title: Automatic radiographic quantification of hand osteoarthritis; accuracy and sensitivity to change in joint space width in a phantom and cadaver study.
abstract: OBJECTIVE
  To validate a newly developed quantification method that automatically detects and quantifies the joint space width (JSW) in hand radiographs. Repeatability, accuracy and sensitivity to changes in JSW were determined. The influence of joint location and joint shape on the measurements was tested.
  
  
  METHODS
  A mechanical micrometer set-up was developed to define and adjust the true JSW in an acrylic phantom joint and in human cadaver-derived phalangeal joints. Radiographic measurements of the JSW were compared to the true JSW. Repeatability, systematic error (accuracy) and sensitivity (defined as the smallest detectable difference (SDD)) were determined. The influence of joint position on the JSW measurement was assessed by varying the location of the acrylic phantom on the X-ray detector with respect to the X-ray beam and the influence of joint shape was determined by using morphologically different human cadaver joints.
  
  
  RESULTS
  The mean systematic error was 0.052 mm in the phantom joint and 0.210 mm in the cadaver experiment. In the phantom experiments, the repeatability was high (SDD = 0.028 mm), but differed slightly between joint locations (p = 0.046), and a change in JSW of 0.037 mm could be detected. Dependent of the joint shape in the cadaver hand, a change in JSW between 0.018 and 0.047 mm could be detected.
  
  
  CONCLUSIONS
  The automatic quantification method is sensitive to small changes in JSW. Considering the published data of JSW decline in the normal and osteoarthritic population, the first signs of OA progression with this method can be detected within 1 or 2 years.
authors.affiliation: Department of Radiology, Leiden University Medical Center, 9600, 2300, RC Leiden, The Netherlands. K.Huetink@lumc.nl
authors.forename: Kasper
authors.initials: K
authors.lastname: Huétink
authors.forename: Ronald
authors.initials: R
authors.lastname: van 't Klooster
authors.forename: Bart L
authors.initials: BL
authors.lastname: Kaptein
authors.forename: Iain
authors.initials: I
authors.lastname: Watt
authors.forename: Margreet
authors.initials: M
authors.lastname: Kloppenburg
authors.forename: Rob G H H
authors.initials: RG
authors.lastname: Nelissen
authors.forename: Johan H C
authors.initials: JH
authors.lastname: Reiber
authors.forename: Berend C
authors.initials: BC
authors.lastname: Stoel
mesh_terms: D000465:Algorithms; D002102:Cadaver; D006225:Hand / Q000000981:diagnostic imaging*; D006801:Humans; D010003:Osteoarthritis / Q000000981:diagnostic imaging*; D010363:Pattern Recognition, Automated / Q000379:methods*; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity