title: MRI as a reference standard for suspected scaphoid fractures.
abstract: OBJECTIVE
  Some have suggested that MRI might be the best reference standard for a true fracture among patients with suspected scaphoid fractures. The primary aim of this study was to determine the rate of false-positive diagnosis of an acute scaphoid fracture in a cohort of healthy volunteers.
  
  
  METHODS
  In a prospective study, 33 healthy volunteers were recruited and both wrists of each were scanned, except for 2 volunteers for whom only one wrist was scanned. To simulate the usual clinical context the 64 scans of healthy volunteers were mixed with 60 MRI scans of clinically suspected scaphoid fractures but normal scaphoid radiographs. These 124 MRI scans were blinded and randomly ordered. Five radiologists evaluated the MRI scans independently for the presence or absence of a scaphoid fracture and other injuries according to a standard protocol.
  
  
  RESULTS
  To answer the primary question, only the diagnoses from the 64 scans of healthy volunteers were used. The radiologists diagnosed a total of 13 scaphoid fractures; therefore, specificity for diagnosis of scaphoid fracture was 96% (95% confidence interval: range 94-98%). The 5 observers had a moderate interobserver agreement regarding diagnosis of scaphoid fracture in healthy volunteers (multirater κ=0.44; p<0.001).
  
  
  CONCLUSIONS
  The specificity of MRI for scaphoid fractures is high (96%), but false-positives do occur. Radiologists have only moderate agreement when interpreting MRI scans from healthy volunteers. MRI is not an adequate reference standard for true fractures among patients with suspected scaphoid fractures.
authors: Department of Surgery, Medical Center Haaglanden, The Hague, Netherlands. andeledezwart@gmail.com
authors: A D
authors: AD
authors: De Zwart
authors: F J P
authors: FJ
authors: Beeres
authors: D
authors: D
authors: Ring
authors: L M
authors: LM
authors: Kingma
authors: E G
authors: EG
authors: Coerkamp
authors: S A G
authors: SA
authors: Meylaerts
authors: S J
authors: SJ
authors: Rhemrev
mesh_terms: D000328:Adult; D005260:Female; D050723:Fractures, Bone / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000592:standards*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D012015:Reference Standards; D021361:Scaphoid Bone / Q000293:injuries*; D012680:Sensitivity and Specificity; D055815:Young Adult