The Influence of Contrast Agent's Osmolarity on Iodine Delivery Protocol in Coronary Computed Tomography Angiography: Comparison Between Iso-Osmolar Iodixanol-320 and Low-Osmolar Iomeprol-370.

OBJECTIVES: This study aims to assess whether iodine-contained contrast agents with different osmolarity affect iodine delivery protocol during coronary computed tomography angiography (CCTA).

METHODS: Patients who underwent CCTA were randomized to receive contrast media either iodixanol-320 (iso-osmolar group) or iopromide-370 (low-osmolar group). Contrast protocols were recorded. Tube voltage of 100 kV was chosen for patients with body mass index of less than or equal to 25 (n = 224) and tube voltage of 120 kV for patients with body mass index of greater than 25 (n = 165). Both groups applied automatic current modulation technique. Mean contrast enhancement of the ascending aorta, left main coronary artery, and descending aorta was calculated. Simulated contrast flow rate and iodine delivery rate (IDR) to reach a mean contrast enhancement level of 350 HU were calculated.

RESULTS: A total of the 389 patients were enrolled in the study. To achieve the same contrast enhancement of 350 HU, iso-osmolar group required higher simulated contrast flow rate (3.90 vs 3.62 mL/s, P = 0.017) but lower simulated IDR (1.34 vs 1.25 g/s, P = 0.024) compared with low-osmolar group.

CONCLUSIONS: To maintain a similar level of contrast enhancement during CCTA, iodixanol-320 needs larger contrast flow rate with lower IDR compared with low-osmolar iopromide-370.