Evaluation of a quantitative blood oxygenation level-dependent (qBOLD) approach to map local blood oxygen saturation

Blood oxygen saturation (SO2) is a promising parameter for the assessment of brain tissue viability in numerous pathologies. Quantitative blood oxygenation level‐dependent (qBOLD)‐like approaches allow the estimation of SO2 by modelling the contribution of deoxyhaemoglobin to the MR signal decay. These methods require a high signal‐to‐noise ratio to obtain accurate maps through fitting procedures. In this article, we present a version of the qBOLD method at long TE taking into account separate estimates of T2, total blood volume fraction (BVf) and magnetic field inhomogeneities. Our approach was applied to the brains of 13 healthy rats under normoxia, hyperoxia and hypoxia. MR estimates of local SO2 (MR_LSO2) were compared with measurements obtained from blood gas analysis. A very good correlation (R2 = 0.89) was found between brain MR_LSO2 and sagittal sinus SO2. Copyright © 2010 John Wiley & Sons, Ltd. We present a version of a quantitative blood oxygenation level‐dependent (qBOLD) approach designed to assess the local blood oxygenation (LSO2). The method is based on an analysis of the free induction decay using a mathematical model and separate estimates of T2, the blood volume fraction (BVf) and magnetic field inhomogeneities. The results obtained in the brains of 13 healthy rats under gaseous challenge showed good agreement with previously reported values and are consistent with the systemic So2 values obtained in the femoral vein and the sagittal sinus.