MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'International Journal of Biomedical Imaging' source. Sat, 20 Mar 2010 15:17:05 +0100 http://www.medworm.com/index.php?rid=3363452&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2010%2F621357.html Size Functions and Support Vector Machines are used to implement a new automatic classifier of melanocytic lesions. This is mainly based on a qualitative assessment of asymmetry, performed by halving images by several lines through the center of mass, and comparing the two halves in terms of color, mass distribution, and boundary. The program is used, at clinical level, with two thresholds, so that comparison of the two outputs produces a report of low-middle-high risk. Experimental results on 977 images, with cross-validation, are reported. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3363452 Sun, 14 Mar 2010 15:18:24 +0100 3363452 http://www.medworm.com/index.php?rid=3345229&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2010%2F308627.html Viruses are infectious agents that can cause epidemics and pandemics. The understanding of virus formation, evolution, stability, and interaction with host cells is of great importance to the scientific community and public health. Typically, a virus complex in association with its aquatic environment poses a fabulous challenge to theoretical description and prediction. In this work, we propose a differential geometry-based multiscale paradigm to model complex biomolecule systems. In our approach, the differential geometry theory of surfaces and geometric measure theory are employed as a natural means to couple the macroscopic continuum domain of the fluid mechanical description of the aquatic environment from the microscopic discrete domain of the atomistic description of the biomolecule.... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3345229 Tue, 09 Mar 2010 15:48:34 +0100 3345229 http://www.medworm.com/index.php?rid=3317478&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2010%2F341242.html Myocardial deformation and strain can be investigated using suitably encoded cine MRI that admits disambiguation of material motion. Practical limitations currently restrict the analysis to in-plane motion in cross-sections of the heart (2D + time), but the proposed method readily generalizes to 3D + time. We propose a new, promising methodology, which departs from a multiscale algorithm that exploits local scale selection so as to obtain a robust estimate for the velocity gradient tensor field. Time evolution of the deformation tensor is governed by a first-order ordinary differential equation, which is completely determined by this velocity gradient tensor field. We solve this matrix-ODE analytically and present results obtained from healthy volunteers as well as from patient data. The p... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3317478 Mon, 01 Mar 2010 16:19:44 +0100 3317478 http://www.medworm.com/index.php?rid=3300513&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F352954.html We describe a computational framework for the comprehensive assessment of contractile responses of enzymatically dissociated adult cardiac myocytes. The proposed methodology comprises the following stages: digital video recording of the contracting cell, edge preserving total variation-based image smoothing, segmentation of the smoothed images, contour extraction from the segmented images, shape representation by Fourier descriptors, and contractility assessment. The different stages are variants of mathematically sound and computationally robust algorithms very well established in the image processing community. The physiologic application of the methodology is evaluated by assessing overall contraction in enzymatically dissociated adult rat cardiocytes. Our results demonstrate the effect... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3300513 Wed, 24 Feb 2010 15:58:28 +0100 3300513 http://www.medworm.com/index.php?rid=3274682&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F847537.html Although x-ray imaging is widely used in biomedical applications, biological soft tissues have small density changes, leading to low contrast resolution for attenuation-based x-ray imaging. Over the past years, x-ray small-angle scattering was studied as a new contrast mechanism to enhance subtle structural variation within the soft tissue. In this paper, we present a detection method to extract this type of x-ray scattering data, which are also referred to as dark-field signals. The key idea is to acquire an x-ray projection multiple times with varying collimation before an x-ray detector array. The projection data acquired with a collimator of a sufficiently high collimation aspect ratio contain mainly the primary beam with little scattering, while the data acquired with an appropriately... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3274682 Tue, 16 Feb 2010 15:27:37 +0100 3274682 http://www.medworm.com/index.php?rid=3253067&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2010%2F618747.html Magnetization transfer imaging (MT) may have considerable promise for early detection and monitoring of subtle brain changes before they are apparent on conventional magnetic resonance images. At 3 Tesla (T), MT affords higher resolution and increased tissue contrast associated with macromolecules. The reliability and reproducibility of a new high-resolution MT strategy were assessed in brain images acquired from 9 healthy subjects. Repeated measures were taken for 12 brain regions of interest (ROIs): genu, splenium, and the left and right hemispheres of the hippocampus, caudate, putamen, thalamus, and cerebral white matter. Spearman's correlation coefficient, coefficient of variation, and intraclass correlation coefficient (ICC) were computed. Multivariate mixed-effects regression mod... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3253067 Tue, 09 Feb 2010 15:29:15 +0100 3253067 http://www.medworm.com/index.php?rid=3224290&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F659836.html Conclusion. High-resolution MR imaging is a very accurate method for evaluating both mural invasion and lymph node metastasis by colorectal carcinoma in surgical specimens. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3224290 Sun, 31 Jan 2010 15:20:32 +0100 3224290 http://www.medworm.com/index.php?rid=3191889&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2010%2F195274.html A method for three-dimensional (3D) reconstruction of macromolecule assembles, that is, octahedral symmetrical adapted functions (OSAFs) method, was introduced in this paper and a series of formulations for reconstruction by OSAF method were derived. To verify the feasibility and advantages of the method, two octahedral symmetrical macromolecules, that is, heat shock protein Degp24 and the Red-cell L Ferritin, were utilized as examples to implement reconstruction by the OSAF method. The schedule for simulation was designed as follows: 2000 random orientated projections of single particles with predefined Euler angles and centers of origins were generated, then different levels of noises that is signal-to-noise ratio (S/N) =0.1,0.5, and 0.8 were added. The structures reconstructed by the OS... