Falsely Normal CT Perfusion Ischemic Core Readings Are Common and Often Associated with Deep Infarcts

Background: Proper identification of infarct extent is crucial for thrombectomy and prognostication. We sought to study the frequency and topographic aspects of those cases in which CT perfusion (CTP) misses a core lesion that is present on initial non-contrast CT (NCCT).

Methods: A review was carried out of a prospectively collected database of endovascular patients with anterior circulation large vessel occlusion strokes from January 2014 to November 2018. Patients with an e-ASPECTS <10 and adequate CTP maps were included. Total missed ischemic core (TMC) was defined as a CTP core lesion (rCBF<30%) <1 mL with a visualized hypodensity on NCCT.

Results: Of 629 patients analyzed, 161 (25.6%) had a TMC. TMC was associated with isolated deep MCA strokes, lower NIHSS, and longer times to treatment; isolated deep MCA stroke was an independent predictor (OR 2.49, p<0.001). TMC was associated with lower rates of parenchymal hematomas and smaller final infarct volumes, with no difference in good outcomes or 90-day mortality.

Conclusions: CTP may completely fail to detect ischemic core in as many as 25% of cases, especially in isolated deep MCA strokes, so technical refinements of post-processing algorithms are warranted. TMC infarcts may carry a lower risk of reperfusion hemorrhage.