Steven R. Kecskemeti

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Time-resolved contrast-enhanced magnetic resonance angiography of the brain is challenging due to the need for rapid imaging and high spatial resolution. Moreover, the significant dispersion of the intravenous contrast bolus as it passes through the heart and lungs increases the overlap between arterial and venous structures, regardless of the acquisition(More)
PURPOSE To develop a method for targeted volumetric, three directional cine phase contrast (PC) imaging with high spatial resolution in clinically feasible scan times. MATERIALS AND METHODS A hybrid radial-Cartesian k-space trajectory is used for cardiac gated, volumetric imaging with three directional velocity encoding. Imaging times are reduced by(More)
PURPOSE To investigate the feasibility of using time-of-flight (TOF) images as a constraint in the reconstruction of a series of highly undersampled time-resolved contrast-enhanced MR images (HYPR TOF), to allow simultaneously high temporal and spatial resolution and increased SNR. MATERIALS AND METHODS Ten healthy volunteers and three patients with(More)
Learning leads to rapid microstructural changes in gray (GM) and white (WM) matter. Do these changes continue to accumulate if task training continues, and can they be reverted by sleep? We addressed these questions by combining structural and diffusion weighted MRI and high-density EEG in 16 subjects studied during the physiological sleep/wake cycle, after(More)
Diffusion tensor imaging is used to measure the diffusion of water in tissue. The diffusion properties carry information about the relative organization and structure of the underlying tissue. In the case of a single voxel containing both tissue and a fast diffusing component such as free water, a single diffusion tensor is no longer appropriate. A(More)
PURPOSE To introduce a new technique called MPnRAGE, which produces hundreds of images with different T1 contrasts and a B1 corrected T1 map. THEORY AND METHODS An interleaved three-dimensional radial k-space trajectory with a sliding window reconstruction is used in conjunction with magnetization preparation pulses. This work modifies the SNAPSHOT-FLASH(More)
Alterations to myelin may be a core pathological feature of neurodegenerative diseases. Although white matter microstructural differences have been described in Parkinson's disease (PD), it is unknown whether such differences include alterations of the brain's myelin content. Thus, the objective of the current study is to measure and compare brain myelin(More)
PURPOSE White matter tractography reconstructions using conventional diffusion tensor imaging (DTI) near cerebrospinal fluid (CSF) spaces are often adversely affected by CSF partial volume effects (PVEs). This study evaluates the ability of free water elimination (FWE) DTI methods to minimize the PVE of CSF for deterministic tractography applications. (More)
Recently, the highly-constrained backprojection (HYPR) and HYPR with local reconstruction (HYPR LR) methods have been introduced to reconstruct magnitude images from a series of highly undersampled data while preserving high spatial and temporal resolution and high signal-to-noise ratio (SNR) in applications with spatiotemporal correlations. However, these(More)