Intravenous injection of high and medium concentrations of computed tomography contrast media and related heat sensation, local pain, and adverse reactions.

Objectives: To evaluate the incidence of acute adverse reactions and degrees of heat sensation and local pain after intravenous injection of high and medium concentrations of iodinated contrast medium for computed tomography (CT).

Methods: A prospective study was performed involving 729 patients who underwent contrast CT scans. High-concentration (370 mgI/mL) and medium-concentration (300 mgI/mL) iodinated contrast medium was assigned to 342 patients (group H, aged 20-90 years, mean = 59.8 years) and to 387 patients (group M, aged 20-95 years, mean = 61.7 years), respectively. An injection rate of contrast medium (1, 2, or 4 mL/s) at a base volume of 2 mL/kg of body weight was selected according to the protocols for the evaluated diseases and regions. Each patient was assessed for heat sensation and local pain at the injection site using a visual analog scale (ranging from none for 0 to severe for 10). Acute adverse reactions were recorded when they occurred.

Results: There were no significant differences in patient background factors, including age, sex, history of prior adverse reactions, and allergies, between the 2 groups. The score for heat sensation was significantly higher in group H than in group M (4.46 +/- 2.44 vs. 3.44 +/- 2.45; P < 0.0001 for heat sensation). The data did not show a higher incidence of adverse reactions in group H than in group M (5 [1.46%] of 342 patients vs. 2 [0.52%] of 387 patients; P = 0.26) or a higher score for local pain in group H than in group M (0.98 +/- 1.70 vs. 0.88 +/- 1.49; P = 0.66), respectively.

Conclusions: High and medium concentrations of iodinated contrast medium can be used for CT study with comparable safety profiles even though heat sensation produced by the high-concentration CM is greater than that produced by the medium-concentration CM.