Hyperemia detection on arterial spin labeling is associated with final infarct volume in stroke post-endovascular...

Patients with acute ischemic stroke (AIS) treated with endovascular therapy (EVT) may develop hyperemia due to loss of relative cerebral blood flow (rCBF) autoregulation. Hyperemia can be detected on two types of MRI perfusion weighted imaging: dynamic susceptibility contrast (DSC) and arterial spin labeling (ASL). The aim of this study was to compare hyperemia on ASL-rCBF to DSC-rCBF post-EVT and explore the association between hyperemia and final infarct volume (FIV).

This is a retrospective analysis of the GUARDS cohort in the ongoing prospective Natural History of Stroke study (ClinicalTrials.gov Identifier: NCT00009243). Patients with AIS who met the following criteria were eligible for this analysis: (i) ≥ 18 years, (ii) no contraindication to 3T MRI, (iii) large vessel occlusion in the anterior circulation, (iv) attempted EVT, and (v) 3T MRI obtained at 24 hours, including DSC-rCBF and ASL-rCBF, and at 5 days post-EVT. Qualitative imaging analysis for hyperemia detection was performed by consensus between two independent raters. Quantitative imaging analysis assessed hyperemic tissue volume, FIV, and Dice coefficients between hyperemia and FIV masks.

Forty patients with median (IQR) age of 70 (62-81) years and admission NIHSS 16 (10-21) were included. Hyperemia was identified on ASL-rCBF in 40 % (16) of patients and on DSC-rCBF in 30 % (12). For 9 patients with hyperemia on both modalities, the ASL-rCBF and DSC-rCBF median volumes were 85.7 (19.4-144.9) and 58.1 (26.2-74.0) (p = 0.10). The Dice coefficient for hyperemia on ASL-rCBF and FIV was higher compared to DSC-rCBF, 0.60 (0.54-0.69) versus 0.39 (0.34-0.49).

Hyperemia volumes measured on ASL-rCBF, compared to DSC-rCBF, at 24 hours were more associated with FIV at 5 days. Hyperemia may be an indicator of impaired cerebral autoregulation and potential target for adjunctive therapy to mitigate infarct growth.