Isotopic research. Radioisotope research methods. Indications for the study

The development of science in the 21st century, allows you to implement in medical practice ever more advanced and reliable methods of diagnosis and treatment. One of these methods is a radioisotope study of the kidneys.

The unique ability of radioactive isotopes, when decaying, to radiate energy, which is transformed on a computer screen and appears as a luminous organ, is the basis of this method. With the help of the introduced isotope, the amount of substance absorbed by the kidneys and the rate of filtration of radioactive isotopes are studied.

In comparison with urography, the method of radioisotope diagnostics allows you to see complete information about the work and condition of the kidneys, to take a number of pictures that represent the genitourinary system renography.

What can you learn about the condition of the kidneys?

For renography, special pharmacological radioactive preparations are used, which are administered intravenously and, getting into the kidneys, are excreted from the body. The study allows you to study the function of not only the kidneys, but the entire genitourinary system, namely:

the state of the renal vessels, the blood flow in them, the blood filling of the kidneys;
condition and functional ability of the renal parenchyma (kidney tissue);
the state of the collecting system of the renal tubules, pelvis, etc.;
reveals cysts and various neoplasms;
the state of the excretory function of the kidneys.

How is the research going?

At the beginning of the study, the patient, as already mentioned, is injected intravenously with a special radioactive pharmacological drug, the radiation of which is calculated so that it does not pose a danger to humans, because the mass of his body is taken into account during the introduction. Before the introduction of the drug, special sensors are put on the body that record the level of radiation. There are three in total.

Only after the introduction of a radioactive drug can further research be carried out.

After the administration of the drug to the patient, a series of images are taken that allow you to determine the time for the isotopes to move along genitourinary system. All images are taken in a strictly defined sequence, this is necessary in order to correctly assess the function of the drug's intake with the help of the bloodstream, then evaluate the work of the collecting system and, finally, the function of the excretory system.

This is done using a gamma camera as follows:

A series of images to determine renal blood flow and renal vascular function (1 frame per 1 second) is taken for 1-2 minutes.
A series of images to determine the health of the kidney tissue (1 frame per 1 minute) - for 15 - 20 minutes.
Pictures to determine the collecting and excretory function of the kidneys are taken after 1-2 hours. They are the final ones.

To conduct a radionuclide study, a gamma camera is required

All manipulations with the patient in this diagnosis are carried out in the supine position. This study is completely safe for humans and painless.

Indications for holding

all chronic inflammatory diseases of the kidneys;
suspicion of hydronephrosis of the kidney;
congenital anomalies of the kidneys;
conditions after kidney injury;
condition after transplantation;
malignant hypertension;
suspicion of neoplasms;
cystic formations of the renal parenchyma.

Research rules

In order to properly conduct an isotope study of the kidneys, the patient must follow some rules on the eve of the procedure:

stop taking all medications, especially antihypertensive, psychotropic, diuretic;
the study should be carried out on an empty stomach;
on the eve you can not take alcoholic beverages;
all metal objects are removed;
the procedure should be carried out with the patient completely immobile.

Only by observing all these conditions, you can get correct result and avoid repetition of the study.

In some cases, a re-examination is necessary. This happens in situations where it is necessary to track the dynamics of the process occurring in the kidneys or the dynamics and stages of the state of the kidneys after or during treatment.

For radioisotope diagnostics of the kidneys in children, there are the same indications as in adults. Usually, this study is not carried out for children of younger and middle age, given their unlimited mobility.

Varieties of radiological research

Depending on what type of radionuclide diagnostics needs to be applied, there are:

radiometry,
radiography,
scintigraphy,
scanning.

Radiometry and radiography are diagnostic methods without an image of the organ itself. Information about the work of the body is displayed on the screen in the form of a graph or diagram.

Graphs display quantification kidney function

Scintigraphy, scanning is a diagnosis with obtaining an image of the organ under study, and a series of images allows you to see problem areas in layers.

Scanning of the organ takes place on special scanners designed for this, approximately 2 hours after the administration of the drug. Pictures taken in this way are called "scans".

Scintigraphy allows you to take a whole series of images, which are called "scintigrams". This data can be played back on a computer screen at any time, and the right parts of the organ are examined.

The analysis of the obtained images is carried out by a doctor who directly specializes in conducting a radiological examination and decoding the obtained images.

Contraindications

There are practically no contraindications for renography of the kidneys. This method research, as already mentioned, is safe and painless for the subject.

However, conditions such as pregnancy and lactation are the main and, perhaps, the only contraindication for this diagnosis. Children under the age of 1 year are examined only for health reasons.

