Quantitative Analysis of Hypoperfusion in Acute Stroke

Abstract

This study compares the concordance between arterial spin labeling (ASL) and dynamic susceptibility contrast (DSC) for the identification of regional hypoperfusion and diffusion-perfusion mismatch tissue classification using a quantitative method. The inclusion criteria for this retrospective study were as follows: patients with acute ischemic syndrome with symptom onset <24 hours and acquisition of both ASL and DSC MR perfusion. The volumes of infarction and hypoperfused lesions were calculated on ASL and DSC multi-parametric maps. Patients were classified into reperfused, matched, or mismatch groups using time to maximum >6 sec as the reference. In a subset of patients who were successfully recanalized, the identical analysis was performed and the infarction and hypoperfused lesion volumes were used for paired pre- and posttreatment comparisons. Forty-one patients met our inclusion criteria. Twenty patients underwent successful endovascular revascularization (TICI>2a), resulting in a total of 61 ASL-DSC data pairs for comparison. The hypoperfusion volume on ASL-cerebral blood flow best approximated the DSC-time to peak volume (r=0.83) in pretreatment group and time to maximum (r=0.46) after recanalization. Both ASL-cerebral blood flow and DSC-TTP overestimated the hypoperfusion volume compared with time to maximum volume in pretreatment (F=27.41, P<0.0001) and recanalized patients (F=8.78, P<0.0001). ASL-cerebral blood flow overestimates the DSC time to maximum hypoperfusion volume and mismatch classification in patients with acute ischemic syndrome. Continued overestimation of hypoperfused volume after recanalization suggests flow pattern and velocity changes in addition to arterial transit delay can affects the performance of ASL.