title: CT colonography with rectal iodine tagging: Feasibility and comparison with oral tagging in a colorectal cancer screening population.
abstract: OBJECTIVE
  To evaluate feasibility, diagnostic performance, patient acceptance, and overall examination time of CT colonography (CTC) performed through rectal administration of iodinated contrast material.
  
  
  METHODS
  Six-hundred asymptomatic subjects (male:female=270:330; mean 63 years) undergoing CTC for colorectal cancer screening on an individual basis were consecutively enrolled in the study. Out of them, 503 patients (group 1) underwent CTC with rectal tagging, of which 55 had a total of 77 colonic lesions. The remaining 97 patients (group 2) were randomly selected to receive CTC with oral tagging of which 15 had a total of 20 colonic lesions. CTC findings were compared with optical colonoscopy, and per-segment image quality was visually assessed using a semi-quantitative score (1=poor, 2=adequate, 3=excellent). In 70/600 patients (11.7%), CTC was performed twice with both types of tagging over a 5-year follow-up cancer screening program. In this subgroup, patient acceptance was rated via phone interview two weeks after CTC using a semi-quantitative scale (1=poor, 2=fair, 3=average, 4=good, 5=excellent).
  
  
  RESULTS
  Mean per-polyp sensitivity, specificity, positive and negative predictive values of CTC with rectal vs oral tagging were 96.1% (CI95% 85.4÷99.3%) vs 89.4% (CI95% 65.4÷98.1%), 95.3% (CI95% 90.7÷97.8%) vs 95.8% (CI95% 87.6÷98.9%), 86.0% (CI95% 73.6÷93.3) vs 85.0% (CI95% 61.1÷96.0%), and 98.8% (CI95% 95.3÷99.8%) vs 97.2% (CI95% 89.4÷99.5%), respectively (p>0.05). Polyp detection rates were not statistically different between groups 1 and 2 (p>0.05). Overall examination time was significantly shorter with rectal than with oral tagging (18.3±3.5 vs 215.6±10.3 minutes, respectively; p<0.0001).
  
  
  CONCLUSIONS
  Rectal iodine tagging can be an effective alternative to oral tagging for CTC with the advantages of greater patient acceptance and lower overall examination time.
authors.affiliation: Diagnostic and Interventional Radiology - Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy. Electronic address: emanuele.neri@med.unipi.it.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Neri
authors.affiliation: Diagnostic and Interventional Radiology - Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Mantarro
authors.affiliation: Diagnostic and Interventional Radiology - Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Faggioni
authors.affiliation: Diagnostic and Interventional Radiology - Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Scalise
authors.affiliation: Diagnostic and Interventional Radiology - Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Bemi
authors.affiliation: Diagnostic and Interventional Radiology - Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Pancrazi
authors.affiliation: Federal University of São Paulo - Sena Madureira 1500 - Vila Mariana, UNIFESP, São Paulo, SP, Brazil.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: D'Ippolito
authors.affiliation: Diagnostic and Interventional Radiology - Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Bartolozzi
mesh_terms: D000285:Administration, Rectal; D000368:Aged; D023881:Colonography, Computed Tomographic / Q000379:methods*; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D003287:Contrast Media / Q000008:administration & dosage*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction / Q000706:statistics & numerical data; D011856:Radiographic Image Enhancement; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D007455:Iodine
keywords: CT colonography; Colorectal cancer; Colorectal polyps; Fluid tagging; Image quality