Optimization and Reliability of Multiple Postlabeling Delay Pseudo-Continuous Arterial Spin Labeling during Rest and Stimulus-Induced Functional Task Activation

Abstract

Arterial spin labeling (ASL) sequences that incorporate multiple postlabeling delay (PLD) times allow estimation of when arterial blood signal arrives within a region of interest. Sequences that account for such variability may improve the reliability of ASL and therefore make the technique well suited for future clinical and experimental investigations of cerebral perfusion. This study assessed the within-and between-session reproducibility of an optimized pseudo-continuous ASL (pCASL) functional magnetic resonance imaging (FMRI) sequence that incorporates multiple postlabeling delays (multi-PLD pCASL). Healthy subjects underwent four identical scans separated by 30 minutes, 1 week, and 1 month using multi-PLD pCASL to image absolute perfusion (cerebral blood flow (CBF) and arterial arrival time (AAT)) during both rest and a visual-cued motor task. We show good test-retest reliability, with strong consistency across subjects and sessions during rest (inter-session within-subject coefficient of variation: gray matter (GM) CBF = 6.44%; GM AAT = 2.20%). We also report high sensitivity and reproducibility during the functional task, where we show robust task-related decreases in AAT corresponding with regions of increased CBF. Importantly, these results give insight into optimal PLD selection for future investigations using single-PLD ASL to image different brain regions, and highlight the necessity of multi-PLD ASL when imaging perfusion in the whole brain.

Test-retest reliability of cerebral blood flow in healthy individuals using arterial spin labeling: Findings from the EMBARC study

“…Thus, ICC estimates the percent of variance accounted for by between-subjects effects and reflects the consistency of measurements from session 1 to session 2. ICCs were calculated using a two-way mixed model single measure (ICC(3,1)) as in previous ASL reliability studies [14,27]. ICCs were categorized as: Poor (< 0.4), Fair (0.4 ≤ IC-C < 0.6), Good (0.6 ≤ ICC < 0.75), and Excellent (≥0.75) [53].…”

Reproducibility of multiphase pseudo-continuous arterial spin labeling and the effect of post-processing analysis methods

“…It should be noted that B1 effects could be also corrected in the global scaling methods by incorporating a separate minimum contrast scan or coil sensitivity data (e.g. from extra data acquired with body coil) in the protocol (Dai et al, 2011;Mezue et al, 2014). Fig.…”

Tonotopic maps in human auditory cortex using arterial spin labeling

“…These choices allow us shorter TR and thus improved sampling of the hemodynamic response. At the same time, PLD was chosen long enough to allow CBF quantification in the auditory cortex, which is adequately perfused by the labeled blood after a PLD of 1.0 s (Donahue et al, 2014; Mezue et al, 2014). …”