J. C. DeLong1, E. P. Ward1, T. M. Lwin1, K. T. Brumund1, K. J. Kelly1, S. Horgan1, M. Bouvet1 1University Of California – San Diego,Surgery,San Diego, CA, USA
Introduction: Surgical resection is the only definitive treatment for primary hyperparathyroidism. Effective treatment requires successful intraoperative localization of the aberrant gland. Classic preoperative imaging includes ultrasound, nuclear scintigraphy, and in some cases axial imaging, however, these modalities have limited utility in the operating room. Indocyanine green (ICG) is a nontoxic organic dye with a high safety profile that can be detected with near infrared fluorescence imaging systems when administered intravenously. ICG is currently used in other surgical procedures as fluorescence intensity is correlated with relative blood supply. In the present report, we evaluated the utility of using ICG for intraoperative localization of parathyroid glands.
Methods: ICG fluorescence angiography was performed during 30 open parathyroidectomies for primary hyperparathyroidism over a 12 month period. 7.5mg of ICG was administered intravenously to guide surgical navigation and confirmation using a commercially available fluorescence imaging system. Video files were evaluated and graded by three independent surgeons for strength of enhancement using an adapted numeric scoring system (Fig. 1).
Results: 70% of patients were female. Patient age ranged from 40 to 87 years old (average 64). 26 (87%) patients had a single adenoma, 1 (3%) patient had a double adenoma, and 3 (10%) had hyperplasia. Of the 30 patients, 22 (73.3%) of the parathyroid glands were rated to have shown strong enhancement, 5 (16.6%) demonstrated mild to moderate enhancement. and 3 (10%) exhibited little or no enhancement. Of the 27 patients who had a preoperative sestamibi scan, parathyroid adenoma was identified in 14 while 13 failed to localize. Of the 13 patients who failed to localize, all 13 patients (100%) had an adenoma that fluoresced on ICG imaging—10 patients (76.9%) had strong fluorescence and 3 patients (23.1%) had moderate fluorescence. There were no adverse events.
Conclusion: ICG fluorescence angiography can effectively be used for intraoperative localization and confirmation of parathyroid glands for patients with primary hyperparathyroidism. ICG proved reliable even in cases where the glands were not identified on preoperative sestamibi scanning. The technique can be used to quickly distinguish parathyroid glands from lymph nodes, thymus, and other benign fatty tissue that may grossly resemble a parathyroid due to variation in blood supply/gland hypervascularity. The technique does not replace intraoperative parathyroid hormone (PTH) testing because ICG angiography cannot distinguish an adenoma from a normal gland presently. ICG angiography has the potential to assist surgeons in identifying parathyroid glands rapidly with minimal risk.
