Use of Indocyanine Green Fluorescence During Total Thyroidectomy to Identify Parathyroid Glands and Prevent Hypoparathyroidism.

Introduction: Total thyroidectomy is associated with a high rate of transient or permanent hypoparathyroidism. During surgery, indocyanine green (ICG) fluorescein angiography can be used to detect and preserve well-vascularized parathyroid glands. This technique has been introduced as an intraoperative support to prevent postoperative hypoparathyroidism.

Material and methods: One-hundred consecutive patients who had undergone total thyroidectomy were included in this study. Autofluoroscopy was used on the first dominant side of thyroidectomy and to identify the contralateral parathyroid glands. An intravenous bolus of 5 mg ICG (VERDYE, Diagnostic Green GmbH, Aschheim-Dornacht, Germany) was administered once. ICG fluorescein angiography was used as a "bridge" at the end of the first dominant hemithyroidectomy and after exposure of the parathyroid glands on the second side. This allowed us to (i) determine the vascularization of the first two parathyroid glands and (ii) define the blood vessels and thus the line of dissection of the parathyroid glands of the second resection side. Finally, autofluoroscopy was then applied outside the surgical area on the surgical specimen to assess forgotten parathyroid glands, which should therefore be re-implanted. Autofluoroscopy and ICG fluorescein angiography were evaluated in real time using the same technology, i.e., FLUOBEAM® LX (EUROPE - Fluoptics Grenoble, France; USA - Fluoptics Imaging Inc., Cambridge, MA, USA). The study was approved by the local ethics committee.

Results: Autofluorescence and ICG fluorescein angiography were performed without any problems in all cases. A total of 370 parathyroid glands were detected in this series. ICG changed the surgical strategy for the first-side parathyroid glands in 5% of cases, i.e,. they were not well-vascularized and were re-implanted. The rate of transient hypoparathyroidism was 19%. The percentage of parathyroids in the surgical specimen was 3.5% and all were re-implanted during the same surgery. There was no case of postoperative definitive hypoparathyroidism when at least one parathyroid gland with a high fluorescence intensity was preserved on the first side of resection.

Conclusion: Use of ICG fluorescein angiography may contribute to predicting and thus preventing postoperative definitive hypoparathyroidism after total thyroidectomy. The results of this case series confirm recent studies. Caution is advised when weakly perfused parathyroid glands are discovered.