Early partial portal venous contrast enhancement in canine CT-Angiography

Early partial portal vein contrast enhancement (EPoVE) during the late arterial phase is seen in computed tomographic-angiography of dogs. Previously, it has been a finding attributed to arterioportal vascular anomalies. However, EPoVE may be a normal feature of venous return from abdominal organs. This descriptive study investigated the origin of EPoVE using 4D-CT. Sixteen dogs undergoing 4D-CT for disease of the cranial abdomen were prospectively collected. Regions-of-interest were placed in the hepatic artery (HA), gastroduodenal vein (GV), extrahepatic portal vein (EHPV) cranial and caudal to the GV and splenic vein (SV) caudal to its EHPV entry. Times to earliest, partial, full and maximal vascular enhancement were recorded. Mixed model ANOVA was used to compare means of time-to-contrast enhancement between vessels. The number, origin and time of EPoVE were recorded if visible. A total of 24 EPoVE areas were observed in all dogs. Most dogs had either 1 (10/16) or 2 (5/16) areas of EPoVE. The origin of EPoVE was identified in 14/24: the GV in 5, cranial mesenteric vein in 4, pancreatic branch of SV in 3 and SV in 2. The time-to-contrast-enhancement was significantly different between veins and the HA. EPoVE during the late arterial phase is a common phenomenon of early portal venous drainage of abdominal organs; it should not be interpreted as pathognomonic for arterioportal vascular anomalies, which should be diagnosed based on additional criteria.