title: Larsen scoring of digitized X-ray images.
abstract: OBJECTIVE
  To determine how Larsen scores from digitized X-rays compare to those from film originals.
  
  
  METHODS
  A hundred sets of radiographs of patients recruited with early rheumatoid arthritis (RA) were assessed using the Larsen scoring system. Digitized copies of these sets were then viewed on a computer screen and scored according to Larsen in a random order. The quality of the digitized image was also recorded. For each set of X-rays, the signed difference between the score from film and the score from the digitized images was calculated.
  
  
  RESULTS
  A total of 95% of the digitized X-ray sets were scored successfully; 5% were not scored due to the images being unreadable. The mean difference between the two sets of scores was -1.2 (95% CI [-2.06, -0.37]). There was no trend in the difference with respect to the mean of the two scores (P>0.1).
  
  
  CONCLUSIONS
  The Larsen scoring of digitized X-ray images has been validated.
authors.affiliation: Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, Clinical Operational Research Unit, University College London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Solymossy
authors.forename: J
authors.initials: J
authors.lastname: Dixey
authors.forename: M
authors.initials: M
authors.lastname: Utley
authors.forename: S
authors.initials: S
authors.lastname: Gallivan
authors.forename: A
authors.initials: A
authors.lastname: Young
authors.forename: N
authors.initials: N
authors.lastname: Cox
authors.forename: P
authors.initials: P
authors.lastname: Davies
authors.forename: P
authors.initials: P
authors.lastname: Emery
authors.forename: A
authors.initials: A
authors.lastname: Gough
authors.forename: D
authors.initials: D
authors.lastname: James
authors.forename: P
authors.initials: P
authors.lastname: Prouse
authors.forename: P
authors.initials: P
authors.lastname: Williams
authors.forename: J
authors.initials: J
authors.lastname: Winfield
mesh_terms: D000703:Analog-Digital Conversion; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement; D012720:Severity of Illness Index