A thyroid scintigraphy is a nuclear medical examination, which, by means low-level radioactive substances presents the functioning of the thyroid tissue. With this method, we can distinguish between so-called cold nodes and hot node
What is a thyroid scintigraphy?
The thyroid scintigraphy is a complementary assessment of the thyroid function that represents the iodine metabolism of the thyroid gland. With the thyroid scintigraphy, the general and regional function of the thyroid gland can be visualized. In particular, it is possible to assess the function and metabolism of the thyroid’s nodular changes to distinguish between normal node, cold and hot node.
When is a thyroid scintigraphy required (indication)?
A thyroid is performed particularly when nodes have been detected in the thyroid gland in the previous ultrasound or if additional information is needed to determine the thyroid function. This information is significant for a further treatment strategy mainly of nodular changes. A qualified physician should make the so-called justifying indication prior to the examination.
How is the examination performed?
For this study we use specific radioactive substances (called radionuclides), which are identical or resemble in their chemical properties the element iodine. The most commonly used substance used is radioactive technetium-99m. This is injected into the patient’s vein in a minimal harmless amount. In about 10 to 20 minutes, it will accumulate in the thyroid gland or the thyroid cells. The light emitted by the technetium-99m radiation (so-called gamma radiation) is recorded by a special camera (Gamma camera) so that the thyroid is presented as an image and the function of the may be assessed. Simultaneously the amount of radionuclide is measured in the thyroid gland and the so-called thyroid technetium uptake (TcTU) is determined. Usually, the scan is performed with the patient sitting down and takes about 10 minutes.
Are special preparations necessary?
No, special preparation is usually not necessary. However it is important to know prior to the examination whether a recently an increased iodine dose was performed by the patient (e.g. through food, the administration of iodinated contrast agents, or by drugs) and whether specific thyroid medications were taken. Sometimes, in special cases, thyroid hormones have to be taken in preparation of a second thyroid scintigraphy. This examination is called suppression test. It provides additional information about the function of the thyroid gland, particularly in patients with so-called "hot nodes.»
Are there side effects?
Technetium-99m and iodine-123 are very well tolerated, and side effects are generally not experienced, not even in patients who are allergic to iodine. Driving a motor vehicle is also not affected by this examination.
When should the examination not be performed?
A thyroid examination should not be performed during pregnancy. Technetium-99m and iodine-123 both accumulate in breast milk, so that even during breast-feeding a scintigraphy should only be performed in exceptional cases. In this case, breastfeeding should be postponed (usually 24 hours with the use of technetium 99m) for a certain time after a consultation with the nuclear medicine physician.
How high is the radiation exposure?
The most commonly used radionuclide is technetium 99m. It is a pure gamma emitter with a short physical half-life of 6 hours and also a short biological half-life. Thus, the analysis is associated with a low radiation load for the patient.
Who pays for the examination?
The thyroid scinitigraphy is a standard benefit of all statutory and private health insurances.