Introduction: Prior studies based on MR data have shown that large perfusion lesions with long perfusion delays (Tmax>10s) are associated with poor functional and imaging outcomes. It is uncertain if the same associations exist for patients imaged with CT perfusion (CTP).
Hypothesis: Patients with large volumes (>100mL) of tissue with a Tmax delay exceeding 10s (malignant Tmax profile) on CTP exhibit more infarct growth and have larger infarct outcomes than patients without this profile.
Methods: The CRISP study is a multi-center NIH-sponsored prospective cohort study designed to evaluate if the presence of a CTP mismatch pattern is associated with a favorable response to reperfusion. All patients underwent CTP prior to endovascular therapy, early follow-up MRI (<36 hours from baseline CTP), and MRI at day 5. Infarct growth was calculated as the difference between the infarct core volume on baseline CTP (tissue with rCBF<30%) and the day 5 FLAIR. Reperfusion was defined as >50% resolution of the Tmax>6s lesion between baseline and early follow-up, or TICI 2b or 3 reperfusion by angiography in the absence of an early follow up scan. The volumes were compared using Wilcoxons rank-sum test, we report median, [IQR].
Results: Baseline mismatch profile, reperfusion status and day 5 MRI were available in 109/201 patients, of whom 99 reperfused. Among patients with reperfusion, those with a malignant Tmax profile (n=24) had more infarct growth than patients without a malignant profile (n=75) (90,[49-116] vs 43,[18-81] mL, p=0.006). Patients with malignant profile also had larger final infarct volumes (110,[61-155] vs 48,[21-99] mL, p=0.001). Both the time from stroke onset and from baseline CTP to intravascular therapy were balanced between the two Tmax profile groups (p=0.32 and 0.53). Of the 10 patients without reperfusion, only 1 had malignant Tmax profile and no comparisons we performed in this group.
Conclusion: A Tmax>10s lesion of 100 mL or more on CTP is associated with more than doubling of both infarct growth and final infarct volume despite successful reperfusion. While this does not exclude potential benefit from intraarterial thrombectomy, it suggests that the beneficial effect of reperfusion may be attenuated among patients with a malignant CTP profile.