MIller JW, Brinkman-Ferguson AJ, Mackin J.
Introduction/Purpose: Hepatobiliary diseases are common in dogs, and there is a need for a non-invasive way to obtain superior images of the hepatobiliary system. The modalities currently used for imaging the biliary system in dogs often do not provide adequate anatomic or functional information, or they are invasive and subject the patient to health risks. Multi-slice computed tomographic cholangiography (CTC) is a non-invasive way to obtain superior images of the hepatobiliary system. The purposes of this study were to determine the best technique for performing multi-slice CTC in normal dogs, and to describe the cross-sectional and three-dimensional anatomy of the hepatobiliary system.
Methods: CTC using a 64-slice, multi-row CT scanner was performed in 4 healthy adult hounds. Two contrast dose groups were established, with 2 dogs receiving 0.5mLlkg of iodipamide meglumine (Choloqrafin”) intravenously and 2 dogs receiving 1mLlkg. Each dog was scanned every 5-15 minutes for 60 minutes. Multiplanar and three-dimensional reconstructions were performed, and the hepatobiliary anatomy of each dog was evaluated. Visibility scores were assigned for the gallbladder, cystic duct, common bile duct, and 1st, 2nd, and 3rd order intrahepatic ducts using a 1 to 4 scale (1 =structure not seen, 2=structure faintly seen, 3=structure seen but not in its entirety, and 4=entire structure seen) for each time scanned. Maximum duct diameter, time to maximum duct diameter, and mean duct diameter were measured using the transverse plane images for the cystic duct, common bile duct, and viewable intrahepatic ducts. The presence or absence of contrast in the lumen of the duodenum was also reported.
Results: High quality images of the hepatobiliary system were obtained in all dogs. Image quality produced by the 2 contrast doses was subjectively equal. Structures visible with contrast enhancement included the gallbladder, cystic duct, common bile duct, and 1st, 2nd, and 3rd order intrahepatic ducts. Each structure had the highest visibility score at 60 minutes post contrast administration. Maximum duct diameter was achieved at 60 minutes for all of the ducts in each dog. Mean duct diameters at maximum distention for each structure were: cystic duct 3.6mm, proximal aspect of common bile duct 4.0mm, distal aspect of common bile duct 3.6mm, 15 order intrahepatic duct 2.2mm, and 2nd order intrahepatic duct 1.3mm. Third order intrahepatic ducts were too small to measure. Contrast was present in the lumen of the duodenum of only one dog at 60 minutes post contrast administration. No adverse effects were noted with contrast administration and CTC in any dog.
Discussion/Conclusion: Multi-slice CTC is feasible in normal dogs and produces high quality images of the hepatobiliary system. This technique should be evaluated further in dogs with hepatobiliary disease.