Analysis of regional pulmonary enhancement in dogs by ultrafast computed tomography

Measurement of regional pulmonary enhancement was made in five anesthetized dogs with intravenous contrast material-enhanced ultrafast computed tomography (CT). Three or four electrocardiogram-gated flow scans were performed in each dog in the prone and supine positions. Immediately after each flow scan was acquired at four levels (8-mm thick slices), 20 times per level, 0.5 mL/kg (10 mL/second) ionic contrast medium was injected into the inferior vena cavae. Each level of each lung was divided into anterior, middle, and posterior regions for time density curve analysis and regional flow estimation. Images were transferred to an off-line workstation for lung pixel colorization and subjective interpretation. There was a statistically significant gravity-related enhancement gradient in both the supine and prone positions; however, the gradient was much greater in the supine position. This study shows that gravity-related contrast medium enhancement gradients in the lung can be demonstrated by ultrafast CT.