Intraoperative MR imaging of cerebral oxygen metabolism during resection of brain lesions

Abstract Objective Tissue oxygen tension is an important parameter for brain tissue viability and its non-invasive intraoperative monitoring in the whole brain is of highly clinical relevance. The purpose of this study was the introduction of a multiparametric quantitative blood oxygenation dependent (qBOLD) MRI approach for intraoperative examination of oxygen metabolism during the resection of brain lesions. Methods Sixteen patients suffering from brain lesions were intraoperatively examined twice (before craniotomy and after gross-total resection) using the qBOLD technique and a 1.5 Tesla MR scanner, which is installed in an operating room. The MR protocol included T2*- and T2-mapping, and dynamic susceptibility-weighted (DSC) perfusion. Data analysis was performed using a custom-made in-house MatLab software for calculation of maps of oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2 ) as well as of cerebral blood volume (CBV) and flow (CBF). Results Perilesional edema showed a significant increase in both perfusion (CBV +21%, CBF +13%) and oxygen metabolism (OEF +32%, CMRO2 +16%) after resection of the lesions. However, in perilesional non-edematous tissue only oxygen metabolism (OEF +19%, CMRO2 +11%) was significantly increased, but not perfusion. No changes were found in normal brain. Fortunately, no neurovascular adverse events were observed. Conclusions This approach for intraoperative examination of oxygen metabolism in the whole brain is a new application of intraoperative MRI additionally to resection control (residual tumor detection) and updating of neuronavigation (brain shift detection). It may help to detect neurovascular adverse events early during surgery.