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Parathyroid scans

Overview

A parathyroid sestamibi scan is a nuclear imaging test used to detect overactive parathyroid glands, which regulate the body’s calcium levels and are located behind the thyroid gland. This scan is especially useful for detecting hyperparathyroidism, a condition where one or more of these glands becomes overactive and produces too much hormone, causing elevated calcium levels.

Your doctor may recommend this scan for:

  • Locating parathyroid adenomas (benign tumours)
  • Diagnosing hyperparathyroidism
  • Evaluating parathyroid gland function before or after surgery

A small amount of a radioactive tracer called sestamibi is injected into a vein. The tracer is absorbed by overactive parathyroid glands. A gamma camera then captures images revealing which parathyroid gland(s) are overactive.

  • Fasting: not required
  • Medications: Inform your doctor about all medications you are taking, especially those that affect calcium levels. Some medications may need to be stopped temporarily before the scan.
  • Pregnancy and breastfeeding: Notify your doctor if you are pregnant, suspect you may be pregnant or are breastfeeding. This test is usually not recommended during pregnancy or while breastfeeding.

The parathyroid sestamibi scan typically involves three stages:

  1. You will receive an injection of the radioactive tracer (Tc99m) into a vein in your arm.
  2. After about 20 minutes, you will be asked to lie down on a table, and a gamma camera will capture images of your neck to visualise your thyroid. This takes about 15 minutes.
  3. Thereafter, you will receive a second injection of another radioactive tracer (sestamibi) into a vein in your arm.
  4. First Scan (Early Images): About 15 to 20 minutes after the injection, you will lie down on a table, and a gamma camera will take images of your neck and chest. This takes about 15 minutes.
  5. Second Scan (Delayed Images): After 1-3 hours, a second set of images will be taken to show how the parathyroid glands have absorbed the tracer. This scan also takes around 15 minutes.
  6. SPECT: At some point during the 1st and 2nd scans, a 3D rotational scan may also be performed to capture images of your neck and chest. This scan also takes around 30 minutes.

  • The injection may feel like a quick pinch, but the procedure itself is painless.
  • You will need to lie still during the scans to ensure clear images.
  • The entire process, including waiting periods between scans, may take between 4 to 5 hours. You may bring something to read or do during the waiting period.

  • You can resume normal activities right away unless directed otherwise.
  • The radioactive material used in the scan is minimal and will naturally leave your body within 24 hours. Drinking plenty of fluids will help flush it out.
  • If you are breastfeeding, ask your doctor if you need to take any precautions afterwards.
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