Development of an intraoperative tool to detect parathyroid gland autofluorescence
McWade, Melanie Ann
The inability to identify the parathyroid glands is a significant challenge during endocrine procedures. Successful parathyroid and thyroid surgeries require careful resection of diseased tissue and preservation of normal tissues, but this is not always the reality. Inaccurate localization of parathyroid glands during these procedures may permanently prevent patients from achieving normal calcium levels after surgery. Current parathyroid detection methods cannot convey real-time information and are limited to localization of only diseased glands. There is, therefore, a large unmet need in endocrine surgery for a technique to find diseased and normal parathyroid glands during surgery. Previous studies have observed an intrinsic near-infrared (NIR) fluorescence signal in the parathyroid gland that is higher than the fluorescence of surrounding neck tissues. The goal of this dissertation is to develop NIR fluorescence spectroscopy and imaging into a reliable, real-time tool for parathyroid detection regardless of disease state. The clinical utility of NIR fluorescence spectroscopy was established over a diverse patient population. Studies show 97% accuracy in NIR fluorescence detection of the parathyroid glands with minimal effects from patient factors. Parathyroid imaging was achieved to replace point measurements acquired from spectroscopy with spatial images to show gland location. A novel Overlay Tissue Imaging System (OTIS) was developed to project fluorescence information directly on the patient in the surgeon’s line of sight. This imaging approach could replace traditional display monitors and reduce errors in image perception. Finally, the mechanism of the NIR fluorescence signal in the parathyroid was investigated. The endogenous NIR fluorophore in the parathyroid gland has an emission peak at a wavelength that has been thought to be devoid of autofluorescence. Studies revealed the biochemical behavior and location of the fluorophore. Ultimately this combination of studies lowers the barrier for clinical translation of the technology. Widespread adoption of NIR fluorescence detection of the parathyroid glands will greatly improve patient care by reducing harmful surgical complications.