Evaluation of 3D stack‐of‐spiral turbo FLASH acquisitions for pseudo‐continuous and velocity‐selective ASL–derived brain perfusion mapping

Abstract

Purpose:The most-used 3D acquisitions for ASL are gradient and spin echo (GRASE)-and stack-of-spiral (SOS)-based fast spin echo, which require multiple shots. Alternatively, turbo FLASH (TFL) allows longer echo trains, and SOS-TFL has the potential to reduce the number of shots to even single-shot, thus improving the temporal resolution. Here we compare the performance of 3D SOS-TFL and 3D GRASE for ASL at 3T. Methods:The 3D SOS-TFL readout was optimized with respect to fat suppression and excitation flip angles for pseudo-continuous ASL-and velocity-selective (VS)ASL-derived cerebral blood flow (CBF) mapping as well as for VSASL-derived cerebral blood volume (CBV) mapping. Results were compared with 3D GRASE readout on healthy volunteers in terms of perfusion quantification and temporal SNR (tSNR) efficiency. CBF and CBV mapping derived from 3D SOS-TFL-based ASL was demonstrated on one stroke patient, and the potential for single-shot acquisitions was exemplified. Results: SOS-TFL with a 15 • flip angle resulted in adequate tSNR efficiency with negligible image blurring. Selective water excitation was necessary to eliminate fat-induced artifacts. For pseudo-continuous ASL-and VSASL-based CBF and CBV mapping, compared to the employed four-shot 3D GRASE with an acceleration factor of 2, the fully sampled 3D SOS-TFL delivered comparable performance (with a similar scan time) using three shots, which could be further undersampled to achieve single-shot acquisition with higher tSNR efficiency. SOS-TFL had reduced CSF contamination for VSASL-CBF. Conclusion:3D SOS-TFL acquisition was found to be a viable substitute for 3D GRASE for ASL with sufficient tSNR efficiency, minimal relaxation-induced blurring, reduced CSF contamination, and the potential of single-shot, especially for VSASL. K E Y W O R D Scerebral blood flow, cerebral blood volume, pseudo-continuous ASL, stack-of-spiral turbo FLASH, velocity-selective arterial spin labelingThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Velocity-Selective Arterial Spin Labeling Perfusion in Monitoring High Grade Gliomas Following Therapy: Clinical Feasibility at 1.5T and Comparison with Dynamic Susceptibility Contrast Perfusion

“…The utility of tSNR in assessing the fraction of viable tumor vs. post-treatment tissue necrosis would be best evaluated in future prospective studies by correlating with histopathologic specimens from patients with previously treated glioblastoma undergoing repeated surgical resection. Recently, 3D single-shot VSASL was achieved using stack-of-spiral FLASH acquisition and compressedsensing acceleration with high temporal resolution [53], which could further improve the tSNR analysis.…”

Direct angiographic comparison of different velocity‐selective saturation, inversion, and DANTE labeling modules on cerebral arteries

“…These FT-VS saturation (FT-VSS) or inversion (FT-VSI) pulse trains were used for non-subtraction-based VSMRA at 1.5 T first with the original form not applying any refocusing pulses 33 and later with one composite refocusing pulse within each velocity encoding step. 34 To mitigate the effects of more severe B0/B1 field inhomogeneities and eddy currents, FT-VSS pulse trains incorporating phase cycled and paired refocusing through the pulse trains were successfully implemented for VSMRA at 3 T. [35][36][37][38][39] Using the same constructions, FT-VSS-labeled and FT-VSI-labeled VSASL were subsequently demonstrated for quantitative mapping of blood flow, [40][41][42][43][44][45][46][47][48][49][50] blood volume, [51][52][53] and venous oxygenation. 54 This study evaluated the labeling characteristics of different VS modules, including DRHT, symmetric BIR-8, DANTE, FT-VSS, and FT-VSI, through Bloch simulations first, and then directly on various cerebral arteries using VSMRA.…”

Evaluation of split renal function using MR-derived structure and arterial spin-labeled perfusion features in obstructive nephropathy

“…Arterial spin labeling (ASL) imaging uses water molecules as freely diffusing tracers to achieve quantitative measurement of blood ow perfusion without contrast agents [4,5]. The value of ASL in evaluating cerebral blood ow perfusion has been recognized, and it has good reproducibility in RBF [6,7]. The renal perfusion characteristics of obstructive nephropathy and its value in evaluating renal dysfunction are worth exploring.…”