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This paper describes an electrical model of the ventricles incorporating real geometry and motion. Cardiac geometry and motion is obtained from segmentations of multiple-slice MRI time sequences. A static heart model developed previously is deformed to match the observed geometry using a novel shape registration algorithm. The resulting electrocardiograms and body surface potential maps are compared...
In clinical first-pass myocardial perfusion studies, physiological and patient motions are inevitable. Such motions impair the sensitivity and reliability in assessing myocardial perfusion abnormalities. The current study aims to correct the misregistration of myocardium during first-pass perfusion imaging by using a normalized mutual information approach. Multi-slice registrations were performed...
High-dimensional deformable registration of MRI brain images is presented here. The deformation is driven by local forces estimated from point similarities based on joint histogram and with the use of prior information obtained from tissue probability maps available in selected commonly used brain atlases. Three point similarity measures are tested in an experiment with data obtained from standard...
A semi-automatic multiple-stage segmentation scheme of brainstem and cerebellum is proposed in this paper. This proposed scheme contains a modified scale-based fuzzy connectedness (FC) algorithm, a morphology operator, Chain code, and active contour mode (ACM). A modified scale-based FC is utilized to delivery a rough segmentation, a morphology operator and Chain code are used to compensate the uncompleted...
The use of two powerful classification techniques (boosting and SVM) is explored for the segmentation of white-matter lesions in the MRI scans of human brain. Simple features are generated from proton density (PD) scans. Radial basis function (RBF) based Adaboost technique and support vector machines (SVM) are employed for this task. The classifiers are trained on severe, moderate and mild cases....
In vivo small animal imaging provides a powerful tool for the study of a variety of diseases. Magnetic resonance imaging (MRI) has become an established technology for the assessment of therapies. In this study, we used high-resolution MRI to evaluate polycystic kidney disease (PKD) in transgenic mice. We used a customized mouse coil to acquire serial MR images from both wide-type and transgenic PKD...
This paper describes an approach to fine scale non-rigid registration for mapping patterns of tissue volume loss in serial MRI studies of the brain. Specifically it addresses the important confound of diffuse tissue contrast changes which can influence local sub-voxel estimates of volume change. Such changes can be induced by neurodegenerative or neurodevelopmental processes, which not only modify...
Blood oxygenation level dependent (BOLD) functional MRI and near infrared optical tomography have been widely used to investigate hemodynamic responses to functional stimulation in the human brain. In this paper, we present a complete methodology for integrating the two imaging modalities to study the underlying physiological mechanism of the hemodynamic response in primary visual cortex. Using a...
Parallel imaging using multiple phased-array coils and receiver channels has become an effective approach to high-speed magnetic resonance imaging (MRI). To obtain high spatiotemporal resolution, the k-space is subsampled and later interpolated using multiple channel data. Higher subsampling factors result in faster image acquisition. However, the subsampling factors are upper-bounded by the number...
We have been developing a computer-aided diagnosis (CAD) system for distinguishing the cirrhosis in MR images by shape and texture analysis. Two shape features are calculated from a segmented liver region, and seven texture features are quantified by using grey level difference method (GLDM) within the small region-of-interests (ROIs). The degree of cirrhosis is derived from integrating the shape...
Invasive intracranial electroencephalography (EEG) studies help identify the epileptogenic focus and assess if the identified zone overlies eloquent cortex by means of cortical stimulation. Proper interpretation and use of the intracranial recording/stimulation studies requires an effective display of multimodal information. We developed a software system which can combine the patient's segmented...
The approach to solve the inverse problem of electrocardiography presented here is using a computer model of the individual heart of a patient. It is based on a 3D-MRI dataset. Electrophysiologically important tissue classes are incorporated using rules. Source distributions inside the heart are simulated using a cellular automaton. Finite element method is used to calculate the corresponding body...
This paper presents an approach for automatically delineating the borders of human primary visual cortex and finding ridges of maximal response due to static phase-encoding stimuli on fMRI t-statistical maps via dynamic programming. The sensitivity of such an approach to the choice of initial starting and ending points and the identification of the ridge path over a wide response region are addressed...
A class of methods of MR image intensity correction extracts the sensitivity map from the image. This usually causes the edge enhancement artifact in the corrected image. A novel method of extrapolating the image in advance is proposed to reduce this effect significantly. The closest point algorithm is used to perform extrapolation
This paper derives and implements a method for recovering MRI signal losses caused by susceptibility-induced magnetic field gradients (SFGs) in regions with large static field inhomogeneities in echo-planar imaging (EPI). Factor to account for SFGs was added in a traditional EPI equation, which was a simple Fourier transform (FT) for expressing the actual k-space data of an EPI scan. The inverse calculation...
In the process that MR signal is quadrature demodulated, the initial phases of sinusoid and cosinusoid used as demodulation reference signal exist errors, which results in artifacts in the image. It is typically overcome through precise control of the initial phases with the help of the special hardware, but the errors are not reduced completely. In this work, a method based on reference scan is proposed...
Parallel imaging using multiple receiver coils has emerged as an effective tool to reduce imaging time in various MRI applications. Although several different image reconstruction methods have been developed and demonstrated to be successful for Cartesian k-space trajectories, there is a lack of efficient reconstruction methods for arbitrary trajectories. In this paper, we formulate the reconstruction...
In magnetic resonance imaging, multi-channel phased array coils enjoy a high signal to noise ratio (SNR) and better parallel imaging performance. But with the increase in number of channels, the reconstruction time and requirement for computer memory become inevitable problems. In this work, principle component analysis is applied to reduce the size of data and protect the performance of parallel...
One of the most common artifacts for echo planar imaging is the ghost artifact, typically overcome with the aid of a reference scan preceding the actual image acquisition. In this work, we describe an automated free-scan-reference method for reducing ghost artifact using image-based correction. The two dimensional Fourier transformation of an entire data of image matrix is used to reconstruct two...
In order to investigate the difference of cortical activation between reading letter string in normal direction and reverse direction, an fMRI study was conducted. In this study, the cortical activations responsible for Japanese string and Chinese string reading were investigated. The subjects performed normal direction reading task (read strings from left to right), and reverse direction reading...
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