Preliminary study of indirect CT lymphography-guided sentinel lymph node biopsy in a tongue VX2 carcinoma model

The feasibility of using indirect CT lymphography (CT-LG) to guide sentinel lymph node (SLN) biopsy in a rabbit model of tongue VX2 carcinoma with cervical lymph node metastasis was studied. Tongue VX2 carcinoma with cervical lymph node metastasis was induced in 19 rabbits by injecting VX2 carcinoma suspension into the tongue submucosa. SLN biopsy was performed under the guidance of indirect CT-LG. SLN identification was performed by indirect CT-LG combined with blue dye injection in 2 rabbits. Tongue SLNs were identified preoperatively by indirect CT-LG and blue-stained SLNs were visualized intraoperatively. Only one SLN was enhanced in each side of the neck, lateral to the larynx-tracheal region. CT attenuation values of the enhanced SLNs were 782.4 ± 46.6, 443.1 ± 68.5, 180.3 ± 20.6 and 80.5 ± 10.7 HU at 1, 5, 15 and 20 min after contrast injection. Overall, ipsilateral SLN identification rate was 97.4% and contralateral SLN identification rate was 100%. Ipsilateral SLN metastasis was verified in all rabbits (100%), bilateral SLN metastasis occurred in 8 rabbits (42%), and micrometastasis was found in 3 rabbits (16%). Indirect CT-LG may be useful for guiding SLN biopsies in tongue cancer. Combining indirect CT-LG with blue dye injection may improve preoperative and intraoperative SLN identification.