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A General Total Variation Minimization Theorem for Compressed Sensing Based Interior TomographyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Recently, in the compressed sensing framework we found that a two-dimensional interior region-of-interest (ROI) can be exactly reconstructed via the total variation minimization if the ROI is piecewise constant (Yu and Wang, 2009). Here we present a general theorem charactering a minimization property for a piecewise constant function defined on a domain in any dimension. Our major mathematical tool to prove this result is functional analysis without involving the Dirac delta function, which was heuristically used by Yu and Wang (2009). (Source: International Journal of Biomedical Imaging)
Source: International Journal of Biomedical Imaging - November 17, 2009 Category: Radiology Source Type: journals

Segmentation of Striatal Brain Structures from High Resolution PET ImagesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We propose and evaluate an automatic segmentation method for extracting striatal brain structures (caudate, putamen, and ventral striatum) from parametric C11-raclopride positron emission tomography (PET) brain images. We focus on the images acquired using a novel brain dedicated high-resolution (HRRT) PET scanner. The segmentation method first extracts the striatum using a deformable surface model and then divides the striatum into its substructures based on a graph partitioning algorithm. The weighted kernel k-means algorithm is used to partition the graph describing the voxel affinities within the striatum into the desi...
Source: International Journal of Biomedical Imaging - November 4, 2009 Category: Radiology Source Type: journals

Multicomponent MR Image DenoisingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Magnetic Resonance images are normally corrupted by random noise from the measurement process complicating the automatic feature extraction and analysis of clinical data. It is because of this reason that denoising methods have been traditionally applied to improve MR image quality. Many of these methods use the information of a single image without taking into consideration the intrinsic multicomponent nature of MR images. In this paper we propose a new filter to reduce random noise in multicomponent MR images by spatially averaging similar pixels using information from all available image components to perform the denois...
Source: International Journal of Biomedical Imaging - October 29, 2009 Category: Radiology Source Type: journals

Hybrid Mammogram Classification Using Rough Set and Fuzzy ClassifierEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We propose a computer aided detection (CAD) system for the detection and classification of suspicious regions in mammographic images. This system combines a dimensionality reduction module (using principal component analysis), a feature extraction module (using independent component analysis), and a feature subset selection module (using rough set model). Rough set model is used to reduce the effect of data inconsistency while a fuzzy classifier is integrated into the system to label subimages into normal or abnormal regions. The experimental results show that this system has an accuracy of 84.03% and a recall percenta...
Source: International Journal of Biomedical Imaging - October 22, 2009 Category: Radiology Source Type: journals

Region-Based PDEs for Cells Counting and Segmentation in 3D+Time Images of Vertebrate Early EmbryogenesisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper is devoted to the segmentation of cell nuclei from time lapse confocal microscopy images, taken throughout early Zebrafish embryogenesis. The segmentation allows to identify and quantify the number of cells in the animal model. This kind of information is relevant to estimate important biological parameters such as the cell proliferation rate in time and space. Our approach is based on the active contour model without edges. We compare two different formulations of the model equation and evaluate their performances in segmenting nuclei of different shapes and sizes. Qualitative and quantitative comparisons are p...
Source: International Journal of Biomedical Imaging - October 8, 2009 Category: Radiology Source Type: journals

Image Restoration Using Functional and Anatomical Information Fusion with Application to SPECT-MRI ImagesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Image restoration is usually viewed as an ill-posed problem in image processing, since there is no unique solution associated with it. The quality of restored image closely depends on the constraints imposed of the characteristics of the solution. In this paper, we propose an original extension of the NAS-RIF restoration technique by using information fusion as prior information with application in SPECT medical imaging. That extension allows the restoration process to be constrained by efficiently incorporating, within the NAS-RIF method, a regularization term which stabilizes the inverse solution. Our restoration method ...
Source: International Journal of Biomedical Imaging - October 1, 2009 Category: Radiology Source Type: journals

Cone Beam Micro-CT System for Small Animal Imaging and Performance EvaluationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A prototype cone-beam micro-CT system for small animal imaging has been developed by our group recently, which consists of a microfocus X-ray source, a three-dimensional programmable stage with object holder, and a flat-panel X-ray detector. It has a large field of view (FOV), which can acquire the whole body imaging of a normal-size mouse in a single scan which usually takes about several minutes or tens of minutes. FDK method is adopted for 3D reconstruction with Graphics Processing Unit (GPU) acceleration. In order to reconstruct images with high spatial resolution and low artifacts, raw data preprocessing and geometry ...
Source: International Journal of Biomedical Imaging - September 22, 2009 Category: Radiology Source Type: journals

Multiple Sclerosis Lesion Detection Using Constrained GMM and Curve EvolutionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper focuses on the detection and segmentation of Multiple Sclerosis (MS) lesions in magnetic resonance (MRI) brain images. To capture the complex tissue spatial layout, a probabilistic model termed Constrained Gaussian Mixture Model (CGMM) is proposed based on a mixture of multiple spatially oriented Gaussians per tissue. The intensity of a tissue is considered a global parameter and is constrained, by a parameter-tying scheme, to be the same value for the entire set of Gaussians that are related to ...
Source: International Journal of Biomedical Imaging - September 10, 2009 Category: Radiology Source Type: journals

Robust and Unbiased Variance of GLM Coefficients for Misspecified Autocorrelation and Hemodynamic Response Models in fMRIEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
As a consequence of misspecification of the hemodynamic response and noise variance models, tests on general linear model coe cients are not valid. Robust estimation of the variance of the general linear model (GLM) coecients in fMRI time series is therefore essential. In this paper an alternative method to estimate the variance of the GLM coe cients accurately is suggested and compared to other methods. The alternative, referred to as the sandwich, is based primarily on the fact that the time series are obtained from multiple exchangeable stimulus presentations. The analytic results show that the sandwich is unbiased. Usi...
Source: International Journal of Biomedical Imaging - September 6, 2009 Category: Radiology Source Type: journals

3D Analytic Cone-Beam Reconstruction for Multiaxial CT AcquisitionsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present numerical experiments to demonstrate that the proposed techniques successfully reduce cone-beam artifacts at very large volumetric coverage. (Source: International Journal of Biomedical Imaging)
Source: International Journal of Biomedical Imaging - August 30, 2009 Category: Radiology Source Type: journals

GPU-Based 3D Cone-Beam CT Image Reconstruction for Large Data VolumeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Currently, 3D cone-beam CT image reconstruction speed is still a severe limitation for clinical application. The computational power of modern graphics processing units (GPUs) has been harnessed to provide impressive acceleration of 3D volume image reconstruction. For extra large data volume exceeding the physical graphic memory of GPU, a straightforward compromise is to divide data volume into blocks. Different from the conventional Octree partition method, a new partition scheme is proposed in this paper. This method divides both projection data and reconstructed image volume into subsets according to geometric symmetrie...
Source: International Journal of Biomedical Imaging - August 26, 2009 Category: Radiology Source Type: journals

Joint Brain Parametric T1-Map Segmentation and RF Inhomogeneity CalibrationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We propose a constrained version of Mumford and Shah's (1989) segmentation model with an information-theoretic point of view in order to devise a systematic procedure to segment brain magnetic resonance imaging (MRI) data for parametric T1-Map and T1-weighted images, in both 2-D and 3D settings. Incorporation of a tuning weight in particular adds a probabilistic flavor to our segmentation method, and makes the 3-tissue segmentation possible. Moreover, we proposed a novel method to jointly segment the T1-Map and calibrate RF Inhomogeneity (JSRIC). This method assumes the averageT1 value of white matter is the same acros...
Source: International Journal of Biomedical Imaging - August 23, 2009 Category: Radiology Source Type: journals

Imaging Multidimensional Therapeutically Relevant Circadian RelationshipsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Circadian clocks gate cellular proliferation and, thereby, therapeutically target availability within proliferative pathways. This temporal coordination occurs within both cancerous and noncancerous proliferating tissues. The timing within the circadian cycle of the administration of drugs targeting proliferative pathways necessarily impacts the amount of damage done to proliferating tissues and cancers. Concurrently measuring target levels and associated key pathway components in normal and malignant tissues around the circadian clock provides a path toward a fuller understanding of the temporal relationships among the ph...
Source: International Journal of Biomedical Imaging - August 17, 2009 Category: Radiology Source Type: journals

