Effect of slice thickness and primary 2D versus 3D virtual dissection on colorectal lesion detection at CT Colonography in 452 asymptomatic adults

Department of Radiology, Mayo Clinic, 200 First St., SW, Rochester, MN 55905, USA.
American Journal of Roentgenology (Impact Factor: 2.74). 10/2007; 189(3):672-80. DOI: 10.2214/AJR.07.2354
Source: PubMed

ABSTRACT The objective of our study was to compare the performance of primary 3D search using 360 degree virtual dissection with primary 2D search using a 2.5- versus a 1.25-mm slice thickness.
Four hundred fifty-two asymptomatic patients underwent CT colonography (CTC) and colonoscopy. Examinations were reconstructed to 1.25- and 2.5-mm slice thicknesses and interpreted using primary 3D search (360 degree virtual dissection) and primary 2D search. Two of three experienced reviewers were randomly assigned to each case; 1,808 interpretations were performed.
There were 64 adenomas > or = 6 mm, 26 of which were large adenomas > or = 1 cm. For adenomas 6-9 mm in diameter, the area under the receiver operating characteristic curve (AUC) using 2.5-mm data sets was 0.66, 0.62, 0.90 and 0.78, 0.69, 0.67 for reviewers 1, 2, and 3, respectively, using primary 3D versus 2D search (p = not significant [NS]). For neoplasms > or = 10 mm, the AUC using 2.5-mm data sets was 0.74, 0.85, 0.89 and 0.66, 0.86, 0.92 for reviewers 1, 2, and 3 using primary 3D versus 2D search (p = NS). There was no significant difference using 1.25-mm collimation. Double review using both primary 3D and 2D search yielded sensitivities of 84% (16/19) and 95% (18/19) for large neoplasms (> or = 1 cm) using 2.5- and 1.25-mm data sets, respectively. Five of five (100%) adenocarcinomas were identified. The sensitivity of colonoscopy for large neoplasms was 77% (20/26) (20% [1/5] for adenocarcinoma).
No advantage exists for 1.25- or 2.5-mm slice thickness or for primary 3D versus 2D search at CTC. Double review using primary 3D (virtual dissection) and 2D search reduces interobserver variability and competes with colonoscopy for the detection of large lesions.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The available evidence was reviewed comparing the effectiveness of CT colonography with colonoscopy for CRC screening. An electronic search was conducted using the databases Pubmed, EMBASE, Cochrane library and Centre for Reviews and Dissemination, from inception to July 2009. Studies were included if investigations used CT colonography for CRC screening in asymptomatic populations. Studies were excluded if investigations were conducted for CRC diagnosis or in elderly, high risk or symptomatic populations. Of the 213 references identified, nine studies were included. The CT colonography specificity in screening for CRC was high, although it decreased with decreasing diameter of polyp to be detected. The CT colonography sensibility for detection of polyps <6 mm in diameter was low and heterogeneous, although it was higher for polyps > 10 mm. The main factors contributing to the greater sensitivity of CT colonography were the inclusion only of populations with an average CRC risk and colonic insufflation with CO2 . The incidence of adverse effects was very low for rate for both tests. CT colonography has high specificity but heterogeneous sensitivity, although in most cases it is not as sensitive or specific as conventional colonoscopy. CT colonography could therefore be useful as a screening test for populations with an average risk of CRC. This article is protected by copyright. All rights reserved.
    Colorectal Disease 12/2013; 16(3). DOI:10.1111/codi.12506 · 2.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: 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. SUBJECTS AND 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. CONCLUSION. 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.
    American Journal of Roentgenology 10/2013; 201(4):787-94. DOI:10.2214/AJR.12.9225 · 2.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objectives Compare public perceptions and intentions to undergo colorectal cancer screening tests following detailed information regarding CT colonography (CTC; after non-laxative preparation or full-laxative preparation), optical colonoscopy (OC) or flexible sigmoidoscopy (FS). Methods A total of 3,100 invitees approaching screening age (45-54 years) were randomly allocated to receive detailed information on a single test and asked to return a questionnaire. Outcomes included perceptions of preparation and test tolerability, health benefits, sensitivity and specificity, and intention to undergo the test. Results Six hundred three invitees responded with valid questionnaire data. Non-laxative preparation was rated more positively than enema or full-laxative preparations [effect size (r) = 0.13 to 0.54; p < 0.0005 to 0.036]; both forms of CTC and FS were rated more positively than OC in terms of test experience (r = 0.26 to 0.28; all p-values < 0.0005). Perceptions of health benefits, sensitivity and specificity (p = 0.250 to 0.901), and intention to undergo the test (p = 0.213) did not differ between tests (n = 144-155 for each test). Conclusions Despite non-laxative CTC being rated more favourably, this study did not find evidence that offering it would lead to substantially higher uptake than full-laxative CTC or other methods. However, this study was limited by a lower than anticipated response rate. Key Points • Improving uptake of colorectal cancer screening tests could improve health benefits • Potential invitees rate CTC and flexible sigmoidoscopy more positively than colonoscopy • Non-laxative bowel preparation is rated better than enema or full-laxative preparations • These positive perceptions alone may not be sufficient to improve uptake • Health benefits and accuracy are rated similarly for preventative screening tests
    European Radiology 07/2014; 24(7). DOI:10.1007/s00330-014-3187-9 · 4.34 Impact Factor