Multiple Fractionated and Single-Dose Irradiation of Bone Marrow: Evaluation by MR and correlation with histopathological findings

Purpose: To evaluate the MR appearance of bone marrow during and after multiple fractionated and single-dose irradiation using SE sequences, with histopathological correlation. Material and Methods: the left hind limbs of Wistar rats were irradiated with doses of either 2 GyX10 fractions or 20 Gy as a single dose. MR images of the femora were taken on days 0, 1, 3, 5, 7, 10, 15, 20, 25, 30, 40, 50, 60, 90, 120, 150 and 180. T1-, proton-density- and T2-weighted images were obtained with SE sequences. the rats were sacrificed on days 3, 12, 40 and 180 for histological study. Results: No significant change in the T1 relaxation time was observed in the fractionated group during the first 15 days after irradiation. T2 did not change during the initial 7 days. There were significant differences in T1 and T2 between nonirradiated and fractionated, and between fractionated and single-dose irradiated marrows (p