NONNEOPLASTIC CAUSES OF HIGH SIGNAL INTENSITY AT T2-WEIGHTED MR-IMAGING AFTER TREATMENT FOR MUSCULOSKELETAL NEOPLASM

Objective. The objective of this study was to describe a variety of non-neoplastic causes of high-signal-intensity areas seen on T2-weighted magnetic resonance (MR) images obtained after treatment for malignant musculoskeletal neoplasm. Design. MR examinations obtained after treatment for malignant musculoskeletal neoplasm in 11 patients were reviewed. The examinations of these patients were selected because at least one MR study of each patient showed high-signal-intensity areas on T2-weighted images at or near the site of the original tumor. The MR imaging findings were correlated with results of biopsy in four patients, and with information from follow-up radiologic examinations and the patients' medical records in all cases, to determine the cause of the high-signal-intensity areas. Results. Non-neoplastic entities responsible for high-signal-intensity areas included postsurgical seroma, hematoma, postradiation therapy changes, fat necrosis and seroma, surgical hemostatic packing material, intercalary bone allograft, strut bone graft, atrophic muscle, and herniated colon and bladder. Knowledge of details of the surgical procedure and the time interval since surgery or irradiation aided in accurate interpretation of the findings, but did not allow immediate biopsy to be deferred in every case. Conclusion. High-signai-intensity areas on T2-weighted images in patients previously treated for malignant musculoskeletal neoplasm may represent a variety of entities other than residual or recurrent neoplasm, even in the presence of a mass. The MR imaging findings should be interpreted in conjunction with details of the specific clinical circumstances to prevent misdiagnosis and unnecessary biopsy.