Isotope renography of the thyroid gland. What is a hardware scan of the thyroid gland? Preparation for scintigraphy of the thyroid and parathyroid glands

The development and expansion of the diagnostic capabilities of modern medicine has made it possible to leave in the past many techniques that do not meet the growing requirements for the quality of visualization, the degree of safety and the amount of information received. Thyroid scintigraphy, being a pioneer among radionuclide diagnostic methods, has managed to retain its position as a highly informative examination with potential for further development.

Emerging new and promising techniques that can provide a similar or greater amount of information are, one way or another, based on the principles of scintigraphy. Radionuclide diagnostics plays a significant role not only in clarifying the nature of the disease, but also in the treatment of malignant neoplasms of the thyroid gland.

The essence of the method

Thyroid scintigraphy is a radionuclide method for assessing the functional activity of the thyroid lobes (TG), based on the properties of its tissues to absorb iodine and use it to produce hormones. The use of radiopharmaceuticals (RPs) in the diagnostic process - chemical compounds perceived by organ tissues as a necessary participant in metabolism and containing radioactive isotopes in their structure, makes it possible to record the intensity and uniformity of absorption, accumulation and distribution of the substance in the thyroid gland.

In the absence of alternative imaging modalities available to diagnostic medicine today, such as ultrasound, MRI or CT, scintigraphy was the only way to obtain an image of an internal organ. Today, using all of the above methods, it is possible to obtain maximum useful information about the shape, structure and location of the thyroid gland, however, none of them is able to assess its functional state.

The mechanism for obtaining information is the introduction into the body of a radiopharmaceutical (for example, radioactive iodine), which is actively absorbed or not absorbed by the endocrine organ. When subsequently recording the radiation intensity, it is possible to obtain a flat or three-dimensional image (in the case of using an emission computed tomograph), reflecting areas of normal, increased or decreased concentration of the radioactive substance.

Areas with increased radiation, highlighted in color or shading, indicate tissue hyperactivity, and areas with reduced or absent radiation indicate their partial or complete functional failure. The use of scintigraphy is advisable only for the purpose of determining the activity of hormone production of one of the parts of the thyroid gland (node or lobe), the pathological condition of which has already been identified using laboratory or instrumental research methods.

On color photographs, inactive thyroid tissues are depicted in blue, and active ones in red.

Important! Scintigraphy cannot be considered an independent research method, based on the results of which any diagnostic decision can be made. Its use is justified only if it is necessary to obtain additional information.

Selection of radiopharmaceutical

Since radionuclide diagnostics is based on the ability to register the intensity and amount of ionizing radiation emanating from radiopharmaceuticals, there are 3 main requirements, compliance with which makes scintigraphy the most informative and safe diagnostic method:

The behavior of the drug in the human body should be identical to the behavior of natural organic substances.
The drug must contain a radioactive nuclide or a radioactive label that allows its location to be determined using recording equipment.
The radiation dose during diagnostics should be minimal.

An important aspect when choosing a radiopharmaceutical is the half-life, the duration of which should not exceed permissible radiation levels, but at the same time allows for the necessary diagnostic manipulations. The use of iodine isotopes (123Ι and 131Ι) in nuclear medicine can be considered a classic, since the first studies carried out with their help were described back in 1951.

Thanks to the ability of the thyroid gland to capture iodine, it became possible to record the rate of its accumulation and distribution in tissues. However, today, the use of 123Ι and 131Ι isotopes is limited by the need for a subsequent course of therapy for cancer or toxic thyroid adenoma.

Due to the fact that the half-life of the 123Ι isotope of iodine is 13 hours, and the 131Ι isotope is 8 days, the latter, as the most traumatic, is used to destroy malignant cells, and the use of the 123Ι isotope for diagnostic purposes allows us to estimate the rate of uptake of molecules and calculate optimal therapeutic dose.

Modern radiopharmaceuticals are isotopes that, as a result of decay lasting about 7 days, form a new unstable element called a radionuclide label. A feature of such a mark is the ability to create symbiosis with any chemical element involved in the metabolic processes of a particular organ. The most common drug in medical practice is technetium (99mTc).

The advantages of technetium can be considered an extremely short half-life (6 hours) and the absence of the need to introduce iodine into the body, which makes it possible to obtain a more “clean” picture from a diagnostic point of view. Another advantage of technetium, which allows minimizing the risks of the negative effects of radiation, is the ability to obtain it from the parent isotope stored in a container immediately before the diagnostic procedure, as well as the ability to adjust its optimal activity.

