title: Assessment of scaphoid viability with MRI: a reassessment of findings on unenhanced MR images.
abstract: OBJECTIVE
  The purpose of this article is to evaluate the accuracy of unenhanced T1-weighted MR images in predicting the vascular status of the proximal pole of the scaphoid in patients with chronic scaphoid fracture nonunions.
  
  
  METHODS
  A database search identified 29 patients with chronic scaphoid nonunions who underwent a preoperative MRI examination and intraoperative assessment of scaphoid viability from 2004 to 2009. T1-weighted MR images were evaluated by two musculoskeletal radiologists. If the proximal pole demonstrated diffusely decreased T1-weighted signal (less than or equal to that of skeletal muscle), the patient was placed in a moderate-to-high risk for avascular necrosis (AVN) category. Otherwise, the patient was placed in a viable-to-low risk for AVN category. Scaphoid viability or necrosis was diagnosed intraoperatively depending on whether punctate bleeding was present. After the patients were classified according to the T1-weighted appearance, the appearance on STIR images was recorded.
  
  
  RESULTS
  There were 29 patients (25 male) with a mean age of 21 years. When we compared the MRI results, using only the T1-weighted images, with the surgical findings, unenhanced MRI had a sensitivity, specificity, and accuracy of 55%, 94%, and 79%, respectively, for diagnosing AVN. Increased proximal pole STIR signal was noted with similar frequencies in patients with and without AVN.
  
  
  CONCLUSIONS
  T1-weighted unenhanced MRI is an acceptable alternative to delayed contrast-enhanced MRI in the preoperative assessment of the vascular status of the proximal pole of the scaphoid in patients with chronic fracture nonunions. STIR images were not beneficial in determining proximal pole viability.
authors.affiliation: Department of Radiology, University of Virginia, Charlottesville, VA 22908, USA. mf3kx@virginia.edu
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fox
authors.forename: Cree M
authors.initials: CM
authors.lastname: Gaskin
authors.forename: A Bobby
authors.initials: AB
authors.lastname: Chhabra
authors.forename: Mark W
authors.initials: MW
authors.lastname: Anderson
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D005599:Fractures, Ununited / Q000150:complications / Q000175:diagnosis*; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010020:Osteonecrosis / Q000175:diagnosis / Q000209:etiology; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D021361:Scaphoid Bone / Q000293:injuries* / Q000473:pathology; D055815:Young Adult