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3191889 Thu, 21 Jan 2010 15:23:04 +0100 3191889 http://www.medworm.com/index.php?rid=3179886&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F108028.html Functional imaging based on tomographic X-ray imaging relies on the reconstruction of a temporal sequence of images which accurately reproduces the time attenuation curves of the tissue. The main constraints of these techniques are temporal resolution and dose. Using current techniques the data acquisition has to be performed fast so that the dynamic attenuation values can be regarded as static during the scan. Due to the relatively high number of repeated scans the dose per single scan has to be low yielding a poor signal-to-noise ratio (SNR) in the reconstructed images. In a previous publication a temporal interpolation scheme in the projection data space was relaxing the temporal resolution constraint. The aim of this contribution is the improvement of the SNR. A temporal smoothing term... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3179886 Sun, 17 Jan 2010 15:13:35 +0100 3179886 http://www.medworm.com/index.php?rid=3138436&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F767805.html Detection of clustered microcalcifications (MCs) in mammograms represents a significant step towards successful detection of breast cancer since their existence is one of the early signs of cancer. In this paper, a new framework that integrates Bayesian classifier and a pattern synthesizing scheme for detecting microcalcification clusters is proposed. This proposed work extracts textural, spectral, and statistical features of each input mammogram and generates models of real MCs to be used as training samples through a simplified learning phase of the Bayesian classifier. Followed by an estimation of the classifier's decision function parameters, a mammogram is segmented into the identified targets (MCs) against background (healthy tissue). The proposed algorithm has been tested using ... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3138436 Mon, 04 Jan 2010 15:14:31 +0100 3138436 http://www.medworm.com/index.php?rid=3132109&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F637867.html Flat panel detector-based cone beam breast CT (CBBCT) can provide 3D image of the scanned breast with 3D isotropic spatial resolution, overcoming the disadvantage of the structure superimposition associated with X-ray projection mammography. It is very difficult for Mammography to detect a small carcinoma (a few millimeters in size) when the tumor is occult or in dense breast. CBBCT featured with circular scan might be the most desirable mode in breast imaging due to its simple geometrical configuration and potential applications in functional imaging. An inherited large cone angle in CBBCT, however, will yield artifacts in the reconstruction images when only a single circular scan is employed. These artifacts usually manifest themselves as density drop and object geometrical distortion th... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3132109 Thu, 31 Dec 2009 15:08:03 +0100 3132109 http://www.medworm.com/index.php?rid=3132108&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F946271.html The purpose of this work is to demonstrate the functionality and performance of a PSF-based geometric distortion correction for high-field functional animal EPI. The EPI method was extended to measure the PSF and a postprocessing chain was implemented in Matlab for offline distortion correction. The correction procedure was applied to phantom and in vivo imaging of mice and rats at 9.4T using different SE-EPI and DWI-EPI protocols. Results show the significant improvement in image quality for single- and multishot EPI. Using a reduced FOV in the PSF encoding direction clearly reduced the acquisition time for PSF data by an acceleration factor of 2 or 4, without affecting the correction quality. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3132108 Thu, 31 Dec 2009 15:08:03 +0100 3132108 http://www.medworm.com/index.php?rid=3123991&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F902326.html Breast cancer is a serious threat worldwide and is the number two killer of women in the United States. The key to successful management is screening and early detection. What follows is a description of the state of the art in screening and detection for breast cancer as well as a discussion of new and emerging technologies. This paper aims to serve as a starting point for those who are not acquainted with this growing field. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3123991 Mon, 28 Dec 2009 15:08:05 +0100 3123991 http://www.medworm.com/index.php?rid=3083873&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F636240.html This paper describes an algorithm for extracting pulmonary vascular trees (arteries plus veins) from three-dimensional (3D) thoracic computed tomographic (CT) images. The algorithm integrates tube enhancement filter and traversal approaches which are based on eigenvalues and eigenvectors of a Hessian matrix to extract thin peripheral segments as well as thick vessels close to the lung hilum. The resultant algorithm was applied to a simulation data set and 44 scans from 22 human subjects imaged via multidetector-row CT (MDCT) during breath holds at 85% and 20% of their vital capacity. A quantitative validation was performed with more than 1000 manually identified points selected from inside the vessel segments to assess true positives (TPs) and 1000 points randomly placed outside of... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3083873 Mon, 14 Dec 2009 15:11:36 +0100 3083873 http://www.medworm.com/index.php?rid=3065738&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F313517.html This paper presents a novel method for the generation of myocardial wall surface meshes from segmented 3D MR images, which typically have strongly anisotropic voxels. The method maps a premeshed sphere to the surface of the segmented object. The mapping is defined by the gradient field of the solution of the Laplace equation between the sphere and the surface of the object. The same algorithm is independently used to generate the surface meshes of the epicardium and endocardium of the four cardiac chambers. The generated meshes are smooth despite the strong voxel anisotropy, which is not the case for the marching cubes and related methods. While the proposed method generates more regular mesh triangles than the marching cubes and allows for a complete control of the number of triangles, th... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=3065738 Tue, 08 Dec 2009 15:09:18 +0100 3065738 http://www.medworm.com/index.php?rid=2998191&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F125871.html 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2998191 Tue, 17 Nov 2009 15:21:04 +0100 2998191 http://www.medworm.com/index.php?rid=2957408&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F156234.html 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 desired number of clusters. The method was experimentally validated with synthetic and real image data. The experiments showed that our method was able to automatically extra... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2957408 Wed, 04 Nov 2009 15:37:37 +0100 2957408 http://www.medworm.com/index.php?rid=2937286&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F756897.html 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 denoising process. The proposed algorithm also uses a local Principal Component Analysis decomposition as a postprocessing step to remove more noise by using information not on... