title: Reduction of false positives on the rectal tube in computer-aided detection for CT colonography.
abstract: OBJECTIVE
  To eliminate false-positive (FP) polyp detections on the rectal tube (RT) in CT colonography (CTC) computer-aided detection (CAD).
  
  
  METHODS
  We use a three-stage approach to detect the RT: detect the RT shaft, track the tube to the tip and label all the voxels that belong to the RT. We applied our RT detection algorithm on a CTC dataset consisting of 80 datasets (40 patients scanned in both prone and supine positions). Two different types of RTs were present, characterized by differences in shaft/bulb diameters, wall intensities, and shape of tip.
  
  
  RESULTS
  The algorithm detected 90% of RT shafts and completely tracked 72% of them. We labeled all the voxels belonging to the completely tracked RTs (72%) and in 11 out of 80 (14%) cases the RT voxels were partially labeled. We obtained a 9.2% reduction of the FPs in the initial polyp candidates' population, and a 7.9% reduction of the FPs generated by our CAD system. None of the true-positive detections were mislabeled.
  
  
  CONCLUSIONS
  The algorithm detects the RTs with good accuracy, is robust with respect to the two different types of RT used in our study, and is effective at reducing the number of RT FPs reported by our CAD system.
authors.affiliation: Department of Radiology, National Institutes of Health Building 10, Bethesda, Maryland 20892-1182, USA.
authors.forename: Gheorghe
authors.initials: G
authors.lastname: Lordanescu
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Summers
mesh_terms: D000465:Algorithms; D001185:Artificial Intelligence; D016000:Cluster Analysis; D023881:Colonography, Computed Tomographic / Q000295:instrumentation* / Q000379:methods*; D019544:Equipment Failure Analysis / Q000379:methods; D005189:False Positive Reactions; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D016247:Information Storage and Retrieval / Q000379:methods; D009716:Numerical Analysis, Computer-Assisted; D010363:Pattern Recognition, Automated / Q000379:methods*; D011127:Polyps / Q000000981:diagnostic imaging*; D012007:Rectum / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted