Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine
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Measurement of single-kidney filtration fraction and glomerular filtration rate (GFR) without exogenous contrast is clinically important to assess renal function and pathophysiology, especially for patients with comprised renal function. The objective of this study is to develop a novel MR-based tool for noninvasive quantification of renal function using conventional MR arterial spin labeling water as endogenous tracer. ⋯ We developed an arterial spin labeling-based MR imaging method that allows us to estimate renal filtration fraction and singe-kidney GFR without use of exogenous contrast.
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Comparative Study
NMR HRMAS spectroscopy of lung biopsy samples: Comparison study between human, pig, rat, and mouse metabolomics.
Using the metabolomics by NMR high-resolution magic angle spinning spectroscopy, we assessed the lung metabolome of various animal species in order to identify the animal model that could be substituted to human lung in studies on fresh lung biopsies. ⋯ Using the metabolomics by NMR high-resolution magic angle spinning spectroscopy on lung biopsy, samples allowed to highlight that pig lung seems to be close to human lung as regarding its metabolite composition with more similarities than dissimilarities.
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Simultaneous multi-slice (SMS) echo planar imaging (EPI) is incorporated into two-dimensional (2D) arterial spin labeling (ASL) imaging to produce more slices for measuring perfusion in a larger region of the brain than currently possible with multi-slice EPI. ⋯ SMS-EPI has a major advantage over EPI-based ASL imaging by increasing slice coverage without lengthening the acquisition time window.
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Partial volume (PV) effects are caused by limited spatial resolution and significantly affect cerebral blood flow investigations with arterial spin labeling. Therefore, accurate PV correction (PVC) procedures are required. PVC is commonly based on PV maps obtained from segmented high-resolution T1 -weighted images. Segmentation of these images is error-prone, and it can be difficult to coregister these images accurately with the single-shot ASL images such as those created by echo-planar imaging (EPI). In this paper, an alternative method for PV map generation is proposed. ⋯ PV maps extraction from LL-EPI is a viable, possibly superior alternative to the standard approach based on segmentation of high-resolution T1 -weighted images.
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Segmented 2D-selective radiofrequency excitations can be used to acquire irregularly shaped target regions, e.g., in single-voxel MR spectroscopy, without involving excessive radiofrequency pulse durations. However, segments covering only outer k-space regions nominally use reduced B1 amplitudes (i.e., smaller flip angles) and yield lower signal contributions, which decreases the efficiency of the measurement. The purpose of this study was to show that applying the full flip angle for all segments and scaling down the acquired signal appropriately (signal scaling) retains the desired signal amplitude but reduces the noise level accordingly and, thus, increases the signal-to-noise ratio. ⋯ Signal scaling can further improve the performance of measurements with segmented 2D-selective radiofrequency excitations, e.g., for MR spectroscopy of anatomically defined voxels.