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2937286 Thu, 29 Oct 2009 15:11:40 +0100 2937286 http://www.medworm.com/index.php?rid=2914649&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F680508.html 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 percentage of 87.28%. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2914649 Thu, 22 Oct 2009 14:12:39 +0100 2914649 http://www.medworm.com/index.php?rid=2870646&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F968986.html 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 performed on both synthetic and real data, by means of suitable gold standard. The best approach is then applied on a number of time lapses for the segmentation and counti... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2870646 Thu, 08 Oct 2009 10:22:47 +0100 2870646 http://www.medworm.com/index.php?rid=2849459&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F843160.html 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 is constrained by anatomical information extracted from a high resolution anatomical procedure such as magnetic resonance imaging (MRI). This structural anatomy-based reg... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2849459 Thu, 01 Oct 2009 17:36:09 +0100 2849459 http://www.medworm.com/index.php?rid=2817671&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F960573.html 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 calibration are implemented before reconstruction. A method which utilizes a wire phantom to estimate the residual horizontal offset of the detector is proposed, and 1D p... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2817671 Tue, 22 Sep 2009 17:21:02 +0100 2817671 http://www.medworm.com/index.php?rid=2780755&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F715124.html 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 the same tissue. MS lesions are identified as outlier Gaussian components and are grouped to form a new class in addition to the healthy t... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2780755 Thu, 10 Sep 2009 17:17:07 +0100 2780755 http://www.medworm.com/index.php?rid=2769496&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F723912.html 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. Using this result, it is possible to obtain an exact statistic which keeps the 5% false positive rate. Extensive Monte Carlo simulations show that the sandwich is robust... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2769496 Sun, 06 Sep 2009 17:10:22 +0100 2769496 http://www.medworm.com/index.php?rid=2745145&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F538389.html 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2745145 Sun, 30 Aug 2009 12:40:39 +0100 2745145 http://www.medworm.com/index.php?rid=2732675&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F149079.html 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 symmetries in circular cone-beam projection layout, and a fast reconstruction for large data volume can be implemented by packing the subsets of projection data into the RGBA chan... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2732675 Wed, 26 Aug 2009 12:48:39 +0100 2732675 http://www.medworm.com/index.php?rid=2723806&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F269525.html 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 across transverse slices in the central brain region, and JSRIC is able to rectify the flip angles to generate calibrated T1-Maps. In order to generate an accurate T1-Map, the... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2723806 Sun, 23 Aug 2009 12:40:19 +0100 2723806 http://www.medworm.com/index.php?rid=2704799&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F231539.html 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 physiologic processes governing the therapeutic index of antiproliferative anticancer therapies. The temporal ordering among these relationships, paramount to determining c... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2704799 Mon, 17 Aug 2009 11:02:31 +0100 2704799 http://www.medworm.com/index.php?rid=2686933&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F281615.html 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 correspondences. An extensive validation of the algorithm was performed on T1-weighted SPGR MR brain images from the NIREP evaluation database. The results were compared with resu... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2686933 Tue, 11 Aug 2009 11:17:24 +0100 2686933 http://www.medworm.com/index.php?rid=2669700&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F528639.html 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 uniprocessor system. This paper presents a parallelization framework using OpenMP runtime support and parallel MATLAB to execute such computationally intensive programs. The... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2669700 Wed, 05 Aug 2009 11:38:19 +0100 2669700 http://www.medworm.com/index.php?rid=2628743&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F464235.html 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 simulation indicates that a (9 mm)3 tumor inside a breast phantom can be reliably depicted, assuming moderate temperature mapping accuracy of 0.5∘C. (Source: Int... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2628743 Thu, 23 Jul 2009 11:34:53 +0100 2628743 http://www.medworm.com/index.php?rid=2624243&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F294545.html 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 significantly speed up the reconstruction process and improve the image quality of FMT. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2624243 Wed, 22 Jul 2009 11:37:30 +0100 2624243 http://www.medworm.com/index.php?rid=2582911&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F406854.html 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 real imaging including fatty tissue, glandular tissue, and tumors. An exponential-form of nonlinear material model is applied. The effect of noise is taken into account.... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2582911 Thu, 09 Jul 2009 11:33:53 +0100 2582911 http://www.medworm.com/index.php?rid=2482561&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F983794.html 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 tags within myocardium. The method we have developed for endocardial and epicardial contours detection is based on the use of texture analysis and active contours models.... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2482561 Wed, 17 Jun 2009 08:08:54 +0100 2482561 http://www.medworm.com/index.php?rid=2482560&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F718157.html 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 quality of reconstruction is substantially improved. The proposed method shows promise in tumor localization and quantification. (Source: International Journal of Biomedical Im... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2482560 Wed, 17 Jun 2009 08:08:54 +0100 2482560 http://www.medworm.com/index.php?rid=2466657&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F526906.html 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. QBI reconstructs the diffusion orientation distribution function (ODF), a spherical function that has its maxima agreeing with the underlying fiber populations. In this pap... