"Thyroid scintigraphy
Is the examination painful? What are the risks? Are there any contraindications?
Thyroid scintigraphy is a simple and painless technique, although often the radioactive tracer or radiopharmaceutical must be administered intravenously. The doses of isotope administered are very low and do not involve significant risks for the patient, even if the use of the technique scintigraphic remains contraindicated in pregnancy. As a precaution, moreover, in women of childbearing age the scintigraphy is generally carried out within ten days following the beginning of the last menstruation, in order to exclude the risk of an ongoing pregnancy. During breastfeeding, some radioactive substances can pass into breast milk; therefore, at the discretion of the doctor specialized in nuclear medicine, the scintigraphy can be postponed or performed unless breastfeeding is suspended more or less prolonged. For example, after scans with Iodine 131, "breastfeeding" must be permanently suspended.
Scintigraphy can also be performed on children (the amount of drug used is proportional to body weight) and repeated over time to assess the course of a disease.
The tracers used, even those based on iodine, should not be confused with contrast media; normally they do not cause any disturbance or allergic phenomena (thyroid scintigraphy can be performed in complete tranquility even by people allergic to iodine).
How is thyroid scintigraphy done?
The examination begins with a preliminary visit aimed at investigating the history and any clinical documentation on the pathology in progress, followed by an objective examination of the neck (palpation). The investigation proceeds with the administration of the radiopharmaceutical, intravenously in the case of technetium 99 or iodine 123 (rarely used) and orally in iodine 131 scintigraphies. the radiopharmaceutical to distribute itself in the thyroid: 20-30 minutes for technetium 99 and up to two / three days for iodine 131.
After the waiting period, the images are acquired and the result interpreted. Depending on whether the scintigraphy is limited to the thyroid or extended to the whole body, this procedure can vary from a few minutes to half an hour. In both cases the patient is lying on a bed with the neck in hyperextension, after removing any metal objects (necklaces, brooches, earrings, watches, etc.). The heads of the apparatus will therefore perform rotational or translational movements around the body; since it is an open instrumentation there is no problem for people suffering from claustrophobia. During the entire procedure it is important that the patient remain as still as possible.
At the end of the scintigraphy, the patient can immediately resume his usual activities, without particular precautions; the doctor can still invite him to drink more liquids than usual to facilitate the elimination of the radiopharmaceutical; after using the toilet it is advisable to run the water abundantly and wash your hands thoroughly. In the first hours after the scintigraphy, always as a precaution (the absorbed radiations are not so dangerous, but it is still right to save unnecessary irradiation), the patient should avoid close contact with small children and pregnant women. If iodine 131 is used, these precautions must be taken both during the waiting period after administration of the radiopharmaceutical, and in the week following the scintigraphy. More generally it is important to follow carefully the instructions received from the health personnel when administering the tracer.
Preparation for the exam
Normally, the examination does not require any particular preparation. The doctor may, however, request the suspension of all those drugs that interfere with thyroid function; it is also important to report any recent subjecting to external sources of iodine, such as iodized salt, hair dyes. , iodized toothpastes, disinfectants or vaginal douches based on iodized products, multi-mineral supplements containing iodine, or recent radiological examination with iodized contrast media.
