What is the best method of parathyroid gland localization intraoperatively when the surgeon cannot detect it normally?

Best Method for Intraoperative Parathyroid Gland Localization

Indocyanine green fluorescence or parathyroid autofluorescence is the best method for intraoperative parathyroid gland localization when the surgeon cannot detect it normally.

Near-Infrared Fluorescence Techniques: The Superior Choice

Near-infrared fluorescence techniques have emerged as the most effective methods for intraoperative parathyroid localization when traditional visual identification fails. These techniques can be divided into two main approaches:

1. Parathyroid Autofluorescence

   • Utilizes the natural fluorescence properties of parathyroid tissue
   • Requires no contrast agent administration
   • Shows 100% detection rate of parathyroid glands in clinical studies 1
   • Peak fluorescence occurs at 820-830 nm wavelength
   • Parathyroid fluorescence is 2-11 times higher than thyroid tissue 2

2. Indocyanine Green (ICG) Fluorescence

   • Requires intravenous administration of ICG (typically 2.5 mg)
   • Demonstrates higher sensitivity for parathyroid detection compared to preoperative ultrasound and sestamibi scanning 3
   • Particularly valuable in reoperative cases and for ectopic parathyroid glands 4
   • Achieves a 95.16% resection rate of pathologic parathyroid glands 3

Advantages Over Alternative Methods

Compared to Intraoperative USG (Option A)

• Intraoperative ultrasound is limited by operator dependency and difficulty in distinguishing parathyroid tissue from surrounding structures
• Cannot provide real-time feedback during dissection like fluorescence techniques

Compared to CT Scanning (Option B)

• CT scanning is primarily a preoperative localization technique
• Not practical for real-time intraoperative guidance
• Involves radiation exposure
• Cannot be easily repeated during surgery

Compared to Sestamibi Scan (Option C)

• Sestamibi scanning is primarily a preoperative localization method
• Has variable sensitivity (ranging from 62-88%) 5
• Less effective for multiglandular disease (sensitivity drops to 43-67%) 5
• Cannot provide real-time feedback during surgery

Clinical Implementation

The implementation of near-infrared fluorescence techniques follows a straightforward approach:

1. For Autofluorescence:

   • Use a probe-based or camera-based fluorescence system with 785 nm excitation
   • No contrast agent required
   • Real-time visualization of parathyroid tissue regardless of pathologic state

2. For ICG Fluorescence:

   • Administer 2.5 mg ICG solution intravenously
   • Use NIR camera system to visualize fluorescence
   • Particularly useful in challenging cases (reoperations, ectopic glands)

Pitfalls and Caveats

• Signal variability: Disease state may affect signal strength but not discrimination ability 1
• Timing: For ICG fluorescence, proper timing between injection and imaging is crucial
• Equipment requirements: Specialized imaging systems are needed for both techniques
• Learning curve: Surgeons need training to interpret fluorescence patterns correctly
• False positives: Some lymph nodes or thyroid nodules may occasionally show fluorescence

Conclusion

Near-infrared fluorescence techniques (either autofluorescence or ICG-enhanced) represent the most effective intraoperative methods for localizing parathyroid glands when conventional visual identification fails. These techniques provide real-time, high-sensitivity detection that significantly improves surgical outcomes and reduces the risk of inadvertent parathyroidectomy 6.