Influence of Contrast Media Temperature and Concentration on Patient Comfort and Safety in Computed Tomography
Authors: Stammen Lion , Mihl Casper , Vandewall Janneke , Pennetta Francesca , Hersbach Ankie , Wildberger Joachim E. , Martens Bibi 
Published: January 2024

Background
Previous research on the necessity to reduce the viscosity of contrast media (CM) by either prewarming CM before injection during computed tomography (CT) or by using less concentrated CM has yielded conflicting results. In addition, there is limited evidence on patient comfort.

Objectives
The aim of the study was to examine if prewarming CM, with varying CM concentrations, is superior to CM at room temperature, with respect to patient comfort and safety in CT.

Materials and Methods
All elective patients scheduled for contrast-enhanced CT scans at Maastricht University Medical Center+ between October 27, 2021 and October 31, 2022 were eligible for inclusion when a questionnaire evaluating patient comfort was completed. This 1-year period was divided into 4 intervals (4 groups): group 1 (370 mg I/mL, 37°C), group 2 (370 mg I/mL, room temperature), group 3 (300 mg I/mL, 37°C), and group 4 (300 mg I/mL, room temperature). All CT scans were performed using state of the art equipment (Siemens Healthineers; SOMATOM Force and SOMATOM Definition AS, Forchheim, Germany). Contrast media injections were performed using a dual-head power injector (Stellant; Bayer Healthcare, Berlin, Germany) and individualized to body weight and/or tube voltage, depending on the CM protocols. After the CT scan, patients completed a questionnaire covering the primary outcomes comfort, pain, and adverse events such as feelings of heat, nausea, vomiting, itchiness, urticaria, difficulty breathing, dizziness, goosebumps, or an odd taste. Technicians were asked to report any adverse events, including extravasation and allergic-like reactions. The secondary outcome involved attenuation (in Hounsfield unit, HU), which was evaluated by assessing the HU of the coronary arteries for vascular CT, and liver enhancement in portal venous CT. The Kruskal-Wallis test was used for continuous scale outcomes and χ2 tests for examining adverse events.

Results
Results showed no significant differences examining comfort score (P = 0.054), pain sensation (P = 0.469), extravasation (P = 0.542), or allergic-like reaction (P = 0.253). Significant differences among the 4 groups were found with respect to heat sensation and dizziness (P = 0.005 and P = 0.047, respectively), showing small effect sizes. All other adverse effects showed no significant results. No significant differences were observed in coronary attenuation among the 4 groups in coronary CT angiography (P = 0.113). When analyzing attenuation in portal venous CT scans, significant differences were found among the 4 groups (P = 0.008).

Conclusions
Administrating prewarmed CM is nonsuperior compared with CM at room temperature in relation to patient comfort and safety, regardless of CM concentration. These findings suggest that prewarming CM before usage is unnecessary, which will improve the efficiency of daily clinical workflow and brings environmentally friendly benefits.