Accuracy of CT perfusion-predicted core in the late window

Background and purpose: Recent endovascular trials have spurred a paradigm shift toward routine use of CT perfusion (CTP) for decision-making in acute ischemic stroke. CTP use in the late window, however, remains under evaluation. Our objective was to assess the accuracy of CTP-predicted core in the late window.

Methods: In a retrospective review of our prospectively identified stroke registry at a single, comprehensive stroke center, we included patients with anterior large vessel occlusions presenting within the 6-24 h window who underwent baseline CTP evaluation and achieved TICI2b or TICI3 reperfusion on endovascular treatment. We recorded baseline CTP-predicted core volumes at relative cerebral blood flow (CBF) thresholds of <30% <34%, and <38% using RAPID software. Final infarct volumes (FIV) were calculated using follow up MRI and CT, obtained within 72 h after stroke onset.

Results: Of the eligible patients, 134 met our inclusion criteria. Mean FIV was 39.5 (SD 49.6). Median CTP to reperfusion time was 93.5 min. Median absolute differences between CTP-predicted core and FIV were 14.7, 14.9, and 16.0 ml at <30%, <34%, and <38%, respectively. Correlation between CTP-predicted ischemic cores and FIV was moderate and statistically significant at all thresholds: r = 0.43 (p <0.001), r = 0.43 (p <0.001), and r = 0.42 (p <0.001) at the <30%, <34%, and <38% cutoffs, respectively.

Conclusion: CTP cores in the 6-24 h period underestimate FIV, especially with larger infarcts. CTP-predicted core volumes in the late window show moderate positive correlation with FIV.