title: Computer-aided detection of colorectal polyps in CT colonography with and without fecal tagging: a stand-alone evaluation.
abstract: OBJECTIVE
  To evaluate the stand-alone performance of a computer-aided detection (CAD) algorithm for colorectal polyps in a large heterogeneous CT colonography (CTC) database that included both tagged and untagged datasets.
  
  
  METHODS
  Written, informed consent was waived for this institutional review board-approved, HIPAA-compliant retrospective study. CTC datasets from 2063 patients were assigned to training (n = 374) and testing (n = 1689). The test set consisted of 836 untagged and 853 tagged examinations not used for CAD training. Examinations were performed at 15 sites in the United States, Asia, and Europe, using 4- to 64-multidetector-row computed tomography and various acquisition parameters. CAD sensitivities were calculated on a per-patient and per-polyp basis for polyps measuring ≥6 mm. The reference standard was colonoscopy in 1588 (94%) and consensus interpretation by expert radiologists in 101 (6%) patients. Statistical testing employed χ, logistic regression, and Mann-Whitney U tests.
  
  
  RESULTS
  In 383 of 1689 individuals, 564 polyps measuring ≥6 mm were identified by the reference standard (347 polyps: 6-9 mm and 217 polyps: ≥10 mm). Overall, CAD per-patient sensitivity was 89.6% (343/383), with 89.0% (187/210) for untagged and 90.2% (156/173) for tagged datasets (P = 0.72). Overall, per-polyp sensitivity was 86.9% (490/564), with 84.4% (270/320) for untagged and 90.2% (220/244) for tagged examinations (P = 068). The mean false-positive rate per patient was 5.14 (median, 4) in untagged and 4.67 (median, 4) in tagged patient datasets (P = 0.353).
  
  
  CONCLUSIONS
  Stand-alone CAD can be applied to both tagged and untagged CTC studies without significant performance differences. Detection rates are comparable to human readers at a relatively low false-positive rate, making CAD a useful tool in clinical practice.
authors.affiliation: Department of Radiology, Medical University of Vienna, Vienna, Austria. thomas.mang@meduniwien.ac.at
authors.forename: Thomas
authors.initials: T
authors.lastname: Mang
authors.forename: Luca
authors.initials: L
authors.lastname: Bogoni
authors.forename: Marcos
authors.initials: M
authors.lastname: Salganicoff
authors.forename: Matthias
authors.initials: M
authors.lastname: Wolf
authors.forename: Vikas
authors.initials: V
authors.lastname: Raykar
authors.forename: Michael
authors.initials: M
authors.lastname: Macari
authors.forename: Perry J
authors.initials: PJ
authors.lastname: Pickhardt
authors.forename: Franco
authors.initials: F
authors.lastname: Iafrate
authors.forename: Andrea
authors.initials: A
authors.lastname: Laghi
authors.forename: Michael
authors.initials: M
authors.lastname: Weber
authors.forename: Mark E
authors.initials: ME
authors.lastname: Baker
authors.forename: Helmut
authors.initials: H
authors.lastname: Ringl
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Herold
authors.forename: Anno
authors.initials: A
authors.lastname: Graser
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D005243:Feces; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010363:Pattern Recognition, Automated / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012002:Rectal Diseases / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling