Utility of diluted contrast materials for pediatric patients with congenital heart disease during the computed tomography angiography

Diluted contrast material is useful, contrast material reduction can be achieved using it in combination with lower-voltage scan. To elucidate the contrast material dilution rates at varying tube voltages and compare the contrast enhancement and contrast material dose between undiluted 120 kVp and diluted 80 kVp protocols in clinicalsettings. Contrast material solution was diluted across a range of 2–1024 times using physiological saline. The injected iodine dose in undiluted 120 kVp protocol (n = 46) and doubly diluted 80 kVp protocol (n = 48) was 600 mg/kg (injection volume was body weight × 2.0 mL) and 300 mg/kg (injection volume was body weight × 2.0［1.0 mL CM + 1.0 mL saline］) during 12 s injection duration. The study included median computed tomography number for ascending aorta and pulmonary artery, image noise, contrast noise ratio, and radiation dose between two groups. Comparable hounsfield unit valueswere achieved by diluting ~2 times at 80 kVp compared to 120 kVp. Under the doubly diluted 80 kVp protocol, contrast material dose was reduced by ~50% compared with undiluted 120 kVp protocol. No significant disparities were observed in median hounsfield unit values for the ascending aorta and pulmonary artery between two protocols (p = 0.95 and 0.82).Analogous range of hounsfield unit values was attained using dilution factor of ~2 at 80 kVp compared to 120 kVp. Doubly diluted 80 kVp protocol curtailed the contrast material dosage by ~50% compared to undiluted 120 kVp protocol while preserving vessel enhancement.