Intrinsic fluorescence of the parathyroid gland reduces risk of endocrine surgery

Recently, our lab--the Biomedical Photonics Research Group at Vanderbilt University--has discovered that the parathyroid glands (four rice-size glands in the throat) emit an intrinsic fluorescence when excited with near-infrared (NIR) light. Without the application of exogenous chemicals, fluorescence spectroscopy can be used to identify the parathyroid glands during endocrine surgery.

Melanie Gault

Parathyroid detection is one of the biggest challenges in endocrine surgeries. These glands produce a hormone which narrowly regulates blood and bone calcium level. Because of their small size and variable location, inadvertent removal or damage of the parathyroid gland during surgery can have life-long effects on patient health.

Our lab has shown that NIR fluorescence spectroscopy is a unique tool to distinguish the parathyroid gland. The spectroscopy system is made up of a spectrofluorimeter, a 785 nm diode laser coupled through a 7-around-1 fiber-optic probe, and a laptop. It is portable to allow easy transfer into the clinic. When excited with 785 nm light, the fluorescence intensity of the parathyroid gland is consistently two to 11 times greater than that of the thyroid, fat, muscle, and other tissues in the neck.¹ Of the 59 patients measured at the Vanderbilt University Medical Center, the parathyroid emitted a greater fluorescent intensity 100% of the time, regardless of disease state. Each of the spectra measured were compared to the gold standard of visual inspection or histology when available.

This work will continue in several directions. First, we will study the mechanism of the fluorescent signal. There are very few biological fluorophores in the NIR region. Discovering the mechanism will allow us to expand the use of this diagnostic tool. We will also perform additional patient studies to determine whether the fluorescent intensity of the parathyroid varies, depending on disease state. Ultimately, we would like to create an imaging system that provides spatial information to guide the surgeon in real time.

REFERENCE
1. C. Paras, M. Keller, L. White, J. Phay, and A. Mahadevan-Jansen, J. Biomed. Opt., 16, 6, 067012 (2011).

MELANIE GAULT is a PhD candidate in the Biomedical Photonics Lab at Vanderbilt University (Nashville, TN). Her research under Anita Mahadevan-Jansen is related to optical guidance during surgery, specifically using fluorescence spectroscopy.