Abstract WP50: Defining the Hyper-acute Infarct Core in Porcine Model of Cerebral Ischemia: A Multi-modality Imaging Study
Background: Defining the hyper-acute infarct core can inform thrombolysis treatment. Clinical outcome and hemorrhagic transformation are correlated with infarct volume at admission. CT perfusion (CTP)-derived parameters and MR-diffusion weighted imaging (DWI) are currently used to delineate infarct volume; however, reversibility of such defects has been shown for both modalities.
Methods: Six domestic pigs (mean weight 34.7kg) had a CTP scan prior to intracranial injection of endothelin-1 (ET-1; 0.01mL/kg) into the left striatum. Subsequent CTP scans at 30min, 1hr, 1.5hrs were done to monitor stroke progression. A second dose of ET-1 (0.01mL/kg) was injected at 2hrs from the first injection. Twenty minutes after the second ET-1 injection, 18F-FDG was injected. The animal was moved to a 3T MRI scanner where MR-DWI was performed. The animal was then moved back to the CT scanner for a final CTP/PET acquisition. The brain was quickly removed, cut into 10mm slices and stained with tetrazolium-chloride (TTC), the gold standard for defining final infarct volume. Using custom software, the infarct volume defined by low intensity TTC stain, low CBF (< 9.3ml•min-1•100g-1), low CBV (< 1.07ml•100g-1), DWI hyper-intensity and low F-18 FDG uptake were determined. A linear regression model was used to correlate the infarct volume measured by each imaging modality to that by the histological gold standard and the coefficients of correlation (R2) compared.
Results: R2 values for CBF, CBV, DWI and FDG versus TTC-histology were 0.83, 0.69, 0.95 and 0.61, respectively. For the CBF and DWI parameters the slope of the fitted line was greater than 1, while the slope of the fitted line for the CBV and CBFxCBV parameters was less than 1. Mean normalized (relative to the histologically defined infarct) values were 1.38, 0.82, 0.99, and 0.67 for CBF, CBV, DWI and FDG, respectively.
Conclusion: In this small sample study, the CTP-CBF and the imaging gold standard DWI both overestimated the TTC-infarct in 100% and 50% of cases, while CTP-CBV and FDG-PET both underestimated the final infarct volume in 100% of animals.
- © 2012 by American Heart Association, Inc.