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Copyright ©2008 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Jul 28, 2008; 14(28): 4499-4504
Published online Jul 28, 2008. doi: 10.3748/wjg.14.4499
CT colonography after incomplete colonoscopy in subjects with positive faecal occult blood test
Lapo Sali, Massimo Falchini, Andrea Giovanni Bonanomi, Guido Castiglione, Stefano Ciatto, Paola Mantellini, Francesco Mungai, Ilario Menchi, Natale Villari, Mario Mascalchi
Lapo Sali, Massimo Falchini, Francesco Mungai, Natale Villari, Mario Mascalchi, Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Florence 50134, Italy
Andrea Giovanni Bonanomi, Guido Castiglione, Stefano Ciatto, Paola Mantellini, Centro per lo Studio e la Prevenzione Oncologica (CSPO), Florence 50100, Italy
Ilario Menchi, Diagnostic Imaging Department, Careggi Hospital, Florence 50134, Italy
Author contributions: Ciatto S, Menchi I and Villari N contributed equally to this work; Sali L, Falchini M, Bonanomi AG and Mantellini P designed research; Sali L, Falchini M, Bonanomi AG, Castiglione G and Mungai F performed research; Sali L and Mascalchi M analysed data; Sali L mainly wrote the paper.
Correspondence to: Dr. Lapo Sali, Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Viale Morgagni 85, Florence 50134, Italy. lapo.sali@alice.it
Telephone: +39-55-4377673
Fax: +39-55-431970
Received: April 22, 2008
Revised: June 2, 2008
Accepted: June 9, 2008
Published online: July 28, 2008
Abstract

AIM: To report our experience with computed tomography colonography (CTC) systematically performed in subjects with positive faecal occult blood test (FOBT) and an incomplete colonoscopy in the setting of a population-based screening for colorectal cancer (CRC).

METHODS: From April 2006 to April 2007, 43 290 individuals (age range 50-70) who adhered to the regional screening program for the prevention of CRC underwent immunochemical FOBT. FOBT was positive in 1882 subjects (4.3%). 1463 (77.7%) of these subjects underwent colonoscopy, 903 performed in a single center. Of 903 colonoscopies 65 (7.2%) were incomplete. Forty-two of these subjects underwent CTC. CTC was performed with a 16-MDCT scanner after standard bowel prep (polyethylene glycole) in both supine and prone position. Subjects whose CTC showed polyps or masses were referred to the endoscopist for repeat colonoscopy under sedation or underwent surgery. Per-lesion and per-segment positive predictive values (PPV) were calculated.

RESULTS: Twenty-one (50%) of 42 CTCs showed polyps or masses. Fifty-five of these subjects underwent a repeat colonoscopy, whereas 2 subjects underwent surgery for colonic masses of indeterminate nature. Four subjects refused further examinations. CTC correctly identified 2 colonic masses and 20 polyps. PPV for masses or polyps greater than 9 mm was of 87.5%. Per-lesion and per-segment PPV were, respectively, 83.3% and 83.3% for polyps greater or equal to 10 mm, and 77.8% and 85.7% for polyps of 6-9 mm.

CONCLUSION: In the context of a screening program for CRC based on FOBT, CTC shows high per-segment and per-lesion PPV for colonic masses and polyps greater than 9 mm. Therefore, CTC has the potential to become a useful technique for evaluation of the non visualized part of the colon after incomplete colonoscopy.

Keywords: Computed tomography colonography; Virtual colonoscopy; Incomplete colonoscopy; Positive faecal occult blood test; Colorectal cancer screening