A little about security

All studies related to the use of radioactive isotopes are carried out in the Department of Radiology and are completely safe for humans.

The preparations are stored in the radioisotope laboratory, from where they are transferred in special containers to the study room. After the vial with isotopes has been opened, the remaining dose is placed in a specialized box for temporary storage. Dosing of the drug to the patient is carried out taking into account his weight, age and severity of the pathology. All radiological pharmaceuticals are on special account.

Specially trained personnel work in the radiology department

Irradiation during radioisotope diagnostics is several times less than during X-ray examination. That is why the study can be repeated several times if the need arises.

At the end of the working day, all specially trained medical personnel undergo dosimetric control of clothes, hair, hands, and shoes. Thus, the exposure of patients to excess radiation is practically reduced to zero.

In the event of a breakdown, accident or other emergency situation, the branch is immediately closed. In order to minimize the penetration of radiation, such departments are located in the basement medical institutions. Walls, ceilings during construction are covered with special protective materials. Radiation control is monitored in the premises of the department with the help of installed counters. In the event of a leak of ionizing radiation, an alarm is triggered.

To conduct a radiological examination, the medical staff did everything possible to make it comfortable and safe. If you have received a referral to the Department of Radiology for a radiological examination, remember that you have been assigned one of the most advanced diagnostic examinations in medical practice.

Radioisotope diagnostics is one of the most informative research methods. With its help, a complete diagnosis of the systems of functioning of internal organs is carried out, all possible violations and deviations from the norms are ascertained.

Radioisotope renography of the kidneys is the most popular and frequently performed method of radioisotope research worldwide.

The essence of diagnosis, goals and benefits

In the role of the main cleansing system of the body, it is the kidneys that act. With their help, blood is filtered, which is cleansed of various toxins and other harmful substances. Conventional research methods, such as blood and urine tests, can reveal various abnormalities in the functioning of the organ, determine the cause of these disorders.

Well, radioisotope renography makes it possible to see exactly how the filtration process occurs, to display the work of glomeruli at the present time, and also to monitor the work of organs separately.

The main purpose of renography is precisely to display the work of internal organs, analyze and monitor their condition. Based on the data of this study, it is impossible to make an accurate diagnosis, but you can definitely see various disorders in the functioning of internal organs, as well as monitor the effectiveness of therapy.

The main advantage of renal renography is the simplicity of the procedure, which practically does not require additional preparation and the absence of high doses of radiation. Renography is prescribed for all patients who have obvious kidney problems.

Methods of radioisotope research

Based on the results of the study, which must be obtained for an informative picture, there are several methods for conducting radioisotope diagnostics. Each of these methods is special in its own way, and the totality of the research results displays a complete picture of the work of the kidneys:

Renography. This technique is not based on visualization of images of the kidneys, but on the quantitative indicators of blood filtration, the rate of formation and outflow of urine. This is the main method for studying the urinary system, with which you can assess the severity of violations, minor deviations from the norm, track the dynamics of all functional indicators.
Scanning. Static renography, or scanning, is a study in which a schematic image of the organ under study is obtained. This helps to determine the shape, size, internal position, placement in proportion to other organs. Diagnosis is carried out with a special scanner that captures radiation from a contrast agent previously introduced into the body. The whole procedure will take about one to two hours, since studies can be carried out only 40 minutes after the injection of contrast.
. This method is also based on obtaining a high-quality image of the internal organs. A special gamma tomograph captures radiation, on the basis of which an image is formed. After collecting all the radiation, the device analyzes all the data and after a while creates an image. The pictures in this study are clearer, they can see the smallest changes. That is why with the help of scintigraphy it is possible to study in detail the work of the entire urinary system, to examine not only the kidneys, but also all the urinary canals.

Indications for examination

Any nephrological pathologies of paired organs, the slightest deviations from the norm in basic blood and urine tests, previous serious illnesses, chronic diseases kidneys, and so on, are indisputable indications for a renographic study. Most often, the procedure is prescribed in the presence of mechanical damage kidneys (deformation, inflammation, rupture). Radioisotope renography is also performed for any diseases of the urinary system:

Diagnostics is also carried out with secondary ones, which led to violations in the work of organs:

arterial hypertension;
autoimmune diseases that cause damage to connective tissues;

It is worth considering that the doctor may prescribe this study for other diseases that can cause complications in the work of the kidneys and adrenal glands. Renography is also used as an observation after surgical procedures above internal organs, with donation (, transplantation).

