A novel optical approach to intraoperative detection of parathyroid glands

Abstract

Background: Inadvertent removal of parathyroid glands is a challenge in endocrine operations. There is a critical need for a diagnostic tool that provides sensitive, real-time parathyroid detection during procedures. We have developed an intraoperative technique using near-infrared (NIR) fluorescence for in vivo, real-time detection of the parathyroid regardless of its pathologic state.

Methods: NIR fluorescence was measured intraoperatively from 45 patients undergoing parathyroidectomy and thyroidectomy. Spectra were measured from the parathyroid and surrounding neck tissues during the operation with the use of a portable, probe-based fluorescence system at 785-nm excitation. Accuracy was evaluated by comparison with histology or visual recognition by the surgeon.

Results: NIR fluorescence detected the parathyroid in 100% of patients. Parathyroid fluorescence was stronger (1.2-18 times) than that of the thyroid with peak fluorescence at 822 nm. Surrounding tissues showed no auto-fluorescence. Disease state did not affect the ability to discriminate parathyroid glands but may account for signal variability.

Conclusion: NIR fluorescence spectroscopy can detect intraoperatively the parathyroid regardless of tissue pathology. The signal may be caused by calcium-sensing receptors present in the parathyroid. The signal strength and consistency indicates the simplicity and effectiveness of this method. Its implementation may limit operative time, decrease costs, and improve operative success rates.

Copyright © 2013 Mosby, Inc. All rights reserved.

Figures

Fig 1

(A) NIR fluorescence spectroscopy system showing a (1) spectrometer, (2) 785-nm diode laser, (3) laptop computer, and (4) hand-held fiber optic probe. (B) Fiberoptic probe next to a quarter to show scale.

Fig 2

Typical normalized NIR spectra. Each spectrum is taken as the average of six measurements at the site of investigation. The parathyroid signal is significantly stronger than the anything else in the neck. It is 7.5 times greater than the thyroid peak intensity.

Fig 3

The ratio of peak parathyroid to thyroid fluorescence intensity ranges from 1.2 to 18 for all disease types. Patients are broken down by disease type to show variation in parathyroid autofluorescence. *Indicates patient also underwent parathyroidectomy for hyperparathyroidism.