Triple/Single quantum filtered sodium MRI of acute brain ischemia

The effectiveness of reperfusion therapies during acute brain ischemia depends on the viability of the underperfused tissue. Specifically, when the ischemic tissue is viable reperfusion leads to improved clinical outcome. However, when the ischemic tissue is non-viable, reperfusion therapy can lead to intra-cerebral hemorrhage and/or an accelerated rate of ischemia formation. Perfusion and diffusion weighted proton MRI (DW MRI) are well-established techniques for the early detection of brain ischemia but are unable to positively establish the viability of the tissue. Tissue sodium concentration (TSC) has been shown to exhibit a linear and reversible response for many hours after ischemia onset. Because sodium accumulation in tissue is closely related to its metabolic status, we believe that the rate of TSC accumulation during evolving ischemia could provide useful information about tissue viability during evolving ischemia. In this paper, we discuss the technical details leading to the application of triple quantum (TQ) sodium MRI for the monitoring of brain ischemia. The proposed methods are then demonstrated in a non-human primate model of temporary middle cerebral artery (MCA) occlusion.