Container for storage and generation of technetium 99mТс

Indications and results

Radioisotope examination of the thyroid gland is carried out according to strictly defined indications. For example, a thyroid disease such as hyperthyroidism (hyperfunction) may be caused by diffuse or nodular changes in the gland tissue. The main purpose of the examination, in this case, is to determine the magnitude of hyperfunction, which in case of diffuse goiter can be done using ultrasound and laboratory blood tests.

In this case, an ultrasound shows the size, structure and blood supply of the thyroid gland, and a blood test shows the level of hormones, which is quite sufficient for making a diagnosis. Scintigraphy is not required even if a small number of nodes up to 3 cm in size are detected, since regardless of the test results, excess (hyperthyroidism) or deficiency of hormones (hypothyroidism) cannot be caused by such nodes.

Thus, thyroid scintigraphy should be prescribed for the following indications:

the presence of one or more nodes more than 5 cm in diameter with a simultaneous increase in hormone levels due to hyperfunction of the gland. In this case, using scintigraphy, it is possible to assess the intensity of absorption of radiopharmaceuticals by the tissues of the node and, based on the results obtained, judge the source of increased hormone production. After identifying the node that caused hyperthyroidism, the optimal method for its removal is selected;
the presence of a large node occupying at least half of one lobe of the thyroid gland (adenoma). The examination is carried out to determine the hormonal activity of adenomatous tissue, which can fully perform the functions of a hormone-producing organ, or may be completely inactive. When determining further treatment tactics, they rely on the results of scintigraphy and the anatomical features of the location of the node (the presence of compression of neighboring organs). If the node is actively growing but does not produce hormones, it is removed;
the likelihood of thyroid tissue formation in uncharacteristic places. An atypical location of the thyroid gland is a rather rare occurrence; much more often, the appearance of thyroid tissue in various places is characteristic of the spread of metastases in thyroid cancer. Scintigraphic examination helps with high accuracy to identify the localization of pathological foci in the lingual, retrosternal and other locations. In the future, as a rule, therapy is carried out with iodine isotopes.

Important! When assessing the results of scintigraphy, terms are used that reflect the degree of activity of the thyroid tissue. The area or node that actively accumulates isotopes is called “hot”, and the passive area is called “cold”.

Scintigraphic images of pathological changes in the thyroid gland

Preparation

It is believed that preparation for scintigraphy includes a list of restrictions, the main purpose of which is to achieve the most reliable results. So, in order to avoid possible distortions, a month before the proposed examination, you should stop eating foods containing iodine (for example, seaweed), and iodine-containing medications should be stopped much earlier - approximately 2-3 months before the procedure.

For 2-3 weeks, you must stop taking medications prescribed as part of hormone replacement therapy (L-thyroxine, Thyreodine, Eutirox), as well as thyreostatics (Tyrozol, Mercazolil, Propicil). However, taking into account the specifics of diagnostic scintigraphy, which is carried out with the aim of differentiating an existing diagnosis, such lengthy preparation is usually not necessary.

In practice, iodine-containing drugs are stopped 1-2 days before the procedure, and the doctor must know exactly the amount and dosage of the drugs taken by the patient and take this data into account when reading the results. The use of technetium 99mTc as a radiopharmaceutical makes it possible to avoid lengthy preparation for the examination, since this radionuclide does not participate in iodine and hormonal metabolism, but reflects natural processes occurring in the body.

Carrying out

Diagnostics includes 2 stages:

taking radiopharmaceuticals;
scanning.

If iodine isotopes are used during a scintigraphic examination, the patient drinks the drug in liquid or capsule form. Depending on the radiopharmaceutical used, scanning may be performed after 2–24 hours. With technetium, the radionuclide is injected directly into a vein and the scan begins a few hours later.

To perform the scan, the patient lies down on a couch located in a special room in front of the gamma camera. Modern gamma cameras record radiation emanating from the patient using a crystal (detector) that reacts to isotopes with flashes, which, in turn, interacting with a cathode ray tube, form an image on photographic paper.

The use of computer technology makes it possible to take not only stationary images, but also serial ones, and, by storing the previous result in memory, to determine the nature and speed of movement of isotopes. Scanning with an emission computed tomograph, the detector of which rotates around the couch with the patient, is extremely informative.