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466657 Tue, 09 Jun 2009 21:58:47 +0100 2466657 http://www.medworm.com/index.php?rid=2466656&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F143238.html 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 to affect task performance for which this region is significantly solicited. Here we applied rTMS to test the hypothesis that the DL-PFC stimulation influences monitoring ... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466656 Tue, 09 Jun 2009 21:58:47 +0100 2466656 http://www.medworm.com/index.php?rid=2466655&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F628718.html 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 test this hypothesis by measuring BOLD-perfusion coupling ratios in spatially averaged signals over V1 during monocular and binocular visual stimulation. It was found that, ... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466655 Tue, 09 Jun 2009 21:58:47 +0100 2466655 http://www.medworm.com/index.php?rid=2466654&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F752340.html 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. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466654 Tue, 09 Jun 2009 21:58:47 +0100 2466654 http://www.medworm.com/index.php?rid=2466653&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F274164.html 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 well as correlation of the target and speckle are naturally accounted for in the MMSE reconstruction algorithm. Thus, the reconstruction process unifies the interpolatio... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466653 Tue, 09 Jun 2009 21:58:47 +0100 2466653 http://www.medworm.com/index.php?rid=2466652&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F827152.html 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 phase-contrast techniques. Feasibility is demonstrated via numerical simulation. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466652 Tue, 09 Jun 2009 21:58:47 +0100 2466652 http://www.medworm.com/index.php?rid=2466651&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F368406.html 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 the q-ball local maxima. A sophisticated mask of propagation computed from a T1-weighted image perfectly aligned with the diffusion data prevents the particles from crossin... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466651 Tue, 09 Jun 2009 21:58:47 +0100 2466651 http://www.medworm.com/index.php?rid=2466650&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F590183.html 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 filter in terms of denoising quality and computation time. Comparison with wellestablished methods, such as nonlinear diffusion filter and total variation minimization, show... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466650 Tue, 09 Jun 2009 21:58:47 +0100 2466650 http://www.medworm.com/index.php?rid=2466649&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F423192.html 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 tractography suggested direct connections which were not included in the original analyses. We therefore conclude that DTI-based fiber tractography can be a valuable tool to study t... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466649 Tue, 09 Jun 2009 21:58:47 +0100 2466649 http://www.medworm.com/index.php?rid=2466648&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F427989.html 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 limited-angle scan. These results improve the classical theory of Hamaker et al. (1980). (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466648 Tue, 09 Jun 2009 21:58:47 +0100 2466648 http://www.medworm.com/index.php?rid=2466647&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F218519.html 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466647 Tue, 09 Jun 2009 21:58:47 +0100 2466647 http://www.medworm.com/index.php?rid=2466646&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F218582.html (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466646 Tue, 09 Jun 2009 21:58:47 +0100 2466646 http://www.medworm.com/index.php?rid=2466645&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F297089.html 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 percent. Using such pseudorandom trajectories, aliasing caused by under-sampling manifests itself as incoherent noise. In this paper, a genetic algorithm (GA) is formulated an... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466645 Tue, 09 Jun 2009 21:58:47 +0100 2466645 http://www.medworm.com/index.php?rid=2466644&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F591618.html 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 total attenuation coefficient and the scattering anisotropy factor are determined with precisions within experimental error margins of 5% and 2%, respectively. Read... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466644 Tue, 09 Jun 2009 21:58:47 +0100 2466644 http://www.medworm.com/index.php?rid=2466643&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F763028.html 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466643 Tue, 09 Jun 2009 21:58:47 +0100 2466643 http://www.medworm.com/index.php?rid=2466642&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F184123.html 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 problem, which can be solved with a nonlinear optimization algorithm. In the presence of substantial noise, a modified approach offers edge-preserving denoising by allowing for... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466642 Tue, 09 Jun 2009 21:58:47 +0100 2466642 http://www.medworm.com/index.php?rid=2466641&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F516359.html 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 measured with PET (average ΔCBF of 21.5±8.2% for FAIR versus 28.2±12.8% for PET at maximum stimulation intensity). Nonetheless, there was a strong ... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466641 Tue, 09 Jun 2009 21:58:47 +0100 2466641 http://www.medworm.com/index.php?rid=2466640&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F242841.html 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 propose a novel method for estimating the unmeasured data and reducing the intensity drop artifacts. Each CB projection is analyzed in the Radon space via Grangeat's first... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466640 Tue, 09 Jun 2009 21:58:47 +0100 2466640 http://www.medworm.com/index.php?rid=2466639&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F513478.html 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466639 Tue, 09 Jun 2009 21:58:47 +0100 2466639 http://www.medworm.com/index.php?rid=2466638&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F759354.html 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 extraction of the lesion in the feature available based mainly on the gradient function. The evaluations of the classification of these lesions are very briefly outlined in thi... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466638 Tue, 09 Jun 2009 21:58:47 +0100 2466638 http://www.medworm.com/index.php?rid=2466637&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F379486.html 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466637 Tue, 09 Jun 2009 21:58:47 +0100 2466637 http://www.medworm.com/index.php?rid=2466636&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F341684.html 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 the correct image is estimated; this ordering can be estimated based on the undersampled measured data. Theory and example applications of the method for accelerating my... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466636 Tue, 09 Jun 2009 21:58:47 +0100 2466636 http://www.medworm.com/index.php?rid=2466635&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F769195.html 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 the condition number of the system, and is therefore more revealing of system performance. This figure is then compared with simulated results of several SPECT systems a... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466635 Tue, 09 Jun 2009 21:58:47 +0100 2466635 http://www.medworm.com/index.php?rid=2466634&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F174283.html 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 summarize important properties of the cone beam transform for three-dimensional solenoidal vector fields and then propose a solution approach based on the method of approximat... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466634 Tue, 09 Jun 2009 21:58:47 +0100 2466634 http://www.medworm.com/index.php?rid=2466633&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F941729.html 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 for up to 1 hour. The CL responses were completely abolished in the presence of superoxide dismutase and catalase, suggesting the primary involvement of superoxide and hyd... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466633 Tue, 09 Jun 2009 21:58:47 +0100 2466633 http://www.medworm.com/index.php?rid=2466632&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F806705.html 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 experimental phantom. The preliminary results demonstrate an improvement in image quality and quantity accuracy with increased image contrast (25% increase compared to uncompens... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466632 Tue, 09 Jun 2009 21:58:47 +0100 2466632 http://www.medworm.com/index.php?rid=2466631&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F686875.html 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 applications since physically incorrect deformations might be obtained if the registration algorithm is not symmetric and transitive. The method was tested on two sequences... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466631 Tue, 09 Jun 2009 21:58:47 +0100 2466631 http://www.medworm.com/index.php?rid=2466630&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F506120.html 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 stabilizing of the Poisson process before applying an adapted Bayesian wavelet shrinkage. The proposed method has been applied on real images, and it has proved its performance.... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466630 Tue, 09 Jun 2009 21:58:47 +0100 2466630 http://www.medworm.com/index.php?rid=2466629&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2008%2F738545.html 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 accuracy of the measurements. The system allows real-time processing as well as a high level of interactivity with the user. This is obtained by a graphical user interface (G... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466629 Tue, 09 Jun 2009 21:58:47 +0100 2466629 http://www.medworm.com/index.php?rid=2466628&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2Fjournals%2Fijbi%2F2009%2F534516.html 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 image reconstruction from projection data generated by an x-ray line source. Our numerical simulation results demonstrate the feasibility of our novel line-source based x-r... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2466628 Tue, 09 Jun 2009 21:58:47 +0100 2466628 http://www.medworm.com/index.php?rid=2372405&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2009%2F534516 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 image reconstruction from projection data generated by an x-ray line source. Our numerical simulation results demonstrate the feasibility of our novel line-source based x-r... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2372405 Wed, 29 Apr 2009 04:28:58 +0100 2372405 http://www.medworm.com/index.php?rid=2316119&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F738545 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 accuracy of the measurements. The system allows real-time processing as well as a high level of interactivity with the user. This is obtained by a graphical user interface (G... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2316119 Thu, 09 Apr 2009 16:23:45 +0100 2316119 http://www.medworm.com/index.php?rid=2291752&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F686875 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 applications since physically incorrect deformations might be obtained if the registration algorithm is not symmetric and transitive. The method was tested on two sequences... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2291752 Fri, 27 Mar 2009 17:14:26 +0100 2291752 http://www.medworm.com/index.php?rid=2291750&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2009%2F506120 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 stabilizing of the Poisson process before applying an adapted Bayesian wavelet shrinkage. The proposed method has been applied on real images, and it has proved its performance.... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2291750 Fri, 27 Mar 2009 17:14:26 +0100 2291750 http://www.medworm.com/index.php?rid=2234775&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F806705 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 experimental phantom. The preliminary results demonstrate an improvement in image quality and quantity accuracy with increased image contrast (25% increase compared to uncompens... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2234775 Thu, 05 Mar 2009 10:09:27 +0100 2234775 http://www.medworm.com/index.php?rid=2212156&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F941729 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 for up to 1 hour. The CL responses were completely abolished in the presence of superoxide dismutase and catalase, suggesting the primary involvement of superoxide and hyd... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2212156 Wed, 25 Feb 2009 09:56:02 +0100 2212156 http://www.medworm.com/index.php?rid=2153357&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F174283 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 summarize important properties of the cone beam transform for three-dimensional solenoidal vector fields and then propose a solution approach based on the method of approximat... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2153357 Tue, 03 Feb 2009 13:19:34 +0100 2153357 http://www.medworm.com/index.php?rid=2056648&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F769195 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 the condition number of the system, and is therefore more revealing of system performance. This figure is then compared with simulated results of several SPECT systems a... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2056648 Mon, 22 Dec 2008 12:54:05 +0100 2056648 http://www.medworm.com/index.php?rid=2028828&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F341684 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 the correct image is estimated; this ordering can be estimated based on the undersampled measured data. Theory and example applications of the method for accelerating my... