Contrast attenuation of the DDFT and arteries − First phase
The contrast attenuation values of the first phase are presented in Table 1. HUpost – HUpre of the DDFT was significantly different among groups (P = 0.005). Of the groups, group C (80 kV and 150 mg I/mL) showed significantly higher CE than other groups (P < 0.05). In 80 kV of voltage, HUpost – HUpre positively correlated with the concentration of CM (P = 0.0004, r = 0.75). A significant difference was observed only in the contrast enhancement of the medial palmar artery (P = 0.008). However, no specific groups showed a significant increase in contrast enhancement in the post-hoc analysis.
We then chose the concentration and scanning parameters of groups C and E, which showed significant CE of the DDFT and no differences among the other groups using low concentrations of CM. Accordingly, in the second study, CT was performed at 80 kV and 250 mA, while maintaining an iodine delivery rate (IDR) of 300 or 180 mg I/s. We scanned CT with different CM volumes and rates (4 or 6 mL/s and 100 or 150 mL).