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Rising healthcare costs combined with an increase in the number of people living with disabilities due to stroke have created a need for affordable stroke therapy that can be administered in both home and clinical environments. Studies show that robot and computer-assisted devices are promising tools for rehabilitating persons with impairment and disabilities due to stroke. Studies also have shown...
Though myocardial viscoelasticity is essential in the evaluation of heart diastolic properties, it has never been noninvasively measured in vivo. By the ultrasonic measurement of the myocardial motion, we have already found that some pulsive waves are spontaneously excited by aortic-valve closure (AVC) at end-systole (T0) (IEEE UFFC-43(1996)791-810). Using a sparse sector scan, in which the beam directions...
High resolution 3D coronary artery MR angiography is time-consuming and can benefit from accelerated data acquisition provided by parallel imaging techniques without sacrificing spatial resolution. Currently, popular maximum likelihood based parallel imaging reconstruction techniques such as the SENSE algorithm offer this advantage at the cost of reduced signal-to-noise ratio (SNR). Maximum a posteriori...
In cardiac image analysis, optical flow techniques are widely used to track ventricular borders as well as estimate myocardial motion fields. The optical flow computation is typically performed in Cartesian coordinates, and not constrained from a priori knowledge of normal myocardium deformation patterns. However, for cardiac motion analysis, displacements along specific directions and their derivatives...
In this paper, we present a novel method for automatically extracting the tagging sheets in tagged cardiac MR images, and tracking their displacement during the heart cycle, using a tunable 3D Gabor filter bank. Tagged MRI is a non-invasive technique for the study of myocardial deformation. We design the 3D Gabor filter bank based on the geometric characteristics of the tagging sheets. The tunable...
The evaluation of the Intima Media Thickness (IMT) of the Common Carotid Artery (CCA) with B-mode ultrasonography represents an important index of cardiovascular risk. The IMT is defined as the distance between the leading edge of the lumen-intima interface and the leading edge of the media-adventitia interface. In order to evaluate the IMT, it is necessary to locate such edges. In this paper we developed...
Coronary flow velocity reserve (CFVR) is conventionally obtained by manual tracings of Doppler profiles, as ratio of stress vs baseline diastolic peak velocity. When ≪1.9, this parameter evidences reduced coronary flow and possible microcirculatory disease. Our goals were: 1) to develop a novel technique for semi-automated detection of Doppler flow velocity profile, allowing the automated computation...
Independent component analysis (ICA) and statistical parametric mapping (SPM) are two commonly used methods of analyzing fMRI measurements. Typically, these methods are applied separately to the measurements to produce brain maps indicating active brain regions in response to a stimulus or a performed task. However, ICA can also be used to develop a hemodynamic response model that can be used as a...
In this paper, we propose a method for observing frequency contents of independent hippocampal signals in time. The method is based on calculating independent component analysis (ICA) on electrophysiological multielectrode field potential measurements (MFPMs) in a running window. We have previously proposed a method for observing independently operating neural populations, i.e., functional populations...
Neural signals recorded in parts of the body where voluntary movement has been retained can be used to control prosthetic devices that assist patients to regain lost function. The number of signals recorded to control these devices can be increased by using a single multi-contact electrode placed over a muti-fasciculated peripheral nerve. Recordings made using these electrodes can then be separated...
Relying on a rank-2 tensor model for diffusion within a voxel, conventional streamline tractography utilizes principal component analysis (PCA) to detect the orientation of a single fiber within a voxel. When more than one fibers or tracts intersect within a voxel, the PCA estimated orientation lies somewhere in-between the multiple fiber directions and is obviously an incomplete and incorrect representation...
Vascular pulsation and cardiac motion compromise image quality in contrast enhanced magnetic resonance angiography (CE-MRA) in the thorax, resulting in blurring and ghosting artifacts. The use of ECG gating has been proposed in the past to mitigate these artifacts but previous methods suffered from increased scanner time because only a fraction of the cardiac cycle was used for image acquisition and...
An absolute positioning technique has been developed for ferromagnetic markers in medical instruments and untethered devices operating in a Magnetic Resonance Imaging (MRI) system. This technique allows high precision 3D readings of the location of the device with respect to the absolute center of the MRI bore. The local magnetic field induced by the device is used as a signature for localization...
Susceptibility-weighted magnetic resonance imaging is a powerful tool for high resolution imaging of the vasculature, aiding in the diagnosis of many pathologic conditions. The technique is especially beneficial at higher field strengths where traditional sequences that measure cerebral blood volume suffer from severe distortions, rendering them inapplicable at 7T. However, conventional susceptibility-weighted...
A number of MRI applications rely on dynamic phase information embedded in the acquired images. Such applications often require multiple acquisitions, leading to possibly long scan time and low temporal resolution. Previously, SENSE method has been used for phase-sensitive data to shorten acquisition time. However, SENSE can be subject to artifacts due to inaccurate coil sensitivities and low SNR...
Two image reconstruction methods currently dominate parallel MR imaging: SENSE and GRAPPA. While both seek to reconstruct images from subsampled multi-channel MRI data, there exist fundamental differences between the two. In particular, SENSE reconstructs an image of the excited spin-density directly whereas GRAPPA reconstructs estimates of the fully sampled raw coil data and then combines them to...
Tissue classification is a necessary step to obtain the spatial distribution of a pathology or nosologic map and typically it is performed by the combination of different medical image modalities, including histopathological studies. In previous work, combination of different magnetic resonance (MR) modalities such as in vivo spectroscopy, relaxometry and diffusometry have been proposed to obtain...
We present a new, simple, and fast computational technique, termed the incremental slope (IS), that can accurately distinguish between deterministic from stochastic systems even when the variance of noise is as large or greater than the signal, and remains robust for time-varying signals. The IS method is more accurate than the widely utilized Poincare plot analysis especially when the data are severely...
A new training algorithm called the Approximated Maximum Mutual Information (AMMI) is proposed to improve the accuracy of myoelectric speech recognition using hidden Markov models (HMMs). Previous studies have demonstrated that automatic speech recognition can be performed using myoelectric signals from articulatory muscles of the face. Classification of facial myoelectric signals can be performed...
This study aims to examine the presence of a possible third renal autoregulatory mechanism in the very low frequency (VLF) band (10 mHz) using a high-resolution time-frequency spectral method. Blood pressure and renal blood flow data were measured from conscious and anesthetized Sprague-Dawley and spontaneously hypertensive rats, at the level of the whole kidney (via ultrasound flow probe) and local...
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