- Background:
- Parathyroid gland identification during thyroidectomy or parathyroidectomy is critical to avoid inadvertent removal or devascularization:
- Which may lead to hypocalcemia
- Parathyroid gland identification during thyroidectomy or parathyroidectomy is critical to avoid inadvertent removal or devascularization:
- In 2011, Paras et al:
- First described the use of near-infrared (NIR) autofluorescence for parathyroid detection
- Parathyroid glands naturally emit autofluorescence:
- When excited by NIR light (785 to 820 nm):
- Which distinguishes them from surrounding tissues
- When excited by NIR light (785 to 820 nm):
- Mechanism:
- Parathyroid tissue emits intrinsic autofluorescence in the NIR spectrum:
- Peaking at around 820 to 830 nm
- The specific fluorophore responsible is still under investigation:
- But mitochondrial content and calcium-sensing receptors have been implicated
- Parathyroid tissue emits intrinsic autofluorescence in the NIR spectrum:
- Key Milestones in the Literature:
- 2011:
- First Description:
- Paras et al., J Biomed Optics: Described intrinsic autofluorescence of parathyroid glands using NIR light in animal models and humans
- Sensitivity and specificity for parathyroid detection were promising:
- Initially ~ 80% to 90%
- First Description:
- 2015 to 2018:
- Early Clinical Studies:
- McWade et al., Surgery (2016):
- Showed high sensitivity (97%) and specificity (95%) in parathyroid identification using NIR autofluorescence
- Autofluorescence was effective without contrast agents
- Faster identification of parathyroids during thyroidectomy
- McWade et al., Surgery (2016):
- Early Clinical Studies:
- 2018 to 2021:
- Commercial Devices & Validation
Fluobeam®, PTeye®, and EleVision IR became available - Systematic reviews and meta-analyses (e.g., Demarchi et al., 2019, Ann Surg Oncol) confirmed:
- Higher parathyroid identification rates
- Reduced inadvertent parathyroidectomy
- Improved preservation of gland vascularity
- Commercial Devices & Validation
- 2021 to 2024:
- Comparative & Outcome Studies:
- Meta-analyses (e.g., Wang et al., Langenbecks Arch Surg, 2022):
- NIR autofluorescence vs. white light: reduced transient hypocalcemia (RR ~ 0.42)
- Time to identify parathyroid was significantly shorter (mean ~ 4 min faster)
- Zhao et al., JAMA Otolaryngol Head Neck Surg (2023):
- Showed that NIR imaging decreased inadvertent excision and increased confidence in preserving parathyroids
- Combination with Indocyanine Green (ICG) angiography has been studied to assess gland viability after identification
- Meta-analyses (e.g., Wang et al., Langenbecks Arch Surg, 2022):
- Comparative & Outcome Studies:
- 2011:
- Clinical Applications:
- Parathyroid preservation in thyroidectomy
- Localization in reoperative neck surgery
- Autotransplantation planning
- Training tool for junior surgeons
- Limitations:
- Autofluorescence intensity can vary between patients and may be affected by lighting, fat tissue, or gland pathology
- Does not assess vascularization; ICG angiography is needed for viability
- Cost and device availability may be limiting factors in community hospitals
- Conclusion:
- Autofluorescence has emerged as a reliable, non-invasive, and real-time tool for parathyroid gland identification
- The technique has consistently shown benefits in reducing complications such as hypocalcemia, minimizing gland devascularization, and enhancing surgical efficiency
- Combining NIR autofluorescence with ICG fluorescence may offer a comprehensive approach to both identifying and preserving functional parathyroid glands
- Key References:
- Paras C et al. J Biomed Opt. 2011;16(6):067004.
- McWade MA et al. Surgery. 2016;159(3):865-871.
- Demarchi MS et al. Ann Surg Oncol. 2019;26(1):165-172.
- Wang X et al. Langenbecks Arch Surg. 2022;407(2):655–664.
- Zhao H et al. JAMA Otolaryngol Head Neck Surg. 2023;149(4):359–367.
Rodrigo Arrangoiz MS, MD, FACS, FSSO 