A novel optical approach to the intraoperative detection of parathyroid glands

Abstract

A major challenge in endocrine surgery is the intraoperative identification of parathyroid during both thyroid and parathyroid surgery. Current localization techniques are mostly preoperative and are imprecise. Optical spectroscopy is fast and sensitive and has been used in many in vivo applications. Here, near-infrared (NIR) fluorescence is used to identify parathyroid glands during thyroid and parathyroidectomies. Fluorescence measurements were obtained from patients undergoing endocrine surgery at Vanderbilt University Medical Center. The intensity of the parathyroid signal was observed to be 2-35 times greater than the fluorescence of the surrounding tissue including the thyroid gland. The classification accuracy of the method was found to be 100%. The molecular basis for this near infrared fluorescence is hypothesized to be due to calcium sensing receptors, which are abundantly present in the parathyroid. This hypothesis was preliminarily validated by the increased fluorescence observed in other tissues known to contain these receptors such as the kidney and colon as well as in diseased tissues where these receptors are known to be compromised. Finally, an imaging based system was developed and tested in vitro such the near infrared fluorescence of the parathyroid could be visualized with spatial context for clinical applicability of the technique.