Use of Intraoperative Autofluorescence Imaging in Surgery for Primary Hyperparathyroidism - a Randomized Controlled Trial.

Parathyroidectomy (PTX) is the only curative treatment for primary hyperparathyroidism (PHPT).1 Prior to surgery, imaging is performed to determine the anatomical location of pathological parathyroid gland (PTGs). Usually two independent localizing imaging methods are used, e.g. sestamibi scintigraphy and neck ultrasound. Additional imaging modalities may be added, e.g. PET/CT. In case of concordant imaging results, a selective/focused PTX may be performed with removal of the identified pathological gland. If imaging is negative or non-concordant, an exploratory parathyroidectomy (ePTX) is performed, either as a bilateral four-gland exploration, or as a unilateral exploration in case of suspicion to one side of the neck.2 In exploratory PTX, the surgeon must use experience to visually identify both normal and pathological PTGs, which may be very challenging. Identification of normal PTGs will usually aid in determining the likely location of missing pathological PTGs. Failure to localize and remove pathological PTGs will result in a failed operation with persistent disease.

Results of a large European survey indicate that approximately 1% of patients undergo re- operation shortly after the first surgery, and 4,3% had persistent hypercalcemia at first follow-up.3 Recently, near-infrared autofluorescence imaging (AF) has been used as an intraoperative adjunct to localize PTGs. This may assist the surgeon in identifying both normal and pathological PTGs. Potentially, the use of AF could the result in higher probability of cure from PTX, as well as shorter operating time and possibly less extensive surgery and less complications.

1. Study design Randomized, controlled trial. Patients will be randomized 1:1 to either control or AF group.
2. Study setting and practical conduct The trial is to be conducted at Department of Otorhinolaryngology - Head & Neck Surgery, Aarhus University Hospital (AUH). Here, approximately 300 patients undergo surgery for PHPT annually, of which approximately half undergo an exploratory PTX, and would be eligible for this study. Thus, there is a steady high flow of eligible patients, and the department as well as the treating surgeons are highly qualified to undertake this study. Autofluorescence imaging with the EleVision IR system is available at the department, and is used ad hoc for thyroid and parathyroid surgery.

Patient flow Patients referred for treatment of PHPT is seen at the parathyroid clinic at AUH in collaboration between a surgeon and an endocrinologist, and will be considered for inclusion in the trial. The investigators aim to include 100 patients, which should be achievable in approximately two years.

Randomization Following patient consent, an electronic case file will be created in the REDCap electronic data capture tool. Randomization is performed electronically in the dedicated REDCap randomization module.