To investigate the performance of indirect computed tomography lymphography with iopamidol for detecting cervical lymph node metastases in a tongue VX2 carcinoma model.

A metastatic cervical lymph node model was created by implanting VX2 carcinoma suspension into the tongue submucosa of 21 rabbits. Computed tomography images were obtained 1, 3, 5, 10, 15 and 20 minutes after iopamidol injection, on days 11, 14, 21 (six rabbits each) and 28 (three rabbits) after carcinoma transplantation. Computed tomography lymphography was performed, and lymph node filling defects and enhancement characteristics evaluated.

Indirect computed tomography lymphography revealed bilateral enhancement of cervical lymph nodes in all animals, except for one animal imaged on day 28. There was significantly slower evacuation of contrast in metastatic than non-metastatic nodes. A total of 41 enhanced lymph nodes displayed an oval or round shape, or local filling defects. One lymph node with an oval shape was metastatic (one of 11, 9.1 per cent), while 21 nodes with filling defects were metastatic (21/30, 70 per cent). The sensitivity, specificity, accuracy, and positive and negative predictive values when using a filling defect diameter of 1.5 mm as a diagnostic criterion were 86.4, 78.9, 82.9, 82.6 and 83.3 per cent, respectively.

When using indirect computed tomography lymphography to detect metastatic lymph nodes, filling defects and slow evacuation of contrast agent are important diagnostic features.