This approach allows you to take several frames from different angles, which, with the help of computer processing, take on the appearance of a three-dimensional image. The most modern achievement of nuclear diagnostics can be considered a positron emission tomograph (PET). The sensitivity of this detector is so high that the examination can be done using significantly lower doses of radiopharmaceuticals or using radiopharmaceuticals with a very short half-life.

PET scan is a commonly used diagnostic method

Contraindications

It is also possible to carry out scintigraphy during breastfeeding, however, from the moment of taking (introducing) the radioactive drug until its final disintegration, breastfeeding should be replaced with artificial, and your own milk should be expressed and poured out. In some cases, when using “hard” iodine isotopes, close contact with the child should be minimized.

Among the side effects that occur in patients with the administration of radiopharmaceuticals are a reaction to iodine-containing drugs:

allergy;
increased body temperature;
hyperemia of the face, neck or hands;
dizziness;
nausea;
change in blood pressure.

If the patient has a history of gastrointestinal diseases, antacids can be taken after taking iodine-containing radiopharmaceuticals. Adequate drinking regimen will also help minimize negative feelings after taking radiopharmaceuticals.

Important! When using technetium as a radiopharmaceutical, the likelihood of an allergic reaction is excluded.

Scintigraphy for thyroid cancer

Despite the fact that scintigraphy remains one of the main methods for the differential diagnosis of thyroid diseases, when diagnosing cancer, the method is considered uninformative. The main reason can be considered the difference in the forms of malignant neoplasms, some of which are capable of absorbing radiopharmaceuticals, and some remain inactive. However, according to statistical data, the number of malignant neoplasms among “cold” nodes is significantly higher than among “hot” ones.

Scintigraphy of infants is performed exclusively using technetium

Another point of support in diagnosing malignant neoplasms of the thyroid gland using scintigraphy can be considered the high rate of metabolic processes in the tumor tissue, and, accordingly, increased glucose consumption. Using the radionuclide label 18FDG, which is perceived by tissues similarly to glucose, and an emission-positron tomograph, it is possible to determine thyroid cancer with 85% accuracy.

The main criterion determining the choice of a clinic where to do scintigraphy can be considered the availability of the latest generation equipment, which allows not only to increase the accuracy of diagnosis, but also to significantly reduce the dose of radiopharmaceuticals used.

The method of scanning the thyroid gland after administration of a radioisotope is called scintigraphy. The main advantage over the main diagnostic methods (ultrasound and tomography)– this is an opportunity to find areas that produce thyroid hormones outside its location during tumor metastasis. The scan also helps detect tissue remains after the organ is removed.

Another advantage is the lower radiation dose, radiopharmaceuticals are quickly eliminated from the body.

Typically, an endocrinologist will refer you for a scan after an ultrasound and a blood test for thyroxine and triiodothyronine if:

nodes and ;
location of thyroid tissue outside the normal anatomical zone (ectopia);
low or high function;
, or acute thyroiditis.

With an already confirmed diagnosis Scintigraphy helps monitor the treatment process, the effectiveness of the operation and the risk of disease relapse. Before surgery the method allows you to determine its volume, and during dispensary observation patients operated on for medullary, papillary or follicular.

For children The reason for examination is the suspicion of absence, underdevelopment or abnormal location, various forms of goiter, thyroiditis.

Contraindications: pregnancy. If diagnosis is necessary for a nursing mother, then the milk is expressed throughout the day, and the baby is fed formula. On the second day it is allowed to continue feeding. During lactation, the radiopharmaceutical Technetium is recommended, It is also used by small children with intolerance to iodine-containing drugs.

Preparation for radioisotope scanning:

it is important to exclude the use of drugs that stimulate organ function (levothyroxine, iodine) or inhibit (Mercazolil, Espa-carb, Tyrozol), dietary supplements, vitamins, iodized salt;
you should not eat foods with iodine (seaweed, midi, shrimp, squid, sea fish);
if the patient was prescribed a study with an iodine preparation (excretory urography, angiography), then they are sent for a scan no earlier than 25 days later.

Examination methodology: The patient is administered a pharmaceutical containing radioisotopes of iodine or technetium. In the first case, they give a capsule or solution and send you home with a recommendation to come for diagnostics in 24 hours. Technetium 99 is administered intravenously and after half an hour the patient lies down on a couch that moves under the scanner. It perceives radiation flows from tissues and converts them into images.

