Fluorescent Techniques for the Detection and Preservation of Parathyroid Glands During Thyroidectomy

Abstract

Abstract

Introduction:

Hypoparathyroidism is a complication of thyroid surgery more frequent than is classically reported by experienced centers, and rates ~10% have been reported for definitive hypoparathyroidism in population-based registries. ¹ Parathyroid gland (PG) preservation is, therefore, a key area of interest in cervical endocrine surgery. Parathyroid tissue has been demonstrated to uniquely possess spontaneous fluorescent properties, meaning that it lengthens the wavelength of light it re-emits. ² This property has been termed “autofluorescence”. Currently, two U.S. Food and Drug Administration (FDA)-approved systems have been developed to enable PG identification by means of their intrinsic fluorescence: the “Pteye” system and the “Fluobeam” system. Various studies have shown that these systems help surgeons better identify PGs than with the naked eye and decrease the number of accidental PG resections. ³

Autofluorescence is an intrinsic property of parathyroid tissue and does not predict PG viability. However, use of a fluorescent dye such as indocyanine green (ICG) enables the assessment of PG perfusion and may predict postoperative function. ⁴ Intraoperative ICG angiography is a useful adjunct in thyroid surgery to predict parathyroid function.

Materials and Methods:

Our center has put into application combined fluorescence techniques, namely autofluorescence and intraoperative ICG angiography, since 2014. Our aim is to demonstrate the usefulness of these technologies for prevention of postoperative hypocalcemia.

Results:

Data gathered from 1058 total thyroidectomies performed at HUG since October 2014 show a steady decrease in cases of postoperative hypoparathyroidism over the years with use of near infrared fluorescence techniques. The rates of parathyroid hormone (PTH) levels below the lower limit of the normal range have decreased from 12% to <5%. Moreover, the mean PTH level on the first postoperative day has increased from 2.77 to 3.34 pmol/L (p < 0.005).

Conclusions:

Our experience shows that combined fluorescence techniques result in better outcomes regarding post-thyroidectomy hypoparathyroidism. They enhance PG identification because of their intrinsic fluorescence and enable prediction of postoperative parathyroid function with use of fluorescent dye angiography by confirming the preservation of critical blood supply. There are, however, some limitations and technical pitfalls associated with these techniques. Autofluorescence may not be assessed after fluorescent dye injection, and false positives in autofluorescence inspection may be caused by surrounding tissues. Besides, all four PGs must be evaluated with ICG angiography to accurately predict postoperative function. Finally, both techniques lack a standardized numerical scale that hinders intergroup comparison.

Frédéric Triponez received consulting fees from Stryker/Novadaq, Medtronic and Fluoptics.

Runtime of video: 15 mins 42 secs

Video submitted to the International Association of Endocrine Surgeons (IAES) 2021 virtual program.