at 4 TEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Spin relaxation taking place during radiofrequency (RF) irradiation can be assessed by measuring the longitudinal and transverse rotating frame relaxation rate constants (R1ρ and R2ρ). These relaxation parameters can be altered by utilizing different settings of the RF irradiation, thus providing a useful tool to generate contrast in MRI. In this work, we investigate the dependencies of R1ρ and R2ρ due to dipolar interactions and anisochronous exchange (i.e., exchange between spins with different chemical shift δω≠0) on the properties of conventional spin-lock and adiabatic pulses, with particular emphasi...
Source: Magnetic Resonance Imaging - June 25, 2009 Category: Radiology Authors: Silvia Mangia, Timo Liimatainen, Michael Garwood, Shalom Michaeli Tags: Research Articles Source Type: journals

ContentsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - June 25, 2009 Category: Radiology Source Type: journals

Editorial BoardEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - June 25, 2009 Category: Radiology Source Type: journals

Diffusion-weighted magnetic resonance imaging in differentiation of postobstructive consolidation from central lung carcinomaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusions: ADC values of central lung carcinoma masses appear to be lower than accompanying postobstructive consolidations. ADC values could be considered useful as a differentiating parameter among central lung carcinomas and accompanying postobstructive consolidations. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - June 25, 2009 Category: Radiology Authors: Tamer Baysal, Deniz Yakar Mutlu, Saim Yologlu Tags: Original Contributions Source Type: journals

Measurement of bone cyst fluid volume using k-means clusteringEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: We designed a semiautomatic segmentation method to easily measure the volume of a bone cyst (simple or aneurysmal) from magnetic resonance imaging (MRI). This method only considers the fluid part of the cyst, even when there are several fluid intensities (fluid-fluid levels) or the cyst is multi-loculated. The nonhomogeneity phenomenon inherent in MRI was handled by a k-means clustering algorithm that classified all of the voxels corresponding to the cyst fluid as the same voxel intensity. Level-set segmentation was expanded into the whole cyst volume and the resulting segmented volume provided the measured cyst ...
Source: Magnetic Resonance Imaging - June 25, 2009 Category: Radiology Authors: Pierre-Louis Docquier, Laurent Paul, Renaud Menten, Olivier Cartiaux, Bernard Francq, Xavier Banse Tags: Original Contributions Source Type: journals

MAgnitude and PHase Thresholding (MAPHT) of noisy complex-valued magnetic resonance imagesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: It is often desirable to separate voxels that contain signal from tissue along with measurement noise from those that contain purely measurement noise. Generally, this separation called thresholding utilizes only the magnitude portion of the images. Recently, methods have been developed that utilize both the magnitude and phase for thresholding voxels. This manuscript is an extension previous work and uses the bivariate normality of the real and imaginary values with phase coupled means. A likelihood ratio statistic is derived that simplifies to a more familiar form that is F-distributed in large samples. It is s...
Source: Magnetic Resonance Imaging - June 24, 2009 Category: Radiology Authors: Daniel B. Rowe, E. Mark Haacke Tags: Original Contributions Source Type: journals

In vivo structural analysis of articular cartilage using diffusion tensor magnetic resonance imagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusion: This method can be used to create images of the articular cartilage structure, not only in vitro but also in vivo. Therefore, it is suggested that this method should support the elucidation of the in vivo structure and function of the knee joint and might be applied to clinical practice. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - June 24, 2009 Category: Radiology Authors: Takashi Azuma, Ryusuke Nakai, Osamu Takizawa, Sadami Tsutsumi Tags: Original Contributions Source Type: journals

Comparison of pulsed arterial spin labeling encoding schemes and absolute perfusion quantificationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we evaluated three pulsed ASL sequences and three absolute quantification schemes. It was found that FAIR-QUIPSSII implementation of ASL yields 10–20% higher signal-to-noise ratio (SNR) and 18% higher CBF as compared with PICORE-Q2TIPS (with FOCI pulses) and PICORE-QUIPSSII (with BASSI pulses). In addition, quantification schemes employed can give rise to up to a 35% difference in CBF values. We conclude that, although all quantitative ASL sequences and CBF calibration methods should in principle result in the similar CBF values and image quality, substantial differences in CBF values and SNR were found. T...
Source: Magnetic Resonance Imaging - June 21, 2009 Category: Radiology Authors: Mustafa Çavuşoğlu, Josef Pfeuffer, Kâmil Uğurbil, Kâmil Uludağ Tags: Research Articles Source Type: journals

