Localization of the sentinel lymph node in tongue VX2 carcinoma via indirect CT lymphography combined with methylene blue dye injection

Abstract

Conclusions: Indirect computed tomography lymphography (CT-LG) combined with blue dye injection can locate the sentinel lymph node (SLN) in tongue carcinoma. Objective: To localize the SLN in tongue VX2 carcinoma using indirect CT-LG combined with methylene blue injection. Methods: Eighteen rabbits were placed into three groups: metastasis, hyperplasia, and control. Indirect CT-LG was performed with an iohexol injection into the tongue submucosa. CT images were acquired at 1, 5, and 15 min after injection. Methylene blue was injected into the same area 24 h after indirect CT-LG, followed by SLN identification and histopathological examination. Results: SLNs were visualized with an identification rate of 100%. SLN location identified using CT lymphography was confirmed by methylene blue dye. Control and hyperplastic enhanced SLNs were round or oval without any filling defects. Control rabbits had enhanced SLN attenuation values of 689.2 ± 55.4 HU, 278.4 ± 33.5 HU, and 71.7 ± 9.2 HU at 1, 5, and 15 min after injection, respectively. Hyperplastic rabbits had values of 877.4 ± 69.4 HU, 352.5 ± 43.3 HU, and 80.2 ± 11.5 HU. Filling defects were only observed in the ipsilateral metastatic SLNs of the metastasis group. CT attenuation values of the metastatic SLNs were 687.4 ± 55.6 HU, 535.1 ± 86.6 HU, and 282.3 ± 19.4 HU at 1, 5, and 15 min, respectively, after iohexol injection. Metastatic lymph node attenuation values were significantly greater than those of the control or hyperplastic nodes at 5 (p < 0.001) and 15 min (p < 0.001) after injection.

Keywords::

• Lymphography
• occult metastasis
• sentinel lymph node biopsy
• rabbit VX2 carcinoma
• lymphoscintigraphy
• head and neck neoplasm
• metastasis diagnosis
• animal model
• lymphatic mapping
• clinic N0

Acknowledgments

The authors thank Dr Guixiang Zhang for providing the VX2 carcinoma tissue. This study was supported by grant no. 2006013 from the Board of Health of Shanghai and also supported by grant no. 09411967500 from Science and Technology Commission of Shanghai Municipality PR China, obtained by Haitao Wu, MD.