Abstract TP56: Insight Into Human Ischemia Reperfusion Injury in Acute Stroke: A Voxel-Based MRI Analysis of Tissue Fate
Background: Reperfusion is characterized by initial restriction of blood supply followed by subsequent vascular restoration and concomitant reoxygenation of downstream tissue. In spite of mitigating initial tissue hypoxia, exacerbation of tissue injury may occur. Animal models have delineated reperfusion injury on the cellular and molecular levels, yet, no study has quantified voxel-based analyses of tissue fate due to reperfusion injury in human stroke.
Methods: Evaluation included 58 stroke patients with an age range of 65±18 years, 65% of whom were woman and 35% men. All patients presented with M1 MCA occlusion and a subset received mechanical thrombectomy (38) while another received intravenous tPA followed by mechanical thrombectomy (20). Serial perfusion MRI images were obtained on presentation as well as 3-6 hours following reperfusion and processed to extract Tmax parameters. These images were co-registered serially at the voxel level with tissue fate outcomes on FLAIR and GRE 4-5 days following presentation. Reperfusion was defined by serial changes observed in Tmax voxels. The volume of reperfusion, injury, as well as tissue fate relative to initial perfusion were calculated.
Results: Hemorrhage was noted on GRE in 28.9% of the patients who received thrombectomy alone and in 20% of those who received IV tPA followed by thrombectomy. In pure thrombectomy cases without later hemorrhage, average voxel-based reperfusion was 72.3% with 18% demonstrating reperfusion injury and tissue death as assessed by FLAIR imaging 4-5 days following presentation, averaging 86.2%. In patients who received IV tPA followed by mechanical thrombectomy without any subsequent hemorrhage, average voxel-based reperfusion was 66.0% with 6.2% demonstrating reperfusion injury in reperfused voxels and tissue death as assessed by FLAIR imaging 4-5 following presentation, averaging 90.3%.
Conclusions: Non-hemorrhagic forms of reperfusion injury are common in acute stroke patients treated with standard therapies. Despite reperfusion and irrespective of treatment modality, substantial amounts of tissue are destined to infarct. Voxel-based analyses of serial imaging studies may provide a framework to develop therapies for reperfusion injury.
- © 2012 by American Heart Association, Inc.