title: Non-neoplastic causes of high signal intensity at T2-weighted MR imaging after treatment for musculoskeletal neoplasm.
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  High-signal-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.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Panicek
authors.forename: L H
authors.initials: LH
authors.lastname: Schwartz
authors.forename: R T
authors.initials: RT
authors.lastname: Heelan
authors.forename: J F
authors.initials: JF
authors.lastname: Caravelli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001847:Bone Diseases / Q000175:diagnosis; D001859:Bone Neoplasms / Q000175:diagnosis / Q000628:therapy*; D016025:Bone Transplantation; D001842:Bone and Bones / Q000473:pathology* / Q000528:radiation effects / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D005122:Exudates and Transudates; D005260:Female; D005500:Follow-Up Studies; D006406:Hematoma / Q000175:diagnosis; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology* / Q000528:radiation effects / Q000601:surgery; D009135:Muscular Diseases / Q000175:diagnosis / Q000628:therapy*; D011183:Postoperative Complications / Q000175:diagnosis; D012983:Soft Tissue Neoplasms / Q000175:diagnosis / Q000628:therapy*