The correlation between CT perfusion deficits and immediate post-endovascular treatment contrast extravasation on dual energy CT in acute ischemic stroke patients

Abstract

Purpose

After endovascular therapy (EVT) for ischemic stroke, post-EVT CT imaging often shows areas of contrast extravasation (CE) caused by blood brain barrier disruption (BBBD). Before EVT, CT-perfusion (CTP) can be used to estimate salvageable tissue (penumbra) and irrevocably damaged infarction (core). In this study, we aimed to correlate CTP deficits to CE, as a surrogate marker for BBBD, after EVT for ischemic stroke.

Methods

In this single center study, EVT patients between 2010 and 2020 in whom both CTP at baseline and DECT post-EVT was performed were included. The presence of core and penumbra on CTP was assessed per ASPECTS region, resulting in a CTP-ASPECTS_core and a CTP-ASPECTS_{core+penumbra}. Likewise, CE on DECT was scored per ASPECTS region, resulting in a CE-ASPECTS. Correlation was assessed using Kendall's tau correlation and positive predictive values (PPV) were calculated per ASPECTS region. Bland-Altman plots were created to visualize the agreement between the two scores.

Results

194 patients met our inclusion criteria. The median core and penumbra were 8 cc (IQR 1–25) and 103 cc (IQR 68–141), respectively. The median CTP-ASPECTS_core, CTP-ASPECTS_{core+penumbra}, and CE-ASPECTS were 7 (IQR 4–9), 3 (IQR 1–4), and 6 (IQR 4–9), respectively. The correlation between CTP-ASPECTS_core and CE-ASPECTS was τ = 0.21, P <.001, and τ = 0.13, P =.02 between CTP-ASPECTS_{core+penumbra} and CE-ASPECTS. Bland-Altman plots showed a mean difference (CTP-ASPECTS minus CE-ASPECTS) of 0.27 (95 %CI −6.7–7.2) for CTP-ASPECTS_core and −3.2 (95 %CI −9.7–3.2) for CTP-ASPECTS_{core+penumbra}. The PPVs of the CTP-ASPECTS_core and CTP-ASPECTS_{core+penumbra} were highest for the basal ganglia.

Conclusion

There is a weak although significant correlation between pre-EVT CTP-ASPECTS and post-EVT CE-ASPECTS. The weak correlation may be attributed to various imaging limitations as well as patient related factors.