64 Parathyroid Adenoma

Clinical Presentation

A 43-year-old woman presents with a recent diagnosis of renal stones. The patient has elevated calcium and parathyroid hormone levels.

Fig. 64.1 Top row: 20-minute images; bottom row: 2-hour images.

Technique

• Approximately 20 mCi of ^99mTc-sestamibi injected intravenously

• High-resolution collimator

• Anterior view of the neck and chest done at 20 minutes and 2 hours after injection

• Pinhole view of the thyroid bed done at 20 minutes and 2 hours after injection

Image Interpretation

Initial images at 20 minutes (Fig. 64.1, top row) show relatively diffuse uptake in the thyroid and a focus of increased tracer uptake in the right lower pole. Two-hour–delayed images (Fig. 64.1, bottom row) show washout of tracer from the thyroid and residual tracer concentration in the region of the right lower pole.

Differential Diagnosis

• Parathyroid adenoma

• Parathyroid hyperplasia

• Thyroid adenoma (less common)

• Thyroid carcinoma

• Parathyroid carcinoma

Diagnosis and Clinical Follow-Up

Ultrasound demonstrated a possible nodule on the left side, but no abnormality on the right side. Surgical exploration revealed a 3 × 2-cm right inferior parathyroid adenoma. Parathyroid hormone levels returned to normal after resection of the adenoma.