The images are taken repeatedly over a period of about 10 minutes, then they are all processed using a computer program. The transcript is made by the doctor who conducted the examination, and the endocrinologist gives the conclusion.

In a healthy person, the scanogram looks like two dark, evenly colored ovals, which are located symmetrically with respect to the thyroid cartilage of the trachea. resembles a butterfly in shape. If there are areas in its tissue that function poorly and poorly accumulate the injected radioisotope, then they are called “cold”. They appear light-colored and have a low ability to produce hormones.

Dark ones that intensively absorb iodine, including radiopharmaceuticals, are hormonally highly active and “hot”.

Thyroid scintigraphy

diffuse increase in the entire gland tissue, the drug is distributed evenly, the color intensity is higher than normal - toxic goiter;
there is a light spot or several slightly colored areas in the gland - acute thyroiditis;
a hot area is characteristic of nodular goiter in hyperthyroidism. The surrounding tissues are weakly stained or the tumor almost completely absorbs all the radiopharmaceutical, and the phenomenon of stealing occurs;

At the same time, detection of a hot node cannot exclude cancer, and a cold node cannot confirm its presence. Scintigraphy is an intermediate stage of the examination.

Read more in our article on thyroid scans.

Read in this article

Diagnostic value

The method of scanning the thyroid gland after administration of a radioisotope is called scintigraphy. It refers to a clarifying study of its hormonal activity. The functioning of an organ can be assessed visually, distinguishing normally functioning tissue from nodes, and determining the degree of tissue damage.

The main advantage over the main diagnostic methods (ultrasound and tomography) is the ability to find areas that produce thyroid hormones outside its location during tumor metastasis.

The scan also helps detect tissue remains after the organ is removed. Another advantage is the lower dose of radiation compared to radiography; radiopharmaceuticals are quickly eliminated from the body.

Although scintigraphy cannot confirm or refute the presence of a malignant tumor, it does suggest it. The technetium isotope is also used to study the processes of metastasis of thyroid cancer to the lymph nodes.

For children, the reason for examination is the suspicion of the absence, underdevelopment or abnormal location of the thyroid gland, various forms of goiter, and thyroiditis.

Contraindications

During the study, radioisotopes enter the body. Its total power does not exceed the dose that the patient receives during X-ray or computed tomography. Therefore, this method is considered relatively safe and can be prescribed even to a one-year-old child. The only condition in which any type of radiation is undesirable is pregnancy.

If diagnosis is necessary for a nursing mother, then the milk is expressed throughout the day, and the baby is fed formula. On the second day it is allowed to continue feeding. During lactation, the radiopharmaceutical technetium is recommended, as it is quickly eliminated from the body, especially with heavy drinking. It is also used by small children who are intolerant to iodine-containing drugs.

Preparing for radioisotope scanning

The method is based on the ability of thyroid cells to accumulate iodine or technetium, which is found in places with the most intense blood flow. Therefore, it is important to exclude the use of drugs that stimulate organ function (levothyroxine, iodine) or inhibit (Mercazolil, Espa-carb, Tyrozol). The first ones are canceled 20 days in advance, and the second ones – 5 days in advance. The same rule applies to dietary supplements, vitamins, and iodized salt.

Drastic changes in diet are not required, but if the daily diet has not previously included iodine-containing foods (seaweed, midi, shrimp, squid, sea fish), then you should not consume them before diagnosis.

Watch the video about scintigraphy:

If the patient has been prescribed a study with an iodine preparation (excretory urography, angiography), then they are sent for a scan no earlier than 25 days later. Women who are breastfeeding should notify their functional diagnostics doctor about this.

Survey methodology

To scan the thyroid gland, the patient is given a pharmaceutical containing radioisotopes of iodine or technetium. In the first case, they give a capsule or solution and send you home with a recommendation to come for diagnostics in 24 hours.

Technetium 99 is administered intravenously and after half an hour the patient lies down on a couch that moves under the scanner. It perceives radiation flows from tissues and converts them into photographs, on which different hormonal activities are reflected in their color.

In order to increase the accuracy of the study, images are taken repeatedly over a period of about 10 minutes, then they are all processed using a computer program. The results obtained are interpreted by the doctor who conducted the study, but the endocrinologist who monitors the patient must evaluate it. The diagnosis cannot be confirmed or excluded based on the scan. Thyroid scintigraphy is just one stage of the examination.

