Autofluorescence can aid in differentiating normal from pathologic parathyroid glands during parathyroidectomy.

Abstract

Several studies suggest that during parathyroidectomy near-infrared autofluorescence may be able to help differentiate hyperfunctional from normal parathyroid glands. However, to date, no clear metric for employing autofluorescence in this manner in real-time during surgery has been described. This study investigated whether a specific measure of autofluorescence heterogeneity can aid discrimination of pathologic from normal parathyroid glands. In patients undergoing curative parathyroidectomy for classic or normohormonal primary hyperparathyroidism, a near-infrared autofluorescence device interrogated all identified parathyroid glands. Minimum and maximum autofluorescence values were obtained for each gland to calculate 2 measures of heterogeneity: variability (maximum minus minimum) and autofluorescence index (maximum/minimum ratio). Receiving operating characteristic analysis was performed to try to identify an autofluorescence index threshold to differentiate normal from pathologic glands. The study included 72 patients. Cure was achieved by treating 57 single adenomas, 5 double adenomas, and 10 cases of 4-gland hyperplasia. Pathologic glands demonstrated significantly higher autofluorescence variability and autofluorescence index. In cases of single adenomas, a gland with autofluorescence index ≥2.4 was statistically more likely to be pathologic (area under the curve = 0.90). In 4-gland hyperplasia, glands with autofluorescence index ≥2.5 were more likely to be pathologic (area under the curve = 0.86). Autofluorescence index and gland weight were not correlated. Autofluorescence index provides a quantitative, intraoperative measure of parathyroid gland heterogeneity that can help differentiate hyperfunctional from normal parathyroid glands in real time. An autofluorescence index ≥2.5 strongly suggests that a parathyroid gland is adenomatous or hyperplastic. Surgeons may use this information in any case in which distinguishing between normal and hyperfunctional glands is challenging.