title: Influence of computer-aided detection false-positives on reader performance and diagnostic confidence for CT colonography.
abstract: OBJECTIVE
  The objective of our study was to investigate whether an increasing number of computer-aided detection (CAD) false-positives decreases reader sensitivity, specificity, and confidence for nonexpert readers of CT colonography (CTC).
  
  
  METHODS
  Fifty CTC data sets (29 men; mean age, 65 years), 25 of which contained 35 polyps > or = 5 mm, were selected in which CAD had 100% polyp sensitivity at two sphericity settings (0 and 75) but differed in the number of false-positives. The data sets were read by five readers twice: once at each sphericity setting. Sensitivity, specificity, report time, and confidence before and after second-read CAD were compared using the paired exact and Student's t test, respectively. Receiver operating characteristic (ROC) curves were generated using reader confidence (1-100) in correct case classification (normal or abnormal).
  
  
  RESULTS
  CAD generated a mean of 42 (range, 3-118) and 15 (range, 1-36) false-positives at a sphericity of 0 and 75, respectively. CAD at both settings increased per-patient sensitivity from 82% to 87% (p = 0.03) and per-polyp sensitivity by 8% and 10% for a sphericity of 0 and 75, respectively (p < 0.001). Specificity decreased from 84% to 79% (sphericity 0 and 75, p = 0.03 and 0.07). There was no difference in sensitivity, specificity, or reader confidence between sphericity settings (p = 1.0, 1.0, 0.11, respectively). The area under the ROC curve was 0.78 (95% CI, 0.70-0.86) and 0.77 (0.68-0.85) for a sphericity of 0 and 75, respectively. CAD added a median of 4.4 minutes (interquartile range [IQR], 2.7-6.5 minutes) and 2.2 minutes (IQR, 1.2-4.0 minutes) for a sphericity of 0 and 75, respectively (p < 0.001). CONCLUSION. CAD has the potential to increase the sensitivity of readers inexperienced with CTC, although specificity may be reduced. An increased number of CAD-generated false-positives does not negate any beneficial effect but does reduce efficiency.
authors.affiliation: Department of Specialist Imaging, University College Hospital, London, United Kingdom. csytaylor@yahoo.co.uk
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Taylor
authors.forename: John
authors.initials: J
authors.lastname: Brittenden
authors.forename: James
authors.initials: J
authors.lastname: Lenton
authors.forename: Hannah
authors.initials: H
authors.lastname: Lambie
authors.forename: Anthony
authors.initials: A
authors.lastname: Goldstone
authors.forename: Peter N
authors.initials: PN
authors.lastname: Wylie
authors.forename: Damian
authors.initials: D
authors.lastname: Tolan
authors.forename: David
authors.initials: D
authors.lastname: Burling
authors.forename: Leslie
authors.initials: L
authors.lastname: Honeyfield
authors.forename: Paul
authors.initials: P
authors.lastname: Bassett
authors.forename: Steve
authors.initials: S
authors.lastname: Halligan
mesh_terms: D000368:Aged; D000465:Algorithms; D001185:Artificial Intelligence; D001291:Attitude of Health Personnel; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D010363:Pattern Recognition, Automated / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity