Gastrointestinal Imaging

CT Colonography with Limited Bowel Preparation: Performance Characteristics in an Increased-Risk Population

Purpose: To prospectively evaluate the sensitivity and specificity of computed tomographic (CT) colonography with limited bowel preparation for the depiction of colonic polyps, by using colonoscopy as the reference standard.

Materials and Methods: Institutional review board approval and written informed consent were obtained. Patients at increased risk for colorectal cancer underwent CT colonography after fecal tagging, which consisted of 80 mL of barium sulfate and 180 mL of diatrizoate meglumine. Bisacodyl was added for stool softening. A radiologist and a research fellow evaluated all data independently by using a primary two-dimensional approach. Discrepant findings for lesions 6 mm or larger in diameter were solved with consensus. Segmental unblinding was performed. Per-patient sensitivity and specificity, per-polyp sensitivity, and number of false-positive findings were found (for lesions ≥ 6 mm and ≥ 10 mm in diameter). Per-patient sensitivities (blinded colonoscopy vs CT colonography) were tested for significance with McNemar statistics. Interobserver variability was analyzed per segment (prevalence-adjusted bias-adjusted κ values [κp]).

Results: One hundred fourteen of 168 patients (105 men, 63 women; mean age, 56 years) had polyps, with 56 polyps 6 mm or larger and 17 polyps 10 mm or larger. Per-patient sensitivities were not significantly different for CT colonography (consensus reading) and colonoscopy (P ≥ .070). Sensitivity of CT colonography for patients with lesions 6 mm or larger and 10 mm or larger was 76% and 82%, respectively, and specificity of CT colonography was 79% and 97%, respectively. Blinded colonoscopy depicted 91% (lesions ≥ 6 mm) and 88% (lesions ≥ 10 mm) of disease in patients. Per-polyp sensitivity for CT colonography was 70% (lesions ≥ 6 mm) and 82% (lesions ≥ 10 mm). Number of false-positive findings was 42 (lesions ≥ 6 mm) and six (lesions ≥ 10 mm). κp Was 0.88 (lesions ≥ 6 mm) and 0.96 (lesions ≥ 10 mm).

Conclusion: CT colonography with limited bowel preparation has a sensitivity of 82% and specificity of 97% for patients with polyps 10 mm or larger.

