Impact of 99mTc-Sesta-MIBI-Positive Thyroid Nodules on PHPT Preoperative Localization

Overview

This study evaluated the influence of 99mTc-sestamibi (MIBI)-positive thyroid nodules on the accuracy of preoperative localization techniques in patients with primary hyperparathyroidism (PHPT). It found that benign and malignant MIBI-positive thyroid nodules can affect the sensitivity of MIBI scintigraphy in localizing hyperfunctioning parathyroids, with implications for surgical planning.

Background

Primary hyperparathyroidism (PHPT) is a common endocrine disorder primarily treated by parathyroidectomy. Preoperative localization using neck ultrasound (US) and 99mTc-sestamibi scintigraphy (MIBI) is critical for surgical success. However, concomitant thyroid nodules, which are common in PHPT patients, can cause false positive or negative MIBI results, complicating localization. The impact of benign and malignant MIBI-positive thyroid nodules on localization accuracy remains controversial, necessitating further investigation in a large patient cohort.

Data Highlights

Key Findings

• 99mTc-sestamibi scintigraphy (MIBI) has high sensitivity (90%) and accuracy (97%) for localizing hyperfunctioning parathyroids in PHPT.
• Thyroid nodules, both benign and malignant, can accumulate MIBI tracer, leading to false positive results and reduced sensitivity in parathyroid localization.
• In endemic goitre regions, 15–84% of PHPT patients have concomitant thyroid disease, with 2–24% diagnosed with thyroid carcinoma.
• Preoperative ultrasound (US) has an overall accuracy of 88% and is essential for detecting thyroid nodules that may require biopsy or concurrent surgery.
• False negative MIBI results are more common in multi-glandular disease, hyperplasia, or small adenomas, and can be influenced by thyroid uptake variations.
• In this large cohort of 497 PHPT patients, 64% had at least one thyroid nodule detected by US, highlighting the clinical relevance of thyroid pathology in preoperative planning.

Clinical Implications

Clinicians should be aware that MIBI-positive thyroid nodules can interfere with accurate localization of hyperfunctioning parathyroids, potentially affecting surgical strategy. Combining MIBI scintigraphy with high-resolution ultrasound and considering thyroid pathology is crucial for optimal preoperative assessment. Careful evaluation of thyroid nodules, including malignancy risk assessment, may guide decisions regarding concurrent thyroid surgery during parathyroidectomy.

Conclusion

Benign and malignant MIBI-positive thyroid nodules significantly impact the sensitivity of preoperative localization techniques in PHPT patients. Integrating multimodal imaging and thorough thyroid evaluation enhances surgical planning and outcomes.

References

1. Primary hyperparathyroidism epidemiology and treatment overview
2. Impact of thyroid disease on PHPT patients in endemic goitre regions
3. Accuracy of ultrasound and MIBI scintigraphy in PHPT localization
4. Factors influencing false positive and negative MIBI results
5. Role of MIBI scintigraphy in thyroid nodule malignancy risk assessment
6. Vienna Criteria for parathyroidectomy outcome assessment