title: Incremental benefit of computer-aided detection when used as a second and concurrent reader of CT colonographic data: multiobserver study.
abstract: OBJECTIVE
  To quantify the changes in reader performance levels, if any, during interpretation of computed tomographic (CT) colonographic data when a computer-aided detection (CAD) system is used as a second or concurrent reader.
  
  
  METHODS
  After institutional review board approval was obtained, 16 experienced radiologists searched for polyps in 112 patients, 56 of whom had 132 polyps. Each case was interpreted on three separate occasions by using an unassisted (without CAD), second-read CAD, or concurrent CAD reading paradigm. The reading paradigm and case order were randomized, with a minimal interval of 1 month between consecutive interpretations. The readers' findings were compared with the reference-truth interpretation. The mean per-patient sensitivity and mean per-patient specificity with CAD were compared with those achieved with unassisted reading. An increase in per-patient sensitivity was considered to be clinically more important than an equivalent decrease in specificity.
  
  
  RESULTS
  The mean per-patient sensitivity for identification of patients with polyps of any size increased significantly with use of second-read CAD (mean increase, 7.0%; 95% confidence interval [CI]: 4.0%, 9.8%) and concurrent CAD (mean increase, 4.5%; 95% CI: 0.8%, 8.2%). The mean per-patient specificity did not decrease significantly with use of second-read CAD (mean decrease, -2.5%; 95% CI: -5.2%, 0.1%) or concurrent CAD (mean decrease, -2.2%; 95% CI: -4.6%, 0.2%). With analysis restricted to patients with polyps 6 mm or larger, the benefit in sensitivity with second-read CAD remained (mean increase, 7.1%; 95% CI: 3.0%, 11.1%), whereas the increase with concurrent CAD was not significant (mean increase, 4.2%; 95% CI: -0.5%, 8.9%). Use of second-read CAD significantly increased the per-polyp sensitivity for polyps 6 mm or larger (mean increase, 9.0%; 98.3% CI: 4.9%, 12.8%) and polyps 5 mm or smaller (mean increase, 5.9%; 98.3% CI: 3.2%, 9.1%), but use of concurrent CAD increased the per-polyp sensitivity for only those polyps 5 mm or smaller (mean increase, 4.8%; 98.3% CI: 2.2%, 7.9%).
  
  
  CONCLUSIONS
  Use of second-read CAD significantly improves readers' per-patient and per-polyp detection. Concurrent CAD is less effective.
  
  
  BACKGROUND
  http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100354/-/DC1.
authors.affiliation: Department of Specialist Radiology, University College Hospital, Podium Level 2, 235 Euston Road, London NW1 2BU, England. s.halligan@ucl.ac.uk
authors.forename: Steve
authors.initials: S
authors.lastname: Halligan
authors.forename: Susan
authors.initials: S
authors.lastname: Mallett
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Altman
authors.forename: Justine
authors.initials: J
authors.lastname: McQuillan
authors.forename: Maria
authors.initials: M
authors.lastname: Proud
authors.forename: Gareth
authors.initials: G
authors.lastname: Beddoe
authors.forename: Lesley
authors.initials: L
authors.lastname: Honeyfield
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Taylor
mesh_terms: D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D012680:Sensitivity and Specificity