Intraoperative near-infrared fluorescence imaging of parathyroid adenomas with use of low-dose methylene blue

Background. Intraoperative identification of parathyroid adenomas can be challenging. We hypothesized that low-doses methylene blue (MB) and near-infrared fluorescence (NIRF) imaging could be used to identify parathyroid adenomas intraoperatively. Methods. MB was injected intravenously after exploration at a dose of 0.5 mg/kg into 12 patients who underwent parathyroid surgery. NIRF imaging was performed using the Mini-FLARE imaging system. Results. In 10 of 12 patients, histology confirmed a parathyroid adenoma. In 9 of these patients, NIRF could clearly identify the parathyroid adenoma during surgery. Seven of these 9 patients had a positive preoperative 99mTc-sestamibi single photon emission CT (SPECT) scan. Importantly, in 2 patients, parathyroid adenomas could be identified only using NIRF. Conclusion. This is the first study to show that low-dose MB can be used as NIRF tracer for identification of parathyroid adenomas, and suggests a correlation with preoperative 99mTc-sestamibi SPECT scanning. © 2013 Wiley Periodicals, Inc