MULti-TImepoint VElocity-selective Reconciled with Spatially-sElective (MULTIVERSE) ASL: Improving robustness to both shortened and prolonged arterial transit time

Abstract

Purpose: To improve the quantification of existing multi-timepoint arterial spin labeling (ASL) methods in estimating cerebral blood flow (CBF) and arterial transit time (ATT) for a wider range of ATTs.

Methods: MULti-TImepoint VElocity-selective Reconciled with Spatially-sElective (MULTIVERSE) ASL utilizes multi-delay pseudo-continuous (PC) ASL and velocity-selective (VS) ASL with spatially defined bolus, and joint fitting to estimate CBF and ATT. Numerical simulations were performed to evaluate the accuracy and precision of single-delay and multi-delay PCASL and VSASL, as well as the proposed MULTIVERSE ASL, in quantifying CBF and ATT across an extended range of ATTs. The CBF and ATT estimates between multi-delay PCASL, VSASL, and MULTIVERSE ASL were compared across healthy volunteers.

Results: Numerical simulations showed that the utility of MULTIVERSE ASL improved the accuracy and precision over an extended ATT range of up to 4000 ms. In vivo scans from healthy subjects demonstrated that MULTIVERSE ASL led to reduced uncertainty in CBF and ATT quantification compared to multi-post-labeling delay PCASL while maintaining comparable repeatability.

Conclusion: This novel and straightforward approach improves the accuracy and precision of the fitted CBF and ATT over an extended range of ATT, which is not possible with existing ASL methods. Brain scans from healthy subjects demonstrated the feasibility and reliability of the technique, highlighting the clinical potential of ASL-based perfusion mapping in various altered physiological and pathological conditions.

Keywords: MULTIVERSE ASL; arterial spin labeling (ASL); arterial transit time (ATT); bolus arrival time (BAT); bolus duration; cerebral blood flow; pseudo‐continuous ASL (PCASL); velocity‐selective ASL (VSASL).