Limited Utility of [99mTc]-Sestamibi Scintigraphy in pHPT with Negative Ultrasound

Overview

This retrospective single-center study evaluated the diagnostic performance of [99mTc]-sestamibi scintigraphy in patients with primary hyperparathyroidism (pHPT) who had negative ultrasound results. The findings suggest that [99mTc]-sestamibi scintigraphy has limited sensitivity in this subgroup, highlighting the need for alternative or additional imaging modalities to improve preoperative localization of parathyroid adenomas.

Background

Primary hyperparathyroidism is a common endocrine disorder characterized by hyperfunctioning parathyroid glands, typically treated successfully by surgical removal. Preoperative localization of parathyroid adenomas is crucial for focused surgical approaches that reduce morbidity. Neck ultrasound and [99mTc]-sestamibi scintigraphy are standard imaging modalities, but their diagnostic accuracy varies, especially when ultrasound results are negative. Extended imaging techniques such as PET/CT with [11C]-methionine or [11C]-choline have been proposed to improve localization in challenging cases.

Data Highlights

The study retrospectively analyzed patients undergoing surgery for pHPT between 2005 and 2021, assessing the sensitivity of various imaging modalities compared to intraoperative findings. Ultrasound was performed by experienced specialists, and scintigraphy included planar and SPECT/CT techniques. The success of surgery was defined by intraoperative PTH drop criteria. The analysis focused on the ability of [99mTc]-sestamibi scintigraphy to localize adenomas when ultrasound was negative.

Key Findings

• [99mTc]-sestamibi scintigraphy demonstrated limited sensitivity in patients with negative ultrasound results for pHPT.
• Preoperative ultrasound remains a critical first-line imaging modality but may fail to detect adenomas in some patients.
• Negative preoperative imaging correlates with reduced surgical success rates and may necessitate bilateral exploration or extended imaging.
• Extended imaging modalities such as [11C]-methionine or [11C]-choline PET/CT may provide improved localization in cases where ultrasound and sestamibi scintigraphy are inconclusive.
• Focused surgical approaches based on accurate preoperative localization reduce morbidity compared to bilateral exploration.

Clinical Implications

Clinicians should be aware of the limited utility of [99mTc]-sestamibi scintigraphy in patients with negative ultrasound findings. In such cases, consideration of advanced imaging techniques is warranted to improve localization accuracy and enable minimally invasive surgery. This approach may reduce operative time and complications associated with bilateral neck exploration.

Conclusion

The study underscores the limitations of [99mTc]-sestamibi scintigraphy in localizing parathyroid adenomas when ultrasound is negative, advocating for a tailored imaging algorithm incorporating advanced modalities to optimize surgical outcomes in pHPT.

References

1. General references on pHPT diagnosis and treatment
2. Surgical success and imaging modalities in pHPT
3. Advanced imaging techniques for parathyroid localization