Abstract:
Computed tomography thoracic angiography studies were performed on five adult beagles
using the bolus tracking (BT) technique and the test bolus (TB) technique, which were
performed at least two weeks apart. For the BT technique, 2 mL/kg of 300 mgI/mL iodinated
contrast agent was injected intravenously. Scans were initiated when the contrast in the aorta
reached 150 Hounsfield units (HU). For the TB technique, the dogs received a test dose of
15% of 2 mL/kg of 300 mgI/mL iodinated contrast agent, followed by a series of low dose
sequential scans. The full dose of the contrast agent was then administered and the scans were
conducted at optimal times as identified from time attenuation curves. Mean attenuation in
HU was measured in the aorta (Ao) and right caudal pulmonary artery (rCPA). Additional
observations included the study duration, milliAmpere (mA), computed tomography dose
index volume (CTDI[vol]) and dose length product (DLP). The attenuation in the Ao (BT =
660 52 HU ± 138 49 HU, TB = 469 82 HU ± 199 52 HU, p = 0.13) and in the rCPA (BT =
606 34 HU ± 143 37 HU, TB = 413 72 HU ± 174.99 HU, p = 0.28) did not differ significantly
between the two techniques. The BT technique was conducted in a significantly shorter time
period than the TB technique (p = 0.03). The mean mA for the BT technique was significantly
lower than the TB technique (p = 0.03), as was the mean CTDI(vol) (p = 0.001). The mean DLP
did not differ significantly between the two techniques (p = 0.17). No preference was given
to either technique when evaluating the Ao or rCPA but the BT technique was shown to be
shorter in duration and resulted in less DLP than the TB technique.