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=2028828 Thu, 11 Dec 2008 15:03:03 +0100 2028828 http://www.medworm.com/index.php?rid=1964736&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F379486 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1964736 Mon, 17 Nov 2008 11:41:05 +0100 1964736 http://www.medworm.com/index.php?rid=1909092&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F759354 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 extraction of the lesion in the feature available based mainly on the gradient function. The evaluations of the classification of these lesions are very briefly outlined in thi... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1909092 Mon, 27 Oct 2008 15:13:30 +0100 1909092 http://www.medworm.com/index.php?rid=1892457&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F513478 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1892457 Tue, 21 Oct 2008 16:13:54 +0100 1892457 http://www.medworm.com/index.php?rid=1860212&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F242841 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 propose a novel method for estimating the unmeasured data and reducing the intensity drop artifacts. Each CB projection is analyzed in the Radon space via Grangeat's first... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1860212 Wed, 08 Oct 2008 17:16:47 +0100 1860212 http://www.medworm.com/index.php?rid=1826949&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F516359 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 measured with PET (average ΔCBF of 21.5±8.2% for FAIR versus 28.2±12.8% for PET at maximum stimulation intensity). Nonetheless, there was a strong ... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1826949 Thu, 25 Sep 2008 18:15:29 +0100 1826949 http://www.medworm.com/index.php?rid=1770862&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F184123 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 problem, which can be solved with a nonlinear optimization algorithm. In the presence of substantial noise, a modified approach offers edge-preserving denoising by allowing for... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1770862 Sun, 07 Sep 2008 14:15:35 +0100 1770862 http://www.medworm.com/index.php?rid=1643147&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F763028 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1643147 Tue, 22 Jul 2008 14:55:36 +0100 1643147 http://www.medworm.com/index.php?rid=1594282&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F591618 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 total attenuation coefficient and the scattering anisotropy factor are determined with precisions within experimental error margins of 5% and 2%, respectively. Read... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1594282 Tue, 08 Jul 2008 12:09:55 +0100 1594282 http://www.medworm.com/index.php?rid=1556765&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F297089 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 percent. Using such pseudorandom trajectories, aliasing caused by under-sampling manifests itself as incoherent noise. In this paper, a genetic algorithm (GA) is formulated an... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1556765 Tue, 01 Jul 2008 11:34:59 +0100 1556765 http://www.medworm.com/index.php?rid=1489832&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F25182 Segmentation of molecular images is a difficult task due to the low signal-to-noise ratio of images. A novel two-dimensional fuzzy C-means (2DFCM) algorithm is proposed for the molecular image segmentation. The 2DFCM algorithm is composed of three stages. The first stage is the noise suppression by utilizing a method combining a Gaussian noise filter and anisotropic diffusion techniques. The second stage is the texture energy characterization using a Gabor wavelet method. The third stage is introducing spatial constraints provided by the denoising data and the textural information into the two-dimensional fuzzy clustering. The incorporation of intensity and textural information allows the 2DFCM algorithm to produce satisfactory segmentation results for images corrupted by noise (outliers) ... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489832 Tue, 03 Jun 2008 22:25:05 +0100 1489832 http://www.medworm.com/index.php?rid=1489831&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F167078 By plotting response times of young and older adults across a variety of tasks, Brinley spurred investigation and debate into the theory of general cognitive slowing. Though controversial, Brinley plots can assess between-task differences, the impact of increasing task demand, and the relationship between responses in two groups of subjects. Since a relationship exists between response times and the blood-oxygen level dependent (BOLD) signal of functional MRI (fMRI), Brinley's plotting method could be applied as a meta-analysis tool in fMRI studies of aging. Here, fledgling “Peiffer plots” are discussed for their potential impact on understanding general cognitive brain activity in aging. Preliminary results suggest that general cognitive slowing may be localized at the... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489831 Tue, 03 Jun 2008 22:25:05 +0100 1489831 http://www.medworm.com/index.php?rid=1489830&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F48989 We present an approach based on the improved Levenberg Marquardt (LM) algorithm of backpropagation (BP) neural network to estimate the light source position in bioluminescent imaging. For solving the forward problem, the table-based random sampling algorithm (TBRS), a fast Monte Carlo simulation method we developed before, is employed here. Result shows that BP is an effective method to position the light source. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489830 Tue, 03 Jun 2008 22:25:05 +0100 1489830 http://www.medworm.com/index.php?rid=1489829&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F65641 Parametric images generated from dynamic positron emission tomography (PET) studies are useful for presenting functional/biological information in the 3-dimensional space, but usually suffer from their high sensitivity to image noise. To improve the quality of these images, we proposed in this study a modified linear least square (LLS) fitting method named cLLS that incorporates a clustering-based spatial constraint for generation of parametric images from dynamic PET data of high noise levels. In this method, the combination of K-means and hierarchical cluster analysis was used to classify dynamic PET data. Compared with conventional LLS, cLLS can achieve high statistical reliability in the generated parametric images without incurring a high computational burden. The effectiveness of the... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489829 Tue, 03 Jun 2008 22:25:05 +0100 1489829 http://www.medworm.com/index.php?rid=1489828&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F90216 We propose a semi-automatic thalamus and thalamus nuclei segmentation algorithm from Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) based on the mean-shift algorithm. Comparing with existing thalamus segmentation algorithms which are mainly based on K-means algorithm, our mean-shift based algorithm is more flexible and adaptive. It does not assume a Gaussian distribution or a fixed number of clusters. Furthermore, the single parameter in the mean-shift based algorithm supports hierarchical clustering naturally. