Hypoparathyroidism is the most frequent complication in thyroid surgery. The aim of this study was to evaluate the impact of intraoperative parathyroid gland identification, using autofluorescence imaging, on the rate of post-operative (PO) hypoparathyroidism in thyroid cancer surgery. Patients undergoing total thyroidectomy with central neck dissection from 2018 to 2022 were included. A prospective cohort of 77 patients operated on using near-infrared autofluorescence (NIRAF+) with the Fluobeam® (Fluoptics, Grenoble, France) system was compared to a retrospective cohort of 94 patients (NIR-). The main outcomes were the rate of PO hypocalcemia, with three cutoffs: corrected calcium (Cac) < 2.10 mmol/L, <2.00 mmol/L and <1.875 mmol/L, and the rate of permanent hypoparathyroidism, at 12 months. The rate of PO Cac < 2.10 mmol/L was statistically lower in the NIRAF+ group, compared to the control group (36% and 60%, p = 0.003, respectively). No statistically significant difference was observed for the other two thresholds. There was a lower rate of permanent hypoparathyroidism in the NIRAF+ group (5% vs. 14% in the control group), although not statistically significant (p = 0.07). NIRAF is a surgically non-invasive adjunct, and can improve patients\' outcomes for thyroid cancer surgery by reducing post-operative temporary hypoparathyroidism. Larger prospective studies are warranted to validate our findings.

In thyroid surgery, autofluorescence allows the parathyroid glands (PTGs) to be located very early to protect them. Moreover, indocyanine green (ICG) fluorescence angiography (ICG-FA) allows for assessing the viability of the PTGs and identifying blood vessels to preserve them. The main limitation of using ICG-FA is that once ICG has been injected, it is no longer possible to observe PTG autofluorescence using existing devices. This study aimed to describe an approach that allows for visualization of the PTGs by autofluorescence, even after ICG injection.
We redesigned the FLUOBEAM® LX system to excite fluorescence at 685 nm and detect fluorescence between 700 and 900 nm. This device had short-pass filters at 775 nm that helped to split the contributions of the PTG autofluorescence and ICG fluorescence. Tests were performed on extemporaneous PTG preparations placed next to ICG droplets to assess for rejection of the ICG signal.
A low-pass filter at 775 nm detected 60% of the autofluorescence signals and 10% of the ICG signals.
These findings support the possibility of visualizing PTG autofluorescence despite multiple ICG injections and measuring the balance between ICG and autofluorescence signals.

UNASSIGNED: Parathyroid carcinoma is very rare, and intraoperative definitive diagnosis can be elusive with currently available diagnostics. Near-infrared (NIR) autofluorescence is an emerging tool that identifies parathyroid glands in real time. It is not known whether NIR autofluorescence can detect parathyroid carcinoma intraoperatively.
UNASSIGNED: Patients with preoperative suspicion for parathyroid carcinoma were identified from ongoing studies examining parathyroid autofluorescence with a NIR camera and probe. Specimens from these patients were examined intraoperatively to determine their autofluorescence patterns.
UNASSIGNED: Three patients with suspected parathyroid carcinoma were identified preoperatively. Intraoperative NIR autofluorescence imaging showed a relative lack of autofluorescence for all cases, in contrast to parathyroid adenomas and normal parathyroid glands, which typically exhibit significant autofluorescence. Final pathology confirmed parathyroid carcinoma in all cases.
UNASSIGNED: Parathyroid carcinoma can be difficult to confirm prior to final pathology review. Our 3 cases suggest that absence of NIR autofluorescence may suggest the likelihood of parathyroid carcinoma, but more studies are needed to investigate this experience.

BACKGROUND: A detection of parathyroid glands by the evaluation of their autofluorescence in the near-infrared spectrum is considered as a promising tool in addition to their visual verification. The aim of this study was to evaluate the role of near-infrared autofluorescence application by using two different image-based systems for the identification of parathyroid glands during surgery of thyroid and parathyroid benign and malignant lesions.
METHODS: Evaluation of near-infrared autofluorescence was performed in 15 patients by using two different image-based systems equipped with a near-infrared laser camera. Intravenous injection of fluorophore indocyanine green was used for the enhancement of near-infrared autofluorescence signal.
RESULTS: Normal parathyroid glands were identified and mobilized after visual inspection in 12 (80%) patients, which was confirmed by near-infrared autofluorescence evaluation. Confident recognition of parathyroid glands by near-infrared autofluorescence signal and their subsequent distinction from lymph nodes was achieved in two (13%) patients with prior surgery for papillary thyroid carcinoma. In one (7%) case, parathyroid gland was identified as fragments of tissue within the postoperative scarring area by near-infrared autofluorescence evaluation, but not by visual inspection. A less intensive near-infrared autofluorescence signal was detected in the parathyroid gland owing to unintentional excision in one (7%) case. Better signal intensity from parathyroid glands was noticed after changes of the near-infrared camera in Fluobeam 800 image-based system in position to an angle of approximately 45-65° in relation to area of interest in all cases as compared with holding straight on the parathyroid gland. Fluobeam LX demonstrated a good near-infrared autofluorescence signal without any specific changes in the camera angle. Thyroid carcinoma demonstrated low-intensity signal in the case of invasion to thyroid capsule. No fluorescent signal was identified from metastatic, or from normal, lymph nodes.
CONCLUSIONS: The application of near-infrared autofluorescence imaging is considered as a useful, but additional, tool for the visual assessment of parathyroid gland in the case of primary neck exploration. The utility of near-infrared autofluorescence imaging for parathyroid detection is increased in the case of repeated surgical intervention owing to increased risk of unintentional parathyroid removal as well as for discrimination of parathyroids from the lymph nodes in cases of thyroid malignancy.