title: CT colonography after incomplete colonoscopy in subjects with positive faecal occult blood test.
abstract: OBJECTIVE
  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, 43290 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 (polyethyleneglycole) 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Clinical Physiopathology, University of Florence, Viale Morgagni 85, Florence 50134, Italy. lapo.sali@alice.it
authors.forename: Lapo
authors.initials: L
authors.lastname: Sali
authors.forename: Massimo
authors.initials: M
authors.lastname: Falchini
authors.forename: Andrea-Giovanni
authors.initials: AG
authors.lastname: Bonanomi
authors.forename: Guido
authors.initials: G
authors.lastname: Castiglione
authors.forename: Stefano
authors.initials: S
authors.lastname: Ciatto
authors.forename: Paola
authors.initials: P
authors.lastname: Mantellini
authors.forename: Francesco
authors.initials: F
authors.lastname: Mungai
authors.forename: Ilario
authors.initials: I
authors.lastname: Menchi
authors.forename: Natale
authors.initials: N
authors.lastname: Villari
authors.forename: Mario
authors.initials: M
authors.lastname: Mascalchi
mesh_terms: D000368:Aged; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007558:Italy; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D009780:Occult Blood; D011446:Prospective Studies