Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine
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Simultaneous multislice (SMS) acquisitions have recently received much attention as a means of increasing single-shot imaging speed. SMS acquisitions combine the advantages of single-shot sampling and acceleration along the slice dimension which was previously limited to three-dimensional (3D) volumetric acquisitions. A two-dimensional description of SMS sampling and reconstruction has become established in the literature. Here, we present a more general 3D Fourier encoding and reconstruction formalism for SMS acquisitions that can easily be applied to non-Cartesian SMS acquisitions. ⋯ The full framework of reconstruction methods can be applied to SMS acquisitions by employing a 3D k-space approach. The blipped-controlled aliasing in parallel imaging method can be viewed as a special case of undersampling an SMS 3D k-space. The extension of SMS methods to non-Cartesian 3D sampling and reconstruction is straightforward.
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The calibratable relationship between blood oxygenation (Y) and T(2) allows quantification of cerebral venous oxygenation. We aim to establish a calibration plot between blood T(2) , Y, and hematocrit at 7 T, and using T(2) -relaxation-under-spin-tagging MRI, determine human venous blood oxygenation in vivo. ⋯ We provided an in vitro calibration plot for conversion of blood T(2) to oxygenation at 7 T and demonstrated its utility in vivo.
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To study balanced steady-state free precession CINE phase-sensitive water-fat separation imaging in four cardiac imaging planes to determine the necessary phase correction and image artifacts particular to this technique. ⋯ Constant and linear phase correction is necessary to provide consistent results in standard imaging planes using a balanced steady-state free precession water-fat separation postprocessing algorithm applied to standard cardiac CINE imaging.
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Chemical exchange saturation transfer (CEST) imaging is a new MRI technology allowing the detection of low concentration endogenous cellular proteins and metabolites indirectly through their exchangeable protons. A new technique, variable delay multi-pulse CEST (VDMP-CEST), is proposed to eliminate the need for recording full Z-spectra and performing asymmetry analysis to obtain CEST contrast. ⋯ VDMP-CEST provides an approach to detect CEST effect by sensitizing saturation experiments to slower exchange processes without interference of direct water saturation and without need to acquire Z-spectra and perform asymmetry analysis.
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To develop a method to acquire a radiofrequency (B1 ) field map when the signal has a short T2 *. ⋯ The proposed technique provides a means to obtain a 3D B1 field map when imaging spins with short T2 (*) .