MR evaluation: Spine changes after radiotherapy

Summary: To explore the changes in MR findings of the bone marrow of vertebral bodies after radiation therapy, 55 subjects who had been on irradiation treatment were studied. Irradiation dosage ranged from 2100 cGy to 7500 cGy. The interval between radiotherapy and MR examination varied from 7 weeks to 20 years. On T1WI images (T1WI) signal intensity increase of the bone marrow of those vertebral bodies was apparent. The areas with altered signal intensity rendered well defined margins corresponding to the field of irradiation. The similar finding was found on T2WI. On STIR or T1WI with fat suppression, the signal intensity of the areas was decreased. It is concluded that the changes of signal intensity on SE or STIR sequence is believed to be secondary to diffuse fatty infiltration and the results of replacement of the normal bone marrow by relatively increased yellow bone marrow.