Abstract DP024: Post-Recanalization Hyperperfusion Following Successful Endovascular Thrombectomy: A Quantitative CT and MR Perfusion Analysis

Background: Post-reperfusion hyperperfusion or hyperemia is occasionally observed following endovascular thrombectomy (EVT), but its diagnostic criteria, prevalence, and clinical significance remain unclear. This study quantified perfusion changes between pre-EVT CT perfusion (CTP) and early post-EVT MR perfusion (MRP) to evaluate post-EVT hyperperfusion. Methods: Sixty-three patients who underwent EVT for isolated MCA occlusion, had no prior disability, achieved successful recanalization (≥TICI 2b) and underwent post-EVT MRP within 24 hours were analyzed. Eight ASPECTS-based regions were assessed, with caudate, lentiform, and internal capsule combined into a single unit. Cerebral blood flow (CBF) and cerebral blood volume (CBV) were measured on both pre-EVT CTP and post-EVT MRP, with values normalized to the contralateral hemisphere or region. For each patient, mean perfusion parameters were calculated both across all the regions from affected hemisphere and within the region demonstrating the most severe initial CBF reduction. Post-procedural hyperperfusion or hyperemia was defined as CBF or CBV >125% of the contralateral normal side. Results: Of the 63 patients included, 66.7% were male with mean age of 64.0±9.1 years, and median NIHSS was 14. Mean last-known-well to arrival time was 3.56±6.70 hours. Atherosclerotic etiology was identified in 17.5%, and atrial fibrillation was documented in 46% (Figure 1). Pre-EVT CTP showed CBF ratios of 0.88±0.16 in the affected hemisphere and 0.65±0.20 in the maximally hypoperfused region. Post-EVT MRP (mean 1.7 ± 2.7 hours after EVT) showed CBF and CBV ratios of 1.03±0.16 and 1.05±0.18 in the affected hemisphere, and 1.10±0.23 and 1.09±0.25 in the maximally hypoperfused region. Hyperperfusion occurred in 22.2% (14/63) by CBF and 17.5% (11/63) by CBV (Figure 2). In post-procedural hyperperfusion group, post-EVT CBF and CBV ratios in the index region were 1.42±0.20 and 1.25±0.26. Baseline CTP CBF in this group was significantly lower compared with that without hyperperfusion (0.55±0.19 vs. 0.68±0.19, P=0.046; Figure 3). Conclusions: Post-recanalization hyperperfusion was observed in about one-fifth of patients following successful EVT and was significantly associated with more severe baseline hypoperfusion. Further investigation of clinical and imaging correlates in larger cohorts is warranted to elucidate the pathophysiological mechanisms and therapeutic implications of this phenomenon.