Abstract T P28: Brain MRI FLAIR Signal Intensity Ratio Is Correlated With Matrix Metalloproteinase-9 Level In Acute Ischemic Stroke

Abstract

Introduction: Increased Matrix Metalloproteinase-9 (MMP9) level is associated with symptomatic hemorrhagic transformation (HT) after stroke. Higher risk of HT has also been reported in patients with early FLAIR hyperintensity on brain MRI. Hypothesis: We assessed whether FLAIR hyperintensity is associated with MMP9 levels. Methods: We retrospectively analyzed a cohort of acute stroke subjects who had acute brain MRI images and blood samples within the first 12 hours after onset of stroke. FLAIR hyperintensity was quantitatively assessed using FLAIR signal intensity ratio between the stroke lesion and corresponding normal contralateral hemispheres. For each subject, the FLAIR ratio was generated from the average of 6 regions of interest: 2 white matter and 2 gray matter regions each on 2 separate slices. MMP9 was measured using standard ELISA technique. Univariate and multivariate analyses were used to evaluate the relationship between FR and MMP9 and clinical covariates. Results: 180 subjects had brain MRI and MMP9 available for analysis. MRI occurred within 6 ±3 hours and blood samples were drawn within 7 ± 4 hours from last seen well time. The mean MMP9 level was 238 ± 242 ng/mL and the mean FLAIR ratio was 1.40± 0.23. In univariate analysis, FLAIR ratio was associated with time to MRI (r= 0.18, p=0.01) and MMP9 (r=0.29, p<0.001). In multivariate analysis both FLAIR ratio (p<0.001) and time to MRI (p=0.003) remained associated with MMP9. Conclusions: There is a significant association between FLAIR ratio and MMP9 in acute stroke subjects. This raises the possibility that FLAIR hyperintensity reflects blood brain barrier changes during ischemia. Future studies to validate the prognostic value of FLAIR ratio in predicting symptomatic hemorrhagic transformation are warranted.