Effects of hematocrit and oxygen saturation level on blood spin-lattice relaxation

In the present study blood T-1 was determined as a function of hematocrit and oxygen saturation. T-1 showed a significant linear dependency on both of these parameters. In addition, oxygen dissolved in blood plasma in hyperoxygenated blood resulted in relaxation enhancement, comparable in size to that due to the change in oxygenation state of hemoglobin. As blood T-1 is a key factor for quantification of flow with arterial spin labeling methods, the influence of T-1 variation in the physiological range of hernatocrit and oxygen saturation to flow determination is discussed. (C) 2003 Wiley-Liss, Inc.