INCIDENCE OF RADIATION-INDUCED INSUFFICIENCY FRACTURES OF THE FEMALE PELVIS - EVALUATION WITH MR-IMAGING

OBJECTIVE. The purpose of this study was to assess the incidence, time of appearance, and evolution of radiation-induced insufficiency fract ures of the female pelvis with MR imaging. SUBJECTS AND METHODS. Eight een women (nine premenopausal and nine postmenopausal) with advanced c ervical carcinoma were studied prospectively with MR imaging. The exam inations totaled 216 and were scheduled before radiation therapy, thre e times during radiation therapy, and eight times after radiation ther apy. T1-weighted and shea inversion time inversion recovery images wer e obtained. The images were evaluated by two radiologists in consensus . The criterion for fracture was edema, indicated by an area of high s ignal intensity on short inversion time inversion recovery images and corresponding low signal intensity on T1-weighted images. CT scans (n = 61) and bone scans (it = 58) were used to confirm each diagnosis of fracture. RESULTS. Sixteen (89%) of Is patients (seven premenopausal a nd nine postmenopausal) showed findings compatible with insufficiency fractures. Thirteen patients had more than one lesion. The first fract ure was detected between 3 and 12 months after the end of radiation th erapy. During the study, the fractures associated with edema subsided without treatment in 41 (79%) of 52 lesions in 15 (94%) of 16 patients . Fractures were confirmed with additional imaging in all 16 patients (CT in 14 patients and bone scanning in nine patients). CONCLUSION. Ra diation-induced insufficiency fractures were frequently seen in premen opausal and postmenopausal women within 12 months after radiation ther apy. Multiple fractures developed within 24 months. Twenty-one percent of the lesions healed during the observation period of 30 months.