Perfluorocarbons Enhance a T2*-Based MRI Technique for Identifying the Penumbra in a Rat Model of Acute Ischemic Stroke

Accurate imaging of ischemic penumbra is crucial for improving the management of acute stroke patients. T 2 * magnetic resonance imaging (MRI) combined with a T 2 * oxygen challenge (T 2 * OC) is being developed to detect penumbra based on changes in blood deoxyhemoglobin. Using 100% O 2 , T 2 * OC-defined penumbra exhibits ongoing glucose metabolism and tissue recovery on reperfusion. However, potential limitations in translating this technique include a sinus artefact in human scans with delivery of 100% OC and relatively small signal changes. Here we investigate whether an oxygen-carrying perfluorocarbon (PFC) emulsion can enhance the sensitivity of the technique, enabling penumbra detection with lower levels of inspired oxygen. Stroke was induced in male Sprague-Dawley rats ( n =17) with ischemic injury and perfusion deficit determined by diffusion and perfusion MRI, respectively. T 2 * signal change was measured in regions of interest (ROIs) located within ischemic core, T 2 * OC-defined penumbra and equivalent contralateral areas during 40% O 2 ± prior PFC injection. Region of interest analyses between groups showed that PFC significantly enhanced the T 2 * response to 40% O 2 in T 2 * -defined penumbra (mean increase of 10.6 ± 2.3% compared to 5.6 ± 1.5% with 40% O 2 , P<0.001). This enhancement was specific to the penumbra ROI. Perfluorocarbon emulsions therefore enhances the translational potential of the T 2 * OC technique for identifying penumbra in acute stroke patients.