Preparation for the procedure

The beauty of this examination method is that it does not require any special preliminary preparation. But still there are certain requirements that should be followed during this procedure, namely:

During the examination, no metal objects (jewelry, piercings) should be on the patient's body.

How is the survey done

Before the examination, it is necessary to introduce a contrast agent - hippuran. If you are allergic to contrast, it is replaced with an analogue. The patient should take a sitting position. Further, special detectors are attached to the body, which are placed at the level of the kidneys, heart and above the largest blood vessels. The device draws curved lines that characterize the purification of blood in the kidneys from the contrast agent. After that, all drawn curves are studied in detail, taking into account the segments.

The secret segment shows the accumulation of contrast in the vessels of the kidneys, that is, draws the vascular lines. The excretory segment shows the release of contrast along with urine. These two curves are the main indicator of the state of the absorptive-excretory state. The time during which the device draws these curves is also taken into account.

The longer the examination lasts, the longer the blood is filtered, which indicates the presence of diseases. If the machine fails to complete the curve within 40 minutes, it is safe to say that there is kidney failure. In addition, this method of examination can reveal not only a clear problem of the excretion function, but also a latent one. kidney failure that cannot be diagnosed with routine blood, urine, or x-ray tests.

This study is considered the most informative in its field, as well as accessible. With it, you can assess the condition of the kidneys, the quality of their work, as well as examine the superficial urinary tract.

Important! If a patient has thrombosis or arterial occlusion, afunctional blood occurs, which sharply reduces the vascular segment, which significantly affects the drawing of the curves during the examination.

Features of the study in children

The development of kidney diseases, insufficiency, weak activity of the adrenal glands, low filtration threshold and many other pathologies are diagnosed in 80% of cases in children. Everything is connected with the development of this body. The fact is that the kidneys do not grow proportionally. In children under 12 years of age, they are almost half as much as necessary, in relation to the whole body.

Therefore, the kidneys are under enormous stress and often fail. To examine the child's body, in almost all cases, radioisotope renography is prescribed, where the amount of harmful radiation exposure 80-100 times lower than with conventional x-rays.

The only restriction for this type of research is the age of up to 1 year. But if absolutely necessary, this study can be applied in such early age. In all other cases, children are given potassium iodide before the procedure, which reduces the effects of radiation, and a grid is drawn with iodine on the body (in the area where the device is connected). With neurological disorders, children are given a mild sedative.

Analysis of results

The curve displayed on paper is divided into three parts:

Vascular curve, which shows the time interval for which hippuron appears in the vessels.
tubular- epithelial secretion of tubular substances.
Curve showing the yield of the used isotope from the kidneys.

The curve is built on two axes, the first value of which is the time range, and the second, the percentage of contrast agent concentration. According to international standards, the following indicators are considered the norm:

The maximum concentration of the substance can manifest itself in 3-4 minutes.
The half-life (two-fold decrease in the curve) is 10 to 12 minutes.
The difference in these indicators between each of their kidneys is no more than 20%. Since one kidney is smaller than the other, a slight deviation is acceptable.

According to this chart you can set the time when a deviation occurs in the work of the organs and to what extent this happens. With the help of this study, it is possible to assess the quality of the excretory and secretory functions of the kidneys, the degree of filtration, to obtain clear information about the size and shape of the organs under study, to study the work of superficial urinary tract, as well as identify kidney failure before it appears clinical manifestations. This will greatly facilitate treatment and halve the risk.

Pathological types of curves

The results of renographic studies are very specific, they are divided into types:

Afunctional- a smooth decrease in the curve in the vascular segment.
Isustenuric- an increase in the curve to a certain level, which indicates the presence of chronic renal failure.
obstructive- gradual elevation of the curve in the absence of a full outflow of urine. Most often, the cause lies in stones or inflammation that block the urinary tract.
Parenchymal– a significant slowdown in all indicators, the line practically does not change. The main problem is .

Remember! According to the results of this study, it is impossible to make an accurate diagnosis. Renography only assesses the condition of the organs!

Precautions and contraindications

Diagnosis of the kidneys by the beam method has no contraindications, but there are still some precautions for its implementation. These include:

children under 1 year of age;
the presence of thrombosis and other cardiovascular diseases;
overweight;
taking psychotropic and sedative drugs.

It is worth remembering that these factors are not a list of contraindications, they only affect the reliability and accuracy of the results during the examination. The only contraindication is if the patient is allergic to a contrast agent or to iodine. But even this will not be a problem, since the hippuran can be easily replaced with a similar contrast.

