Comparison of the effectiveness of a single versus split dose of Iohexol for fecal tagging at CT Colonography

Background: Fecal and fluid tagging plays a critical role in ensuring high-quality CT colonography (CTC). To date, there is no unified fecal tagging scheme. In this regard, it is necessary to study the effect of contrast media administration regimen on tagging quality. Aims: comparison of the effectiveness of a single versus split dose of Iohexol for fecal tagging at CTC, as well as studying the effect of changing the fecal tagging scheme on the patient tolerability of bowel preparation. Methods: This retrospective study included two groups of patients: those who underwent split dose (SpD) fecal tagging and single dose (SiD) fecal tagging. In both groups was used 50 ml of iodinated contrast agent iohexol at a concentration of 350 mg/ml . The residual fluid density and the residual fluid homogeneity was assessed. The severity of the bowel preparation was assessed using a 10-point visual analogue scale (VAS). Results: The final sample included 338 patients: 116 patients in the SpD group and 222 in the SiD group. The values of average density in the SiD group were statistically significantly higher than in the SpD group: in the SiD group were 943 HU (Q1-Q3: 722-1245 HU), while in the SpD group 681 HU (Q1-Q3: 420-907 HU), p 0.001. The residual fluid in the SiD group was statistically significantly more homogeneous, p=0.012. The subjective feeling of the severity of bowel preparation was statistically significantly lower in the SiD group, p=0.004. Conclusions: A single dose of iohexol with an iodine concentration of 350 mg/ml improves the quality of fecal and fluid tagging compared to split dose administration of the same dose of iohexol by increasing the residual fluid density without deteriorating homogeneity parameters. Single dose fecal tagging is better tolerated by patients compared to split dose tagging.