title: CT colonography before colonoscopy in subjects with positive faecal occult blood test. Preliminary experience.
abstract: OBJECTIVE
  We report a preliminary evaluation of the performance of computed tomography colonography (CTC) systematically obtained before optical colonoscopy (OC) in subjects with positive faecal occult blood test (FOBT) within a population-based screening programme for colorectal cancer (CRC).
  
  
  METHODS
  Seventy-nine subjects with positive FOBT from a regional screening programme were invited to perform same day CTC and OC. CTC was performed with standard bowel preparation. OC with segmental unblinding was the reference standard. A per-patient per-adenoma analysis was performed.
  
  
  RESULTS
  Forty-nine of 79 subjects (62%) with positive FOBT adhered to the study and completed both examinations. Twenty-two (44.9%) of the 49 had a cancer or an adenoma ≥6 mm. Per-patient sensitivity, specificity, negative predictive value and positive predictive value for cancer or adenoma ≥6 mm were 95.5% (95%CI:77.2%-99.9%), 51.9% (95%CI:32.0%-71.3%), 93.3% (95%CI:68.1%-99.8%) and 61.8% (95%CI:43.6%-77.8%).
  
  
  CONCLUSIONS
  In the setting of a FOBT-based screening programme for CRC, CTC showed a high sensitivity, but relatively low specificity and positive predictive value, for cancer and adenoma ≥6 mm. Probably performing CTC without faecal tagging as second line test after a positive FOBT is not a cost-effective strategy.
authors.affiliation: Radiodiagnostic Section--Department of Clinical Physiopathology, University of Florence, Viale G.B. Morgagni 85, Florence, Italy. lapo.sali@unifi.it
authors.forename: L
authors.initials: L
authors.lastname: Sali
authors.forename: M
authors.initials: M
authors.lastname: Falchini
authors.forename: P
authors.initials: P
authors.lastname: Della Monica
authors.forename: D
authors.initials: D
authors.lastname: Regge
authors.forename: A G
authors.initials: AG
authors.lastname: Bonanomi
authors.forename: G
authors.initials: G
authors.lastname: Castiglione
authors.forename: G
authors.initials: G
authors.lastname: Grazzini
authors.forename: M
authors.initials: M
authors.lastname: Zappa
authors.forename: F
authors.initials: F
authors.lastname: Mungai
authors.forename: C
authors.initials: C
authors.lastname: Volpe
authors.forename: M
authors.initials: M
authors.lastname: Mascalchi
mesh_terms: D000368:Aged; D023881:Colonography, Computed Tomographic / Q000379:methods*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000453:epidemiology; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009780:Occult Blood; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted; D012680:Sensitivity and Specificity