Collateral status contributes to differences between observed and predicted 24-h infarct volumes in DEFUSE 3

Abstract

We previously demonstrated that in the DEFUSE 3 trial, the union of the baseline core and the 24-h Tmax > 6 s perfusion lesion predicts the infarct volume at 24 h. Presently, we assessed if collateral robustness measured by the hypoperfusion intensity ratio (HIR) and cerebral blood volume (CBV) index accounts for the variance in these predictions. DEFUSE 3 patients underwent MRI/CT perfusion imaging at baseline and 24 h post-randomization. We compared baseline and follow-up HIR and CBV index across subgroups stratified by differences between predicted and observed 24-h infarct volumes. Of 123 eligible patients, 34 with 24-h infarcts larger than predicted had less favorable collaterals at baseline (HIR 0.43 vs. 0.32, p = 0.006; CBV Index 0.78 vs. 0.85, p = 0.001) and 24 h (HIR 0.56 vs. 0.07, p = 0.004; CBV Index 0.47 vs. 0.73, p = 0.006) compared to 71 patients with more accurate infarct volume prediction. Eighteen patients with 24-h infarcts smaller than predicted had similar baseline collateral scores but more favorable 24-h CBV indices (0.81 vs. 0.73, p = 0.040). Overall, patients with 24-h infarcts larger than predicted had evidence of less favorable baseline collaterals that fail within 24 h, while patients with 24-h infarcts smaller than predicted typically had favorable collaterals that persisted for 24 h.

Keywords: Stroke; brain imaging; brain ischemia; collaterals; diffusion-weighted MRI; perfusion-weighted MRI; reperfusion; thrombectomy.

Figure 1.

Hypoperfusion intensity ratios (HIR) in patients across estimation groups, (a), at baseline (b), at 24 h after randomization and (c), comparing the difference between baseline and 24 h post-randomization.

Figure 2.

Cerebral blood volume (CBV) index in patients across estimation groups (a), at baseline (b), at 24 h after randomization and (c), comparing the difference between baseline and 24 h post-randomization.

Figure 3.

Imaging from a patient who partially reperfused, for whom the union-predicted 24-h infarct volume (74 ml) was larger than the observed volume (10 ml), likely due to improving collaterals between baseline and 24-h imaging. (a) Baseline RAPID map showing core (left) and penumbra (right). (b) RAPID map at 24 h after randomization. (c) Infarct at 24 h after randomization.

Figure 4.

Imaging from a patient who did not reperfuse, for whom the baseline Tmax > 6 s predicted 24-h infarct volume (46 ml) was smaller than the observed volume (145 ml) presumably due to worsening collaterals between baseline and 24-h imaging. (a) Baseline RAPID map showing core (left) and penumbra (right). (b) RAPID map at 24 h after randomization. (c) Infarct at 24 h after randomization.