Purpose: To describe MR imaging characteristics of osteoradionecrosis (ORN) of the pelvis as a result of radiation therapy (RT) on gynecological tumors.
Material and methods: Radiography, computed tomography (CT) and magnetic resonance imaging (MRI) were performed on 9 women (mean age 67.5 years) with gynecological tumors to identify ORN. T1- and T2-weighted sequences and contrast-enhanced t1-weighted sequences with and without fat saturation were used. The patients began developing pain after the completion of RT indicating a possible ORN a which time MRI was performed. MR images were correlated with the results of clinical examinations.
Results: Depending on the time elapsed after RT, ORN presented with different signal intensities. The acquired images suggested that signal changes in T2-weighted images as well as the different enhancement behaviour of ORN could be dependent on the time elapsed after RT. Visualisation of the affected regions was best achieved with fat-saturated T1-weighted sequences. CT showed increased density in the affected regions corresponding to osteosclerosis. In all cases the sacroiliac joint was affected, some times bilaterally.
Conclusion: MRI is helpful in detecting and characterizing ORN. Changes in signal intensity, based on histopathological tissue changes could make a chronological classification possible.