Reduced cathartic bowel preparation for CT colonography: prospective comparison of 2-L polyethylene glycol and magnesium citrate

Abstract

Purpose: To prospectively compare adequacy of colonic cleansing, adequacy of solid stool and fluid tagging, and patient acceptance by using reduced-volume, 2-L polyethylene glycol (PEG) versus magnesium citrate bowel preparations for CT colonography.

Materials and methods: This study was approved by the institutional Committee on Human Research and was compliant with HIPAA; all patients provided written consent. In this randomized, investigator-blinded study, 50 patients underwent oral preparation with either a 2-L PEG or a magnesium citrate solution, tagging with oral contrast agents, and subsequent CT colonography and segmentally unblinded colonoscopy. The residual stool (score 0 [best] to 3 [worst]) and fluid (score 0 [best] to 4 [worst]) burden and tagging adequacy were qualitatively assessed. Residual fluid attenuation was recorded as a quantitative measure of tagging adequacy. Patients completed a tolerance questionnaire within 2 weeks of scanning. Preparations were compared for residual stool and fluid by using generalized estimating equations; the Mann-Whitney test was used to compare the qualitative tagging score, mean residual fluid attenuation, and adverse effects assessed on the patient experience questionnaire.

Results: The mean residual stool (0.90 of three) and fluid burden (1.05 of four) scores for PEG were similar to those for magnesium citrate (0.96 [P = .58] and 0.98 [P = .48], respectively). However, the mean fecal and fluid tagging scores were significantly better for PEG (0.48 and 0.28, respectively) than for magnesium citrate (1.52 [P < .01] and 1.28 [P < .01], respectively). Mean residual fluid attenuation was higher for PEG (765 HU) than for magnesium citrate (443 HU, P = .01), and mean interpretation time was shorter for PEG (14.8 minutes) than for magnesium citrate (18.0 minutes, P = .04). Tolerance ratings were not significantly different between preparations.

Conclusion: Reduced-volume PEG and magnesium citrate bowel preparations demonstrated adequate cleansing effectiveness for CT colonography, with better tagging and shorter interpretation time observed in the PEG group. Adequate polyp detection was maintained but requires further validation because of the small number of clinically important polyps.

Figure 1:

Residual solid stool assessment according to segment. Data are mean residual solid stool score for both the prone and supine positions. Data are arranged from proximal to distal colon. Differences between preparation groups were not significant (P = .58). PEG = 2-L PEG, MC = magnesium citrate, C = cecum, A = ascending colon, T = transverse colon, D = descending colon, S = sigmoid colon, R = rectum, * = segment had a significant difference in residual solid stool compared with the rectum for both preparations combined.

Figure 2:

Residual fluid assessment according to segment. Data are mean residual fluid score for both the prone and supine positions. Data are arranged from proximal to distal colon. Differences between preparation groups were not significant (P = .48). * = Segment had a significant difference in residual fluid compared with the rectum for both preparations combined. Other keys are the same as in Figure 1.

Figure 3:

Residual fluid attenuation assessment according to segment. Data are mean residual fluid attenuation (Hounsfield units) for both the prone and supine positions. Data are arranged from proximal to distal colon. * = Segment had a significant difference in residual fluid attenuation between preparation groups. Other keys are the same as in Figure 1.