This study aims to develop a standardized universal imaging protocol for ICG-guided fluorescent total thyroidectomy, including quantitative evaluations of the fluorescent signal. Therefore, patients will undergo thyroid surgery (total thyroidectomy) with the use of ICG fluorescence.

Background Thyroid surgery volume continues to increase worldwide over the past few decades. During a total thyroidectomy (TTx), the ultimate goal is to remove all thyroid tissue, whereas damage to adjacent tissue is prevented. However, iatrogenic hypoparathyroidism, as a result of surgical removal or damage to the parathyroid glands, occurs in approximately 30% of the cases. In 2016 near-infrared fluorescence guided surgery with indocyanine green (ICG) was proposed for visualizing viability and blood supply of parathyroid glands during TTx. ICG can visualize tissue perfusion, since it becomes completely and permanently fixed to plasma proteins once in the bloodstream, and circulates in the intravascular compartment only. However, one of the limitations of ICG imaging is the subjectivity of the interpretation of fluorescence, which makes the assessment of images inconsistent among studies. There is a clear need for standardization of the evaluation of the perfusion with ICG, since visual evaluation of the fluorescent signal of ICG is not sufficient to reliably predict the perfusion of parathyroid glands.

Main research question To develop a standardized universal imaging protocol for ICG-guided fluorescent total thyroidectomy including quantitative evaluations of the fluorescent signal.

Design This will be a proof-of-concept , prospective cohort study of patients undergoing a total thyroidectomy with ICG-guided fluorescent surgery to evaluate tissue perfusion The main study endpoint is quantification of the fluorescent signal of ICG. Secondary outcomes are data from surgery, postoperative lab values (including calcium, PTH, albumin) and postoperative medication use.

Inclusion Criteria:

1. Patients ≥ 18 years
2. Patients undergoing total thyroidectomy as surgical procedure for thyroid cancer, Graves' disease or goiter
3. Patients are eligible for surgery
4. Patients are mentally competent and are able and willing to comply with study procedures
5. Written informed consent

Exclusion Criteria:

1. Patients with a known allergy to ICG or iodinated contrast
2. Pregnant or lactating women
3. Patients with previous neck surgery