Impact of different concentration iodinated contrast media on pain and comfort in abdominal computed tomography

Objectives: To investigate whether high concentration iodinated contrast media (CM), compared with low concentration CM, could reduce pain and discomfort levels in patients who had level II and III venous conditions. Methods: This prospective, single-center study enrolled patients who had level II and III venous conditions and underwent abdominal contrast-enhanced CT scan between July 2021 and February 2022. The venous condition to establish peripheral venous access for CM injection was graded using the Intravenous Access Scoring system, of which level II and III indicated poor venous condition and difficult venous access. Patients received iomeprol 400 in high concentration group and ioversol 320 in low group at an identical iodine delivery rate of 1.12 gI/s. The primary outcomes were pain and comfort levels. The secondary outcomes included adverse events and image quality. Patients rated pain intensity via Numerical Rating Scale and comfort level via Visual Analogue Scale with higher scores indicating higher levels of pain and discomfort. Quantitative and qualitative image assessment were compared between two groups. Continuous variables were compared using Student's t test or Mann- Whitney U test. Categorical variables were compared using chi(2) test, chi(2) test for trend or Fisher's exact test. Results: A total of 206 patients (mean age, 60.13 +/- 12.14 years; 81 males) were included with 99 in the high concentration group and 107 in the low concentration group. The high group had significantly lower pain scores (median 1 [IQR: 0-2] vs 2 (IQR 2-4), p < 0.001) and comfort scores (1 [IQR: 0-3] vs 3 [IQR: 2-5], p < 0.001) than the low group. Incidence of CM extravasation did not significantly differ (1.0 % vs 4.5 %, p = 0.214). No hypersensitivity reaction was observed. Qualitative assessment showed higher clarity scores of intrahepatic hepatic artery and portal vein in the high group. Quantitative assessment results were comparable between two groups. Conclusion: High concentration iodinated CM could lower pain intensity and improve comfort levels without comprising image quality of CT scan. High concentration CM is a preferable choice in patients with poor venous conditions during contrast-enhanced CT scan.