Noncathartic CT colonography: Image quality assessment and performance and in a screening cohort

Joel G Fletcher, Alvin C Silva, Jeff L Fidler, Joseph G Cernigliaro, Armando Manduca, Paul J Limburg, Lynn A Wilson, Trudy A Engelby, Garrett Spencer, W Scott Harmsen, Jay Mandrekar, C Daniel Johnson, Joel G Fletcher, Alvin C Silva, Jeff L Fidler, Joseph G Cernigliaro, Armando Manduca, Paul J Limburg, Lynn A Wilson, Trudy A Engelby, Garrett Spencer, W Scott Harmsen, Jay Mandrekar, C Daniel Johnson

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.

Figures

Fig. 1
Fig. 1
Flowchart shows summary of study recruitment and index and reference standard tests. CTC = CT colonography, IBD = inflammatory bowel disease.
Fig. 2
Fig. 2
Chart used to assess oral tagging image quality rank according to amount of residual fluid, size of residual stool particles, and colonic distention.
Fig. 3
Fig. 3
54-year-old woman. A–D, Supine (A and B) and prone (C and D) CT colonography (CTC) images show 1.1-cm sigmoid adenocarcinoma arising in tubular adenoma (arrows) that was prospectively identified at noncathartic CTC before endoscopy. B and D show results after electronic stool subtraction.
Fig. 4
Fig. 4
Noncathartic CT colonography (CTC) image quality. (Gastroview [diatrizoate meglumine and diatrizoate sodium solution] is manufactured by Mallinckrodt Pharmaceuticals and Omnipaque, [iohexol] is manufactured by GE Healthcare). A, Bar graph shows mean percentage of labeled stool by colonic segment for each noncathartic CTC oral tagging regimen. Percentage of labeled stool differed across tagging preparations (p < 0.001) and was greater for oral regimens containing iodine than for those without iodine (93–99% vs 75–84%, respectively; p ≤ 0.0002). B, Bar graph shows mean colonic distention, amount of residual colonic fluid, and size of residual particulate stool by colonic segment for each noncathartic CTC oral tagging regimen. Image quality ranks are provided in Figure 2. For residual fluid, sorbitol alone resulted in less fluid compared with 60 mL of Gastroview or 100 mL of Omnipaque (p < 0.05 for all comparisons). Use of 60 mL of Gastroview resulted in smaller solid stool particles (p < 0.02), likely because of increased osmotic pull of Gastroview. There were no significant differences in patterns of residual stool or colonic distention between oral tagging regimens.
Fig. 5
Fig. 5
57-year-old woman. A–D, Coronal supine (A and B) and prone (C and D) noncathartic CT colonography (CTC) images without (A and C) and with (B and D) electronic stool subtraction show prospectively identified 2.6-cm sessile tubular adenoma (arrows) straddling haustral fold in ascending colon. Electronic stool subtraction (B and D) was thought to be potentially helpful.

Source: PubMed

3
订阅