CTTHORACIC DUCT LYMPHOGRAPHY IN CATS BY POPLITEAL LYMPH NODE IOHEXOL INJECTION

Abstract

Three different doses (1.0, 1.5, and 2.0 ml) of iohexol (300 mgl/ml) were injected percutaneously into the popliteal lymph node of eight adult cats under ultrasound guidance. Serial transverse CT images of five regions of interest (L3, T13, T8, T4, and T1 level) were performed at 2-min intervals, and the attenuation in Hounsfield Units (HU) of the lymphatic vessels was measured for determination of the optimal dose of iohexol and CT scan parameters. The optimal dose was 1.5 ml and helical CT acquisition is recommended to be performed as soon as possible after iohexol injection. In helical scans, the thoracic duct was characterized by variable branch numbers that formed a single trunk and entered the venous system at variable levels. CT lymphography using this protocol was performed in a cat with chylothorax. The thoracic duct was tortuous and focally dilated, and leakage of contrast medium was observed. Percutaneous CT lymphography using ultrasound-guided administration of iohexol into the popliteal lymph node appears reliable for delineation of the thoracic duct in cats.

Pleura

“…11,46,48 The addition of pericardectomy was proposed as some animals also have marked thickening of the pericardium that may impede chyle drainage into the venous circulation. 47 It should be noted that identification of the thoracic duct branches is extremely challenging in cats and in the aforementioned study the authors suggested their high success rate could be attributed to surgeon experience and the use of magnification techniques. Resolution of chylothorax was seen in eight of ten cats undergoing thoracic duct ligation and pericardectomy, although in some of these patients the procedures were performed during two separate surgeries (Box 44-3).…”

“…Pericardectomy can be achieved via a second thoracotomy at the left 5 th intercostal space or, alternatively, median sternotomy may be performed to facilitate concurrent thoracic duct ligation and pericardectomy (see Chapter 48). 47 There is no reported correlation between chronicity of chylothorax and success of surgery or for the extent of fibrosing pleuritis in those cats where it is present. 47 It should be noted that identification of the thoracic duct branches is extremely challenging in cats and in the aforementioned study the authors suggested their high success rate could be attributed to surgeon experience and the use of magnification techniques.…”

“…Resolution of chylothorax was seen in eight of ten cats undergoing thoracic duct ligation and pericardectomy, although in some of these patients the procedures were performed during two separate surgeries (Box 44-3). 47 For those cases where thoracic duct ligation has failed, repeat thoracotomy to attempt further ligation may be of benefit. 47 There is no reported correlation between chronicity of chylothorax and success of surgery or for the extent of fibrosing pleuritis in those cats where it is present.…”

“…47 For popliteal lymphangiography, 1.5 mL of iohexol (300 mg/mL) is injected into the popliteal lymph node. 47 For popliteal lymphangiography, 1.5 mL of iohexol (300 mg/mL) is injected into the popliteal lymph node.…”

Chyloabdomen in a cat with pancreatic carcinoma

“…It is frequently used for exploration of chylous effusion when first-line diagnostic procedures have failed to identify the underlying cause of the effusion. Ultrasound-guided percutaneous lymphography by mesenteric or popliteal lymph node injection has been recently described in cats (Kim et al, 2011;Lee et al, 2012). However, the mobility of the lymph nodes and the volume of contrast agent to administer (1.5mL) can make the procedure tedious (Kim et al, 2011;Lee et al, 2012).…”