[MR relaxation times in diffuse bone marrow disorders: evaluation of their clinical usefulness in differentiation...

T1 and T2 relaxation time measurements of the femoral marrow were performed in 20 patients with acute myeloid leukemia (AML) and 9 patients with iron deficiency or other severe anemia who had shown diffuse abnormal signals on MR imaging of the femoral marrow. The ability of T1 and T2 values to differentiate between leukemic infiltration and hyperplastic hematopoietic marrow was evaluated. T1 and T2 ratios (T1 abnormal marrow/T1 normal marrow and T2 abnormal/T2 normal) were calculated, and the ratios of T1 to T2 (T1/T2) and of the T1 ratio to the T2 ratio (T1 ratio/T2 ratio) were also analyzed. Diffuse infiltrative marrows revealed prolonged T1 relaxation times in all patients with AML and other severe anemia, and it was not possible to distinguish the two groups of diseases on the basis of T1 values. The T2 relaxation times varied widely in AML, but the mean T2 value of the AML group was not statistically significantly different from that of the anemia group. There were also no significant differences in the T1 ratio, T2 ratio, T1/T2, and the T1 ratio/T2 ratio between leukemic infiltration and hyperplastic hematopoietic marrow. We concluded that measurement of T1 and T2 relaxation times was of limited clinical importance for the histological characterization of diffuse bone marrow disorders.