Results of radionuclide scanning of the thyroid gland

In a healthy person, the scanogram looks like two dark, evenly colored ovals, which are located symmetrically with respect to the thyroid cartilage of the trachea. The gland is shaped like a butterfly. If there are areas in its tissue that function poorly and poorly accumulate the injected radioisotope, then they are called “cold”. They appear light-colored and have a low ability to produce hormones.

Depending on the disease, scintigraphy detects:

diffuse enlargement of the entire gland tissue, a radioactive iodine or technetium preparation is distributed evenly, the color intensity is higher than normal - toxic goiter with increased production of hormones, thyrotoxicosis;
in the gland there is a light spot or several slightly colored areas - acute thyroiditis; due to the inflammatory process, the cells do not include radioactive iodine in hormonal synthesis. With a less pronounced reaction (subacute inflammation), the storage capacity of thyrocytes decreases;
a hot area is characteristic of a toxic adenoma or nodular goiter in hyperthyroidism. The surrounding tissues have weak staining or the tumor almost completely absorbs all the radiopharmaceutical. The phenomenon of stealing arises;
cold zones indicate a cyst, replacement of functioning tissue with fibrous fibers, depletion of the thyroid gland in the elderly or due to radiation therapy, a malignant tumor.

We recommend reading the article about. From it you will learn about the indications for prescribing an organ examination, whether an MRI of the thyroid gland is done with contrast, why an examination of the neck is necessary after removal of an organ, as well as about MRI, what is found in diseases.

Learn more about diagnosing thyroid diseases.

Thyroid scanning is used as an auxiliary method. It can be prescribed if the results of blood tests and ultrasound are questionable to study the hormonal activity of the organ and the degree of damage to the gland. Most often, its role is to detect tissue remnants after removal of the thyroid gland, tumor metastasis, or abnormalities in the location of thyroid cells.

This diagnostic method is considered relatively safe. Contraindicated only during pregnancy. The result is a scanogram with uniform color enhancement, weakening, and areas of weak or intense staining.

Endocrinology specialists practice non-invasive techniques for examining the thyroid gland. Modern technologies in radiation diagnostics make it possible to assess the topographic anatomy and functional activity of internal organs.

Radioisotope imaging involves a number of techniques to produce images depicting the distribution of radiotracer-labeled substances in the body. Scintigraphy is considered one of the most informative and safe studies. The main task of scintigraphy is to visualize and study the kinetics of radiopharmaceutical drugs in human internal organs.

Radionuclide examination of the thyroid gland

Thyroid scintigraphy is a radioisotope study of the functional state of thyroid tissue and nodular formations, based on assessing the accumulation of a radioindicator in the required quantity.

The study provides an opportunity to identify and obtain information about the following parameters of the thyroid gland:

In world medical practice, radioisotope scanning of the thyroid gland is used in the following cases:

Diagnosis of pathological changes in the gland.
The presence of nodular formations detected by palpation.
Differential diagnosis of thyrotoxicosis.
Evaluation of the effectiveness of surgical intervention.
Ectopia of thyroid tissue.
Monitoring drug treatment for thyroid dysfunction.
Diagnosis of possible residual tumor tissues and distant sites of the pathological process.

The study has contraindications for:

The option of conducting a scintigraphic examination during lactation still exists. Scintigraphy of the gland is performed using technetium (99 mTc-pertechnetate).

Technetium is a short-lived isotope that appears in the body like iodine. These radionuclides are used in medicines with high specific activity. The trace element has been used in nuclear medicine since 1980. Among modern diagnostic procedures using radionuclides, scintigraphy with technetium is most often performed.

Pertechnetate is not involved in hormone synthesis. The half-life is six hours, complete disintegration occurs within 60 hours. Technetium has a higher excretion rate than iodine-based radiopharmaceuticals. Technetium has a low dose load on the patient’s body, which is why the isotope is used for research in children and nursing women.

The radioisotope study under consideration on the distribution of a radioactive drug in the tissues of the thyroid gland has a number of advantages and disadvantages.

Advantages and disadvantages of the study

Scintigraphic examination of the thyroid gland has a number of quite significant advantages over other methods of radiation diagnostics, namely:

Thyroid scintigraphy is a specialized and safe examination. However, this radiation technique has a number of disadvantages:

Among endocrinological examinations of the thyroid gland, scintigraphy occupies a leading place.

