Clinical Report: Advances in Parathyroid Localization Techniques in Primary Hyperparathyroidism

Overview

This single-center study reviews the evolution of imaging modalities over the last decade for preoperative localization of parathyroid glands in primary hyperparathyroidism (pHPT). It highlights the strengths and limitations of conventional and advanced imaging techniques, including ultrasound, 99mTc-sestamibi scintigraphy, 4D-CT, MRI, and 18F-fluorocholine PET/CT, emphasizing their impact on surgical planning and outcomes.

Background

Primary hyperparathyroidism is a common endocrine disorder characterized by elevated serum calcium and parathyroid hormone levels, often caused by adenomas, hyperplasia, or rarely carcinomas. Accurate preoperative localization of hyperfunctioning parathyroid tissue is critical for successful parathyroidectomy, the only curative treatment. Conventional imaging methods such as neck ultrasound and 99mTc-sestamibi scintigraphy are widely used but have limitations in sensitivity and detection of ectopic or multiglandular disease. Emerging hybrid imaging techniques like 18F-fluorocholine PET/CT offer improved spatial resolution and faster scanning times, potentially enhancing diagnostic accuracy.

Data Highlights

The study included patients undergoing surgery for pHPT from July 2009 to April 2024, collecting demographic, biochemical, imaging, surgical, and follow-up data. Imaging modalities assessed were neck ultrasound, 99mTc-sestamibi scintigraphy, 4D-CT, MRI, and 18F-FCH PET/CT (introduced in 2018). Intraoperative PTH monitoring was performed in 98.2% of surgeries, with a ≥50% drop in PTH levels considered indicative of successful gland removal. The study excluded patients with renal hypercalciuria, familial hypocalciuria/hypercalcemia, and genetic causes of hyperparathyroidism.

Key Findings

• Neck ultrasound is accessible, rapid, and radiation-free but has limited sensitivity, especially for ectopic glands.
• 99mTc-sestamibi scintigraphy effectively localizes adenomas, including ectopic ones, but is less sensitive for small lesions and multiglandular disease and requires several hours to complete.
• 4D-CT provides rapid identification of small or ectopic parathyroid tissue but involves significant radiation exposure, limiting its use mainly to reoperative cases.
• MRI is useful for imaging parathyroids in anatomically challenging locations but is typically part of a multimodal approach rather than a standalone modality.
• 18F-fluorocholine PET/CT offers superior spatial resolution and faster scanning, improving detection of small adenomas, but its cost and availability may restrict widespread use.
• Intraoperative PTH monitoring is a valuable tool to confirm successful excision, with a ≥50% drop indicating adequate removal of hyperfunctioning tissue.

Clinical Implications

Clinicians should consider a tailored imaging approach based on patient characteristics and available resources. Combining neck ultrasound with 99mTc-sestamibi scintigraphy remains a practical first-line strategy. Advanced imaging modalities like 18F-fluorocholine PET/CT can be reserved for cases with inconclusive conventional imaging or reoperative scenarios. Intraoperative PTH monitoring is recommended to guide surgical completeness and improve outcomes.

Conclusion

Over the past decade, advancements in imaging techniques have enhanced the preoperative localization of parathyroid glands in pHPT, facilitating more precise and effective surgical interventions. Integrating conventional and novel imaging modalities alongside intraoperative PTH monitoring optimizes patient management and surgical success.

References

1. Multiple Authors/Various Years -- The Advancement of Parathyroid Localization Diagnostic Techniques Over the Last Ten Years: A Single-Center Perspective