Radiotherapy effects on vertebral bone marrow: Easily recognizable changes in T-2 relaxation times

The effect of localized radiotherapy on vertebral bone marrow was demonstrated in two patients using quantitative MRI studies with pixel-by-pixel measurement of T-2 relaxation times with generation of T-2 images, Conventional T-1-weighted spin-echo images were obtained as well. Irradiated vertebral bone marrow was found to have longer T-2 relaxation times than the neighboring nonirradiated bone marrow. These changes corresponded to the increased signal intensity on T-1-weighted images and to the field of radiotherapy and were noted 2.5 to 32 mo after radiotherapy, Radiologists should be aware of the increased T-2 relaxation times in irradiated bone marrow to correctly assess spinal disorders in irradiated patients, The reported T-2 changes may reflect the abundance of adipose cells that proliferate in bone marrow after radiotherapy, or may indicate an additional histological change, such as bone marrow necrosis or edema, Conclusive histological proof remains to be obtained.