Design
This research was a prospective study. Each horse underwent nine CT scannings (Aquilion, Canon, Osaka, Japan) at >72 h intervals to avoid the effect of CM that had been previously injected. The experiments were conducted in two phases. First, we measured contrast attenuation of the DDFT and arteries depending on the scanning parameters (120 kV and 150 mA; 80 kV and 250 mA) and concentration of CM (150, 120, or 90 mg I/mL; Table 1). The injection rate of CM (Omnipaque 300; GE Healthcare, Chicago, IL) and the scan timing were 2 mL/s and 3 s, respectively. Two groups were selected for the second experiment, wherein, at a fixed IDR and total iodine dose (TID), contrast attenuation was measured depending on the volume and rate of CM (4 or 6 mL/s and 100 or 150 mL, respectively; Table 2). Scan parameters were set as 1 mm slice thickness and 0.75 sec rotation time, and the field of view was adjusted to include both limbs and from the carpal joint to the toe of limb of the interests in both phases.