Time related changes of T1, T2, and T 2 * of human blood in vitro

Abstract In view of a potential future use for dating hemorrhage in forensic medicine the correlation of MR relaxation parameters with time was evaluated in blood samples. A systematic relationship could be valuable for using MRI for estimating the age of hemorrhage and soft tissue hematomas particularly in clinical forensic medicine. Relaxation times T 1 , T 2 , and T 2 * of venous blood samples from 6 volunteers were measured using 3 T MRI regularly up to 30 days. The time progression of the relaxation parameters was systematically analyzed and examined for possible interrelations. T 2 initially decreased to a minimum, and then increased again (range 24–97 ms), while T 1 started with a plateau phase followed by an almost linear decrease (range 333–2153 ms). T 2 * remained relatively constant during the entire investigation period. The higher the initial T 2 was, the lower was its minimum, and the greater was the decrease of the associated T 1 . The inter- and intra-individual variability was relatively large, one reason being very likely the metabolic differences in the blood samples. The observed characteristic changes in blood samples over time measured by quantitative MR techniques add objective information in view of an estimation of the age of hemorrhage. However, in vivo studies will be needed to verify the data with respect to influencing metabolic factors.