Yousef Mazaheri

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A multishot partial-k-space EPI technique is presented and validated by fMRI at high spatial resolution. High-resolution phase maps corrected by phase-encoded reference scans have less off-resonance effects. Phantom studies demonstrate that this method can substantially improve partial-k-space EPI image formation. BOLD fMRI at submillimeter spatial(More)
The 3D TRICKS method for contrast-enhanced, time-resolved MR DSA has been recently described. In this paper, computer simulations are used to investigate the relative frame rate, temporal window, artery-vein temporal separation, contrast-to-noise ratio, and spatial resolution of TRICKS and conventional scans for breath-hold and non-breath-hold applications.(More)
PURPOSE To compare ADC values measured from diffusion-weighted MR (DW-MR) images of the prostate obtained with both endorectal and phased-array coils (ERC+PAC) to those from DW-MRI images obtained with an eight-channel torso phased-array coil (PAC) at 3.0 T. METHODS The institutional review board issued a waiver of informed consent for this(More)
PURPOSE To extend the intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) model to restricted diffusion and to simultaneously quantify the perfusion and restricted diffusion parameters in neck nodal metastases. MATERIALS AND METHODS The non-gaussian (NG)-IVIM model was developed and tested on diffusion-weighted MRI data collected on a(More)
The signal intensity during the dynamic approach to the equilibrium state of longitudinal magnetization is a function of sequence parameters, such as repetition time and flip angle, and depends on tissue characteristics, including longitudinal relaxation time of stationary tissue and the rate of blood inflow. A method is presented to extract information(More)
Information theory provides a mathematical framework for analysis of fMRI experiments. By modeling the fMRI experiment as a communication system, various results from information theory can be applied to measure information transfer rate in fMRI experiments. The information transfer rate has important implications for design and analysis of brain-computer(More)
1. Introduction 2. Figure 1: Pixel signal model Figure 2: A simplified model of an ASL experiment Figure 3: Example showing calculation of cardiac phase Figure 4: Example showing calculation respiratory phase Figure 5: Example data showing estimated cardiac and respiratory components Figure 6: Spatial power in BOLD images (TR 250ms) centered around(More)
PURPOSE This study aimed to compare the intraclass correlation coefficients of parameters estimated with stretched exponential and biexponential diffusion models of in vivo diffusion-weighted magnetic resonance imaging (MRI) of the prostate. METHODS After the institutional review board issued a waiver of informed consent for this Health Insurance(More)
RATIONALE AND OBJECTIVES Motion artifacts are a significant source of error in the acquisition and quantification of parameters from multi-b-value diffusion-weighted imaging (DWI). The objective of this article is to present a reliable method to reduce motion-related artifacts during free-breathing at higher b-values when signal levels are low. MATERIALS(More)
The blood oxygenation level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments in response to input stimuli is temporally delayed and distorted due to the blurring effect of the voxel hemodynamic impulse response function (IRF). Knowledge of the IRF, obtained during the same experiment, or as the result of a(More)