Determination of optimal dosage and delay time for computed tomographic lymphography after percutaneous injection of Iohexol into popliteal lymph nodes in dogs.

The purposes of this study were to determine the optimal dose and delay time for lymphography by injection of Iohexol into popliteal lymph nodes and to assess images of computed tomography by the established protocol. Three different doses (30, 60 and 90 mgI/kg) of water-soluble iodinated contrast medium were injected into 15 popliteal lymph nodes of 10 adult beagles, and fluoroscopy was performed. Filling and duration of contrast media and the number of visible ducts from popliteal lymph nodes to the thoracic duct and its branches were recorded. CT lymphography was performed, and the number of visible thoracic ducts was compared with that found by radiographic lymphography. Radiographs obtained between 130 and 800 seconds after injection of contrast medium provided a detailed view of the thoracic duct. The dose of 60 mgI/kg was determined to enable quality diagnostic imaging without extranodal leakage in radiographic lymphography. There was no significant difference in the number of thoracic ducts between the two modalities at each anatomic location. However, CT lymphography provided images of the thoracic duct with better spatial resolution and without superimposition of surrounding tissue. The present study provides an adequate delay time and injection for identification of the canine thoracic duct, and therefore, this technique could be applied to diagnosis of disease associated with chest lymphatic drainage.

Evaluation of partial cranial cruciate ligament rupture with positive contrast computed tomographic arthrography in dogs.

Computed tomographic arthrography (CTA) of four cadaveric canine stifles was performed before and after partial cranial cruciate ligament rupture in order to verify the usefulness of CTA examination for the diagnosis of partial cranial cruciate ligament rupture. To obtain the sequential true transverse image of a cranial cruciate ligament, the computed tomography gantry was angled such that the scanning plane was parallel to the fibula. True transverse images of cranial cruciate ligaments were identified on every sequential image, beginning just proximal to the origin of the cranial cruciate ligament distal to the tibial attachment, after the administration of iodinated contrast medium. A significant decrease in the area of the cranial cruciate ligament was identified on CTA imaging after partial surgical rupture of the cranial cruciate ligament. This finding implies that CTA can be used for assessing partial cranial cruciate ligament ruptures in dogs.