The Parathyroid Study depicts hypertrophied parathyroid tissue, due to uptake of Tc-99m-sestamibi in the mitochondria of hyperactive cells. The main function of the parathyroid is to make, store, and secrete PTH. PTH regulates the level of calcium and phosphorus in the blood. The parathyroid and thyroid tissue takes up Tc99m-Sestamibi. The clearance rate of the tracer is faster in normal thyroid or parathyroid than in abnormal parathyroid.


  • Detect and localize parathyroid adenomas.

Study Description

A radiopharmaceutical is injected intravenously and allowed to circulate for 10 minutes. The patient is brought into the imaging room and positioned supine on the imaging table with a pillow under the mid back to hyperextend the neck. A 10-minute image is taken and the patient is allowed to leave. (If SPECT, allow 45 minutes for early exam time.) The patient will then return 3-hours post injection for a repeat image that will last 10 minutes.

Examination Time

  • Initially, 30-45 Minutes (with SPECT-45 minutes)
  • Delayed imaging at three hours: 15 minutes

Patient Preparation

  • Ensure the patient is not pregnant or breastfeeding
  • None