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

Abstract

Accurate imaging of ischemic penumbra is crucial for improving the management of acute stroke patients. T2* magnetic resonance imaging (MRI) combined with a T2*oxygen challenge (T2*OC) is being developed to detect penumbra based on changes in blood deoxyhemoglobin. Using 100% O2, T2*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. T2* signal change was measured in regions of interest (ROIs) located within ischemic core, T2*OC-defined penumbra and equivalent contralateral areas during 40% O2± prior PFC injection. Region of interest analyses between groups showed that PFC significantly enhanced the T2* response to 40% O2 in T2*-defined penumbra (mean increase of 10.6 ± 2.3% compared to 5.6 ± 1.5% with 40% O2, P<0.001). This enhancement was specific to the penumbra ROI. Perfluorocarbon emulsions therefore enhances the translational potential of the T2*OC technique for identifying penumbra in acute stroke patients.

Autophagy Upregulation and Apoptosis Downregulation in DAHP and Triptolide Treated Cerebral Ischemia

“…Both the DAHP treatment group and TP treatment group have less hyperintensity than the MCAO group. From this result, we can deduce that both DAHP and TP attenuate cerebral ischemia [ 22 ].…”

Perfluorocarbon Enhanced Glasgow Oxygen Level Dependent (GOLD) Magnetic Resonance Metabolic Imaging Identifies the Penumbra Following Acute Ischemic Stroke

“…We have previously demonstrated enhanced detection of penumbra with T2*OC using our b-PFC combined with a lower level (40%) of inhaled oxygen 21 . Therefore, the addition of PFC to OC has demonstrated potential to overcome the limitations encountered in early clinical studies.…”

T2*-weighted fMRI time-to-peak of oxygen challenge in ischemic stroke

“…5,[7][8][9] OC with reduced oxygen concentration (40% O 2 ) to minimize possible toxic effects of oxygen has also been proposed. 10,11 Basal T 1 increased slightly in the ischemic core 24 h after stroke due to edema, whereas OC decreased T 1 significantly in the core, indicating the substantial increases in dissolved oxygen occurred in the core as the results of hyperperfusion 24 h after stroke. 5 Although OC offer useful insight into ischemic tissue fate, the OC T 2 *-weighted signals have a few confounding factors that preclude potential widespread utility.…”