*Review* **Fluorescence Image-Guided Surgery for Thyroid Cancer: Utility for Preventing Hypoparathyroidism**

**Marco Stefano Demarchi 1,2 , Barbara Seeliger 3,4,5,6 , Jean-Christophe Lifante 2,7, Pier Francesco Alesina 6,8 and Frédéric Triponez 1,\***


**Simple Summary:** The most frequent post-operative complication in thyroid surgery is hypoparathyroidism leading to temporary or definitive low blood calcium levels. This complication can result from intentional or inadvertent extirpation, trauma, or devascularization of the parathyroid glands. They are located right next to the thyroid, and are responsible for the blood calcium level regulation. Hypoparathyroidism is even more common when a lymph node dissection is needed in addition to thyroidectomy in case of thyroid cancer. The safeguarding of all four parathyroid glands with their vascularization can be extremely challenging, even for experienced surgeons. Fluorescence imaging is a relatively novel intraoperative tool to help identify, visualize, and preserve the parathyroid glands during thyroid surgery. In this review, we summarize the current scientific landscape and the potential benefits of fluorescence imaging to preserve the parathyroid glands and to prevent post-operative hypoparathyroidism in thyroid cancer surgery.

**Abstract: Background:** Hypoparathyroidism is one of the most frequent complications of thyroid surgery, especially when associated with lymph node dissection in cases of thyroid cancer. Fluorescence-guided surgery is an emerging tool that appears to help reduce the rate of this complication. The present review aims to highlight the utility of fluorescence imaging in preserving parathyroid glands during thyroid cancer surgery. **Methods:** We performed a systematic review of the literature according to PRISMA guidelines to identify published studies on fluorescence-guided thyroid surgery with a particular focus on thyroid cancer. Articles were selected and analyzed per indication and type of surgery, autofluorescence or exogenous dye usage, and outcomes. The Methodological Index for Non-Randomized Studies (MINORS) was used to assess the methodological quality of the included articles. **Results:** Twenty-five studies met the inclusion criteria, with three studies exclusively assessing patients with thyroid cancer. The remaining studies assessed mixed cohorts with thyroid cancer and other thyroid or parathyroid diseases. The majority of the papers support the potential benefit of fluorescence imaging in preserving parathyroid glands in thyroid surgery. **Conclusions:** Fluorescence-guided surgery is useful in the prevention of post-thyroidectomy hypoparathyroidism via enhanced early identification, visualization, and preservation of the parathyroid glands. These aspects are notably beneficial in cases of associated lymphadenectomy for thyroid cancer.

**Citation:** Demarchi, M.S.; Seeliger, B.; Lifante, J.-C.; Alesina, P.F.; Triponez, F. Fluorescence Image-Guided Surgery for Thyroid Cancer: Utility for Preventing Hypoparathyroidism. *Cancers* **2021**, *13*, 3792. https:// doi.org/10.3390/cancers13153792

Academic Editor: Mary F. McMullin

Received: 25 May 2021 Accepted: 23 July 2021 Published: 28 July 2021

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**Keywords:** thyroid surgery; thyroid cancer; hypoparathyroidism; fluorescence-guided surgery; near-infrared autofluorescence
