[Usefulness of a Split-bolus Injection Protocol for Pediatric Cardiac CT in Congenital Heart Disease]

To propose a split-bolus contrast injection protocol for pediatric cardiac CT and to evaluate its usefulness by comparing it with the early phase protocol and systemic circulation protocol.

Thirty patients were included in each of the following three protocols: the early phase protocol; the systemic circulation protocol, in which contrast medium was injected slowly over a prolonged period and CT was performed after systemic circulation; and the split-bolus protocol. CT attenuation values were measured in the ascending aorta, descending aorta, pulmonary artery, pulmonary veins, and superior vena cava and compared among the three protocols. In addition, two radiologic technologists independently assessed vascular visualization using a four-point visual scoring system.

CT attenuation values obtained with the split-bolus protocol showed no significant differences from those of the early phase protocol in the ascending aorta, descending aorta, pulmonary artery, or pulmonary veins (p=0.282, 0.174, 0.632, and 0.159, respectively), whereas significant differences were observed compared with the systemic circulation protocol (all p<0.001). In contrast, no significant difference in CT attenuation of the superior vena cava was observed between the split-bolus protocol and the systemic circulation protocol (p=0.923). In the visual evaluation, the split-bolus protocol achieved a median score of 4 for all evaluated vessels across all cases.

The split-bolus protocol may enable visualization of the superior vena cava while maintaining contrast enhancement of the aorta, pulmonary artery, and pulmonary veins, suggesting that it may be a useful contrast injection protocol for pediatric cardiac CT.