title: Diagnostic performance of MR imaging in the assessment of subchondral fractures in avascular necrosis of the femoral head.
abstract: OBJECTIVE
  A prospective study was conducted to determine the accuracy of routine magnetic resonance (MR) imaging in correctly identifying subchondral fracture in avascular necrosis of the femoral head without apparent focal collapse on standard radiographs.
  
  
  METHODS
  Spiral computed tomography (CT) with coronal and sagittal reformations and routine MR imaging with spin-echo T1WI and fat-suppressed spin-echo T2WI coronal, axial, and sagittal images were performed in 28 hips of 25 patients (M/F = 20:5; age 16-76 years) suffering from early-stage avascular necrosis of the femoral head on standard radiographs. The MR images were reviewed by a musculoskeletal radiologist and a general radiologist in blinded fashion. Using CT as the standard of reference, the accuracy of MR imaging in diagnosing subchondral fractures in avascular necrosis was evaluated.
  
  
  RESULTS
  When the diagnoses of the two readers were compared with each other, only 16 of the 28 diagnoses (57.5%) agreed. Seventeen of the 28 MR imaging readings (60.7%) made by the musculoskeletal radiologist and 15 of the 28 (53.5%) made by the general radiologist agreed with those of the CT standard. False-positive diagnosis (that is, diagnosis of fracture when no fracture could be seen on CT) was more common than false-negative diagnosis.
  
  
  CONCLUSIONS
  The accuracy of routine MR imaging in the evaluation of subchondral fracture is not satisfactory. False-positive diagnosis is not uncommon. Interpretation of routine MR imaging readout should be guarded.
authors.affiliation: Department of Radiology, E-Da Hospital and I-Shou University, Jiau-Shu Tsuen, Yan-Chau Shiang, Kaohsiung County, Taiwan, ROC.
authors.forename: Lee-Ren
authors.initials: LR
authors.lastname: Yeh
authors.forename: Clement K H
authors.initials: CK
authors.lastname: Chen
authors.forename: Yi-Luan
authors.initials: YL
authors.lastname: Huang
authors.forename: Huay-Ben
authors.initials: HB
authors.lastname: Pan
authors.forename: Chien-Fang
authors.initials: CF
authors.lastname: Yang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005264:Femoral Fractures / Q000175:diagnosis* / Q000209:etiology*; D005271:Femur Head Necrosis / Q000150:complications* / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D055815:Young Adult