Autofluorescence imaging of parathyroid glands: An assessment of potential indications

The aim of this study was to determine both the accuracy of near infrared fluorescence imaging to detect parathyroid glands and the potential indications of near infrared fluorescence imaging in thyroid and parathyroid surgery by correlating the autofluorescence signature with the pathologic specimen.

This was an institutional review board-approved, prospective study of patients undergoing thyroidectomy and parathyroidectomy with near infrared fluorescence imaging. Each specimen sent to pathology was inspected with near infrared fluorescence imaging and predicted to be either parathyroid or non-parathyroid tissue by its autofluorescence signature and then correlated with the pathologic findings.

Autofluorescence was demonstrated to be present in 98% of the parathyroid glands, with 23% identified correctly with infrared based on the autofluorescence signature before visual identification by the surgeon. There were 550 specimens that were imaged with autofluorescence and then sent to pathology. For these samples, sensitivity, specificity, and positive and negative predictive values to predict parathyroid tissue were 98.5%, 97.2%, 95.1%, and 99.1%. In 5% of the total thyroidectomy specimens, incidentally resected parathyroid glands were identified with autofluorescence, leading to their subsequent reimplantation. In patients with parathyroid disease and negative preoperative localization, 21% of abnormal glands were recognized with autofluorescence before visual identification by the surgeon.

Although the ability of infrared autofluorescence to confirm the presence of parathyroid tissue within surgical specimens was high, its power to find parathyroid glands in situ before visual recognition by surgeons was low. These advantages and limitations should be kept in mind when incorporating this technology into an endocrine surgical practice. Once a parathyroid seems to have been identified by the surgeon or tissue that looks like a parathyroid gland is identified, the autofluorescence signature is a very accurate assurance of parathyroid tissue.