This examination method is based on the ability of radioactive isotopes to emit radiation. Now most often they conduct a computer radioisotope study - scintigraphy. First, a radioactive substance is injected into a vein, mouth or inhalation into the patient. Most often, compounds of the short-lived isotope of technetium with various organic substances are used.

Radiation from isotopes is captured by a gamma camera, which is placed above the organ under study. This radiation is converted and transmitted to a computer, on the screen of which an image of the organ is displayed. Modern gamma cameras make it possible to obtain its layer-by-layer "sections". It turns out a color picture, which is clear even to non-professionals. The study is carried out for 10-30 minutes, and all this time the image on the screen changes. Therefore, the doctor has the opportunity to see not only the organ itself, but also to observe its work.

All other isotopic studies are gradually being replaced by scintigraphy. So, scanning, which before the advent of computers was the main method of radioisotope diagnostics, is used less and less today. When scanning, the image of an organ is not displayed on a computer, but on paper in the form of colored shaded lines. But with this method, the image turns out to be flat and, moreover, gives little information about the work of the organ. Yes, and scanning delivers certain inconvenience to the patient - it requires him to be completely immobile for thirty to forty minutes.

right on target

With the advent of scintigraphy, radioisotope diagnostics received a second life. This is one of the few methods that detects the disease on early stage. For example, cancer metastases in the bones are detected by isotopes six months earlier than on x-rays. These six months can cost a person a life.

In some cases, isotopes are generally the only method that can give the doctor information about the state of the diseased organ. With their help, kidney diseases are detected when nothing is determined by ultrasound, microinfarcts of the heart are diagnosed, which are invisible on the ECG and ECHO cardiogram. Sometimes a radioisotope study allows the doctor to "see" a pulmonary embolism that is not visible on an x-ray. Moreover, this method provides information not only about the shape, structure and structure of the organ, but also allows you to evaluate it. functional state, which is extremely important.

If earlier only the kidneys, liver, gallbladder and thyroid gland were examined with the help of isotopes, now the situation has changed. Radioisotope diagnostics is used in almost all areas of medicine, including microsurgery, neurosurgery, and transplantology. In addition, this diagnostic technique allows not only to make and clarify the diagnosis, but also to evaluate the results of treatment, including continuous monitoring of postoperative patients. For example, scintigraphy is indispensable when preparing a patient for coronary artery bypass grafting. And in the future, it helps to evaluate the effectiveness of the operation. Isotopes reveal states, life threatening human: myocardial infarction, stroke, pulmonary embolism, traumatic cerebral hemorrhage, bleeding and acute diseases bodies abdominal cavity. Radioisotope diagnostics helps to distinguish cirrhosis from hepatitis, to see a malignant tumor at the first stage, and to identify signs of rejection of transplanted organs.

Under control

There are almost no contraindications to radioisotope research. For its implementation, an insignificant amount of short-lived and quickly leaving the body isotopes is introduced. The amount of the drug is calculated strictly individually, depending on the weight and height of the patient and on the state of the organ under study. And the doctor necessarily selects a sparing mode of research. And most importantly: radiation exposure during radioisotope research is usually even less than with X-ray. Radioisotope research is so safe that it can be carried out several times a year and combined with x-rays.

In the event of an unforeseen breakdown or accident, the isotope department in any hospital is reliably protected. As a rule, it is located far from the medical departments - on the ground floor or in the basement. The floors, walls and ceilings are very thick and covered with special materials. The stock of radioactive substances is located deep underground in special lead storages. And the preparation of radioisotope preparations is carried out in fume hoods with lead screens.

Constant radiation monitoring is also carried out with the help of numerous counters. The department employs trained personnel who not only determine the level of radiation, but also know what to do in the event of a leak of radioactive substances. In addition to the employees of the department, the level of radiation is controlled by specialists from the SES, Gosatomnadzor, Moskompriroda and the Department of Internal Affairs.

Simplicity and reliability

The patient must adhere to certain rules during a radioisotope study. It all depends on which organ is supposed to be examined, as well as on age and physical condition sick person. So, when examining the heart, the patient should be prepared for physical activity on a bicycle ergometer or on a walking path. The study will be better if it is done on an empty stomach. And, of course, you can't take medications a few hours before the study.

Before a bone scan, the patient will need to drink plenty of water and urinate frequently. Such washing will help to remove isotopes from the body that have not settled in the bones. When examining the kidneys, you also need to drink plenty of fluids. Liver scintigraphy and biliary tract do on an empty stomach. A thyroid, lungs and brain are examined without any preparation at all.

