Background: Intrinsic near-infrared (NIR) autofluorescence of the parathyroid gland may improve intraoperative gland identification without the need for contrast agent injection. Compared with patients undergoing surgery for thyroid disease, identification of pathologic parathyroid tissue in patients with hyperparathyroidism is essential. This study analyzed the utility of a novel real-time autofluorescence imaging system in patients with primary hyperparathyroidism enrolled in a prospective feasibility clinical trial.
Methods: Data on patients undergoing surgery for primary hyperparathyroidism by two experienced endocrine surgeons were prospectively collected. Intraoperative imaging was performed with a handheld NIR device, and images were captured for analysis. The collected data included the surgeon's confidence in parathyroid identification, both with ambient light and use of NIR imaging, as well as how the imaging affected the surgical procedure. Images were quantified by Image J software, with autofluorescence reported as mean values ± SD.
Results: From 2017 to 2018, 59 consecutive patients with a diagnosis of primary hyperparathyroidism underwent resection of 69 parathyroid glands. Use of NIR imaging increased the intraoperative confidence of parathyroid identification (on a scale of 0-5) from an average of 4.1 to an average of 4.4 (+0.3, p = 0.003), all of which were confirmed pathologically. The addition of autofluorescence helped to identify the parathyroid gland in 12 patients (20%), and to rule out other soft tissue as not parathyroid in an additional 9 patients (15%). The mean autofluorescence for the parathyroid in situ (75.9 ± 21.3) was significantly greater than that for the thyroid (61.1 ± 17.4) or soft tissue (53.3 ± 19.2) (p < 0.001 for both). The mean absolute difference in parathyroid versus background thyroid autofluorescence was +15.2 (range, 2.4-53.1).
Conclusion: This is the first prospective trial to examine the utility of parathyroid autofluorescence for identifying glands exclusively in patients with parathyroid disease. Intraoperative identification and localization of parathyroid glands by real-time, NIR imaging using their intrinsic autofluorescence is feasible and may provide a useful adjunct during parathyroid surgery.