Mjolnir: Extending HAMMER Using a Diffusion Transformation Model and Histogram Equalization for Deformable Image RegistrationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Image registration is a crucial step in many medical image analysis procedures such as image fusion, surgical planning, segmentation and labeling, and shape comparison in population or longitudinal studies. A new approach to volumetric intersubject deformable image registration is presented. The method, called Mjolnir, is an extension of the highly successful method HAMMER. New image features in order to better localize points of correspondence between the two images are introduced as well as a novel approach to generate a dense displacement field based upon the weighted diffusion of automatically derived feature correspon...
Source: International Journal of Biomedical Imaging - August 11, 2009 Category: Radiology Source Type: journals

Reconstruction for Time-Domain In Vivo EPR 3D Multigradient Oximetric Imaging—A Parallel Processing PerspectiveEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Three-dimensional Oximetric Electron Paramagnetic Resonance Imaging using the Single Point Imaging modality generates unpaired spin density and oxygen images that can readily distinguish between normal and tumor tissues in small animals. It is also possible with fast imaging to track the changes in tissue oxygenation in response to the oxygen content in the breathing air. However, this involves dealing with gigabytes of data for each 3D oximetric imaging experiment involving digital band pass filtering and background noise subtraction, followed by 3D Fourier reconstruction. This process is rather slow in a conventional uni...
Source: International Journal of Biomedical Imaging - August 5, 2009 Category: Radiology Source Type: journals

Temperature-Change-Based Thermal TomographyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Thermal properties of biological tissues play a critical role in the study of tumor angiogenesis and the design and monitoring of thermal therapies. To map thermal parameters noninvasively, we propose temperature-change-based thermal tomography (TTT) that relies on relative temperature mapping using magnetic resonance imaging (MRI). Our approach is unique in two aspects: (1) the steady-state body temperature in thermal equilibrium is not restricted to be spatially invariant, and (2) absolute temperature mapping is not required. These two features are physiologically realistic and technically convenient. Our numerical simul...
Source: International Journal of Biomedical Imaging - July 23, 2009 Category: Radiology Source Type: journals

A Wavelet-Based Multiresolution Reconstruction Method for Fluorescent Molecular TomographyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Image reconstruction of fluorescent molecular tomography (FMT) often involves repeatedly solving large-dimensional matrix equations, which are computationally expensive, especially for the case where there are large deviations in the optical properties between the target and the reference medium. In this paper, a wavelet-based multiresolution reconstruction approach is proposed for the FMT reconstruction in combination with a parallel forward computing strategy, in which both the forward and the inverse problems of FMT are solved in the wavelet domain. Simulation results demonstrate that the proposed approach can significa...
Source: International Journal of Biomedical Imaging - July 22, 2009 Category: Radiology Source Type: journals

Elastography Method for Reconstruction of Nonlinear Breast Tissue PropertiesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Elastography is developed as a quantitative approach to imaging linear elastic properties of tissues to detect suspicious tumors. In this paper a nonlinear elastography method is introduced for reconstruction of complex breast tissue properties. The elastic parameters are estimated by optimally minimizing the difference between the computed forces and experimental measures. A nonlinear adjoint method is derived to calculate the gradient of the objective function, which significantly enhances the numerical efficiency and stability. Simulations are conducted on a three-dimensional heterogeneous breast phantom extracting from...
Source: International Journal of Biomedical Imaging - July 9, 2009 Category: Radiology Source Type: journals

Segmentation of Myocardial Boundaries in Tagged Cardiac MRI Using Active Contours: A Gradient-Based Approach Integrating Texture AnalysisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The noninvasive assessment of cardiac function is of first importance for the diagnosis of cardiovascular diseases. Among all medical scanners only a few enables radiologists to evaluate the local cardiac motion. Tagged cardiac MRI is one of them. This protocol generates on Short-Axis (SA) sequences a dark grid which is deformed in accordance with the cardiac motion. Tracking the grid allows specialists a local estimation of cardiac geometrical parameters within myocardium. The work described in this paper aims to automate the myocardial contours detection in order to optimize the detection and the tracking of the grid of ...
Source: International Journal of Biomedical Imaging - June 17, 2009 Category: Radiology Source Type: journals

