Intraoperative detection of parathyroid glands by autofluorescence identification using image-based system: report of 15 cases

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[degrees] 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 discrimin