Usha S. Sinha

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We present a new method for automatic segmentation of heterogeneous image data that takes a step toward bridging the gap between bottom-up affinity-based segmentation methods and top-down generative model based approaches. The main contribution of the paper is a Bayesian formulation for incorporating soft model assignments into the calculation of(More)
Age-related microstructural changes in brain white matter can be studied by utilizing indices derived from diffusion tensor imaging (DTI): apparent diffusion coefficient (ADC) and fractional anisotropy (FA). The objective of this study is to examine alterations in FA and ADC by employing exploratory voxel-based analysis (VBA) and region(s) of interest(More)
PURPOSE To investigate the potential of apparent diffusion coefficients (ADCs) in characterizing breast lesions in vivo. MATERIALS AND METHODS Two diffusion-weighted (DW) sequences were implemented on a 1.5 Tesla scanner, with low b-value orthogonal and high b-value tetrahedral sensitized sequences. The orthogonal sequence was evaluated on 16 normal(More)
This review is focused on two relatively new developments in magnetic resonance imaging (MRI) and their application to breast lesion characterization: diffusion and perfusion MRI. Diffusion MRI measures the mobility of the water protons and thus provides a window to tissue microstructure. Perfusion MRI measures the rate at which blood is delivered to tissue(More)
PURPOSE To demonstrate the feasibility of in vivo calf muscle fiber tracking in human subjects. MATERIALS AND METHODS An EPI-based diffusion tensor imaging (DTI) sequence with six-direction diffusion gradient sensitization was implemented, and DT images were acquired at 3 Tesla on five subjects using an extremity coil. The mean diffusivity, fractional(More)
PURPOSE To investigate a tetrahedral diffusion gradient encoding scheme to measure the diffusion tensor in vivo for human calf muscle. MATERIALS AND METHODS The theoretical TE which maximizes the signal-to-noise ratio (SNR) of the diffusion images was derived for both the orthogonal and tetrahedral sampling strategies and the SNR advantage verified(More)
OBJECTIVE Positron emission tomography (PET), the reference technique for in vivo noninvasive assessment of myocardial perfusion and metabolism, is hampered by limited resolution and low signal-to-noise ratio. Cardiac MR imaging, on the other hand, provides excellent soft-tissue contrast. This study examines the feasibility of combining the information of(More)
Magnetic resonance spectroscopy and diffusion magnetic resonance imaging (MRI) characteristics of human intracranial glioma were studied. Present knowledge suggests a hypothetical inverse relationship between the characteristic choline signal intensity elevation and the apparent diffusion coefficient (ADC) in glioma. Twenty cases of glioma were examined(More)
This study demonstrates the feasibility of in vivo prostate diffusion tensor imaging (DTI) in human subjects. We implemented an EPI-based diffusion-weighted (DW) sequence with seven-direction diffusion gradient sensitization, and acquired DT images from six subjects using cardiac gating with a phased-array prostate surface coil operating in a linear mode.(More)
We generalize the total variation restoration model, introduced by Rudin, Osher, and Fatemi in 1992, to matrix-valued data, in particular, to diffusion tensor images (DTIs). Our model is a natural extension of the color total variation model proposed by Blomgren and Chan in 1998. We treat the diffusion matrix D implicitly as the product D = LL(T), and work(More)