title: Retrorectal tumors in adults: magnetic resonance imaging findings.
abstract: OBJECTIVE
  To retrospectively evaluate the magnetic resonance imaging (MRI) features of adult retrorectal tumors and compare with histopathologic findings.
  
  
  METHODS
  MRI features of 21 patients with preoperative suspicion of retrorectal tumors were analyzed based on the histopathological and clinical data.
  
  
  RESULTS
  Fourteen benign cystic lesions appeared hypointense on T1-weighted images, and hyperintense on T2-weighted images with regular peripheral rim. Epidermoid or dermoid cysts were unilocular, and tailgut cysts were multilocular. Presence of intracystic intermediate signal intensity was observed in one case of tailgut cyst with a component of adenocarcinoma. Six solid tumors were malignant lesions and showed heterogeneous intensity on MRI. Mucinous adenocarcinomas showed high signal intensity on T2-weighted and mesh-like enhancing areas on fat-suppressed T2-weighted images. There was a fistula between the mass and anus with an internal opening in mucinous adenocarcinomas arising from anal fistula. Gastrointestinal stromal tumors displayed low signal intensity on T1-weighted images, and intermediate to high signal intensity on T2-weighted images. Central necrosis could be seen as a high signal on T2-weighted images.
  
  
  CONCLUSIONS
  MRI is a helpful technique to define the extent of the retrorectal tumor and its relationship to the surrounding structures, and also to demonstrate possible complications so as to choose the best surgical approach.
authors.affiliation: Department of Radiology, The Affiliated Hospital of Nanjing University of Chinese Medicine, No.155 Hanzhong Road, Nanjing 210029, China.
authors.forename: Bo-Lin
authors.initials: BL
authors.lastname: Yang
authors.forename: Yun-Fei
authors.initials: YF
authors.lastname: Gu
authors.forename: Wan-Jin
authors.initials: WJ
authors.lastname: Shao
authors.forename: Hong-Jin
authors.initials: HJ
authors.lastname: Chen
authors.forename: Gui-Dong
authors.initials: GD
authors.lastname: Sun
authors.forename: Hei-Ying
authors.initials: HY
authors.lastname: Jin
authors.forename: Xin
authors.initials: X
authors.lastname: Zhu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000473:pathology* / Q000601:surgery; D012189:Retrospective Studies; D055815:Young Adult