Test-retest reliability of 3D velocity-selective arterial spin labeling for detecting normal variations of cerebral blood flow

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Purpose: To develop velocity selective arterial spin labeling (VSASL) protocols for prostate blood flow (PBF) and prostate blood volume (PBV) mapping. Methods: Fourier-transform based velocity-selective inversion and saturation pulse trains were utilized in VSASL sequences to obtain blood flow and blood volume weighted perfusion signal, respectively. Here four cutoff velocities (V cut = 0.25, 0.50, 1.00, and 1.50 cm/s) for PBF and PBV mapping sequences were evaluated with a parallel implementation in brain for measuring cerebral blood flow (CBF) and cerebral blood volume (CBV) with identical 3D readout. This study was performed at 3T on eight young and middle-aged healthy subjects comparing both perfusion weighted signal (PWS) and temporal SNR (tSNR). Results:In contrast to CBF and CBV, the PWS of PBF and PBV were rather unobservable at V cut of 1.00 or 1.50 cm/s and both PWS and tSNR of PBF and PBV considerably increased at the lower V cut , indicating that blood moves much slower in prostate than in brain. Similar to the brain results, the tSNR of PBV-weighted signal was about two to four times over the corresponding values of PBF-weighted signal. The results also suggested a trend of reduced vascularity within prostate during aging. Conclusion: For prostate, a low V cut of 0.25-0.50 cm/s seemed necessary for both PBF and PBV measurements to obtain adequate perfusion signal. As in brain, PBV mapping yielded a higher tSNR than PBF.

Section: Discussionmentioning

confidence: 99%

“…35,36 The reproducibility of VSASL based perfusion mapping for prostate will need to be established as having been done for brain recently. 37…”

Section: F I G U R Ementioning

confidence: 99%

Prostate perfusion mapping using Fourier‐transform based velocity‐selective arterial spin labeling: Choice of cutoff velocity and comparison with brain

Liu

Zhu

et al. 2023

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“…Further technical development is underway to improve its performance by employing variable density spiral trajectories, 31 golden angle rotation, 12 and better image reconstruction. As recently being done for VSASL with multi-shot GRASE readout, 32 the reproducibility of VSASL with single-shot SOS-TFL acquisition will also need to be evaluated. The higher temporal resolution could allow applications such as functional and resting state ASL, 12,16,17 along with more effective motion correction.…”

Section: F I G U R Ementioning

confidence: 99%

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

Zhu

Liu

et al. 2023

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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.

“…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 35–39 . Using the same constructions, FT‐VSS‐labeled and FT‐VSI‐labeled VSASL were subsequently demonstrated for quantitative mapping of blood flow, 40–50 blood volume, 51–53 and venous oxygenation 54 …”

Section: Introductionmentioning

confidence: 99%

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

Liu,

Zhu,

Qin

2024

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PurposeThis study evaluated the velocity‐selective (VS) MRA with different VS labeling modules, including double refocused hyperbolic tangent, eight‐segment B1‐insensitive rotation, delay alternating with nutation for tailored excitation, Fourier transform–based VS saturation, and Fourier transform–based inversion.MethodsThese five VS labeling modules were evaluated first through Bloch simulations, and then using VSMRA directly on various cerebral arteries of healthy subjects. The relative signal ratios from arterial ROIs and surrounding tissues as well as relative arteria‐tissue contrast ratios of different methods were compared.ResultsDouble refocused hyperbolic tangent and eight‐segment B1‐insensitive rotation showed very similar labeling effects. Delay alternating with nutation for tailored excitation yielded high arterial signal but with residual tissue signal due to the spatial banding effect. Fourier transform–based VS saturation with half the time of other techniques serves as an efficient nonsubtractive VSMRA method, but the remaining tissue signal still obscured some small distal arteries that were delineated by other subtraction‐based VSMRA, allowing more complete cancelation of static tissue. Fourier transform–based inversion produced the highest arterial signal in VSMRA with minimal tissue background.ConclusionThis is the first study that angiographically compared five different VS labeling modules. Their labeling characteristics on arteries and tissue and implications for VSMRA and VS arterial spin labeling are discussed.