European Radiology

, Volume 18, Issue 8, pp 1666–1673

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

  • Stuart A. Taylor
  • Gen Iinuma
  • Yutaka Saito
  • Jie Zhang
  • Steve Halligan
Computer Tomography


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.


Colonography Computed tomographic Diagnosis Computer-assisted Colonic neoplasms 


  1. 1.
    Kim DH, Pickhardt PJ, Taylor AJ, Leung WK, Winter TC, Hinshaw JL, Gopal DV, Reichelderfer M, Hsu RH, Pfau PR (2007) CT colonography versus colonoscopy for the detection of advanced neoplasia. N Engl J Med 4(357):1403–1412CrossRefGoogle Scholar
  2. 2.
    Halligan S, Altman DG, Taylor SA et al (2005) CT colonography in the detection of colorectal polyps and cancer: systematic review, meta-analysis, and proposed minimum data set for study level reporting. Radiology 237:893–904PubMedCrossRefGoogle Scholar
  3. 3.
    Sosna J, Morrin MM, Kruskal JB, Lavin PT, Rosen MP, Raptopoulos V (2003) CT colonography of colorectal polyps: a metaanalysis. AJR Am J Roentgenol 181:1593–1598PubMedGoogle Scholar
  4. 4.
    Macari M, Bini EJ (2005) CT colonography: where have we been and where are we going. Radiology 237:819–833PubMedCrossRefGoogle Scholar
  5. 5.
    The Paris endoscopic classification of superficial neoplastic lesions: esophagus, stomach, and colon. Gastrointest Endosc 2003;58:S3–S43Google Scholar
  6. 6.
    Fidler JL, Johnson CD, MacCarty RL, Welch TJ, Hara AK, Harmsen WS (2002) Detection of flat lesions in the colon with CT colonography. Abdom Imaging 27:292–300PubMedGoogle Scholar
  7. 7.
    Taylor SA, Halligan S, Bartram CI (2003) CT colonography: methods, pathology and pitfalls. Clin Radiol 58:179–190PubMedCrossRefGoogle Scholar
  8. 8.
    Macari M, Bini EJ, Jacobs SL, Lange N, Lui YW (2003) Filling defects at CT colonography: pseudo- and diminutive lesions (the good), polyps (the bad), flat lesions, masses, and carcinomas (the ugly). Radiographics 23:1073–1091PubMedCrossRefGoogle Scholar
  9. 9.
    Park SH, Lee SS, Choi EK et al (2007) Flat colorectal neoplasms: definition, importance, and visualization on CT colonography. AJR Am J Roentgenol 188:953–959PubMedCrossRefGoogle Scholar
  10. 10.
    Pickhardt PJ, Nugent PA, Choi JR, Schindler WR (2004) Flat colorectal lesions in asymptomatic adults: implications for screening with CT virtual colonoscopy. AJR Am J Roentgenol 183:1343–1347PubMedGoogle Scholar
  11. 11.
    Jensch S, van Gelder RE, Florie J et al (2007) Performance of radiographers in the evaluation of CT colonographic images. AJR Am J Roentgenol 188:W249–W255PubMedCrossRefGoogle Scholar
  12. 12.
    Effect of directed training on reader performance for CT colonography: multicenter study. Radiology 242:152–161Google Scholar
  13. 13.
    O’Brien MJ, Winawer SJ, Zauber AG et al (2004) Flat adenomas in the National Polyp Study: is there increased risk for high-grade dysplasia initially or during surveillance. Clin Gastroenterol Hepatol 2:905–911PubMedCrossRefGoogle Scholar
  14. 14.
    Soetikno R, Friedland S, Kaltenbach T, Chayama K, Tanaka S (2006) Nonpolypoid (flat and depressed) colorectal neoplasms. Gastroenterology 130:566–576PubMedCrossRefGoogle Scholar
  15. 15.
    Summers RM, Yao J, Pickhardt PJ et al (2005) Computed tomographic virtual colonoscopy computer-aided polyp detection in a screening population. Gastroenterology 129:1832–1844PubMedCrossRefGoogle Scholar
  16. 16.
    Mang T, Peloschek P, Plank C et al (2007) Effect of computer-aided detection as a second reader in multidetector-row CT colonography. Eur Radiol 17:2598–2607PubMedCrossRefGoogle Scholar
  17. 17.
    Nappi J, Yoshida H (2002) Automated detection of polyps with CT colonography: evaluation of volumetric features for reduction of false-positive findings. Acad Radiol 9:386–397PubMedCrossRefGoogle Scholar
  18. 18.
    Dachman AH, Lefere P, Gryspeerdt S, Morin M (2007) CT colonography: visualization methods, interpretation, and pitfalls. Radiol Clin North Am 45:347–359PubMedCrossRefGoogle Scholar
  19. 19.
    Fidler JL, Fletcher JG, Johnson CD et al (2004) Understanding interpretive errors in radiologists learning computed tomography colonography. Acad Radiol 11:750–756PubMedCrossRefGoogle Scholar
  20. 20.
    Slater A, Taylor SA, Tam E et al (2006) Reader error during CT colonography: causes and implications for training. Eur Radiol 16:2275–2283PubMedCrossRefGoogle Scholar
  21. 21.
