Research on Indocyanine Green Angiography for Predicting Postoperative Hypoparathyroidism

Hao Jin; Qichao Dong; Zhuocheng He; Jinrui Fan; Kun Liao; Min Cui

Disclosures

Clin Endocrinol. 2019;90(3):487-493. 

In This Article

Abstract and Introduction

Summary

Background It may be critical to locate the parathyroid for surgeons during thyroidectomy or parathyroidectomy due to the significant function of the parathyroid in calcium balance. According to recent reports, the intrinsic fluorescence of the parathyroid has been found. There is some evidence supporting that new equipment can detect fluorescence via imaging technology. In this study, a newly invented intraoperative fluorescence imaging system and indocyanine green dye were applied to detect the parathyroid glands and evaluate the vascularization of the parathyroid. The report is as follows.

Methods From 1 May to 8 August 2018, 26 patients underwent total thyroidectomy in Zhuhai People's Hospital and were recruited into our research. All identified parathyroid glands were scored visually from grade 0 to grade 2 according to the vascularity of the parathyroid before ICG angiography was performed. After ICG angiography, parathyroid glands were scored from score 0 to score 2 according to the FI.

Results Visual scores were significantly higher than ICG angiography scores. In the 22 patients with at least one parathyroid gland with an ICG score of 2, postoperative PTH levels were in the normal range. In the four patients with no parathyroid gland with an ICG score of 2, two of them developed transient hypoparathyroidism, with recovery on POD 7 for the first patient and after 3 months for the second one.

Conclusion This study has identified that the fluorescence imaging system applied with indocyanine green is a safe, easy and effective method to protect the parathyroid and predict postoperative hypoparathyroidism. Registration number: ChiCTR1800016864.

Introduction

One of the most important events in 1956 was that indocyanine green (ICG) was first approved by the Food and Drug Administration for human use to study the hepatic and cardiac system.[1] In the 1980s, some Japanese researchers applied the ICG angiography to the ophthalmic field.[2] At the same time, a considerable amount of literature has been published on ICG in the USA.[3] These studies highlighted the potential application of ICG angiography in clinical treatment of patients with occult choroidal neovascularization. Early examples of research into ICG include Reichel et al in 1994,[4] concluding that ICG dye has an absorption peak of 805 mm, similar to the emission peak of the near-infrared (NIR) light (810 mm). And ICG would emit fluorescence when it was excited by NIR fluorescence with a wavelength of 800 nm.[5] In modern times, ICG angiography is one of the most widely used methods in surgical procedures and have been extensively applied in angiography to identify sentinel lymph nodes in cervical cancers.[6] Moreover, it was used to determine the resection region of hepatic carcinomas.[7]

After total thyroidectomy, postoperative hypocalcaemia is a common complication which is sometimes difficult to avoid. Main reason causing postoperative hypocalcaemia is intraoperative damage of parathyroid glands. Hypocalcaemia presenting for over 6 months after thyroid surgeries was defined as permanent hypocalcaemia. It has been reported that about 1%-3%[8] patients who have underwent total thyroidectomy experienced permanent hypocalcaemia. Long-term hypoparathyroidism may cause various dysfunctions in nervous, ocular, vascular and urologic systems.[9] Serious hypoparathyroidism may even threaten the lives of patients. To avoid postoperative hypoparathyroidism, intraoperative parathyroid autotransplantation may be helpful. In order to protect or autotransplant parathyroid, the accurate localization of parathyroid is essential. As the rapid development of science and technology, a series of new techniques emerged to localized parathyroid intraoperation. In these techniques, intraoperative indocyanine green (ICG) angiography stands out which provides a method for accurate and valid verification of perfusion and function of parathyroid in just a few minutes during the procedure of surgery.[10] Evidences suggest that ICG angiography is easy and safe in parathyroid detection and protection.[11]

While a variety of literatures of the term ICG angiography have been suggested, this paper will use the technique first suggested by Desmettre et al[12] who used it as a good way to identify parathyroid. The main text of this paper is divided into four parts. The first part describes the methods applied. The second part deals with the result of study. The third part discusses the experience we obtained from this study. The fourth section presents the findings of the research, focusing on the key theme that ICG angiography is easy, safe and effective in detecting the parathyroid.

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