Comparison of single-dose and split-dose fecal tagging with iohexol in computed tomographic colonography

BACKGROUND: Proper fecal tagging allows for high-quality computed tomography colonography. However, there is no single tagging scheme. Therefore, the effects of a contrast enhancement regimen on fecal tagging should be evaluated. AIM: This study aimed to compare the quality of single-dose fecal tagging with that of split-dose fecal tagging with iohexol during computed tomographic colonography and to assess the impact of these regimens on procedure tolerability. METHODS: In this retrospective, selective, single-center study, the patients were divided into two groups based on whether they received single-dose (group 1) or split-dose (group 2) fecal tagging. Both groups received 50 mL of the iodine-containing contrast agent iohexol, with iodine concentration of 350 mg/mL. The residual liquid density was assessed using three parameters: maximum, minimum, and mean values. Additionally, the residual fluid homogeneity was assessed by calculating the mean standard deviation within the region of interest. Tolerability of preparation for colonography was assessed using a 10-point visual analog scale. RESULTS: The final sample included 338 patients: 116 in group 1 and 222 in group 2. The mean, minimum, and maximum density values in group 2 were significantly higher than those in group 1: 943 [722; 1245], 753 [525; 1082], and 1079 HU [801; 1456] versus 681 [420; 907], 570 [374; 820], and 825 HU [496; 1154], respectively (p 0.001). The residual fluid homogeneity was significantly higher in group 2 than in group 1: 59 [46; 78] versus 67 HU [54; 81] (р = 0.012). Group 2 showed a significantly lower subjective difficulty of preparation than did group 1: 4 [2; 6] and 5 [4; 7], respectively (p = 0.004). CONCLUSION: A single dose of 50 mL of iohexol (iodine concentration: 350 mg/mL) provides higher-quality fecal tagging than a split-dose provides because of higher residual fluid density with maintained homogeneity. Moreover, single-dose tagging was found to be more tolerable.