Effect of Hematocrit on MR Estimates of BVf, VSI and Local Blood Oxygen Saturation. an in Vivo Study.

Thomas Christen¹, Benjamin Lemasson¹, Nicolas Pannetier¹, Regine Farion¹, Christoph Segebarth¹, Chantal Remy¹, Emmanuel Louis Barbier¹

We have investigated the influence of the hematocrit on the MR estimates of Blood Volume fraction (BVf), Vessel Size Index (VSI) and local SO2 (lSO2). In healthy rats, the hematocrit was either decreased using isovolumic hemodilution or increased using an intermittent hypoxia preconditionning. Measurements obtained with MR were compared to quantitative histology and blood gas analysis. Our results showed variations of lSO2 (consistent with a stable tissue oxygenation level), variations of BVf and no changes in VSI between groups of animals. In all cases MRI and biology remains correlated suggesting a linear effect of hematocrit on the MR estimates.