Blind Deblurring Reconstruction Technique with Applications in PET ImagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We developed an empirical PET model taking into account system blurring and a blind iterative reconstruction scheme that estimates both the actual image and the point spread function of the system. Reconstruction images of high quality can be acquired by using the proposed reconstruction technique for both synthetic and experimental data. In the synthetic data study, the algorithm reduces image blurring and preserves the edges without introducing extra artifacts. The localized measurement shows that the performance of the reconstruction image improved by up to 100%. In experimental data studies, the contrast and qualit...
Source: International Journal of Biomedical Imaging - June 17, 2009 Category: Radiology Source Type: journals

Diffusion Maps Clustering for Magnetic Resonance Q-Ball Imaging SegmentationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
White matter fiber clustering aims to get insight about anatomical structures in order to generate atlases, perform clear visualizations, and compute statistics across subjects, all important and current neuroimaging problems. In this work, we present a diffusion maps clustering method applied to diffusion MRI in order to segment complex white matter fiber bundles. It is well known that diffusion tensor imaging (DTI) is restricted in complex fiber regions with crossings and this is why recent high-angular resolution diffusion imaging (HARDI) such as Q-Ball imaging (QBI) has been introduced to overcome these limitations. QB...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Repetitive Transcranial Magnetic Stimulation of Dorsolateral Prefrontal Cortex Affects Performance of the Wisconsin Card Sorting Task during Provision of FeedbackEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Early functional neuroimaging studies of tasks evaluating executive processes, such as the Wisconsin card sorting task (WCST), only assessed trials in blocks that may contain a large amount of different cognitive processes. More recently, we showed using event-related fMRI that the dorsolateral prefrontal cortex (DL-PFC) significantly increased activity during feedback but not matching periods of the WCST, consistent with its proposed role in the monitoring of information in working memory. Repetitive transcranial magnetic stimulation (rTMS) is a method that allows to disrupt processing within a given cortical region and t...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

BOLD-Perfusion Coupling during Monocular and Binocular StimulationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Previous studies have suggested that during selective activation of a subset of the zones comprising a columnar system in visual cortex, perfusion increases uniformly in all columns of the system, while increases in oxidative metabolism occur predominantly in the activated columns. This could lead to disproportionately large blood oxygenation level-dependent (BOLD) signal increases for a given flow increase during monocular (relative to binocular) stimulation, due to contributions from columns which undergo large increases in perfusion with little or no change in oxidative metabolism. In the present study, we sought to tes...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Spectroscopic OCT by Grating-Based Temporal Correlation Coupled to Optical Spectral AnalysisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present an alternative for optically accessing the spectroscopic information in OCT, that is, without postprocessing, by using a grating-based correlation and a wavelength demultiplexing system. Spectrally resolved A-scan is directly recorded on the image sensor. Due to the grating-based system, no correlation scan is necessary. The signal is registered in the wavelength-depth plane on a 2D camera that provides a large number of resolved points. In the frame of this paper, we present the principle of the system as well as demonstration results. Advantages and drawback of this system compared to others are discussed. (So...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

MMSE Reconstruction for 3D Freehand Ultrasound ImagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The reconstruction of 3D ultrasound (US) images from mechanically registered, but otherwise irregularly positioned, B-scan slices is of great interest in image guided therapy procedures. Conventional 3D ultrasound algorithms have low computational complexity, but the reconstructed volume suffers from severe speckle contamination. Furthermore, the current method cannot reconstruct uniform high-resolution data from several low-resolution B-scans. In this paper, the minimum mean-squared error (MMSE) method is applied to 3D ultrasound reconstruction. Data redundancies due to overlapping samples as...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

X-Ray Phase-Contrast Imaging with Three 2D GratingsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
X-ray imaging is of paramount importance for clinical and preclinical imaging but it is fundamentally restricted by the attenuation-based contrast mechanism, which has remained essentially the same since Roentgen's discovery a century ago. Recently, based on the Talbot effect, groundbreaking work was reported using 1D gratings for X-ray phase-contrast imaging with a hospital-grade X-ray tube instead of a synchrotron or microfocused source. In this paper, we report an extension using 2D gratings that reduces the imaging time and increases the accuracy and robustness of phase retrieval compared to current grating-based ...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Connectivity-Based Parcellation of the Cortical Mantle Using q-Ball Diffusion ImagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper exploits the idea that each individual brain region has a specific connection profile to create parcellations of the cortical mantle using MR diffusion imaging. The parcellation is performed in two steps. First, the cortical mantle is split at a macroscopic level into 36 large gyri using a sulcus recognition system. Then, for each voxel of the cortex, a connection profile is computed using a probabilistic tractography framework. The tractography is performed from q-ball fields using regularized particle trajectories. Fiber ODF are inferred from the q-balls using a sharpening process focusing the weight around th...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

