Spin-lattice relaxation times of bound water—Its determination and implications for tissue discrimination

Measurements were made of T1 of bound water ( T1 b) and bound water fraction (α) for gelatin solutions and human tissues (sera, brain tumor, cerebral white matter). Bound water fraction in each sample was measured by means of thermal analysis (differential scanning calorimetry: DSC). T1 values were measured by FONAR QED 80-α. T1 b values were calculated by an equation derived from the fast-exchange two-state model. In the study of gelatin solutions, the relationship between T1 and water content differed depending on the sort of solutions. This was considered to be due to differences in T1 b values. In each biological tissue the values of T1 b and α had different distributions. These results indicate that values of T1 b and α for biological tissues may be altered in correspondence to the changes in pathophysiological states in those tissues.