Abstract P373: Persistent Hyperintensity on Diffusion Weighted Imaging One Month After Stroke is Associated With Larger Ischemic Lesions and Greater Loss of Function

Background: Diffusion weighted imaging (DWI) becomes hyperintense within minutes of ischemic insult to cerebral tissue. While apparent diffusion coefficient maps evolve rapidly during the days after ischemia, DWI typically remains bright for weeks to months after a stroke. This phenomenon is often referred to as “T2-shine through.” We sought to investigate factors that influence persistent hyperintensity on DWI. Methods: The study population included ischemic stroke patients who were admitted to two regional stroke centers and imaged with MRI <=4.5 hours from stroke onset and then again 30 days later. DWI images were independently reviewed for each time point. 30-day DWI images were compared to initial images and were rated accordingly: 1. absent hyperintensity, 2. mixed hyperintensity, 3. bright hyperintensity. Hyperintensity rating was treated as an continuous variable and compared with demographics, risk factors, laboratory values, imaging measurements, and outcome measures using univariate linear regression. Results: Thirty-one patients were included in the study; median age was 63 and 58% were women. Hyperintensity on DWI was absent at 30 days in 9 patients (29%), mixed in 11 patients (35%) and bright in 11 patients (35%). Greater DWI hyperintensity 30 days post stroke was associated with larger volume of the perfusion deficit on presentation (p=0.037) but not with core stroke volume (p=0.621) or mismatch ratio (p=0.719). DWI hyperintensity was not associated with demographic or clinical variables. Greater DWI hyperintensity rate was associated with worse post-stroke disability when comparing premorbid modified Rankin score (mRS) with the follow up mRS (p=0.026) as depicted in the figure that showing a box plot of change in mRS vs. degree of “T2-shine through”. Conclusions: Persistent hyperintensity on DWI a month after stroke may be an indicator of greater disability. Larger studies are needed to confirm these findings and understand their implications for further recovery.