What is a thyroid scan?

A thyroid scan involves the injection of a radioactive tracer, so that images can be taken to assess the structure and function of the thyroid gland.

Why is it performed?

Your doctor will recommend a thyroid scan to assess the following conditions:

• Hyper or hypothyroidism (overactive or underactive thyroid)
• Thyroid nodules

How does it work?

An intravenous injection of a radioactive tracer is administered. The radioactive tracer will enter the bloodstream and concentrate in the thyroid gland. Once it has been absorbed, images will be taken after 20-30 minutes, which will allow your doctor to see any abnormalities or thyroid problems.

What is a parathyroid MIBI scan?

A parathyroid MIBI scan involves the scanning of the parathyroids (four small glands that are located in the back surface of the thyroid gland). A small amount of radioactive tracer is injected intravenously into the body and absorbed by one or more of the parathyroid glands only if they are overactive.

Why is it performed?

The scan will pick up overactive parathyroid gland/s (hyperparathyroidism), which could indicate a parathyroid adenoma or hyperplasia of the parathyroids.

How does it work?

A small amount of radioactive tracer is injected into a vein in your arm, and you will be asked to lay on a scanning bed. A camera will record images of the parathyroid glands as the tracer is absorbed. These images can take up to 45 min. Once the initial scanning is finished, you will be asked to return in 1 – 3h for additional views of the neck and chest. This session can take another 20 min.

What is an adrenal scan?

Adrenal imaging, involves the injection of a small amount of radioactive tracer into the body, so that images can be taken to locate or confirm the presence of tumours. These tumours are known as neuroendocrine tumours (pheochromocytoma, carcinoids, paragangliomas, neuroblastomas etc).

Why is it performed?

This kind of scan helps to diagnose and locate tumours, and allows your doctor to see if the tumour (if malignant) has spread anywhere else.

How does it work?

First, you will be injected intravenously with a radioactive tracer (normally I-123 MIBG). Once it has distribute through the body, you will be scanned 24 hours later so that your doctor can evaluate images.