Establishment of injection protocol of contrast material in pulmonary angiography using test bolus method and 16-detector-row computed tomography in normal beagle dogs

The aim of this study was to establish an injection protocol of a test bolus and a main bolus of contrast material for computed tomographic pulmonary angiography (CTPA) for visualizing optimal pulmonary arteries in normal beagle dogs. CTPA using a test bolus method from either protocol A or B were performed in each of four normal beagle dogs. In protocol A, CTPA was conducted with a scan duration for around 8 s, setting the contrast enhancement peak of the pulmonary trunk in the middle of the scan duration. The arrival time to the contrast enhancement peak was predicted from a previous dynamic scan using a test bolus (150 mg iodine/kg) injected with the same injection duration using for a main bolus (450 mg iodine/kg). In protocol B, CTPA was started at the predicted appearance time of contrast material in the pulmonary trunk based on a previous dynamic scan using a test bolus injected with the same injection rate as a main bolus. CTPA using protocol A showed the optimal opacification of the pulmonary artery with pulmonary venous contamination. Proper CTPA images in the absence of venous contamination were obtained in protocol B. CTPA with a scan duration for 8 s should be started at the appearance time of contrast enhancement in the pulmonary trunk, which can be identified exactly when a test bolus is injected at the same injection rate used for the main bolus.