Indocyanine green (ICG) angiography, a real-time intraoperative imaging technique, is associated with better parathyroid identification and functional evaluation during open thyroidectomy. However, the benefits of ICG fluorescence imaging application in transoral endoscopic thyroidectomy are not well-documented. Consecutive patients who underwent transoral endoscopic thyroidectomy were retrospectively reviewed. Parathyroid glands were assessed with visual inspection followed by ICG angiography. The fluorescence intensity of all parathyroid glands was recorded. In total, 158 parathyroid glands from 60 patients (41 underwent lobectomy and 19 underwent total thyroidectomy) were eligible for evaluation. A total of 135 parathyroid glands (85.4%) were identified, including nine glands (5.7%) that were solely localized because of ICG angiography. Incidental parathyroidectomy occurred in 12 patients with predominant inferior gland (83.3%) and associated with central neck dissection (66.7%). Among patients receiving total thyroidectomy, patients who retained at least one well-perfused parathyroid gland had higher parathyroid hormone (PTH) level and were less likely to develop hypoparathyroidism on postoperative day one than those without any well-perfused ICG-enhanced parathyroid gland (p = 0.038). In addition, the duration of calcium supplementation to maintain normocalcemia was also shorter. ICG angiography is a feasible adjunct procedure for parathyroid identification and postoperative functional prediction in transoral endoscopic thyroidectomy.
Keywords: indocyanine green, fluorescence, transoral endoscopic thyroidectomy, parathyroid, thyroid
1. IntroductionIndocyanine green (ICG) angiography has gained popularity in the field of thyroid and parathyroid surgery recently [1,2]. By capturing the emitting near infrared fluorescence, it offers two kinds of benefits. The first benefit is the identification and localization of parathyroid, so that surgeons can preserve the healthy parathyroid gland, as in the case of thyroidectomy, and remove the diseased parathyroid gland, as in patient with primary hyperparathyroidism [3]. The second benefit is the assessment of the viability of the parathyroid gland, which may predict the postoperative parathyroid function and help in appropriate patient management [4].
In recent years, various kinds of endoscopic and robotic approaches for thyroidectomy and parathyroidectomy he been proposed and he shown equivalent safety with superior cosmetic outcome when compared with the open surgery [5,6,7,8]. Among these techniques, the transoral approach is one of the most popular and promising routes because it requires less flap dissection and lees no scar on the body surface [9].
Currently, few studies are ailable that he evaluated the implementation of ICG angiography in endoscopic or robotic thyroidectomy [10,11,12]. Yu et al. analyzed the patients who underwent robotic thyroidectomy via the bilateral axillo-breast approach and found that the patients who had received ICG for parathyroid localization using the Firefly technology had a significantly lower rate of incidental parathyroidectomy [10]. However, their study only evaluated the inferior glands without concurrently assessing the superior glands [10]. With respect to the endoscopic transoral approach, Turan et al. reported the first clinical study applying ICG angiography to localize the parathyroid adenoma in seven patients with hyperparathyroidism [11]. The target parathyroid glands were identified and removed. The parathyroid hormone (PTH) level fell back into normal range in all patients. Nevertheless, their study did not enroll patients with normal parathyroid function and their sample size was relatively small [11].
To assess the benefits of ICG angiography in transoral endoscopic thyroidectomy more thoroughly, we aimed to evaluate the fluorescence intensity of both superior and inferior parathyroid glands. The associated clinical data, including PTH, serum calcium level, and duration of calcium supplementation, were also recorded. Collectively, these objectives were aimed to help us to be able to evaluate the contribution of ICG angiography in parathyroid localization and postoperative functional prediction more clearly.
2. Materials and Methods 2.1. PatientsBetween January 2020 and March 2021, the medical records of all patients who underwent transoral endoscopic thyroidectomy via vestibular approach at Kaohsiung Veterans General Hospital were reviewed. The same surgeon (T.J.L.) performed all the operations. At our institute, ICG angiography was routinely implemented during endoscopic thyroidectomy, unless there was an unailability of the laparoscopic infrared imaging system. The surgical indications included benign thyroid nodules with diameter