VESPA ASL: VElocity and SPAtially Selective Arterial Spin Labeling

Woods, Joseph G.; Wong, Eric C.; Boyd, Emma; Bolar, Divya S.

doi:10.1002/mrm.29159

Cited by 11 publications

(24 citation statements)

References 57 publications

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“…Despite improved quantitative accuracy, VSASL does not capture any information related to arterial transit, which can be useful in its own right. As mentioned above, a combined VSASL/PCASL approach 55 for steno‐occlusive disease may be optimal to assess perfusion and stenosis/collaterals. Arteriovenous malformations or fistulae may also benefit from a combined approach for detecting arteriovenous shunting with high sensitivity.…”

Section: Neuro Applicationsmentioning

confidence: 99%

Velocity‐selective arterial spin labeling perfusion MRI: A review of the state of the art and recommendations for clinical implementation

Qin

Alsop

Bolar

et al. 2022

Magnetic Resonance in Med

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108

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This review article provides an overview of the current status of velocity-selective arterial spin labeling (VSASL) perfusion MRI and is part of a wider effort arising from the International Society for Magnetic Resonance in Medicine (ISMRM) Perfusion Study Group. Since publication of the 2015 consensus paper on arterial spin labeling (ASL) for cerebral perfusion imaging, important advancements have been made in the field. The ASL community has, therefore, decided to provide an extended perspective on various aspects of technical development and application. Because VSASL has the potential to become a principal ASL method because of its unique advantages over traditional approaches, an in-depth discussion was warranted. VSASL labels blood based on its velocity and creates a magnetic bolus immediately proximal to the microvasculature within the imaging volume. VSASL is, therefore, insensitive to transit delay effects, in contrast to spatially selective pulsed and (pseudo-) continuous ASL approaches. Recent technical developments have improved the robustness and the labeling efficiency of VSASL, making it a potentially moreThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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Section: Neuro Applicationsmentioning

confidence: 99%

Velocity‐selective arterial spin labeling perfusion MRI: A review of the state of the art and recommendations for clinical implementation

Qin

Alsop

Bolar

et al. 2022

Magnetic Resonance in Med

Self Cite

108

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“…SVS excitation was first used in a recent study of intracranial arterial spin labeling (ASL) as an alternative to velocity-selective ASL (VSASL). 32 The additional spatial selectivity in SVS preparation allowed for the use of pseusocontinuous ASL immediately after VSASL and therefore enabled simultaneous measurements of arterial transit time (ATT) and ATT-insensitive cerebral blood flow. The concept of improving arterial signal by preserving upstream blood magneitzation was utilized in an earlier work on coronary MRA.…”

Section: Discussionmentioning

confidence: 99%

Spatially and velocity‐selective magnetization preparation for noncontrast‐enhanced peripheral MR angiography

Shin

Lee²,

Zun

et al. 2023

NMR in Biomedicine

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The purpose of the current study was to develop spatially and velocity‐selective (SVS) magnetization preparation pulses for noncontrast‐enhanced peripheral MR angiography (MRA) to provide comparisons with velocity‐selective (VS) MRA with comparison to velocity‐selective (VS). VS preparation pulses were designed by concatenating multiple excitation steps, each of which was a combination of a hard RF pulse, VS unipolar gradient pulses, and refocusing RF pulses. SVS preparation pulses were designed by replacing the hard RF pulse with a sinc‐shaped RF pulse combined with a symmetric tripolar gradient pulse (which does not perturb the velocity encoding by the VS unipolar gradient pulses). Numerical simulations were performed to verify the intended hybrid excitation selectivity of SVS pulses taking account of tissue relaxation, magnetic field errors, and eddy currents. In vivo experiments were performed in healthy subjects to verify the hybrid excitation selectivity, as well as to demonstrate the visualization of the entire peripheral arteries using six‐station protocols. As demonstrated by numerical simulations, SVS preparation yielded a notch‐shaped longitudinal magnetization (Mz)‐velocity response within the spatial stopband (the same as VS preparation) and preserved the Mz of spins outside the stopband, regardless of its velocity. We confirmed these observations also through in vivo tests with good agreement in normalized arterial and muscle signal intensities. In six‐station peripheral MRA experiments, the proposed SVS‐MRA yielded significantly higher arterial signal‐to‐noise ratio (SNR) (51.6 ± 14.3 vs. 38.9 ± 10.9; p < 0.001) and contrast‐to‐noise ratio (CNR) (41.2 ± 13.0 vs. 31.3 ± 10.5; p < 0.001) compared with VS‐MRA. The proposed SVS‐MRA improves arterial SNR and CNR compared with VS‐MRA by mitigating undesired presaturation of arterial blood upstream the imaging field of view.

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“…Subsequent experiments would likely involve such a scan in a prior session. ATT-insensitive approaches such as VS-ASL (Wong et al, 2006) and the more recently introduced VESPA ASL (Woods et al, 2022) which additionally provides measures of ATT are interesting alternatives to consider in this regard. The study could have also benefitted from retinotopic scans which would have substantiated the anatomical locations of the positive and negative ROIs.…”

Section: Discussionmentioning

confidence: 99%

Multi-Echo Investigations of Positive and Negative CBF and Concomitant BOLD Changes

Devi

Lepsien

Lorenz

et al. 2022

Preprint

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Unlike the positive blood oxygenation level-dependent (BOLD) response (PBR), commonly taken as an indication of an 'activated' brain region, the physiological origin of negative BOLD signal changes (i.e. a negative BOLD response, NBR), also referred to as 'deactivation' is still being debated. In this work, an attempt was made to gain a better understanding of the underlying mechanism by obtaining a comprehensive measure of the contributing cerebral blood flow (CBF) and its relationship to the NBR in the human visual cortex, in comparison to a simultaneously induced PBR in surrounding visual regions. To overcome the low signal-to-noise ratio (SNR) of CBF measurements, a newly developed multi-echo version of a center-out echo planar-imaging (EPI) readout was employed with pseudo-continuous arterial spin labeling (pCASL). It achieved very short echo and inter-echo times and facilitated a simultaneous detection of functional CBF and BOLD changes at 3 T with improved sensitivity. Evaluations of the absolute and relative changes of CBF and the effective transverse relaxation rate, R2*, the coupling ratios, and their dependence on CBF at rest, CBFrest, indicated differences between activated and deactivated regions. Analysis of the shape of the respective functional responses also revealed faster negative responses with more pronounced post-stimulus transients. Resulting differences in the flow-metabolism coupling ratios were further examined for potential distinctions in the underlying neuronal contributions.

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VESPA ASL: VElocity and SPAtially Selective Arterial Spin Labeling

Cited by 11 publications

References 57 publications

Velocity‐selective arterial spin labeling perfusion MRI: A review of the state of the art and recommendations for clinical implementation

Velocity‐selective arterial spin labeling perfusion MRI: A review of the state of the art and recommendations for clinical implementation

Spatially and velocity‐selective magnetization preparation for noncontrast‐enhanced peripheral MR angiography

Multi-Echo Investigations of Positive and Negative CBF and Concomitant BOLD Changes

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