All elective patients scheduled for a contrast-enhanced CT, who filled in a questionnaire evaluating patient comfort, between October 27, 2021 and the end of October 2022 at Maastricht University Medical Center+, were eligible for inclusion. Exclusion criteria were hemodynamic instability, pregnancy, renal insufficiency (estimated glomerular filtration rate <30 mL/min per 1.73 m 2 ), prior adverse reactions to iodinated CM, and age younger than 18 years. Scans conducted at the emergency department scanner were excluded, as the scanning experience for these patients may differ from those who receive a CT scan in outpatient clinical setting. Repeated inclusion was allowed because it was not expected to influence outcome. The 1-year period was divided into 4 periods, each period with a duration of approximately 3 months. Group 1 received CM prewarmed to 37°C (99°F) at a concentration of 370 mg I/mL (iopromide, Ultravist 370; Bayer Healthcare, Berlin, Germany). The same concentration was used in group 2, but at room temperature (~21°C [~73.4°F]). In group 3, the concentration was switched to 300 mg I/mL (iopromide, Ultravist 300; Bayer Healthcare, Berlin, Germany) prewarmed at 37°C. Finally, group 4 received CM 300 mg I/mL at room temperature (Fig. 1). All patients were asked to fill in a questionnaire directly after the CT scan was performed.
To provide an overview of the participation rate, PACS workstation (IDS7 version 24.2; Sectra AB, Linköping, Sweden) was used to compute the total number of contrast-enhanced CT scans conducted during the 4 periods.