Abstract 2855: The Application of Time-of-Flight MR Source Images in Predicting Hemorrhagic Transformation in Ischemic stroke

Abstract

Introduction: Hemorrhagic transformation (HT) is a feared complication in ischemic stroke. Its prediction has remained a challenge. It is more common among patients with worse stroke severity, early infarct signs, hyperdense artery sign, and hyperglycemia. Increased blood brain barrier permeability within the ischemic area is also associated with HT. Bleeding probably occurs from damaged vessels within the necrotic or edematous brain tissue. Time-of-Flight MR (TOF) source images provide parenchymal and vascular information relevant to HT: they are sensitive to T1 relaxation time and can detect hypointense areas that represent edema or necrosis which are early infract changes, and can also detect vessels with slow flow. Methods: We sought to define “ v essels i n hy p ointensity s ign” (VIPS), hyperintense signals of vessels within the hypointense area of necrotic or edematous tissues, on TOF source images. We hypothesized that VIPS would be associated with an increased risk of HT if identified on early MRI. We retrospectively reviewed our consecutive ischemic stroke patient registry from January 2009 to April 2011. We included patients with ischemic strokes in middle cerebral artery (MCA) or posterior cerebral artery territory and MR TOF obtained within 12 hours after symptom onset, who had inpatient follow-up CT scans. Patients with lacunar infarction, malignant infarction, endovascular acute treatment, HT limited to petechial hemorrhage on MRI, or poor quality images were excluded. The HT was recorded according to the ECASS morphologic definitions. Participation in the ethical review board-approved database requires informed consent. Results: A total of 35 patients met the inclusion criteria from 787 patients. VIPS was seen in 14 (40%) patients (age 65 years, women 43%, NIHSS median 14.5). The prevalence of HT was greater in patients with VIPS than those without (78% vs. 19%, p<0.001). PH2 type of HT was also more common in patients with VIPS than those without (64% vs. 25%, but not statistical significant due to small number of patients). The figure illustrates a VIPS in the right MCA territory and subsequent HT in that area. Patients with VIPS were younger than those without (65 vs. 75 years, p<0.05), but there were no statistical differences in sex, IV thrombolysis, proximal vessel occlusion, and admission NIHSS, blood pressure, glucose, and lipid level. Conclusion: VIPS may be a risk factor for HT in ischemic stroke if seen within 12 hours on MRI after symptom onset. Further studies are needed to confirm these findings.