Abstract W MP71: Quantification of Cerebral Vascular Reserve Mapping from Dynamic Susceptibility Contrast Magnetic Resonance Imaging

Accurate measurement of cerebral vascular reserve (CVR) can be used as an indicator of cerebral hemodynamic impairment. The NIH/NINDS Stroke Progress Review Group has identification of CVR imaging as a top research priority. The Bookend Technique is a dynamic susceptibility contrast perfusion imaging technique that can quantify absolute cerebral blood flow (qCBF, ml/100g/min) and cerebral blood volume (qCBV, ml/100g). We report on first results using bookend perfusion scans to quantify CVR. We hypothesize that quantitative images of cerebral perfusion can be used to quantitate cerebral vascular reserve over the whole brain. We conducted an IRB approved, retrospective study with seven patients (4 male, 3 female, ages 61 ± 13.1 years) selected for angiographically confirmed occlusive vessel disease. The water exchange response curve, which mitigates the compartmentalization effects of the Gadolinium, was found to introduce a bias in multi-injection exams. We developed a new water exchange response curve that accounts for residual T1-shortening from the pre-stress images. Quantitative perfusion images were acquired before and after injection of vasodilator acetazolamide (ACZ) and the computed qCBF maps were coregistered and subtracted to generate CVR maps. We successfully measured the reactivity of cerebral vasculature. The CVR increase was found to be +10.3% ± 14.2% in unimpaired regions, and a net decrease of -8.63% ± 17.1% was observed in affected territories. We found the expected linear relationship between CVR and Cerebral Perfusion Pressure (CVR = 58.2*(CPP)-14.5). In conclusion, our results indicate that CVR can be successfully quantified from MR perfusion images using ACZ induced vascular reactivity and the Bookend Technique. Therefore, the resulting CVR maps can describe and present stages of hemodynamic failure of patients.