Table 1:

Protocol designed for PTeye™ after surgeons’ learning curve with initial 19 patients.

Step of PTeye™ Use	Description of Protocol
Step 1: Set-up	Turn on and set up the device as instructed
Step 2: Thyroid exposure	Expose as much of the thyroid lobe and isthmus as possible. This may not be possible in cases with a substernal component and/or retropharyngeal thyroid extension. Ligation of the middle thyroid vein is recommended.
Step 3: Obtain the baseline	The goal is to assess the highest areas of autofluorescence on the thyroid so that baseline reflects its NIRAF heterogeneity. Place the sterile probe in contact with the thyroid, press the foot pedal to activate the NIR light to detect thyroid NIRAF. Repeat 5 times on the thyroid. After the fifth measurement, the device will automatically set the baseline. * If there is no thyroid the baseline can be set using neck muscle.
Step 4: Double-check the baseline	After the device baseline is set the surgeon should always scan/survey the thyroid/muscle with the probe to ensure accuracy of baseline NIRAF. To double-check the baseline- place the probe on the thyroid lobe and press the foot-pedal to scan the thyroid lobe in as many places as possible. If any areas show “high” detection ratios (ratios > 1.2) after the initial baseline, then the surgeon should aim to re-adjust the baseline to include those thyroid areas with high detection ratio. *Beware of subcapsular parathyroids when obtaining/checking baseline.
Step 5: Readjust the baseline if necessary	Turn the device off and then back on. Repeat Steps 3 and 4 above. The goal is to scan the thyroid with the probe and not detect any areas that give high detection ratios on the thyroid.
Step 6: Expose suspected PG tissue	Properly expose the tissue of interest before obtaining the NIRAF measurement. Obtain measurements at various locations on the possible PG tissue. Parathyroid adenomas tend to have heterogenous NIRAF and could have areas of low detection ratio and areas of very high ratios. Always ensure that the probe tip is clean and free from tissue/blood residue before and after interrogation.
Step 7: Interpreting the PTeye™ display	When the probe touches PG tissue, the device should typically display a detection ratio >1.2 and generate high-frequency auditory beep. The surgeon should however question low detection ratios that range from 1.2-2.0 particularly when he/she has low confidence that the tissue is a PG. Or when he/she has high confidence it is a parathyroid adenoma.
(a) During thyroidectomy	The probe can be used to confirm PGs when the surgeon has high confidence. When the surgeon has lower confidence and the PG has not been visualized clearly, the surgeon can use the probe to interrogate or map suspicious PG, fat, thyroid, thymus, lymph nodes.
(b) During parathyroidectomy	The probe can be used to confirm PGs when the surgeon has high confidence. When the surgeon has lower confidence and/or the PG has not been localized or visualized clearly, the surgeon can use the probe to interrogate or map suspicious PG, fat, thyroid, thymus, and lymph nodes.
(c) Excised specimen(s)	Any removed specimen can be interrogated/scanned with the probe to look for possible PGs. The excised thyroid should be scanned with the probe to look for incidentally excised PGs. Parathyroid adenomas tend to have heterogenous NIRAF and could have areas of low detection ratio and areas of very high ratios.