3D Wavelet Subbands Mixing for Image DenoisingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A critical issue in image restoration is the problem of noise removal while keeping the integrity of relevant image information. The method proposed in this paper is a fully automatic 3D blockwise version of the nonlocal (NL) means filter with wavelet subbands mixing. The proposed wavelet subbands mixing is based on a multiresolution approach for improving the quality of image denoising filter. Quantitative validation was carried out on synthetic datasets generated with the BrainWeb simulator. The results show that our NL-means filter with wavelet subbands mixing outperforms the classical implementation of the NL-means fil...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Exploring the Anatomical Basis of Effective Connectivity Models with DTI-Based Fiber TractographyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we investigate the potential of DTI to provide the anatomical basis of paths that are used in studies of effective connectivity, using structural equation modeling. We have taken regions of interest from eight previously published studies, and examined the connectivity as defined by DTI-based fiber tractography between these regions. The resulting fiber tracts were then compared with the paths proposed in the original studies. For a substantial number of connections, we found fiber tracts that corresponded to the proposed paths. More importantly, we have also identified a number of cases in which tractograph...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Exact Interior Reconstruction from Truncated Limited-Angle Projection DataEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Using filtered backprojection (FBP) and an analytic continuation approach, we prove that exact interior reconstruction is possible and unique from truncated limited-angle projection data, if we assume a prior knowledge on a subregion or subvolume within an object to be reconstructed. Our results show that (i) the interior region-of-interest (ROI) problem and interior volume-of-interest (VOI) problem can be exactly reconstructed from a limited-angle scan of the ROI/VOI and a 180 degree PI-scan of the subregion or subvolume and (ii) the whole object function can be exactly reconstructed from nontruncated projections from a l...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Contribution of Exploratory Methods to the Investigation of Extended Large-Scale Brain Networks in Functional MRI: Methodologies, Results, and ChallengesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A large-scale brain network can be defined as a set of segregated and integrated regions, that is, distant regions that share strong anatomical connections and functional interactions. Data-driven investigation of such networks has recently received a great deal of attention in blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI). We here review the rationale for such an investigation, the methods used, the results obtained, and also discuss some issues that have to be faced for an efficient exploration. (Source: International Journal of Biomedical Imaging)
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Recent Advances in Neuroimaging MethodsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
(Source: International Journal of Biomedical Imaging)
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Random Volumetric MRI Trajectories via Genetic AlgorithmsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A pseudorandom, velocity-insensitive, volumetric k-space sampling trajectory is designed for use with balanced steady-state magnetic resonance imaging. Individual arcs are designed independently and do not fit together in the way that multishot spiral, radial or echo-planar trajectories do. Previously, it was shown that second-order cone optimization problems can be defined for each arc independent of the others, that nulling of zeroth and higher moments can be encoded as constraints, and that individual arcs can be optimized in seconds. For use in steady-state imaging, sampling duty cycles are predicted to exceed 95 perce...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

