Low-dose CT colonography in children: initial experience, technical feasibility, and utility

Ultrasonography with the colonic segment-approach for colonic polyps in children

BACKGROUND

Ultrasonography (US) has been widely applied and has validated efficacy in the diagnosis of colonic polyps in children. However, little attention has been paid to improving the detection rate of polyps, optimizing the ultrasonic examination process and reducing misdiagnosis.

OBJECTIVE

To investigate the diagnostic performance of the colonic segment-approach by US in the diagnosis of colonic polyps in pediatric patients.

MATERIALS AND METHODS

One hundred fifty-nine patients who were going to have a colonoscopy from September 2014 to August 2016 were enrolled in this study. All patients received US before colonoscopy. In a preliminary study, 50 patients were chosen to determine the interobserver agreement, with half of the cases with and half of the cases without a colonic segment-approach. The other 109 patients were examined by both approaches. The sensitivity and the specificity of each approach were compared based on the outcome of colonoscopy as the gold criteria.

RESULTS

The interobserver agreement was high (0.816 for the non-segmental approach, 0.754 for the colonic segment-approach). The diagnostic sensitivity of the colonic segment-approach was higher than that of the traditional approach (82.1% vs. 57.7%, P<0.05) with 89.3% vs. 64.2% detection rate of colonic polyps in the descending colon, 81.8% vs. 60.6% in the sigmoid colon, and 81.3% vs. 43.8% in the rectum, respectively. The specificity of both methods was 100% (95% confidence interval: 86.3%-100%).

CONCLUSION

The US colonic segment-approach can improve diagnostic sensitivity for colonic polyps as a convenient method with no special requirement for equipment and examination conditions.

Feasibility study of computed tomography colonography using limited bowel preparation at normal and low-dose levels study

The purpose was to evaluate low-dose CT colonography without cathartic cleansing in terms of image quality, polyp visualization and patient acceptance. Sixty-one patients scheduled for colonoscopy started a low-fiber diet, lactulose and amidotrizoic-acid for fecal tagging 2 days prior to the CT scan (standard dose, 5.8–8.2 mSv). The original raw data of 51 patients were modified and reconstructed at simulated 2.3 and 0.7 mSv levels. Two observers evaluated the standard dose scan regarding image quality and polyps. A third evaluated the presence of polyps at all three mSv levels in a blinded prospective way. All observers were blinded to the reference standard: colonoscopy. At three times patients were given questionnaires relating to their experiences and preference. Image quality was sufficient in all patients, but significantly lower in the cecum, sigmoid and rectum. The two observers correctly identified respectively 10/15 (67%) and 9/15 (60%) polyps ≥10 mm, with 5 and 8 false-positive lesions (standard dose scan). Dose reduction down to 0.7 mSv was not associated with significant changes in diagnostic value (polyps ≥10 mm). Eighty percent of patients preferred CT colonography and 13% preferred colonoscopy (P<0.001). CT colonography without cleansing is preferred to colonoscopy and shows sufficient image quality and moderate sensitivity, without impaired diagnostic value at dose-levels as low as 0.7 mSv.