Identifying infarct core or irreversible infarct on admission is essential in order to establish the amount of salvageable tissue and indicate reperfusion therapies. CT perfusion (CTP) has been reported to be useful differentiating the penumbra as the mismatch between infarct core and hypoperfused brain. Infarct core is established on CTP as the severely hypoperfused areas, however the correlation between hypoperfusion and infarct core may be time dependent and not always true as it is not a direct tissue damage indicator.
We aim to characterize those cases in which admission core lesion on CTP does not reflect an infarct on follow-up imaging.
Methods: We studied patients with ICA/MCA occlusion who underwent CTP on admission but received endovascular thrombectomy based on initial non-contrast CT ASPECTS≥7. Admission infarct core was measured on initial CBV-CTP and final infarct on follow-up imaging. We defined ghost infarct core (GIC) as: initial core - final infarct>10cc. Time from symptom onset to CTP was recorded. Recanalization (TICI2b3) was assessed after thrombectomy.
Results: 79 patients were studied: ICA/MCA occlusion 21/58, median NIHSS 17(11-20), mean time from symptoms to CTP: 218±143minutes. Recanalization rate was: 77% Mean CBV infarct core was 44±59cc, and mean final infarct volume was 38±70cc. 30 patients (38%) presented a GIC>10cc and 22(29%) a GIC>20cc. GIC>10cc was associated with recanalization (TICI2b3:44 Vs 17%; p=0.034), admission glicemia (<185mg/dl:42% Vs 0%; p=0.028) and time to CTP (185:26%; p=0.033). An adjusted logistic regression model showed time from symptom to CTP imaging 10cc (OR: 2.89, 95%CI: 1.04-8.09). Similar results were observed if infarct core was defined with CBF maps.
Conclusion: CT perfusion may overestimate final infarct core especially in the early window from symptom onset. Selecting patients for reperfusion therapies based on the CTP mismatch concept may deny treatment to patients who may still benefit from reperfusion.