    Hart AR, Kudo S, Mackay EH, Mayberry JF, Atkin WS (1998) Flat adenomas exist in asymptomatic people: important implications for colorectal cancer screening programmes. Gut 43:229–231PubMedCrossRefGoogle Scholar
  22. 22.
    Saito Y, Fujii T, Kondo H et al (2001) Endoscopic treatment for laterally spreading tumors in the colon. Endoscopy 33:682–686PubMedCrossRefGoogle Scholar
  23. 23.
    Uraoka T, Saito Y, Matsuda T et al (2006) Endoscopic indications for endoscopic mucosal resection of laterally spreading tumours in the colorectum. Gut 55:1592–1597PubMedCrossRefGoogle Scholar
  24. 24.
    Taylor SA, Halligan S, Burling D et al (2006) Computer-assisted reader software versus expert reviewers for polyp detection on CT colonography. AJR Am J Roentgenol 186:696–702PubMedCrossRefGoogle Scholar
  25. 25.
    Halligan S, Altman DG, Mallett S et al (2006) Computed tomographic colonography: assessment of radiologist performance with and without computer-aided detection. Gastroenterology 131:1690–1699PubMedCrossRefGoogle Scholar
  26. 26.
    Dehmeshki J, Halligan S, Taylor SA et al (2007) Computer assisted detection software for CT colonography: effect of sphericity filter on performance characteristics for patients with and without fecal tagging. Eur Radiol 17:662–668PubMedCrossRefGoogle Scholar
  27. 27.
    Muto T, Bussey HJ, Morson BC (1975) The evolution of cancer of the colon and rectum. Cancer 36:2251–2270PubMedGoogle Scholar
  28. 28.
    Saitoh Y, Waxman I, West AB et al (2001) Prevalence and distinctive biologic features of flat colorectal adenomas in a North American population. Gastroenterology 120:1657–1665PubMedCrossRefGoogle Scholar
  29. 29.
    Rembacken BJ, Fujii T, Cairns A et al (2000) Flat and depressed colonic neoplasms: a prospective study of 1000 colonoscopies in the UK. Lancet 355:1211–1214PubMedCrossRefGoogle Scholar
  30. 30.
    Halligan S, Taylor SA, Dehmeshki J et al (2006) Computer-assisted detection for CT colonography: external validation. Clin Radiol 61:758–763PubMedCrossRefGoogle Scholar
  31. 31.
    Yoshida H, Dachman AH (2005) CAD techniques, challenges, and controversies in computed tomographic colonography. Abdom Imaging 30:26–41PubMedCrossRefGoogle Scholar
  32. 32.
    Kiss G, Van Cleynenbreugel J, Thomeer M, Suetens P, Marchal G (2002) Computer-aided diagnosis in virtual colonography via combination of surface normal and sphere fitting methods. Eur Radiol 12:77–81PubMedCrossRefGoogle Scholar
  33. 33.
    Yoshida H, Nappi J, MacEneaney P, Rubin DT, Dachman AH (2002) Computer-aided diagnosis scheme for detection of polyps at CT colonography. Radiographics 22:963–979PubMedGoogle Scholar
  34. 34.
    Summers RM, Beaulieu CF, Pusanik LM et al (2000) Automated polyp detector for CT colonography: feasibility study. Radiology 216:284–290PubMedGoogle Scholar
  35. 35.
    Paik DS, Beaulieu CF, Rubin GD et al (2004) Surface normal overlap: a computer-aided detection algorithm with application to colonic polyps and lung nodules in helical CT. IEEE Trans Med Imaging 23:661–675PubMedCrossRefGoogle Scholar
  36. 36.
    Kim SH, Lee JM, Lee JG et al (2007) Computer-aided detection of colonic polyps at CT colonography using a Hessian matrix-based algorithm: preliminary study. AJR Am J Roentgenol 189:41–51PubMedCrossRefGoogle Scholar
  37. 37.
    Acar B, Beaulieu CF, Gokturk SB et al (2002) Edge displacement field-based classification for improved detection of polyps in CT colonography. IEEE Trans Med Imaging 21:1461–1467PubMedCrossRefGoogle Scholar
  38. 38.
    Nappi JJ, Frimmel H, Dachman AH, Yoshida H (2004) Computerized detection of colorectal masses in CT colonography based on fuzzy merging and wall-thickening analysis. Med Phys 31:860–872PubMedCrossRefGoogle Scholar
  39. 39.
    Update on the paris classification of superficial neoplastic lesions in the digestive tract. Endoscopy 37:570–578Google Scholar

Copyright information

© European Society of Radiology 2008

Authors and Affiliations

  • Stuart A. Taylor
    • 1
    • 5
  • Gen Iinuma
    • 2
  • Yutaka Saito
    • 3
  • Jie Zhang
    • 4
  • Steve Halligan
    • 1
  1. 1.Department of Specialist X-RayUniversity College HospitalLondonUK
  2. 2.Diagnostic Radiology DivisionNational Cancer Centre HospitalTokyoJapan
  3. 3.Endoscopy DivisionNational Cancer Centre HospitalTokyoJapan
  4. 4.Department of RadiologyBeijing Friendship HospitalXuanwu DistrictChina
  5. 5.Department of ImagingUniversity College HospitalLondonUK

Personalised recommendations