title: Retroperitoneal low-flow vascular malformations: characteristic MRI findings correlated with histopathological findings.
abstract: OBJECTIVE
  To evaluate the MRI findings of retroperitoneal low-flow vascular malformations (RLVMs) correlated with histopathological findings.
  
  
  METHODS
  Two radiologists reviewed the MRI findings of 4 RLVMs (3 with capillary malformations and 1 with a venous malformation). First, they evaluated the visibility, signal intensities, and signal homogeneity of each lesion on non-fat-suppressed breath-hold T2-weighted single-shot fast spin-echo (non-FS SSFSE) images and fat-suppressed T2-weighted fast spin-echo (FS T2-weighted FSE) images. Second, the kinetic patterns and the internal enhancement patterns were analyzed for each lesion on multi-phasic contrast-enhanced (CE) images. After these image analyses, the MRI findings were correlated with the histopathological findings.
  
  
  RESULTS
  Histopathologically, the 4 RLVMs did not exhibit remarkable degeneration and were present in the retroperitoneal fat tissue without clear capsules. On the non-FS SSFSE images, 3 of the 4 RLVMs could not be discriminated from the surrounding retroperitoneal fat tissue (invisible), and the remaining lesion was barely visible with an indistinct margin. On the FS T2-weighted FSE images, however, all the RLVMs were clearly visualized as homogeneous high-signal intensities. On the multi-phasic CE images, all the capillary malformations exhibited fast enhancement, while a venous malformation showed slow enhancement. Furthermore, the RLVMs tended to exhibit a centripetal filling pattern.
  
  
  CONCLUSIONS
  The RLVMs blended in with the surrounding retroperitoneal fat tissue on non-FS SSFSE images, like phantoms, whereas they were clearly visualized on FS T2-weighted FSE images. On multi-phasic CE images, the RLVMs tended to exhibit a centripetal filling pattern. These imaging features may be useful diagnostic clues for RLVMs.
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Akita
authors.forename: Yoshitake
authors.initials: Y
authors.lastname: Yamada
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ito
authors.forename: Shuji
authors.initials: S
authors.lastname: Mikami
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sugiura
authors.forename: Shigeo
authors.initials: S
authors.lastname: Okuda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Jinzaki
mesh_terms: D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012187:Retroperitoneal Space / Q000473:pathology; D054079:Vascular Malformations / Q000473:pathology*