Abstract 2451: Arterial Spin Labelling Provides Usual Clinical Information In Acute Stroke

Abstract

Introduction Arterial Spin Labelling (ASL) is a readily available MR scanning technique and may provide similar information to conventional bolus-tracking dynamic susceptibility MR sequences. However, there is little comparative data in acute stroke. Methods: Patients with an acute ischemic stroke were imaged within 6 hours of ischeamic stroke onset with perfusion CT (CTP) and at 24 hours with MRI, including diffusion weighted MR (DWI),ASL and Perfusion Weighted Magnetic Resonance Imaging (PWI). Patient neurological status was determined using the National institutes of stroke score acutely and at 24 hours, as well as a modified Rankin score at 90 days. The ASL baseline perfusion value was defined as the mean value of the healthy, non ischeamic stroke hemisphere of the patient. Values 20% higher or lower than the mean healthy hemisphere were considered abnormal. A pixel based analysis was also undertaken to compare the perfusion lesion on ASL to the perfusion lesion on the baseline CTP and concurrent PWI maps of CBV, CBF, MTT and Tmax. Results Of the 80 patients in this study there were 32 patients with hyperperfusion in the ischaemic region and 48 with persistent hypoperfusion on follow-up ASL imaging. Hyperperfusion was linked to greater penumbral salvage (defined by the acute CTP and 24 hour DWI) and an improved early clinical outcome (mean improvement in between acute and 24 hour NIHSS = 9) as well as better 3 month outcome (mRS mean = 2, p=0.15). Patients with persistent ASL hypoperfusion showed less improvement in NIHSS (mean improvement 3) and had a poorer 90 day outcome (mean mRS 4). Interestingly, The ASL hypoperfusion lesion was closest to the Tmax PWI map (AUC=0.85) rather than CBF(AUC=0.66) or MTT(AUC=0.73). Discussion. At 24 hours, hyper- or hypo-perfusion on ASL was strongly correlated to clinical outcome. ASL may have clinical utility in the prediction of stroke prognosis based on the difference in clinical outcome (mRS) between the patient groups with hyper- or hypo- perfusion.