In Vitro Assessment of Optical Properties of Blood by Applying the Extended Huygens-Fresnel Principle to Time-Domain Optical Coherence Tomography Signal at 1300 nmEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A direct method for the measurement of the optical attenuation coefficient and the scattering anisotropy parameter based on applying the extended Huygens-Fresnel principle to optical coherence tomography images of blood is demonstrated. The images are acquired with a low-power probing beam at the wavelength of 1300 nm. Values of 12.15 mm−1 and 0.95 are found for the total attenuation coefficient and the scattering anisotropy factor, respectively. Also, as a preliminary step, the optical refraction index is determined with a precision of two decimal numbers directly from optical coherence images. The to...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Digital Eversion of a Hollow Structure: An Application in Virtual ColonographyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A new methodology is presented for digital eversion of a hollow structure. The digital eversion is advantageous for better visualization of a larger portion of the inner surface with preservation of geometric relationship and without time-consuming navigation. Together with other techniques, digital eversion may help improve screening, diagnosis, surgical planning, and medical education. Two eversion algorithms are proposed and evaluated in numerical simulation to demonstrate the feasibility of the approach. (Source: International Journal of Biomedical Imaging)
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Suppression of MRI Truncation Artifacts Using Total Variation Constrained Data ExtrapolationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The finite sampling of k-space in MRI causes spurious image artifacts, known as Gibbs ringing, which result from signal truncation at the border of k-space. The effect is especially visible for acquisitions at low resolution and commonly reduced by filtering at the expense of image blurring. The present work demonstrates that the simple assumption of a piecewise-constant object can be exploited to extrapolate the data in k-space beyond the measured part. The method allows for a significant reduction of truncation artifacts without compromising resolution. The assumption translates into a total variation minimization proble...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Cerebral Blood Flow Measurement Using fMRI and PET: A Cross-Validation StudyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present a comparison of cerebral blood flow changes (ΔCBF) measured using a flow-sensitive alternating inversion recovery (FAIR) ASL perfusion method to those obtained using H2O15 PET, which is the current gold standard for in vivo imaging of CBF. To study regional and global CBF changes, a group of 10 healthy volunteers were imaged under identical experimental conditions during presentation of 5 levels of visual stimulation and one level of hypercapnia. The CBF changes were compared using 3 types of region-of-interest (ROI) masks. FAIR measurements of CBF changes were found to be slightly lower than those measur...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

An Efficient Estimation Method for Reducing the Axial Intensity Drop in Circular Cone-Beam CTEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Reconstruction algorithms for circular cone-beam (CB) scans have been extensively studied in the literature. Since insufficient data are measured, an exact reconstruction is impossible for such a geometry. If the reconstruction algorithm assumes zeros for the missing data, such as the standard FDK algorithm, a major type of resulting CB artifacts is the intensity drop along the axial direction. Many algorithms have been proposed to improve image quality when faced with this problem of data missing; however, development of an effective and computationally efficient algorithm remains a major challenge. In this work, we propo...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Registration and Fusion of the Autofluorescent and Infrared Retinal ImagesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article deals with registration and fusion of multimodal opththalmologic images obtained by means of a laser scanning device (Heidelberg retina angiograph). The registration framework has been designed and tested for combination of autofluorescent and infrared images. This process is a necessary step for consecutive pixel level fusion and analysis utilizing information from both modalities. Two fusion methods are presented and compared. (Source: International Journal of Biomedical Imaging)
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Semi-Automatic Integrated Segmentation Approaches and Contour Extraction Applied to Computed Tomography Scan ImagesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We propose to segment two-dimensional CT scans traumatic brain injuries with various methods. These methods are hybrid, feature extraction, level sets, region growing, and watershed which are analysed based upon their parametric and nonparametric arguments. The pixel intensities, gradient magnitude, affinity map, and catchment basins of these methods are validated based upon various constraints evaluations. In this article, we also develop a new methodology for a computational pipeline that uses bilateral filtering, diffusion properties, watershed, and filtering with mathematical morphology operators for the contour extrac...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Effect of Edge-Preserving Adaptive Image Filter on Low-Contrast Detectability in CT Systems: Application of ROC AnalysisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Conclusion. The QDS was found to be useful for reducing the radiation dose without affecting the low-contrast resolution in MSCT studies. (Source: International Journal of Biomedical Imaging)
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Reordering for Improved Constrained Reconstruction from Undersampled k-Space DataEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Recently, there has been a significant interest in applying reconstruction techniques, like constrained reconstruction or compressed sampling methods, to undersampled k-space data in MRI. Here, we propose a novel reordering technique to improve these types of reconstruction methods. In this technique, the intensities of the signal estimate are reordered according to a preprocessing step when applying the constraints on the estimated solution within the iterative reconstruction. The ordering of the intensities is such that it makes the original artifact-free signal monotonic and thus minimizes the finite differences norm if...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

SVD-Based Evaluation of Multiplexing in Multipinhole SPECT SystemsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Multipinhole SPECT system design is largely a trial-and-error process. General principles can give system designers a general idea of how a system with certain characteristics will perform. However, the specific performance of any particular system is unknown before the system is tested. The development of an objective evaluation method that is not based on experimentation would facilitate the optimization of multipinhole systems. We derive a figure of merit for prediction of SPECT system performance based on the entire singular value spectrum of the system. This figure of merit contains significantly more information than...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

