Adeola Olowu, MD
Amukotuwa S, Straka M, Aksoy D, Fischbein N, Desmond P, Albers G, et al. Cerebral Blood Flow Predicts the Infarct Core: New Insights From Contemporaneous Diffusion and Perfusion Imaging. Stroke. 2019;50:2783–2789.
The purpose of this study was to assess if cerebral blood flow (CBF) from perfusion studies could accurately estimate infarct core size in ischemic stroke patients during acute stroke management for appropriate thrombectomy triage. Relative cerebral blood flow (rCBF) accuracy would be determined by comparing infarct size to DWI of MRI.
Imaging data was assessed from the DEFUSE 2 and SENSE 3 studies. DEFUSE 2 (Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evaluation) evaluated if MRI can be used to determine which patients would most likely benefit from endovascular reperfusion. SENSE 3 (Sensitivity Encoding) compared DWI and CT perfusion to reliably detect ischemic core tissue, at risk tissue, and tissue at risk of hemorrhagic transformation. Between the two studies, 119 patients had both DWI and perfusion studies within 24 hours of symptoms onset.
Relative CBF (rCBF) was divided into 12 thresholds (0.20-0.44), and each of those thresholds were compared to the corresponding DWI. rCBF threshold of 0.32 provided the best prediction of infarct core estimate with DWI. When applying an infarct core limit of 70 mL for thrombectomy, approximately 94% of patients were correctly triaged to the appropriate therapy.
Using rCBF of CT Perfusion to determine patient eligibility for mechanical thrombectomy (MT) was sensitive (0.76) when ischemic core was > 70 mL. The sensitivity did decrease (0.38-0.49) for ischemic core volumes less than 70 mL. Contrarily, specificity increased as ischemic core volume decreased. See Table 3 in the original article.
This study is valuable for: 1) identifying an image marker than can be quickly obtained to appropriately triage patients for possible thrombectomy. Stroke is an acute, medical emergency. The faster an accurate decision can be made for therapy, the better it is for the patient; and 2) The rCBF marker is likely more accurate than non-contrast CT Head and will also be helpful in terms of decision making when there are cases of discrepant non-contrast CT Head ASPECTS analysis (which can be a potential area of study as well).