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489828 Tue, 03 Jun 2008 22:25:05 +0100 1489828 http://www.medworm.com/index.php?rid=1489827&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F17131 Conclusion. PET/CT is of greater value in characterization of lung masses than PET and CT performed separately. The examination of lung tumor can be further specified by the correlation between the size of pulmonary malignant neoplasm and the ROI's SUVmax. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489827 Tue, 03 Jun 2008 22:25:05 +0100 1489827 http://www.medworm.com/index.php?rid=1489826&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F74143 In this study, phantom experiments have been conducted using a prototyped Stokes polarization imaging device. In particular, several types of phantoms, consisting of polystyrene latex spheres in various diameters, were prepared to simulate different conditions of epidermal layer of skin. The experimental results from phantom studies and a plant cell study show that the classification performance using Stokes images is significantly improved over that using the intensity image only. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489826 Tue, 03 Jun 2008 22:25:05 +0100 1489826 http://www.medworm.com/index.php?rid=1489825&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F15635 In this work, we propose a simple and effective scheme to incorporate prior knowledge about the sources of interest (SOIs) in independent component analysis (ICA) and apply the method to estimate brain activations from functional magnetic resonance imaging (fMRI) data. We name the proposed method as feature-selective ICA since it incorporates the features in the sample space of the independent components during ICA estimation. The feature-selective scheme is achieved through a filtering operation in the source sample space followed by a projection onto the demixing vector space by a least squares projection in an iterative ICA process. We perform ICA estimation of artificial activations superimposed into a resting state fMRI dataset to show that the feature-selective scheme improves the de... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489825 Tue, 03 Jun 2008 22:25:05 +0100 1489825 http://www.medworm.com/index.php?rid=1489824&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F64954 (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489824 Tue, 03 Jun 2008 22:25:05 +0100 1489824 http://www.medworm.com/index.php?rid=1489823&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F372125 We studied whether five sessions of 10 Hz repetitive transcranial magnetic stimulation (rTMS treatment) applied over the dorsolateral prefrontal cortex (DLPFC) or the primary motor cortex (MC) in advanced Parkinson's disease (PD) patients would have any effect on L-dopa-induced dyskinesias and cortical excitability. We aimed at a randomised, controlled study. Single-pulse transcranial magnetic stimulation (TMS), paired-pulse transcranial magnetic stimulation, and the Unified Parkinson's Disease Rating Scale (UPDRS parts III and IV) were performed prior to, immediately after, and one week after an appropriate rTMS treatment. Stimulation of the left DLPFC induced a significant motor cortex depression and a trend towards the improvement of L-dopa-induced dyskinesias. (Source: I... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489823 Tue, 03 Jun 2008 22:25:05 +0100 1489823 http://www.medworm.com/index.php?rid=1489822&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F63750 An SPECT image can be approximated as the convolution of the ground truth spatial radioactivity with the system point spread function (PSF). The PSF of an SPECT system is determined by the combined effect of several factors, including the gamma camera PSF, scattering, attenuation, and collimator response. It is hard to determine the SPECT system PSF analytically, although it may be measured experimentally. We formulated a blind deblurring reconstruction algorithm to estimate both the spatial radioactivity distribution and the system PSF from the set of blurred projection images. The algorithm imposes certain spatial-frequency domain constraints on the reconstruction volume and the PSF and does not otherwise assume knowledge of the PSF. The algorithm alternates between two iterative update ... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489822 Tue, 03 Jun 2008 22:25:05 +0100 1489822 http://www.medworm.com/index.php?rid=1489821&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F320195 Using geodesics for inferring white matter fibre tracts from diffusion-weighted MR data is an attractive method for at least two reasons: (i) the method optimises a global criterion, and hence is less sensitive to local perturbations such as noise or partial volume effects, and (ii) the method is fast, allowing to infer on a large number of connexions in a reasonable computational time. Here, we propose an improved fast marching algorithm to infer on geodesic paths. Specifically, this procedure is designed to achieve accurate front propagation in an anisotropic elliptic medium, such as DTI data. We evaluate the numerical performance of this approach on simulated datasets, as well as its robustness to local perturbation induced by fiber crossing. On real data, we demonstrate the feasibility... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489821 Tue, 03 Jun 2008 22:25:05 +0100 1489821 http://www.medworm.com/index.php?rid=1489820&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F672582 Noninvasive techniques such as functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) have provided insight into understanding how neural connections are altered in consequence to cerebrovascular injury. The first part of this review will briefly survey some of the methodological issues and limitations related to noninvasive poststroke motor recovery studies. The second section will investigate some of the different neural mechanisms that underlie neurorehabilitation in stroke patients. The third part will explore our current understanding of motor memory processing, describe the neural structures that subserve motor memory consolidation, and discuss the current literature related to memory reconsolidation in healthy adults. Lastly, this paper will suggest... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489820 Tue, 03 Jun 2008 22:25:05 +0100 1489820 http://www.medworm.com/index.php?rid=1489819&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F789539 Previous studies in nonhuman primates and cats have shown that the pulvinar receives input from various cortical and subcortical areas involved in vision. Although the contribution of the pulvinar to human vision remains to be established, anatomical tracer and electrophysiological animal studies on cortico-pulvinar circuits suggest an important role of this structure in visual spatial attention, visual integration, and higher-order visual processing. Because methodological constraints limit investigations of the human pulvinar's function, its role could, up to now, only be inferred from animal studies. In the present study, we used an innovative imaging technique, Diffusion Tensor Imaging (DTI) tractography, to determine cortical and subcortical connections of the human pulvin... