Noncathartic CT colonography: Image quality assessment and performance and in a screening cohort.
OBJECTIVE
Cathartic bowel preparation is a major barrier for colorectal cancer screening. We examined noncathartic CT colonography (CTC) quality and performance using four similar bowel-tagging regimens in an asymptomatic screening cohort.


METHODS
This prospective study included 564 asymptomatic subjects who underwent noncathartic CTC without dietary modification but with 21 g of barium with or without iodinated oral contrast material (four regimens). The quality of tagging with oral agents was evaluated. A gastrointestinal radiologist evaluated examinations using primary 2D search supplemented by electronic cleansing (EC) and 3D problem solving. Results were compared with complete colonoscopy findings after bowel purgation and with retrospective unblinded evaluation in 556 of the 564 (99%) subjects.


RESULTS
Of the 556 subjects, 7% (37/556) and 3% (16/556) of patients had 52 and 20 adenomatous polyps ≥ 6 and ≥ 10 mm, respectively. The addition of iodine significantly improved the percentage of labeled stool (p ≤ 0.0002) and specificity (80% vs 89-93%, respectively; p = 0.046). The overall sensitivity of noncathartic CTC for adenomatous polyps ≥ 6 mm was 76% (28/37; 95% CI, 59-88%), which is similar to the sensitivity of the iodinated regimens with most patients (sensitivity: 231 patients, 74% [14/19; 95% CI, 49-91%]; 229 patients, 80% [12/15; 95% CI, 52-96%]). The negative predictive value was 98% (481/490), and the lone cancer was detected (0.2%, 1/556). EC was thought to improve conspicuity of 10 of 21 visible polyps ≥ 10 mm.


CONCLUSIONS
In this prospective study of asymptomatic subjects, the per-patient sensitivity of noncathartic CTC for detecting adenomas ≥ 6 mm was approximately 76%. Inclusion of oral iodine contrast material improves examination specificity and the percentage of labeled stool. EC may improve polyp conspicuity.
1 Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.
Joel G
JG
Fletcher
Alvin C
AC
Silva
Jeff L
JL
Fidler
Joseph G
JG
Cernigliaro
Armando
A
Manduca
Paul J
PJ
Limburg
Lynn A
LA
Wilson
Trudy A
TA
Engelby
Garrett
G
Spencer
W Scott
WS
Harmsen
Jay
J
Mandrekar
C Daniel
CD
Johnson
D000328:Adult; D000368:Aged; D001466:Barium Sulfate; D002400:Cathartics; D015331:Cohort Studies; D003111:Colonic Polyps / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D023881:Colonography, Computed Tomographic / Q000706:statistics & numerical data*; D003287:Contrast Media; D004733:Enema; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data*; D008875:Middle Aged; D015995:Prevalence; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology
D002400:Cathartics; D003287:Contrast Media; D001466:Barium Sulfate