Evaluation of the clinical value of carbon nanoparticles as lymph node tracer in differentiated thyroid carcinoma requiring reoperation

The incidence of parathyroid injury in patients with differentiated thyroid carcinoma (DTC) who underwent reoperation is significantly higher than that incurred from the initial surgery. The aim of this study was to investigate the clinical value of carbon nanoparticles (CN) as tracers for lymph nodes to guide cervical lymph node dissection and protect the parathyroid during reoperation for DTC. Our study recruited 116 patients with DTC who previously underwent thyroidectomy and later received remedial surgical treatment at the Department of Breast and Thyroid Surgery, Hunan Provincial People's Hospital, China, between February 2011 and February 2014. Those patients were randomly divided into the experimental group (the CN group) with 64 cases and the control group with 52 cases. Carbon nanoparticle suspension (CNS, 0.1-0.3 ml) was intraoperatively injected into the residual thyroid or enlarged lymph nodes in the CN group; in the control group, CNS was not applied intraoperatively. The differences in identification of the parathyroid glands, the number of lymph nodes resected intraoperatively, and the incidence of common complications after thyroidectomy in both groups were recorded and analyzed. The accuracy of identification of the parathyroid in the CN group and control group was 92.2 % and 28.8 %, respectively, and the identification rate of three glands or more in both groups was 75 % and 36.5 %, respectively; those differences were statistically significant between the two groups (P < 0.05). There was also a significant difference between the two groups in the number of lymph nodes removed in the central and lateral cervical compartments (P < 0.05). There was no increase in common complications after the second surgery compared with the previous surgery; in addition, there was a decline in the incidence of transient hypoparathyroidism (HPT) (P < 0.05). By tracing the thyroid and cervical regional lymph nodes with carbon nanoparticles, the parathyroid glands can be easily identified and protected to reduce the complications of transient hypoparathyroidism resulting from reoperation for residual or missed DTC. Carbon nanoparticle tracers also facilitate radical resection of lymph nodes at the central and lateral compartments of the neck.