Clinical Scorecard: Evaluating the Impact of 99mTc-Sesta-MIBI-Positive Thyroid Nodules on Preoperative Localization Techniques in Patients with Primary Hyperparathyroidism

At a Glance

Key Highlights

• PHPT is the third most common endocrine disease with parathyroidectomy as the only curative treatment.
• Preoperative localization uses neck ultrasound (US) and 99mTc-sestamibi scintigraphy (MIBI) with high accuracy but can be affected by thyroid nodules.
• MIBI-positive thyroid nodules may cause false positive or false negative results, impacting surgical planning and risk assessment.

Guideline-Based Recommendations

Diagnosis

• Use neck ultrasound to identify hyperfunctioning parathyroids and evaluate thyroid nodules preoperatively.
• Perform double-phase 99mTc-sestamibi scintigraphy with SPECT for localization of hyperfunctioning parathyroid glands.
• Apply Vienna Criteria to interpret MIBI and US results for surgical decision-making.

Management

• Perform minimally invasive parathyroidectomy (MIP) guided by MIBI localization when a single gland is identified.
• Extend to unilateral or bilateral neck exploration if MIBI or intraoperative PTH monitoring is inconclusive.
• Consider concurrent thyroid surgery for suspicious thyroid nodules ≥5 mm with malignant US features.

Monitoring & Follow-up

• Use intraoperative parathyroid hormone (IOPTH) monitoring to confirm adequacy of parathyroid gland removal.
• Postoperative monitoring of calcium and PTH levels to assess surgical success.

Risks

• False positive MIBI scans due to thyroid nodules can lead to incorrect localization and surgical planning.
• False negative MIBI results may occur in multi-gland disease or small adenomas, risking incomplete excision.
• Concurrent thyroid carcinoma occurs in 2–24% of PHPT patients, necessitating careful evaluation.

Patient & Prescribing Data

497 patients with sporadic PHPT undergoing parathyroidectomy with or without thyroid surgery

Preoperative US and MIBI scans guide surgical approach; presence of MIBI-positive thyroid nodules influences localization accuracy and surgical strategy.

Clinical Best Practices

• Perform combined preoperative US and MIBI scintigraphy for accurate localization of hyperfunctioning parathyroids and assessment of thyroid nodules.
• Interpret MIBI results cautiously in presence of thyroid nodules to avoid false positives and negatives.
• Use intraoperative PTH monitoring to guide extent of surgery and confirm complete removal of hyperfunctioning tissue.
• Plan concurrent thyroid surgery based on US features suggestive of malignancy and nodule size.

References

• Primary hyperparathyroidism overview and parathyroidectomy
• Prevalence of thyroid disease in PHPT patients
• Incidence of thyroid carcinoma in PHPT
• Accuracy of ultrasound in parathyroid localization
• Accuracy and sensitivity of 99mTc-sestamibi scintigraphy
• Causes of false positive and negative MIBI scans
• MIBI use in thyroid nodule malignancy risk assessment
• Impact of thyroid nodules on MIBI sensitivity
• Vienna Criteria for interpretation of localization studies
• ESES consensus statement on surgical strategy