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virtual (CT) colonoscopy (CT colonography)

Indications: - screening for colorectal carcinoma Procedure: 1) a narrow rectal catheter is inserted 2) a CT scanner produces images of the colon 3) cathartic bowel preparation may not be necessary [3] 4) low-dose radiation [3] Notes: 1) in initial studies CT virtual colonoscopy was as effective as conventional colonoscopy in screening for colorectal carcinoma [2] 2) a follow-up study was not as promising - Study: 600 patients from 9 clinics - CT colonoscopy detected - 55% of tumors > 20 mm in diameter - 39% of tumors > 6 mm in diameter - 8 patients diagnosed with colon cancer - CT colonoscopy missed 2 of them (75% detection) [1] 3) prospective study [4] of 641 patients, comparing ACBE, CT colonography & colonoscopy for lesions > 6 mm 4) referral rate for colonoscopy is 6% [5] 5) patients with polyps > 6 mm in size should be referred for colonoscopy & polypectomy [7] 6) more effective in patients with family history of colon cancer or adenomatous polyps than in patients with positive fecal occult blood test (FOBT) [8] 7) detects lesions 10 mm or larger without use of laxatives [9] 8) patients prefer CT colonoscopy 2:1 over endoscopic colonoscopy [9] ACBE (35/82)* CT colonography (49/89)* colonoscopy (98.7/99.6)* * (sensitivity/specificity) in % [4]

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colonoscopy

General

computerized tomography (CT)

References

  1. Journal Watch 24(10):79, 2004 Cotton PB, Durkalski VL, Pineau BC, Palesch YY, Mauldin PD, Hoffman B, Vining DJ, Small WC, Affronti J, Rex D, Kopecky KK, Ackerman S, Burdick JS, Brewington C, Turner MA, Zfass A, Wright AR, Iyer RB, Lynch P, Sivak MV, Butler H. Computed tomographic colonography (virtual colonoscopy): a multicenter comparison with standard colonoscopy for detection of colorectal neoplasia. JAMA. 2004 Apr 14;291(14):1713-9. PMID: 15082698
  2. Journal Watch 24(1):12, 2004 Pickhardt PJ et al, N Engl J Med 349:2191, 2003 PMID: 14657426 Morrin MM & LaMont JT N Engl J Med 349:2261, 2003
  3. Journal Watch 25(1):12, 2005 Iannaccone R, Laghi A, Catalano C, Mangiapane F, Lamazza A, Schillaci A, Sinibaldi G, Murakami T, Sammartino P, Hori M, Piacentini F, Nofroni I, Stipa V, Passariello R. Computed tomographic colonography without cathartic preparation for the detection of colorectal polyps. Gastroenterology. 2004 Nov;127(5):1300-11. PMID: 15520999 - McFarland EG, Zalis ME. CT colonography: progress toward colorectal evaluation without catharsis. Gastroenterology. 2004 Nov;127(5):1623-6. No abstract available. PMID: 15521027
  4. Journal Watch 25(4):29, 2005 Rockey DC, Paulson E, Niedzwiecki D, Davis W, Bosworth HB, Sanders L, Yee J, Henderson J, Hatten P, Burdick S, Sanyal A, Rubin DT, Sterling M, Akerkar G, Bhutani MS, Binmoeller K, Garvie J, Bini EJ, McQuaid K, Foster WL, Thompson WM, Dachman A, Halvorsen R. Analysis of air contrast barium enema, computed tomographic colonography, and colonoscopy: prospective comparison. Lancet. 2005 Jan 22;365(9456):305-11. PMID: 15664225 - Halligan S, Atkin W. Unbiased studies are needed before virtual colonoscopy can be dismissed. Lancet. 2005 Jan 22;365(9456):275-6. No abstract available. PMID: 15664205
  5. Pickhardt PJ, Taylor AJ, Kim DH, Reichelderfer M, Gopal DV, Pfau PR. Screening for colorectal neoplasia with CT colonography: initial experience from the 1st year of coverage by third-party payers. Radiology. 2006 Nov;241(2):417-25. Epub 2006 Sep 18. PMID: 16982816
  6. Lin OS, Kozarek RA, Schembre DB, Ayub K, Gluck M, Cantone N, Soon MS, Dominitz JA. Risk stratification for colon neoplasia: screening strategies using colonoscopy and computerized tomographic colonography. Gastroenterology. 2006 Oct;131(4):1011-9. PMID: 17030171
  7. Schoen RE et al, Yield of advanced adenoma and cancer based on polyp size detected at screening flexible sigmoidoscopy. Gastroenterology 2006, 131:1683 PMID: 17188959
  8. Regge D et al Diagnostic Accuracy of Computed Tomographic Colonography for the Detection of Advanced Neoplasia in Individuals at Increased Risk of Colorectal Cancer. JAMA. 2009;301(23):2453-2461 PMID: 19531785
  9. Zalis ME et al Diagnostic Accuracy of Laxative-Free Computed Tomographic Colonography for Detection of Adenomatous Polyps in Asymptomatic Adults: A Prospective Evaluation Annals of Internal Medicine, May 15, 2012; 156(10):692-702 PMID: 22586008 http://www.annals.org/content/156/10/692.abstract