Preparation for the event

Thyroid scintigraphy requires specific preparation for the procedure. First of all, it is more expedient to create conditions of iodine and thyroid hormone deficiency. To achieve this goal it is necessary:

An examination involving the use of pertechnetate does not require special preparatory measures. This is due to the fact that the microelement is not involved in the production of hormones by the gland.

Before the procedure, consultation with an endocrinologist is necessary. Repeated discussion of the need for the procedure and the possibility of taking medications regularly used by the patient.

Order of conduct

Thyroid scintigraphy is performed in radioisotope diagnostic laboratories. A gamma camera is required in a special room. This installation has a complex mechanical structure and includes:

Gamma cameras are scanners necessary to record the concentration of a substance in the thyroid gland. The installation is indispensable when carrying out radionuclide diagnostics. Modern devices allow scintograms to be obtained in an arbitrarily oriented plane, without the need to change the patient's position.

Scintigraphy order:

Introduction into the bloodstream of an isotope substance (minimal doses of pertechnetate or iodine isotopes).
The patient assumes a horizontal position.
Placing the patient in a gamma chamber.
Registration of radiation emitted by radiopharmaceuticals absorbed by glandular tissues.
A three-dimensional image of the gland is displayed on the monitor screen and recorded on the computer’s hard drive.
Taking pictures.
End of the procedure.

The duration of the procedure ranges from 20-80 minutes. However, due to possible obstructive changes in the gland, the time of the procedure may vary.

The thyroid gland is an organ of the endocrine system that produces hormones for normal human functioning.

Unfortunately, sometimes the organ synthesizes an excess amount of hormones, for example, due to iodine deficiency in the body.

In this case, a diagnostic study is necessary, which allows you to accurately determine the disease and prescribe treatment.

One such study is radioisotope scanning of the thyroid gland.

Thyroid scan

Thyroid scan: what is it?

Radioisotope examination of the thyroid gland makes it possible to determine the degree of activity of the organ depending on the number of assimilated isotopes.

For diagnosis in this case, a special radioisotope of iodine is used.

The use of the iodine component J123 provides minimal radiation exposure and virtually no side effects.

Isotope study of the thyroid gland: preparation for diagnosis

Such radionuclide diagnostics of the thyroid gland does not require careful preparation.

However, a few days beforehand, the patient should stop taking medications with iodine, and also avoid diagnostic procedures using contrast components (for example,).

In addition, a week before the procedure, it is recommended to refrain from taking aspirin, cough syrups and antihistamines.

How is thyroid technetium scintigraphy performed?

Radionuclide testing of the thyroid gland () is carried out using a drug that contains technetium or an iodine isotope.

This drug is administered intravenously or taken orally by the patient. After this, the patient is placed in a special chamber, where a counter is turned on, which begins scanning the organ.

The results of such a study will be displayed on a specialist’s computer, as a result of which a full diagnosis and interpretation of data is possible.

Features of processing the received information

Technetium thyroid scans require careful interpretation.

Radioisotope study of the thyroid gland

During processing, the density of the main isotopic background, as well as the distribution of isotopes in tissues, is taken into account.

In a normal state, the thyroid gland is presented in the form of a butterfly, which has a uniform color.

This diagnostic method makes it possible to identify the following pathologies:

Thyroid oncology.
Presence of fibrosis.

This occurs when certain areas are weakly stained. If certain areas have too saturated tones, we can talk about the presence of toxic goiter.

Despite many advantages, radioisotope diagnostics of the thyroid gland also has a drawback - it cannot accurately diagnose malignant tumors on the endocrine organ.

Precautions and contraindications

Please note that after the procedure you should refrain from eating for two hours and should wear.

Only the next day is it possible to switch to your usual diet.

The following are contraindications to this diagnostic study:

The period of gestation and breastfeeding.
Allergic reactions to iodine and its components.
Serious illnesses, poor health.

This technique can also be used in children, but in this case it is recommended to use a drug that has a minimal half-life.

The following factors may distort the results of a thyroid isotope scan:

Prolonged stool disorder in the form of diarrhea.
Frequent urge to urinate.
Presence of renal failure.
Recent diagnosis with contrast agent.
Iodine deficiency in the daily menu.