A Reconstruction Approach for Imaging in 3D Cone Beam Vector Field TomographyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
3D cone beam vector field tomography (VFT) aims for reconstructing and visualizing the velocity field of a moving fluid by measuring line integrals of projections of the vector field. The data are obtained by ultrasound measurements along a scanning curve which surrounds the object. From a mathematical point of view, we have to deal with the inversion of the vectorial cone beam transform. Since the vectorial cone beam transform of any gradient vector field with compact support is identically equal to zero, we can only hope to reconstruct the solenoidal part of an arbitrary vector field. In this paper we will at first summa...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

In Situ Real-Time Chemiluminescence Imaging of Reactive Oxygen Species Formation from CardiomyocytesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We have applied the highly sensitive chemiluminescence (CL) imaging technique to investigate the in situ ROS formation in cultured monolayers of rat H9c2 cardiomyocytes. Photon emission was detected via an innovative imaging system after incubation of H9c2 cells in culture with luminol and horseradish peroxidase (HRP), suggesting constitutive formation of ROS by the cardiomyocytes. Addition of benzo(a)pyrene-1,6-quinone (BPQ) to cultured H9c2 cells resulted in a 4-5-fold increase in the formation of ROS, as detected by the CL imaging. Both constitutive and BPQ-stimulated CL responses in cultured H9c2 cells were sustained f...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Scatter and Blurring Compensation in Inhomogeneous Media Using a Postprocessing MethodEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
An efficient postprocessing method to compensate for the scattering and blurring effects in inhomogeneous medium in SPECT is proposed. A two-dimensional point spread function (2D-PSF) was estimated in the image domain to model the combination of these two physical effects. This 2D-PSF in the inhomogeneous medium is fitted with an asymmetric Gaussian function based on Monte Carlo simulation results. An efficient further blurring and deconvolution method was used to restore images from the spatially variant 2D-PSF kernel. The compensation is performed using a computer-simulated NCAT phantom and a flanged Jaszczak experimenta...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Symmetric and Transitive Registration of Image SequencesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper presents a method for constructing symmetric and transitive algorithms for registration of image sequences from image registration algorithms that do not have these two properties. The method is applicable to both rigid and nonrigid registration and it can be used with linear or periodic image sequences. The symmetry and transitivity properties are satisfied exactly (up to the machine precision), that is, they always hold regardless of the image type, quality, and the registration algorithm as long as the computed transformations are invertable. These two properties are especially important in motion tracking ap...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

A Based Bayesian Wavelet Thresholding Method to Enhance Nuclear ImagingEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Nuclear images are very often used to study the functionality of some organs. Unfortunately, these images have bad contrast, a weak resolution, and present fluctuations due to the radioactivity disintegration. To enhance their quality, physicians have to increase the quantity of the injected radioactive material and the acquisition time. In this paper, we propose an alternative solution. It consists in a software framework that enhances nuclear image quality and reduces statistical fluctuations. Since these images are modeled as the realization of a Poisson process, we propose a new framework that performs variance stabili...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Model-Based Analysis of Flow-Mediated Dilation and Intima-Media ThicknessEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present an end-to-end system for the automatic measurement of flow-mediated dilation (FMD) and intima-media thickness (IMT) for the assessment of the arterial function. The video sequences are acquired from a B-mode echographic scanner. A spline model (deformable template) is fitted to the data to detect the artery boundaries and track them all along the video sequence. The a priori knowledge about the image features and its content is exploited. Preprocessing is performed to improve both the visual quality of video frames for visual inspection and the performance of the segmentation algorithm without affecting the accu...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals

Line-Source Based X-Ray TomographyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Current computed tomography (CT) scanners, including micro-CT scanners, utilize a point x-ray source. As we target higher and higher spatial resolutions, the reduced x-ray focal spot size limits the temporal and contrast resolutions achievable. To overcome this limitation, in this paper we propose to use a line-shaped x-ray source so that many more photons can be generated, given a data acquisition interval. In reference to the simultaneous algebraic reconstruction technique (SART) algorithm for image reconstruction from projection data generated by an x-ray point source, here we develop a generalized SART algorithm for im...
Source: International Journal of Biomedical Imaging - June 9, 2009 Category: Radiology Source Type: journals