T-2 RELAXATION-TIMES OF IRRADIATED VERTEBRAL BONE-MARROW IN PATIENTS WITH SEMINOMA

Our purpose was to demonstrate the effects of localized radiotherapy o n lumbar vertebral bone marrow with the use of quantitative MRT with m easurements of T-2 relaxation times. Ten patients with early stage tes ticular seminoma with a history of radiation therapy to a ''dog-leg'' field including the lumbar vertebrae underwent MR imaging of their lum bar spine using a 0.5 Tesla magnet. Five healthy subjects and two noni rradiated patients were imaged as well. The intervals from the beginni ng of radiotherapy to MRI examination varied from 1.5 to 52 months, an d the radiation dose ranged from 3000-4200 cGy. The T-2 relaxation tim es of the lumbar vertebral bone marrow and subcutaneous fat were calcu lated for each subject, Postirradiation bone marrow in irradiated semi noma patients exhibited significantly longer T-2 relaxation times than nonirradiated bone marrow in controls (71.1 vs. 63.6 ms, p = 0.047, t -test). The differences between the T-2 relaxation times of bone marro w and subcutaneous fat for each subject allowed for even better differ entiation between irradiated patients and controls (10.4 vs. 0.4 ms, p = 0.0004, t-test). Postirradiation bone marrow had significantly long er T-2 relaxation times than subcutaneous fat in irradiated patients ( N = 10, 71.1 vs. 60.7 ms, p = 0.00009, t-test), while nonirradiated bo ne marrow had T-2 relaxation times not statistically different from su bcutaneous fat in nonirradiated subjects (N = 7, 63.6 vs. 63.2 ms). Me asurements of T-2 relaxation times of bone marrow enabled us to differ entiate between irradiated seminoma patients and controls. Postirradia tion bone marrow undergoes late radiation effects resulting in longer T-2 relaxation times than nonirradiated bone marrow and subcutaneous f at. (C) 1997 Elsevier Science Inc.