title: Comparison of the accuracy rates of 3-T and 1.5-T MRI of the knee in the diagnosis of meniscal tear.
abstract: OBJECTIVE
  The purpose of this study was to compare the accuracy of 3-T MRI with that of 1.5-T MRI of the knee in the diagnosis of meniscal tear and to analyze the causes of diagnostic error.
  
  
  METHODS
  We reviewed the medical records and original MRI interpretations of 100 consecutive patients who underwent 3-T MRI of the knee and of 100 consecutive patients who underwent 1.5-T MRI of the knee to determine the accuracy of diagnoses of meniscal tear. Knee arthroscopy was the reference standard. We retrospectively reviewed all MRI diagnostic errors to determine the cause of the errors.
  
  
  RESULTS
  At arthroscopy, 109 medial and 77 lateral meniscal tears were identified in the 200 patients. With two abnormal MR images indicating a meniscal tear, the sensitivity and specificity for medial tear were 92.7% and 82.2% at 1.5-T MRI and 92.6% and 76.1% at 3-T MRI (p = 1.0, p = 0.61). The sensitivity and specificity for lateral tears were 68.4% and 95.2% at 1.5-T MRI and 69.2% and 91.8% at 3-T MRI (p = 1.0, p = 0.49). Of the false-positive diagnoses of medial meniscal tear, five of eight at 1.5 T and seven of 11 at 3 T were apparent peripheral longitudinal tears of the posterior horn. Fifteen of the 26 missed medial and lateral meniscal tears were not seen in retrospect even with knowledge of the tear type and location.
  
  
  CONCLUSIONS
  Allowing for sample size limitations, we found comparable accuracy of 3-T and 1.5-T MRI of the knee in the diagnosis of meniscal tear. The causes of false-positive and false-negative MRI diagnoses of meniscal tear are similar for 3-T and 1.5-T MRI.
authors.affiliation: Department of Radiology, University of Wisconsin Hospital and Clinics, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave., E3/311, Madison, WI 53792, USA.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Grossman
authors.forename: Arthur A
authors.initials: AA
authors.lastname: De Smet
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Shinki
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001182:Arthroscopy; D002648:Child; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D022125:Lacerations / Q000175:diagnosis* / Q000453:epidemiology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology*; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D017678:Sex Distribution; D000070600:Tibial Meniscus Injuries; D055815:Young Adult