Parathyroid scintigraphy

What is a parathyroid scintigraphy?

A scintigraphy is a diagnostic procedure in nuclear medicine used to determine the metabolic activity of an organ, in this case, the parathyroid glands.

Scintigraphy can be used in a variety of ways in nuclear medicine to diagnose different tissues. The principle always follows the same pattern. Firstly, a radioactive substance is injected and acts like a tracer. This substance is absorbed and processed by the body. Following this, the radiation emitted by the tracer can be detected using a special camera.

Tissues with higher metabolic activity absorb more of the radioactive substance and emit more radiation. This means these areas appear brighter in the images.

The parathyroid glands are small, lens-shaped organs located behind the thyroid. Usually, there are two parathyroid glands on the right and two on the left side, but this number may vary.  These glands produce parathyroid hormone. This hormone is cruical in regulating calcium and phosphate levels. It increases calcium levels and promotes phosphate excretion.

In parathyroid scintigraphy, the tracers typically used are technetium (99mTc) or thallium (201TI). After being processed by the tissue, these tracers emit gamma rays, which can then be detected.

The 99mTc-MIBI scintigraphy is commonly used. This special method helps determine whether a tumor is benign or malignant. The advantage of this technique is that the tracers are absorbed more efficiently by parathyroid tissue than by thyroid tissue, making it easier to distinguish between the two.

When and why is a parathyroid scintigraphy recommended?

Parathyroid scintigraphy is used in the diagnosis of parathyroid tumors. These may be a growth of hormone-active tissue, known as adenomas. These are usually detected during ultrasound or MRI examinations. However, these imaging procedures do not allow any conclusions to be drawn about the metabolic activity of the cells in question.

The most common indication for parathyroid scintigraphy is the presence of primary hyperparathyroidism. This is a disease in which the parathyroid glands secrete too much parathyroid hormone, resulting in patients having excessive calcium and low phosphate levels. Possible symptoms include kidney stones, stomach or bone pain.

The procedure can be done before parathyroid surgery. However, in some cases, scintigraphy is also used to find a tumor that could not be located during surgery, especially if the tumor is very small or in an unusual location outside the typical area of the parathyroid glands.

How should patients prepare for a parathyroid scintigraphy?

A detailed diagnosis is carried out before a parathyroid scintigraphy is performed. This includes an ultrasound or MRI examination and a blood sample. If the attending specialist considers a scintigraphy to be necessary, this is discussed in detail with the patient.

The examination itself does not require any special preparation from the patient. The patient does not need to fast, and medication can usually be taken as usual. It usually takes no longer than two hours in total and can be performed on an outpatient basis.

How is a parathyroid scintigraphy performed by a specialist?

First, a small amount of radioactive tracer is administered to the patient through an intravenous line. Then, the patient waits for about 15 minutes to allow the substance to distribute and be absorbed by the cells.

The first images are taken while the patient remains lying on their back and tries to move as little as possible. Additional images are usually taken about two hours later. A special camera, which can detect gamma rays, is used for the imaging. To get a better spatial view, the camera may move around the patient. The typical area captured is the chest, from the base of the skull to the diaphragm.

To better distinguish the parathyroid glands from the thyroid tissue, a technique called subtraction imaging may be used. This involves first performing a thyroid scintigraphy, typically with technetium. Then, the 99mTc-MIBI scintigraphy of the parathyroid glands is done. The images from the thyroid scan are then subtracted, leaving only the parathyroid glands visible.

What diagnostic information can be derived from parathyroid scintigraphy?

Parathyroid scintigraphy enables the assessment of tumors with respect to their metabolic activity. The higher the gamma radiation of the absorbed tracer in the cells, the higher the metabolic performance of the tissue.

Abnormal tissue typically shows a relatively higher metabolic activity, which results in increased gamma radiation intensity. This is usually most noticeable in the later images. Benign adenomas, on the other hand, exhibit a rapid "wash-out" phenomenon, where the radiation intensity decreases over time.

The results of the scintigraphy are then discussed with the patient and can be used to guide treatment decisions. Abnormal tissue should be surgically removed, and the scintigraphy can help locate the tumor more easily.

Are there any risks or possible side effects associated with parathyroid scintigraphy?

As the substances used are only slightly radioactive and are only administered to patients in small quantities, it is very rare for any notable side effects to occur. A temporary feeling of heat, itchiness, a metallic taste or slight nausea may occur.

The dose of radiation is approximately twice the annual natural radiation exposure in Germany and is therefore less than the radiation exposure from a CT scan. Parathyroid scintigraphy is considered a low-risk examination method.

Which doctors and clinics are specialists in evaluating parathyroid scintigraphy?

Parathyroid scintigraphy is a specialized diagnostic procedure that should only be performed in specialized nuclear medicine practices or clinics. Specialists in nuclear medicine are trained to perform and interpret scintigraphy. Endocrinologists are specialized in treating parathyroid disorders and are closely involved in the examination.

Finding the right specialist can be a great challenge for patients. To make this process easier, we have made it our goal to assist in this search. All of the specialists listed here are experts in performing parathyroid scintigraphy and have extensive experience in evaluating the results. Get in touch with our experts quickly and easily, and receive personal consultation.