Purpose: To compare and find the optimal combination of bowel preparation regimens and different concentrations of barium-based fecal-tagging agents on computed tomographic colonography in terms of tagging efficacy, patients' compliance, and diagnostic performance.
Materials and methods: Sixty-nine consecutive patients were prospectively enrolled and randomly divided into 4 groups according to a combination of bowel preparation regimens (sodium phosphate [Colclean] vs magnesium citrate [LoSoPrep]) and different concentrations of barium-based fecal-tagging agents (Tagitol V [thick, 40% wt/vol] 60 mL vs EasyCT [thin, 4.6% wt/vol] 600 mL). Patients who received Colclean and EasyCT were designated as group 1; Colclean and Tagitol V as group 2; LoSoPrep and EasyCT, group 3; and LoSoPrep and Tagitol V, group 4. For objective analysis, the volume of tagged feces and fluid was semiautomatically calculated using a threshold of 150 Hounsfield units. The volume of untagged feces and fluid was also calculated using the seeded region-growing method. The tagging efficacy was then calculated and compared using the analysis of variance test. For subjective analysis, 2 radiologists visually determined the overall tagging efficacy on a segmental basis. The numbers of homogeneously tagged, heterogeneously tagged, heterogeneously untagged, and homogeneously untagged feces greater than or equal to 6 mm and fluid were counted in each segment. The rates of homogeneously tagged stool and fluid were compared between the groups using the chi test. Patients' compliance for taking the regimens was recorded and compared using the Kruskal-Wallis test. Per-polyp and per-patient sensitivity for polyps greater than or equal to 6 mm were analyzed and compared using the chi or Fisher exact test.
Results: Objective analysis showed that tagging efficacy was significantly lower in group 1 than in the other 3 groups. In a subjective analysis, overall tagging efficacy was significantly higher in group 4 than in the other groups. The rate of homogeneously tagged fluid was significantly higher in group 4 than in the other groups. The rate of homogeneously tagged feces was significantly higher in the thick barium group than in the thin barium group. Patients' compliance was significantly worse in group 1 than in the other 3 groups. Per-polyp and per-patient sensitivities for polyps greater than or equal to 6 mm were not significantly different among all groups. However, per-patient specificity for lesions greater than or equal to 10 mm was significantly lower in group 2 than in the other groups.
Conclusions: With better tagging efficacy and compliance while maintaining comparable diagnostic performance, it is our belief that the best combination of bowel preparation and fecal-tagging regimen is a combination of magnesium citrate and a high concentration of a barium tagging agent.