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489819 Tue, 03 Jun 2008 22:25:05 +0100 1489819 http://www.medworm.com/index.php?rid=1489818&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F73198 (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489818 Tue, 03 Jun 2008 22:25:05 +0100 1489818 http://www.medworm.com/index.php?rid=1489817&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F24826 We propose a new context-sensitive active contour for 2D corpus callosum segmentation. After a seed contour consisting of interconnected parts is being initialized by the user, each part will start to deform according to its own motion law derived from high-level prior knowledge, and is constantly aware of its own orientation and destination during the deformation process. Experimental results demonstrate the accuracy and robustness of our algorithm. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489817 Tue, 03 Jun 2008 22:25:05 +0100 1489817 http://www.medworm.com/index.php?rid=1489816&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F10693 Using the backprojection filtration (BPF) and filtered backprojection (FBP) approaches, respectively, we prove that with cone-beam CT the interior problem can be exactly solved by analytic continuation. The prior knowledge we assume is that a volume of interest (VOI) in an object to be reconstructed is known in a subregion of the VOI. Our derivations are based on the so-called generalized PI-segment (chord). The available projection onto convex set (POCS) algorithm and singular value decomposition (SVD) method can be applied to perform the exact interior reconstruction. These results have many implications in the CT field and can be extended to other tomographic modalities, such as SPECT/PET, MRI. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489816 Tue, 03 Jun 2008 22:25:05 +0100 1489816 http://www.medworm.com/index.php?rid=1489815&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2007%2F87319 Here we propose a cone-beam composite-circling mode to solve the quasi-short object problem, which is to reconstruct a short portion of a long object from longitudinally truncated cone-beam data involving the short object. In contrast to the saddle curve cone-beam scanning, the proposed scanning mode requires that the X-ray focal spot undergoes a circular motion in a plane facing the short object, while the X-ray source is rotated in the gantry main plane. Because of the symmetry of the proposed mechanical rotations and the compatibility with the physiological conditions, this new mode has significant advantages over the saddle curve from perspectives of both engineering implementation and clinical applications. As a feasibility study, a backprojection filtration (BPF) algorithm is develop... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489815 Tue, 03 Jun 2008 22:25:05 +0100 1489815 http://www.medworm.com/index.php?rid=1489814&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F526906 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. QBI reconstructs the diffusion orientation distribution function (ODF), a spherical function that has its maxima agreeing with the underlying fiber populations. In this pap... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489814 Tue, 03 Jun 2008 22:25:05 +0100 1489814 http://www.medworm.com/index.php?rid=1489813&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F143238 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 to affect task performance for which this region is significantly solicited. Here we applied rTMS to test the hypothesis that the DL-PFC stimulation influences monitoring ... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489813 Tue, 03 Jun 2008 22:25:05 +0100 1489813 http://www.medworm.com/index.php?rid=1489812&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F628718 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 test this hypothesis by measuring BOLD-perfusion coupling ratios in spatially averaged signals over V1 during monocular and binocular visual stimulation. It was found that, ... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489812 Tue, 03 Jun 2008 22:25:05 +0100 1489812 http://www.medworm.com/index.php?rid=1489811&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F752340 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. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489811 Tue, 03 Jun 2008 22:25:05 +0100 1489811 http://www.medworm.com/index.php?rid=1489810&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F274164 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 well as correlation of the target and speckle are naturally accounted for in the MMSE reconstruction algorithm. Thus, the reconstruction process unifies the interpolatio... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489810 Tue, 03 Jun 2008 22:25:05 +0100 1489810 http://www.medworm.com/index.php?rid=1489809&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F827152 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 phase-contrast techniques. Feasibility is demonstrated via numerical simulation. (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489809 Tue, 03 Jun 2008 22:25:05 +0100 1489809 http://www.medworm.com/index.php?rid=1489808&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F368406 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 the q-ball local maxima. A sophisticated mask of propagation computed from a T1-weighted image perfectly aligned with the diffusion data prevents the particles from crossin... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489808 Tue, 03 Jun 2008 22:25:05 +0100 1489808 http://www.medworm.com/index.php?rid=1489807&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F590183 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 filter in terms of denoising quality and computation time. Comparison with wellestablished methods, such as nonlinear diffusion filter and total variation minimization, show... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489807 Tue, 03 Jun 2008 22:25:05 +0100 1489807 http://www.medworm.com/index.php?rid=1489806&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F423192 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 tractography suggested direct connections which were not included in the original analyses. We therefore conclude that DTI-based fiber tractography can be a valuable tool to study t... International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489806 Tue, 03 Jun 2008 22:25:05 +0100 1489806 http://www.medworm.com/index.php?rid=1489805&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F427989 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 limited-angle scan. These results improve the classical theory of Hamaker et al. (1980). (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489805 Tue, 03 Jun 2008 22:25:05 +0100 1489805 http://www.medworm.com/index.php?rid=1489804&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F218519 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) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489804 Tue, 03 Jun 2008 22:25:05 +0100 1489804 http://www.medworm.com/index.php?rid=1489803&cid=s_37041_37_f&fid=37041&url=http%3A%2F%2Fwww.hindawi.com%2FGetArticle.aspx%3Fdoi%3D10.1155%2F2008%2F218582 (Source: International Journal of Biomedical Imaging) International Journal of Biomedical Imaging journals http://www.medworm.com/rss/comments.php?id=1489803 Tue, 03 Jun 2008 22:25:05 +0100 1489803