M. H. Squires1, R. Jarvis1, L. A. Shirley1, J. E. Phay1 1Ohio State University,Division Of Surgical Oncology,Columbus, OH, USA
Introduction: Intrinsic near-infrared (NIR) autofluorescence (AF) of the parathyroid gland enables intraoperative gland identification and localization, without the need for contrast agent injection. Whether real-time AF imaging is useful in patients with multiple endocrine neoplasia type 1 (MEN1) and primary hyperparathyroidism, however, is unknown.
Methods: Patients undergoing surgery for primary hyperparathyroidism by two experienced endocrine surgeons were enrolled in a prospective clinical trial. Intraoperative imaging was performed with a handheld NIR AF device and images were captured for analysis. Representative areas of greatest AF from the parathyroid, thyroid, and adjacent soft tissue were quantified by Image J software and reported as mean values with standard deviation. Rates of false negative (lack of significant parathyroid gland AF compared to background AF, defined as parathyroid AF:background AF ratio <1.10) and false positive AF (aberrant AF of non-parathyroid tissue confirmed by pathology) were analyzed.
Results: Seventy-one consecutive patients with primary hyperparathyroidism underwent parathyroidectomy from 2017-2018. These included 6 patients with MEN1 diagnosed either genetically or clinically and 65 non-MEN1 patients. No significant differences in serum preoperative parathyroid hormone level or parathyroid gland size or weight on pathology were observed between the two cohorts (all p>0.2).
The mean absolute value of in situ parathyroid AF was significantly lower for MEN1 patients than non-MEN1 patients (55.2 +/- 9.5 vs. 76.7 +/- 21.4; p=0.001), as was the ratio of parathyroid to background AF (0.99 vs. 1.64; p=0.005). Three of six MEN1 patients (50%) had falsely negative non-fluorescent parathyroid adenomas (Fig D) versus a false negative rate of 12% (8 of 65) among non-MEN1 patients. The fibroadipose and lymphatic tissue of MEN1 patients exhibited greater background AF (Fig F), leading to high false positive rates (5 of 6 patients; 83%) versus only 3 of 65 (5%) false positive AF non-parathyroid specimens among non-MEN1 patients.
Conclusion: Intraoperative identification of parathyroids using their intrinsic autofluorescence by real-time NIR imaging appears to have utility in patients with primary hyperparathyroidism. In this cohort of MEN1 patients, decreased parathyroid AF and increased background AF of non-parathyroid tissue led to high rates of false negative and false positive fluorescence, potentially limiting the utility of this intraoperative imaging adjunct in this specific subset of patients.
