Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine
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To evaluate the feasibility of simultaneous MR spectroscopic imaging (MRSI) of gamma-aminobutyric acid (GABA) and glutathione (GSH) in the human brain using Hadamard Encoding and Reconstruction of MEGA-Edited Spectroscopy (HERMES). ⋯ HERMES-MRSI of GABA+ and GSH was found to be practical in the human brain with minimal measurement bias and comparable variability to separate MEGA-edited acquisitions of each metabolite performed in double the scan time. The HERMES-MRSI is a promising method for simultaneously mapping the distribution of multiple low-concentration metabolites.
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To design a pulse sequence for efficient 3D T2-weighted imaging and T2 mapping. ⋯ The proposed stack-of-stars turbo spin echo pulse sequence with pseudorandom view ordering and variable refocusing flip angles allows high resolution isotropic T2 mapping in clinically acceptable scan times. The optimization framework for the selection of refocusing flip angles improves T2 estimation accuracy while generating T2-weighted contrast comparable to conventional Cartesian imaging.
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To measure the transverse relaxation rate (T2 ) of aspartate (Asp) from Asp-edited MEGA-PRESS spectra and use the measured T2 values to estimate the Asp concentrations in gray matter (GM)- and white matter (WM)-dominant brain regions. ⋯ MEGA-PRESS is the most common editing method used for low-concentration metabolites detection. Estimation of the absolute Asp concentrations has potential in many research applications, such as studying the processes underlying the reduction of N-acetyl aspartate as well as studying mitochondrial diseases etc. The T2 measurement method described has been successfully applied for edited Asp signals. This method can also be used for other strongly J-coupled signals.
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To develop a motion-corrected 3D flow-insensitive imaging approach interleaved T2 prepared-inversion recovery (iT2 prep-IR) for simultaneous lumen and wall visualization of the great thoracic vessels and cardiac structures. ⋯ The proposed interleaved T2 prep-IR sequence enables the simultaneous lumen and wall visualization of cardiac structures and shows promising results in terms of SNR, CNR, and wall thickness measurement.
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For free-breathing renal perfusion imaging using arterial spin labeling (ASL), retrospective image realignment has been found essential to reduce subtraction artifacts and, independently, background suppression has been demonstrated to reduce physiologic noise. However, negative results on ASL precision and accuracy have been reported for the combination of both. In this study, the effect of background suppression -level in combination with image registration on free-breathing renal ASL signal quality, with registration either on ASL-images themselves or guided by additionally acquired fat-images, was investigated. The results from free-breathing acquisitions were compared with the reference paced-breathing motion compensation strategy. ⋯ Background suppression was found beneficial for free-breathing renal pCASL precision without compromising accuracy, despite motion challenges. In combination with ASLReg or FatReg, background suppression enabled clinically viable free-breathing renal pCASL.