Contraindication
There is no strict contraindication for a scintigraphy. Even in the case of pregnancy, this imaging procedure does not have to be dispensed with in principle, but should only be performed in extremely exceptional cases after thorough assessment of the indication. There is a relative contraindication for women who are in the breastfeeding phase, since small amounts of the radioactive pharmacon can be passed on to the child via breast milk.
Breastfeeding should therefore be interrupted for at least 48 hours after the scintigraphic examination in order to avoid exposing the newborn to unnecessary exposure to the radioactive substance. Scintigraphy should not be performed during pregnancy. Although the radiation exposure is relatively low, especially children are very susceptible and a disturbed development and permanent damage can occur.
For this reason, a scintigraphy should be performed at the earliest after delivery and, if necessary, only after breastfeeding. Before each scintigraphy, the doctor should also ask whether the patient is using safe contraception or whether a pregnancy could exist. If in doubt, a pregnancy test should be carried out before the examination.
Complications
Since scintigraphy involves the administration of radioactive substances which then lead to radiation, patients should avoid direct contact with pregnant women and children after treatment. Scintigraphy is generally not used for pregnant women. Nevertheless, it should be said that the radiation exposure during scintigraphy is very low and is in the range of X-rays, i.e. about 0.5mSv (milli Sievert).
Most complications arise when the radioactive material is injected into the vein. This can result in minor injuries to blood vessels or nerves, as happens every time the injection is made. Infections can also occur if the needle is inserted in an unsterile manner. Cardiac arrhythmia can also occur in rare cases. In general, however, the complications after or during a scintigraphy are very minor.
Scintigraphy of the thyroid gland
Scintigraphy of the thyroid gland is used to examine the function of thyroid tissue and nodes and is a frequently used method. Unlike ultrasound or sectional imaging (e.g. CT), it does not show the structure but the activity and thus the production of thyroid hormones. For this purpose, a substance is introduced into the blood through an arm vein, which accumulates in the thyroid gland and emits radioactive radiation.
Radioactive iodine or iodine-like substances such as pertechnetate (radioactive element: technetium) are used here, which are incorporated into the thyroid gland just like iodine. The radioactive particles are distributed with the blood in the body and thus also reach the thyroid gland. Almost exclusively there they are partially absorbed.
The radiation can be measured by a special camera and converted into an image by a computer. With the help of scintigraphy, overactive hormone-producing areas (autonomies or “hot nodes”) as well as functionally inactive areas (“cold nodes”) can be identified. The latter must be subjected to further diagnostics, as in some cases malignant growths are involved.
In addition, scintigraphy of the thyroid gland after therapy can be used to monitor the progress of success or failure. In the case of the thyroid disease Hashimoto thyroiditis, scintigraphy is not usually performed. In order to make or exclude the diagnosis, it is necessary to examine the blood for certain antibodies (proteins directed against the body’s own structures). Nevertheless, a scintigraphy can also be useful in patients suffering from Hashimoto’s thyroiditis, for example if additional nodules are found in the thyroid gland. However, there is no connection to Hashimoto’s disease, but only a simultaneous occurrence of two thyroid changes.