Comparative Popliteal and Mesenteric Computed Tomography Lymphangiography of the Canine Thoracic Duct

Abstract

Thoracic duct computed tomography (CT) lymphangiograms were performed on seven clinically normal dogs. The appearance of the thoracic duct system was compared following administration of contrast medium through a mesenteric lymphatic vessel vs. ultrasound guided percutaneous injection into a popliteal lymph node using helical and sequential CT acquisition modes. The number of visible thoracic duct branches and the largest thoracic duct branch cross-sectional area and mean Hounsfield units (HU) were determined from thoracic vertebra 9 to lumbar vertebra 1. Procedural time and patient discomfort were also assessed. Popliteal administration produced a successful thoracic duct lymphangiogram in eight of 11 dogs (73%) after two attempts, while mesenteric administration was successful in eight of 10 dogs (80%) after a single attempt. Popliteal lymphography required 46% of the time and was associated with less patient discomfort than mesenteric lymphangiography. The number of thoracic duct branches seen was not significantly different for either administration technique (P=0.256) or CT acquisition mode (P=0.417). However, the cross-sectional area and mean HU of the largest thoracic duct branch were greater with mesenteric administration (P<0.001), and helical image acquisition (P<0.001). The thoracic duct branch number, size, and location were highly variable between dogs. Percutaneous popliteal lymphography appears to be an acceptable alternative to mesenteric lymphangiography for the detection of thoracic duct branches in the dog when using either helical or sequential CT acquisition modes.

Advanced Ultrasound Techniques

“…[37][38][39][40][41] Two basic approaches have been described: popliteal lymph node injection and mesenteric lymph node injection. However, the thoracic duct commonly has multiple tributaries, so that identifying the location of a common duct before branching is useful for presurgical planning.…”

“…26 The most common complication was leakage of contrast material through the needle tract, which occurred in 8 of 18 studies and rendered 5 studies nondiagnostic. 41 A common theme from these investigations is the variation in number of thoracic duct branches, and their size and location, which is essential information for presurgical planning and identification of complete ductal ligation following surgery. PV SV A compared the two techniques and concluded that popliteal injection was faster and less painful than mesenteric injections for CT thoracic duct lymphangiography.…”

“…One cat required surgical repair of an iatrogenically lacerated renal pelvis. [39][40][41] Ultrasound is used to identify a mesenteric lymph node. 41 A common theme from these investigations is the variation in number of thoracic duct branches, and their size and location, which is essential information for presurgical planning and identification of complete ductal ligation following surgery.…”

Computed Tomography and Radiographic Lymphography of the Thoracic Duct by Subcutaneous or Submucosal Injection

“…Unlike conventional methods requiring procedural experience, in present method, it is possible to obtain a better understanding of individual differences in the thoracic duct more easily. Direct administration into the popliteal lymph node in a hind leg, which has recently been reported, is less invasive because it only involves injection into subcutaneous lymph nodes [9,10], but these lymph nodes are small and mobile, meaning that a certain amount of experience is required for administration at this site. Unlike conventional methods requiring procedural experience, in the experiments in the present study, angiography contrast medium, used clinically on an everyday basis, was injected beneath the rectal membranes continuous with the anus and the vaginal membranes continuous with the vulva, as well as into perianal tissue, all sites that are easy to approach.…”

“…The position and course of the thoracic duct and cisterna chyli must be confirmed preoperatively when thoracic duct ligation or cisterna chyli ablation is performed, for which lymphography of the thoracic duct is of course required [1]. Current methods for performing lymphography of the thoracic duct involve the injection of contrast medium into the mesenteric lymph nodes during laparotomy under anesthesia or contrast imaging of the thoracic duct after the injection of contrast medium into the popliteal lymph node of a pelvic limb [2,9,10]. However, laparotomy is an invasive procedure, and reliable results cannot be obtained by percutaneous penetration of lymph nodes when the size and position of these lymph nodes are undetermined.…”