© RSNA, 2008

References

  • 1 FenlonHM, Nunes DP, Schroy PC, et al. A comparison of virtual and conventional colonoscopy for the detection of colorectal polyps. N Engl J Med1999;341(20):1496–1503. [Published correction appears in N Engl J Med 2000;342(7):524.] Crossref, MedlineGoogle Scholar
  • 2 PickhardtPJ, Choi JR, Hwang I, et al. Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults. N Engl J Med2003;349(23):2191–2200. Crossref, MedlineGoogle Scholar
  • 3 PineauBC, Paskett ED, Chen GJ, et al. Virtual colonoscopy using oral contrast compared with colonoscopy for the detection of patients with colorectal polyps. Gastroenterology2003;125(2):304–310. Crossref, MedlineGoogle Scholar
  • 4 JohnsonCD, Harmsen WS, Wilson LA, et al. Prospective blinded evaluation of computed tomographic colonography for screen detection of colorectal polyps. Gastroenterology2003;125(2):311–319. Crossref, MedlineGoogle Scholar
  • 5 Van GelderRE, Nio CY, Florie J, et al. Computed tomographic colonography compared with colonoscopy in patients at increased risk for colorectal cancer. Gastroenterology2004;127(1):41–48. Crossref, MedlineGoogle Scholar
  • 6 HarewoodGC, Wiersema MJ, Melton LJ 3rd. A prospective, controlled assessment of factors influencing acceptance of screening colonoscopy. Am J Gastroenterol2002;97(12):3186–3194. Crossref, MedlineGoogle Scholar
  • 7 van GelderRE, Birnie E, Florie J, et al. CT colonography and colonoscopy: assessment of patient preference in a 5-week follow-up study. Radiology2004;233(2):328–337. LinkGoogle Scholar
  • 8 RistvedtSL, McFarland EG, Weinstock LB, Thyssen EP. Patient preferences for CT colonography, conventional colonoscopy, and bowel preparation. Am J Gastroenterol2003;98(3):578–585. Crossref, MedlineGoogle Scholar
  • 9 ZalisME, Perumpillichira JJ, Magee C, Kohlberg G, Hahn PF. Tagging-based, electronically cleansed CT colonography: evaluation of patient comfort and image readability. Radiology2006;239(1):149–159. [Published correction appears in Radiology 2006;240(1):304.] LinkGoogle Scholar
  • 10 CallstromMR, Johnson CD, Fletcher JG, et al. CT colonography without cathartic preparation: feasibility study. Radiology2001;219(3):693–698. LinkGoogle Scholar
  • 11 WeitzmanER, Zapka J, Estabrook B, Goins KV. Risk and reluctance: understanding impediments to colorectal cancer screening. Prev Med2001;32(6):502–513. Crossref, MedlineGoogle Scholar
  • 12 GlueckerTM, Johnson CD, Harmsen WS, et al. Colorectal cancer screening with CT colonography, colonoscopy, and double-contrast barium enema examination prospective assessment of patient perceptions and preference. Radiology2003;227(2):378–384. LinkGoogle Scholar
  • 13 RexDK. Current colorectal cancer screening strategies overview and obstacles to implementation. Rev Gastroenterol Disord2002;2(suppl 1):S2–S11. Google Scholar
  • 14 LefereP, Gryspeerdt S, Marrannes J, et al. CT colonography after fecal tagging with a reduced cathartic cleansing and a reduced volume of barium. AJR Am J Roentgenol2005;184(6):1836–1842. Crossref, MedlineGoogle Scholar
  • 15 LeferePA, Gryspeerdt SS, Dewyspelaere J, et al. Dietary fecal tagging as a cleansing method before CT colonography: initial results—polyp detection and patient acceptance. Radiology2002;224(2):393–403. LinkGoogle Scholar
  • 16 McFarlandEG, Zalis ME. CT colonography: progress toward colorectal evaluation without catharsis. Gastroenterology2004;127(5):1623–1626. Crossref, MedlineGoogle Scholar
  • 17 ThomeerM, Carbone I, Bosmans H, et al. Stool tagging applied in thin-slice multidetector computed tomography colonography. J Comput Assist Tomogr2003;27(2):132–139. Crossref, MedlineGoogle Scholar
  • 18 BielenD, Thomeer M, Vanbeckevoort D, et al. Dry preparation for virtual CT colonography with fecal tagging using water-soluble contrast medium: initial results. Eur Radiol2003;13(3):453–458. Crossref, MedlineGoogle Scholar
  • 19 IannacconeR, Laghi A, Catalano C, et al. Computed tomographic colonography without cathartic preparation for the detection of colorectal polyps. Gastroenterology2004;127(5):1300–1311. Crossref, MedlineGoogle Scholar
  • 20 MacCartyRL, Johnson CD, Fletcher JG, Wilson LA. Occult colorectal polyps on CT colonography: implications for surveillance. AJR Am J Roentgenol2006;186(5):1380–1383. Crossref, MedlineGoogle Scholar
  • 21 PepeMS. The statistical evaluation of medical tests for classification and prediction: Oxford statistical science series 28. New York, NY: Oxford University Press,2003; 35–65. Google Scholar
  • 22 ByrtT, Bishop J, Carlin J. Bias, prevalence and kappa. J Clin Epidemiol1993;46(5):423–429. Crossref, MedlineGoogle Scholar
  • 23 PetersenHH, Enøe C, Nielsen EO. Observer agreement on pen level prevalence of clinical signs in finishing pigs. Prev Vet Med2004;64(2-4):147–156. Crossref, MedlineGoogle Scholar
  • 24 ZalisME, Hahn PF. Digital subtraction bowel cleansing in CT colonography. AJR Am J Roentgenol2001;176(3):646–648. Crossref, MedlineGoogle Scholar
  • 25 SummersRM, Jerebko AK, Franaszek M, et al. Colonic polyps: complementary role of computer-aided detection in CT colonography. Radiology2002;225(2):391–399. LinkGoogle Scholar
  • 26 HalliganS, Altman DG, Mallett S, et al. Computed tomographic colonography: assessment of radiologist performance with and without computer-aided detection. Gastroenterology2006;131(6):1690–1699. Crossref, MedlineGoogle Scholar
  • 27 BodilyKD, Fletcher JG, Engelby T, et al. Nonradiologists as second readers for intraluminal findings at CT colonography. Acad Radiol2005;12(1):67–73. Crossref, MedlineGoogle Scholar
  • 28 JenschS, Van Gelder RE, Florie J, et al. Performance of radiographers in the evaluation of CT colonographic images. AJR Am J Roentgenol2007;188(3):W249–W255. Crossref, MedlineGoogle Scholar
  • 29 TaylorSA, Halligan S, Burling D, et al. CT colonography: effect of experience and training on reader performance. Eur Radiol2004;14(6):1025–1033. Crossref, MedlineGoogle Scholar
  • 30 LuiYW, Macari M, Israel G, Bini EJ, Wang H, Babb J. CT colonography data interpretation: effect of different section thicknesses—preliminary observations. Radiology2003;229(3):791–797. LinkGoogle Scholar
  • 31 TaylorSA, Halligan S, Bartram CI, et al. Multi–detector row CT colonography: effect of collimation, pitch, and orientation on polyp detection in a human colectomy specimen. Radiology2003;229(1):109–118. LinkGoogle Scholar
  • 32 JenschS, van Gelder RE, Venema HW, et al. Effective radiation doses in CT colonography: results of an inventory among research institutions. Eur Radiol2006;16(5):981–987. Crossref, MedlineGoogle Scholar

Article History

Published in print: 2008