Smaller parathyroids have higher near-infrared autofluorescence intensity in hyperparathyroidism

Abstract

BackgroundIntraoperative parathyroid gland identification can be challenging. Parathyroid glands have an intrinsic autofluorescence when excited by wavelengths in the near-infrared region. Studies using near-infrared cameras to detect parathyroid gland near-infrared autofluorescence have suggested improved identification. The pathologic parathyroid glands in primary hyperparathyroidism have variable near-infrared autofluorescence intensity, but how this correlates with different characteristics of hyperparathyroidism is unknown. Our objective was to correlate the fluorescent intensity of excited glands with clinical variables to enhance a surgeon’s ability to identify parathyroid glands. MethodsThe data on patients undergoing surgery for primary hyperparathyroidism were collected. The images were collected intraoperatively with a handheld near-infrared device and analyzed. The data consisted of the ratio of mean parathyroid gland near-infrared autofluorescence over background (white gauze) near-infrared autofluorescence. The variables assessed for correlation with autofluorescence intensity were gland volume and weight, preoperative serum calcium and parathyroid hormone, age, body mass index, and sex. The images were quantified by Image J software (National Institutes of Health, Bethesda, MD). The lasso regression was analyzed by R version 4.1.3 to calculate adjusted P values (R Foundation for Statistical Computing, Vienna, Austria). ResultsFrom 2017 to 2021, 131 patients with primary hyperparathyroidism underwent parathyroidectomies of 151 parathyroid glands. The mean near-infrared autofluorescence intensity of parathyroid glands had a negative correlation with weight with lighter glands fluorescing more (P = .019) and a positive correlation with age with glands from older patients fluorescing more (P = .013). There were no significant correlations with preoperative serum calcium and parathyroid hormone, body mass index, and sex (P > .05). ConclusionIn patients with primary hyperparathyroidism, we found that autofluorescence intensity correlated with parathyroid gland weight and patient age. This suggested that near-infrared camera use may be particularly helpful in identifying smaller adenomas and in older patients.