Heterogeneous and low-intensity parathyroid autofluorescence: Patterns suggesting hyperfunction at parathyroid...

Although parathyroid glands have been found to exhibit autofluorescence with near-infrared fluorescence imaging, it is unknown if autofluorescence characteristics vary between hyperfunctioning and normofunctioning glands. The hypothesis was that pattern of autofluorescence exhibited by hyperfunctioning versus normofunctioning parathyroid glands would be different.

This is an Institutional Review Board-approved, prospective clinical study. Patients underwent bilateral neck exploration for primary hyperparathyroidism, during which autofluorescence from each gland was assessed with near-infrared fluorescence imaging. Pattern and intensity of autofluorescence between hyperfunctioning and normofunctioning parathyroid glands were compared.

Overall, 199 parathyroid glands were identified in 50 patients (single gland disease, n = 31; multigland disease, n = 19). Autofluorescence was detected from 96% (n = 192) of parathyroid glands, all of which exhibited a higher intensity autofluorescence than the background tissues. Parathyroid gland location was revealed by near-infrared fluorescence imaging before dissection in 26% (n = 52). A total of 77 glands that were large or firm were excised and 122 were preserved because of normal appearance. Hyperfunctioning parathyroid glands had a lower mean normalized autofluorescence intensity than normofunctioning parathyroid glands (1.8, and 2.6, respectively, P < .001). Moreover, hyperfunctioning parathyroid glands more often exhibited a heterogeneous pattern of autofluorescence (75% and 5%, respectively, P < .001). On multivariate analysis, only parathyroid gland hyperfunction correlated with normalized autofluorescence intensity. On receiver operative characteristic curve, optimal cutoff of normalized autofluorescence intensity to differentiate hyperfunctioning from normofunctioning parathyroid glands was 2.0.

Our results indicate that hyperfunctioning and normofunctioning parathyroid glands exhibit different patterns of autofluorescence in hyperparathyroidism. Given these findings, autofluorescence pattern could be implemented as another adjunctive parameter for gland assessment during parathyroid exploration.