Reliability of pseudocontinuous arterial spin labeling in ischemic stroke and comparison with other perfusion techniques: systematic review and meta-analysis

ABSTRACT BACKGROUND: Pseudocontinuous arterial spin labeling (pCASL) is a non-invasive, gadolinium-free MRI technique for assessing brain perfusion. PURPOSE: To evaluate the test-retest reliability of pCASL-CBF measurements in ischemic stroke (IS) and compare pCASL metrics with those from DSC, CTP, and PET. DATA SOURCES: Systematic searches were conducted in MEDLINE, EMBASE, and LILACS. Risk of bias and methodological quality were evaluated using QUADAS-2 and QAREL tools. STUDY SELECTION: 11 studies, encompassing 383 participants with IS were included. DATA ANALYSIS: Random-effects meta-analysis with inverse variance method and heterogeneity assessed using I² statistics. DATA SYNTHESIS: No PET studies were identified. Only one low-quality, high-risk-of-bias study assessed test-retest reliability, finding no significant differences in repeated absolute CBF measurements over time and excellent reliability across regions. Most studies comparing pCASL with DSC, and all comparing pCASL with CTP, had a low risk of bias. In the hyperacute phase of IS, pCASL and DSC showed no significant differences in infarct core relative CBF (95% CI: -0.11 to 0.13; I² = 0%) or hypoperfusion volumes (95% CI: -0.28 to 0.68; I² = 69%). Evidence on the comparability of pCASL with other DSC or CTP metrics was limited. LIMITATIONS: The small number of included studies prevented a meta-analysis for the primary outcome and limited conclusions for secondary outcomes. CONCLUSIONS: Robust conclusions about the test-retest reliability of pCASL or the comparability of metrics obtained with this technique and DSC, CTP, or PET in different phases following ischemic stroke could not be drawn. ABBREVIATIONS: pCASL=pseudocontinuous arterial spin labeling; IS: ischemic stroke; QUADAS-2=Quality Assessment of Diagnostic Accuracy Studies-2; QAREL= Quality Appraisal for Reliability Studies.