The disadvantages of such research include the need for the presence of highly qualified specialists, and such professionals must have access to obtaining isotope substances.

It is quite difficult to deliver such radioactive substances to remote regions, and the preparations must be carefully guarded, and their transportation is carried out under control.

That is why such research is carried out mainly only in large populated areas.

Where is radioisotope scanning of the thyroid gland done?

Where to get a thyroid scan? Such a diagnostic study is carried out in specialized clinics, including multidisciplinary medical centers that have appropriate diagnostic equipment.

note that such a procedure should only be performed by a professional radiologist. In this case, a conclusion on decoding the study can be made by a clinical specialist (for example, an endocrinologist, surgeon or oncologist).

The cost of this diagnosis depends on the pricing policy of the medical center itself, as well as on the locality in which you live.

Thus, scanning the thyroid gland using isotopes makes it possible to identify pathologies in the area of this organ at an early stage and prescribe timely treatment.

In recent decades, the problem of thyroid diseases in medicine has become very relevant. In this regard, many methods have been developed for studying this organ and diagnosing disorders of its functioning.

One of the simple, safe and accurate methods for studying the condition of the thyroid gland is radioisotope scanning (scintigraphy).

Basis of radioisotope research methodology

Radioisotope scanning is based on the ability of the thyroid gland to capture and accumulate molecules of radioactive iodine or technetium.

Labeled atoms of these microelements produce gamma radiation, which is detected by special devices.

A sensor is installed above the thyroid gland that measures the level of radioactivity in it and determines what percentage of the total radioactivity it constitutes.

This forms an idea of the intensity with which the thyroid gland absorbs iodine or technetium.

Thanks to this, it is possible to obtain information about the size, shape, location of the thyroid gland, the presence of areas of hyper- or hypoactivity of the organ tissue, indicating the intensity of production.

Preparing for a thyroid scan

Carrying out radionuclide scanning of the thyroid gland using radioactive iodine requires certain preparatory measures:

stopping taking iodine-containing drugs, thyroid hormones, eliminating foods containing iodine from the diet 30 days before the procedure;
within three months before scintigraphy, do not undergo fluoroscopy with contrast;
stop taking cordarone (amiodarone) 3 months before;
1 week before the procedure, do not take sulfonamides, propylthiouracil, Mercazolil, aspirin, cough syrups, anticoagulants, antihistamines, phenylbutazone, phenothiazines.
Do not eat before bed the night before the test and come on an empty stomach.

When conducting radioisotope scanning with the introduction of technetium, such preparatory measures are not required.

This is explained by the fact that this microelement does not take part in the formation of thyroid hormones and its accumulation in the thyroid tissues is not affected by drugs.

But sometimes it becomes necessary to repeat the use of iodine.

Carrying out the procedure

When using different radioisotopes, the research methodology has some differences.

a) Slight enlargement (hyperplasia) of the right lobe of the thyroid gland.
b) “Cold” thyroid nodules.
c) Toxic goiter - .
d) “Cold” nodule in the lower part of the left lobe of the thyroid gland.

The iodine-based radiotracers used are taken orally.

If the radioisotope iodine-123 is used, then the images are taken after 5-6 hours.

When introducing the iodine-131 isotope - after 2-5 days.

If the radioisotope technetium-99 is used, it is administered intravenously.

For this purpose, the drug is prepared immediately before administration. A solution of the specified microelement from a special generator is combined with a stabilizer in a syringe and after 10-20 minutes is injected into a vein.

The drug quickly accumulates in the thyroid tissue, so pictures are taken within 10-30 minutes. Technetium is also quickly eliminated from the body.

Before recording radiation from labeled atoms, the patient must remove all jewelry and existing dentures (they may interfere with the visualization of the thyroid gland). Then he lies on his back and throws his head back.

A gamma camera is installed above the projection area of the thyroid gland, which detects the corresponding radiation.

The resulting image of the thyroid gland falls on the monitor and is recorded by x-ray film.

Images of the gland are obtained in three projections: two lateral oblique and anteroposterior.

After the procedure, the patient can resume taking prescribed medications and return to his usual diet.

A type of radioisotope scanning is considered monophatonic emission. It makes it possible to obtain a three-dimensional image of the endocrine organ.

Interpretation of the results obtained

As a result of the study, a series of images is obtained that shows the dynamics of the accumulation of the administered drug from the moment of its administration.

