Thoracic Duct Branch Identification Is Comparable Between T2-W 3D Fat-Suppressed Magnetic Resonance Imaging and Computed Tomography Lymphangiography in Normal Dogs.

In dogs with chylothorax that are refractory to medical management, surgical intervention is often recommended. Computed tomographic lymphangiography (CTL) is the most commonly used preoperative imaging study, but it has the disadvantages of being time-consuming and requiring contrast medium administration. In human medicine, magnetic resonance imaging (MRI) allows noninvasive visualization of lymphatic ducts. The aim of this prospective study was to compare the use of a T2-W 3D fat-suppressed MRI sequence to traditional CTL for identifying the number and anatomic location of thoracic duct branches. MRI and CTL studies were performed in six healthy dogs. Images were anonymized and independently reviewed by a board-certified veterinary surgeon and a board-certified veterinary radiologist. For each study, the number of duct branches was recorded at four sites (T9, T11, T13, and L2) in addition to the location of the cisterna chyli. Additionally, the surgeon's proposed surgical site and duration of MRI and CTL procedures were noted. There was no significant difference in the number of branches identified between MRI and CTL (p = 0.751). Each dog had at least one location with only one observed thoracic duct branch on both CT and MRI, and this was chosen as the proposed surgical site for the dog. There was no statistical difference in study duration between CTL and MRI (p = 0.294). MRI may prove to be a beneficial and efficient alternative to CTL for surgical planning in dogs with chylothorax.