Comparison of Computed Tomographic and Radiographic Popliteal Lymphangiography in Normal Dogs

Abstract

To (1) describe computed tomographic (CT) popliteal lymphangiography; (2) compare the number of thoracic duct (TD) branches detected by CT and by radiography after popliteal lymphangiography; and (3) to compare the number of branches detected after left and right popliteal lymphangiography. Experimental study. Adult dogs (n=6). A randomly selected popliteal lymph node was percutaneously injected with 12 L iodinated contrast medium through a 25-g butterfly catheter over 4-5 minutes. Lateral and ventrodorsal (VD) thoracic radiograph projections and thoracic CT were performed. The procedure was repeated using the contralateral lymph node after a 48-72 hours washout period. One dog had TD branches visible on CT but not on radiographs. A significantly greater number of TD branches were observed with CT popliteal lymphangiography compared with lateral and VD radiographic popliteal lymphangiography (P=.003 and P<.001, respectively). The number of visible TD branches observed between the 6th thoracic and 1st lumbar vertebrae were not significantly different in these dogs (P=.146). A significant difference in number of TD branches observed was not found after left or right popliteal lymph node injection (P=.097). CT popliteal lymphangiography consistently identified a greater number of TD branches when compared with radiographic popliteal lymphangiography. Injection of either popliteal lymph node resulted in the same number of TD branches being observed.