Hot thyroid nodule detected using radioisotope scanning (scintigraphy)

In the resulting images, areas painted red, are called “hot” and indicate intense production of thyroid hormones by this part of the organ.

Blue areas, or “cold” areas, correspond to parts of the gland with low activity and weak hormone production.

Picture options may be as follows:

homogeneous gland structure with a uniform accumulation of a substance of medium intensity - the normal state of the organ;
intensive uptake of the drug by the entire gland tissue, indicating the active functioning of the thyroid gland and the production of its hormones, characteristic of Graves’ disease;
several fragments intensively absorbing radiopharmaceuticals, indicate (Plummer's disease);
a single area in the area of the isthmus of the gland, releasing a lot of thyroid hormones, indicates the presence of a thyroid adenoma;
uniform weak absorption of the drug tissues characteristic of hypothyroidism with thyroiditis;
single plot capturing little substance may indicate organ carcinoma.

Indications for radionuclide scanning

This study is prescribed in certain cases for:

identifying the exact localization of the thyroid gland in its unusual location;
determining the shape and correctness of the structures of the gland in case of anomalies of its development;
differential diagnosis of the organ (clarification of the diagnosis);
complex diagnostics for unclear diagnosis;
determining the cause of thyrotoxicosis detected in the laboratory (thyroiditis or diffuse toxic goiter);
assessment of the functional activity of detected thyroid nodules;
clarifying the diagnosis of hypo- and hyperthyroidism;
dose calculation in preparation for radioactive iodine therapy.

Contraindications for the procedure

This study cannot be performed during pregnancy, lactation, or in patients with allergies to iodine or seafood.

If scintigraphy becomes necessary during lactation, then breastfeeding is stopped for several hours or days, depending on the isotope used.

If you are allergic to iodine-containing products

Radioisotope scanning is carried out using technetium.

To carry out this procedure in children, a radiopharmaceutical with a short half-life (technetium-99 or iodine-123) is selected.

Disadvantages of scintigraphy

Despite the effectiveness and safety of radioisotope scanning, this method has some disadvantages.

In diagnostic terms, they are expressed in the fact that scintigraphy is not effective in differentiating non-toxic goiter of the thyroid gland.

It also does not detect areas smaller than 1 cm, which can cause late diagnosis of diseases.

As for the side effects of the study under discussion, they may be associated with allergic reactions and intolerance to the drugs used.

In terms of scinigraphy, it is completely safe.

Another disadvantage of the type of research under discussion is the high cost of the equipment required for it.

This explains the low prevalence of scintigraphy in our country. Whereas in the USA and Europe it is a routine diagnostic method.

In addition, radionuclide scanning imposes certain requirements for its implementation:

highly qualified personnel;
access to a medical nuclear reactor to obtain the necessary isotopes;
the difficulty of timely delivery of drugs with a half-life of 6 hours to remote areas;
compliance with safety precautions when working with radioactive substances.

Justification of the radiation safety of the study

Fears related to the danger of radiation exposure during scintigraphy are completely unfounded.

This is explained by the fact that the total dose of radiation used during this procedure does not exceed 5 mSv with the use of radioactive iodine and 3 mSv with technetium.

These figures are much lower than those that people receive in ordinary life.

Thus, airplane flight attendants receive a dose of 2 mSv, and people living in mountainous areas receive up to 10 mSv annually.

The radiation background of the surrounding nature is 2.4 mSv. The maximum permissible dose of radiation exposure for humans is 50-200 mSv per year.

So the radiation exposure during scintigraphy is negligible.

In addition, the administered radioisotopes decay and are completely eliminated from the body.

With technetium-99 and iodine-123 this occurs after 24-48 hours, with iodine-131 - after 8 days.

The real danger to human health is posed by radioactive elements with a half-life of tens and hundreds of thousands of years.

In the process of radionuclide scanning of the thyroid gland, such isotopes are not used.

Despite the safety of this procedure, it should not be performed too often. It is recommended to prescribe scintigraphy no more than 3-4 times a year.

Of course, radioisotope scanning of the thyroid gland is a highly informative, effective and safe method that helps make the correct diagnosis.

But to fully assess the condition of the thyroid gland, it is necessary to use other diagnostic methods in combination with scintigraphy. These are ultrasound examination and tissue biopsy of the specified organ.