title: Pseudotear of the peroneus longus tendon on MRI, secondary to a fibrocartilaginous node.
abstract: OBJECTIVE
  The purpose of this study was to identify the presence of a fibrocartilaginous node within the distal peroneus longus tendon (PLT) just proximal to the cubital tunnel and correlate this with MRI signal characteristics of the distal PLT, which could result in a pseudotear appearance on MRI. We correlated imaging characteristics with pathologic specimens.
  
  
  METHODS
  Institutional review board approval was obtained. Retrospectively, 91 ankle MRIs utilizing a standard ankle protocol were reviewed by two musculoskeletal radiologists. Four cadaver ankles were imaged using a standard ankle MRI protocol and reviewed by the same radiologists. All the MRIs were examined for signal changes in the PLT. The cadaver ankles then underwent PLT dissection by an orthopaedic surgeon, and a pathologic review was undertaken by a pathologist with orthopaedic specialization, who looked for an os peroneum or proposed fibrocartilaginous node relating to the signal change found on the MRIs.
  
  
  RESULTS
  In the 91 ankle MRI studies, the PLT demonstrated normal low and increased signals. On the fat-saturated T2-weighted sequence, 76 (83.5%) ankles demonstrated low signal and 15 (16.5%) demonstrated increased signal. Of the cadaver ankle MRIs, all four demonstrated increased signal within the PLT; three contained a fibrocartilaginous node and one contained an os peroneum in that same region.
  
  
  CONCLUSIONS
  The MRI signal of the PLT can change with the presence of a fibrocartilaginous node, which may be due to the molecular and chemical content of the fibrocartilage. This node increases the MRI signal in the distal PLT and gives the appearance of a pseudotear.
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA. mdidolka@bidmc.harvard.edu
authors.forename: Manjiri M
authors.initials: MM
authors.lastname: Didolkar
authors.forename: Alfred L
authors.initials: AL
authors.lastname: Malone
authors.forename: James A
authors.initials: JA
authors.lastname: Nunley
authors.forename: Leslie G
authors.initials: LG
authors.lastname: Dodd
authors.forename: Clyde A
authors.initials: CA
authors.lastname: Helms
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016512:Ankle Injuries / Q000175:diagnosis*; D002102:Cadaver; D002648:Child; D004210:Dissection; D005260:Female; D051445:Fibrocartilage / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013708:Tendon Injuries / Q000175:diagnosis*