title: Diagnostic performance of MRI measurements to assess hindfoot malalignment. An assessment of four measurement techniques.
abstract: OBJECTIVE
  To investigate the ability of coronal non-weight-bearing MR images to discriminate between normal and abnormal hindfoot alignment.
  
  
  METHODS
  Three different measurement techniques (calcaneal axis, medial/lateral calcaneal contour) based on weight-bearing hindfoot alignment radiographs were applied in 49 patients (mean, 48 years; range 21-76 years). Three groups of subjects were enrolled: (1) normal hindfoot alignment (0°-10° valgus); (2) abnormal valgus (>10°); (3) any degree of varus hindfoot alignment. Hindfoot alignment was then measured on coronal MR images using four different measurement techniques (calcaneal axis, medial/lateral calcaneal contour, sustentaculum tangent). ROC analysis was performed to find the MR measurement with the greatest sensitivity and specificity for discrimination between normal and abnormal hindfoot alignment.
  
  
  RESULTS
  The most accurate measurement on MR images to detect abnormal hindfoot valgus was the one using the medial calcaneal contour, reaching a sensitivity/specificity of 86 %/75 % using a cutoff value of >11° valgus. The most accurate measurement on MR images to detect abnormal hindfoot varus was the sustentaculum tangent, reaching a sensitivity/specificity of 91 %/71 % using a cutoff value of <12° valgus.
  
  
  CONCLUSIONS
  It is possible to suspect abnormal hindfoot alignment on coronal non-weight-bearing MR images.
  
  
  CONCLUSIONS
  • Abnormal hindfoot alignment can be identified on coronal non-weight-bearing MR images. • The sustentaculum tangent was the best predictor of an abnormally varus hindfoot. • The medial calcaneal contour was the best predictor of a valgus hindfoot.
authors.affiliation: Radiology, University Hospital Balgrist & University of Zurich, Forchstrasse 340, 8008, Zürich, Switzerland. florian.buck@balgrist.ch
authors.forename: Florian M
authors.initials: FM
authors.lastname: Buck
authors.forename: Adrienne
authors.initials: A
authors.lastname: Hoffmann
authors.forename: Nadja
authors.initials: N
authors.lastname: Mamisch-Saupe
authors.forename: Mazda
authors.initials: M
authors.lastname: Farshad
authors.forename: Donald
authors.initials: D
authors.lastname: Resnick
authors.forename: Norman
authors.initials: N
authors.lastname: Espinosa
authors.forename: Juerg
authors.initials: J
authors.lastname: Hodler
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D002111:Calcaneus / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D005528:Foot / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005530:Foot Deformities / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012372:ROC Curve; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016474:Weight-Bearing; D055815:Young Adult