Comparison of Autofluorescence With Near‐Infrared Fluorescence Imaging Between Primary and Secondary Hyperparathyroidism

A major challenge in endocrine surgery is the intraoperative detection of parathyroid glands during both thyroidectomies and parathyroidectomies. Current localization techniques such as ultrasound and sestamibi scan are mostly preoperative and rely on an abnormal parathyroid for its detection. In this paper, we present near-infrared (NIR) autofluorescence as a nonintrusive, real-time, automated in vivo method for the detection of the parathyroid gland. A pilot in vivo study was conducted to assess the ability of NIR fluorescence to identify parathyroid glands during thyroid and parathyroidectomies. Fluorescence measurements at 785 nm excitation were obtained intra-operatively from the different tissues exposed in the neck region in 21 patients undergoing endocrine surgery. The fluorescence intensity of the parathyroid gland was found to be consistently greater than that of the thyroid and all other tissues in the neck of all patients. In particular, parathyroid fluorescence was two to eleven times higher than that of the thyroid tissues with peak fluorescence occurring at 820 to 830 nm. These results indicate that NIR fluorescence has the potential to be an excellent optical tool to locate parathyroid tissue during surgery.

Background Inability to accurately identify parathyroid glands during cervical endocrine surgery hinders patients from achieving post-operative normocalcemia. An intrinsic near-infrared fluorescence method was developed for real-time parathyroid identification with high accuracy. This study assesses the clinical utility of this approach. Methods Autofluorescence measurements were obtained from 137 patients (264 parathyroid glands) undergoing parathyroidectomy and/or thyroidectomy. Measurements were correlated to disease state, calcium levels, parathyroid hormone (PTH), vitamin D levels, age, sex, ethnicity and body-mass index (BMI). Statistical analysis identified which factors significantly affect parathyroid detection. Results High parathyroid fluorescence was consistently detected and showed wide variability across patients. Near-infrared fluorescence was used to correctly identify 256/264 (97%) of glands. The technique showed high accuracy over a wide variety of disease states, though patients with secondary hyperparathyroidism demonstrated confounding results. Analysis revealed BMI (P<0.01), disease state (P<0.01), vitamin D (P<0.05), and calcium levels (P<0.05) account significantly for variability in signal intensity. Age, gender, PTH, and ethnicity had no effect. Conclusions This intrinsic fluorescence-based intraoperative technique can accurately detect nearly all parathyroid glands in real-time. Its discrimination capacity is largely unlimited by patient variables, but several factors affect signal intensity. These results demonstrate potential clinical utility of optical guidance for parathyroid detection.