European Radiology

, Volume 18, Issue 8, pp 1666–1673

CT colonography: computer-aided detection of morphologically flat T1 colonic carcinoma


    • Department of Specialist X-RayUniversity College Hospital
    • Department of ImagingUniversity College Hospital
  • Gen Iinuma
    • Diagnostic Radiology DivisionNational Cancer Centre Hospital
  • Yutaka Saito
    • Endoscopy DivisionNational Cancer Centre Hospital
  • Jie Zhang
    • Department of RadiologyBeijing Friendship Hospital
  • Steve Halligan
    • Department of Specialist X-RayUniversity College Hospital
Computer Tomography

DOI: 10.1007/s00330-008-0936-7

Cite this article as:
Taylor, S.A., Iinuma, G., Saito, Y. et al. Eur Radiol (2008) 18: 1666. doi:10.1007/s00330-008-0936-7


The purpose was to evaluate the ability of computer-aided detection (CAD) software to detect morphologically flat early colonic carcinoma using CT colonography (CTC). Twenty-four stage T1 colonic carcinomas endoscopically classified as flat (width over twice height) were accrued from patients undergoing staging CTC. Tumor location was annotated by three experienced radiologists in consensus aided by the endosocpic report. CAD software was then applied at three settings of sphericity (0, 0.75, and 1). Computer prompts were categorized as either true positive (overlapping tumour boundary) or false positive. True positives were subclassified as focal or non focal. The 24 cancers were endoscopically classified as type IIa (n=11) and type IIa+IIc (n=13). Mean size (range) was 27 mm (7–70 mm). CAD detected 20 (83.3%), 17 (70.8%), and 13 (54.1%) of the 24 cancers at filter settings of 0, 0.75, and 1, respectively with 3, 4, and 8 missed cancers of type IIa, respectively. The mean total number of false-positive CAD marks per patient at each filter setting was 36.5, 21.1, and 9.5, respectively, excluding polyps. At all settings, >96.1% of CAD true positives were classified as focal. CAD may be effective for the detection of morphologically flat cancer, although minimally raised laterally spreading tumors remain problematic.


ColonographyComputed tomographicDiagnosisComputer-assistedColonic neoplasms

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© European Society of Radiology 2008