title: Nonlaxative PET/CT colonography: feasibility, acceptability, and pilot performance in patients at higher risk of colonic neoplasia.
abstract: CT colonography without bowel preparation is a safer and better-tolerated alternative to full laxation protocols, but comparative sensitivity and specificity are potentially reduced. Uptake of (18)F-FDG by colonic neoplasia is well described, and combining PET with nonlaxative CT colonography could improve accuracy. The purpose was to prospectively test the technical feasibility and acceptability of combined nonlaxative PET/CT colonography in patients at higher risk of colorectal neoplasia and to provide pilot data on diagnostic performance.
  
  
  METHODS
  Fifty-six patients (median age, 64 y; 30 women) at high risk of colonic neoplasia underwent nonlaxative PET/CT colonography with barium fecal tagging within 2 wk of scheduled colonoscopy. Colonic segmental distension was graded 1 (poor) to 3 (good). A radiologist, experienced in CT colonography, and nuclear medicine physician in consensus analyzed the datasets. The diagnostic performance for standalone CT colonography and combined PET/CT colonography was compared with the reference colonoscopy. Patient experience for 25 items (each scored from 1 to 7) pertaining to satisfaction, worry, and physical discomfort was canvassed after both PET/CT colonography and colonoscopy.
  
  
  RESULTS
  Distension was good in 298 of 334 segments (89%; 95% confidence interval [CI], 85%-92%). Patients experienced more physical discomfort during colonoscopy (median, 4; interquartile range [IQR], 2-7) than during PET/CT colonography (median, 5; IQR, 3-7; P = 0.03) and were more willing to undergo PET/CT colonography again (36/43 [84%; 95% CI, 73%-95%] vs. 31/43 [72%; 95% CI, 59%-86%]; P = 0.001). Twenty-one patients had 54 polyps according to colonoscopy (10 with at least 1 polyp >or=6 mm and 8 with at least 1 polyp >or=10 mm). Of 14 polyps 6 mm or greater, 12 (86%; 95% CI, 67%-100%) were (18)F-FDG-avid, including all those 10 mm or greater (mean standardized uptake value, 10.1). CT colonography sensitivity for polyps 6 mm or larger was 92.9% (95% CI, 79.4%-100%) and was not improved by the addition of PET. However, combined PET/CT colonography review improved per-patient positive predictive value for a polyp 10 mm or greater from 73% (95% CI, 39-92) to 100% (95% CI, 60-100).
  
  
  CONCLUSIONS
  In this feasibility study, simultaneous PET acquisition during nonlaxative CT colonography is technically feasible, is well tolerated, and potentially improves specificity.
authors.affiliation: Department of Specialist Radiology, University College London Hospital NHS Trust, London, United Kingdom. csytaylor@yahoo.co.uk
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Taylor
authors.forename: Jamshed B
authors.initials: JB
authors.lastname: Bomanji
authors.forename: Levi
authors.initials: L
authors.lastname: Manpanzure
authors.forename: Charlotte
authors.initials: C
authors.lastname: Robinson
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Groves
authors.forename: John
authors.initials: J
authors.lastname: Dickson
authors.forename: Nickolaos D
authors.initials: ND
authors.lastname: Papathanasiou
authors.forename: Rebecca
authors.initials: R
authors.lastname: Greenhalgh
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ell
authors.forename: Steve
authors.initials: S
authors.lastname: Halligan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D054368:Laxatives; D008297:Male; D008875:Middle Aged; D010342:Patient Acceptance of Health Care; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D012306:Risk
chemical_list: D054368:Laxatives