Introduction: Previous studies suggested that low cerebral blood volume (CBV) lesion predicts hemorrhagic transformation after endovascular therapy.
Hypothesis: We assessed the hypothesis that delays in time to reperfusion lead to hemorrhagic transformation on T2*-weighted MRI after endovascular therapy in patients with low CBV obtained from pre-treatment CT perfusion (CTP).
Methods: We retrospectively analyzed 62 consecutive patients with acute ischemic stroke who were obtained successful reperfusion (TICI 2A-3) by endovascular thrombectomy for internal carotid artery or M1 occlusion. CTP maps were assessed for relative CBV (rCBV) values obtained separately for cortical and basal ganglia regions in the MCA territory. The presence of cortical and basal ganglia hemorrhage (either HI or PH) was assessed on T2*-weighted MRI after endovascular therapy. We analyzed the influence of rCBV in each region, CTP-to-reperfusion time and degree of reperfusion on cortical and basal ganglia hemorrhage.
Results: Forty patients developed hemorrhagic transformation. HIs occurred in 16, PH1s in 21, PH2s in 3 and symptomatic hemorrhage in 1 of the patients. rCBV of the cortical region (0.77 versus 0.98, P=0.002) and basal ganglia region (0.64 versus 0.88, P<0.001) were significantly lower in the patients with hemorrhage than in those without. There was no significant difference in CTP-to-reperfusion time between cortical hemorrhage and no cortical hemorrhage groups. However, in the patients with low cortical rCBV (rCBV <0.8) and TICI ≥2b, mean CTP-to-reperfusion time was significantly shorter (70 versus 108 minutes, p=0.021) in the non-cortical hemorrhage group. There was no significant difference in CTP-to-reperfusion time between basal ganglia hemorrhage and non-basal ganglia hemorrhage groups.
Conclusions: Early reperfusion decreases risk of cortical hemorrhage in patients with low cortical rCBV. Low rCBV in basal ganglia region is more predictive of basal ganglia hemorrhage than time to reperfusion.