Improvement of spectral density-based activation detection of event-related fMRI dataEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: For event-related data obtained from an experimental paradigm with a periodic design, spectral density at the fundamental frequency of the paradigm has been used as a template-free activation detection measure. In this article, we build and expand upon this detection measure to create an improved, integrated measure. Such an integrated measure linearly combines information contained in the spectral densities at the fundamental frequency as well as the harmonics of the paradigm and in a spatial correlation function characterizing the degree of co-activation among neighboring voxels. Several figures of merit are de...
Source: Magnetic Resonance Imaging - June 17, 2009 Category: Radiology Authors: Shing-Chung Ngan, Xiaoping Hu, Li-Hai Tan, Pek-Lan Khong Tags: Original Contributions Source Type: journals

A nonrigid registration algorithm for longitudinal breast MR images and the analysis of breast tumor responseEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can estimate parameters relating to blood flow and tissue volume fractions and therefore may be used to characterize the response of breast tumors to treatment. To assess treatment response, values of these DCE-MRI parameters are observed at different time points during the course of treatment. We propose a method whereby DCE-MRI data sets obtained in separate imaging sessions can be co-registered to a common image space, thereby retaining spatial information so that serial DCE-MRI parameter maps can be compared on a voxel-by-voxel basis. In performin...
Source: Magnetic Resonance Imaging - June 14, 2009 Category: Radiology Authors: Xia Li, Benoit M. Dawant, E. Brian Welch, A. Bapsi Chakravarthy, Darla Freehardt, Ingrid Mayer, Mark Kelley, Ingrid Meszoely, John C. Gore, Thomas E. Yankeelov Tags: Original Contributions Source Type: journals

On MRI turbulence quantificationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Turbulent flow, characterized by velocity fluctuations, accompanies many forms of cardiovascular disease and may contribute to their progression and hemodynamic consequences. Several studies have investigated the effects of turbulence on the magnetic resonance imaging (MRI) signal. Quantitative MRI turbulence measurements have recently been shown to have great potential for application both in human cardiovascular flow and in engineering flow. In this article, potential pitfalls and sources of error in MRI turbulence measurements are theoretically and numerically investigated. Data acquisition strategies suitable...
Source: Magnetic Resonance Imaging - June 14, 2009 Category: Radiology Authors: Petter Dyverfeldt, Roland Gårdhagen, Andreas Sigfridsson, Matts Karlsson, Tino Ebbers Tags: Original Contributions Source Type: journals

In vivo diffusion tensor imaging of thoracic and cervical rat spinal cord at 7 TEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: In vivo diffusion tensor imaging (DTI) of rat cervical and thoracic spinal cord was performed using a three-element phased array coil at 7 T. The magnetic field was shimmed over the spinal cord in real time using an in-house developed automatic algorithm. Echo planar imaging (EPI)-based diffusion-weighted images (DWIs) were acquired with 21 gradient encoding directions. The DWIs were tensor encoded, and diffusion tensor metrics, fractional anisotropy (FA), mean diffusivity (MD), longitudinal diffusivity (λ0) and transverse diffusivity (λ⊥) were determined for both white matter (WM) and gray matter (GM). The r...
Source: Magnetic Resonance Imaging - June 10, 2009 Category: Radiology Authors: Kishore V. Mogatadakala, Ponnada A. Narayana Tags: Original Contributions Source Type: journals

Detection of focal liver lesions in unenhanced and ferucarbotran-enhanced magnetic resonance imaging: a comparison of T2-weighted breath-hold and respiratory-triggered sequencesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusion: We find that respiratory-triggered fast spin-echo sequences produce a higher image quality and a more precise liver-lesion detection rate thereby justifying the increased acquisition time necessary for this method. (Source: Magnetic Resonance Imaging)
Source: Magnetic Resonance Imaging - June 10, 2009 Category: Radiology Authors: Matthias Rief, Moritz Wagner, Tobias Franiel, Viola Bresan, Matthias Taupitz, Christian Klessen, Bernd Hamm, Patrick Asbach Tags: Original Contributions Source Type: journals