Radioisotope research can interfere with metal objects caught between the body and the gamma camera. After the introduction of the drug into the body, you must wait until it reaches the desired organ and is distributed in it. During the study itself, the patient should not move, otherwise the result will be distorted.

The simplicity of radioisotope diagnostics makes it possible to examine even extremely severe patients. It is also used in children, starting from the age of three, mainly they examine the kidneys and bones. Although, of course, children require additional training. Before the procedure, they are given a sedative so that during the study they do not spin. But pregnant women do not conduct a radioisotope study. This is due to the fact that the developing fetus is very sensitive to even minimal radiation.

Radioisotope examination of the kidneys (scintigraphy) is nowadays quite simple and accessible method diagnosis. It is performed not only in a hospital, but also on an outpatient basis with a device called a renograph.

Such an examination is superior in information content even to traditional ultrasound, and the harm from it is less on the body than from x-rays. However, there is contraindication to its use- and breastfeeding. Why, we will find out later in the article.

Indications for examination

Recommended for patients with various kidney diseases get regular x-rays. Often it is repeated without harm to a person in order to identify the effectiveness of the prescribed. It can also be done in combination with x-rays.

However, it must be remembered that x-rays are taken no more than once a year.

Scanning the kidneys with a radioisotope method is indicated in the presence of the following pathologies:

Vascular diseases of the parenchyma: glomerulonephritis, nephritic syndrome, amyloidosis.
Hydronephrosis.
Malignant hypertension.

What is being researched?

The majority of patients examined with a renograph are with pathologies of the urinary system.

Radioisotope renography will help the doctor to carry out the following manipulations:

fix the excretory functions of the proximal tubules;
check the blood flow of the kidneys;
detect the presence of vesicoureteral reflux;
determine the state of kidney tissues in the largest and smallest segments of the kidneys;
consider the ability of the kidneys to function after transplantation.

How to prepare?

In order for the survey to qualitative results, must be observed certain rules before going through this process:

Renography should not be performed on a full stomach.
Refrain from taking medication for several hours before the procedure.
Drink plenty of fluids.
Do not have metal objects on the body.

In no case during the examination should not be under the influence of alcohol, narcotic, psychotropic drugs.

Renography in children

At up to one year, a radioisotope study of the kidneys is not used, similarly in pregnant women, because even small doses of radiation can negatively affect the fetus and fragile body of the baby.

Instead of renography, the doctor will prescribe screening ultrasound for children of this age to examine the kidneys.

However, if the child has a pathology, then in this situation the attending physician assesses the need for this research method.

Babies up to 3 years before the procedure are given sedative drug so that the child is calm, and the result of the scintigraphy is objective and of high quality.

For small patients, in the form of the necessary preparation, a preliminary intake of iodine in small quantities is carried out. For three days before renography, adults should give the child 3 drops of Lugol's solution orally or 3-5 drops 3 times a day 5% tincture of iodine to block the reactive functions of the thyroid gland.

Carrying out the procedure

Isotopes demonstrates appearance kidneys, evaluates their functional abilities, helps to detect pathologies that appear in them at an early stage. This is especially important in oncology.

In renography, a new generation radioisotope study, they use drug Hippuran. It helps to get a view of the affected areas of the kidneys, while ultrasound in this case useless. It is administered in doses calculated in relation to body weight.

The kidneys have the ability to capture the radiopharmaceutical in the required quantities and remove it from the body. Gippuran is able to quickly disintegrate, so the exposure of the body is minimal.

renogram- this is a record of isotopic radiation that appears above the organs under study at the time of passage of Hippuran through them. The renogram displays all the ongoing changes in the internal organs.

The patient is examined in a static state, sitting. Seriously ill patients are examined lying down. The drug is injected into the vein of the subject, and special renograph sensors, which are installed on the patient's body, record its accumulation, passage and excretion from the kidneys.

Thus, the renogram is divided into 3 parts for each kidney:

Vascular, which shows the placement of the radioisotope in the vessels of the kidneys.
Secretory, shows the accumulation of Hippurine in the kidney.
Evacuation room, where the outcome of the drug from the kidneys is recorded.

Radiologists analyze the resulting result by the method mathematical analysis and using it to reveal the effectiveness of the cleansing functions of the kidneys, its filling rate vascular system, the period of excretion of the drug from the kidney, especially its accumulation in the urinary system.

All about scintigraphy in children will be told by a radiologist in a video clip:

CHAPTER 75

1. List the main advantages of radioisotope diagnostic methods compared to other imaging modalities.

In almost every case, radioisotope research methods have one or more advantages over other methods:
1. Obtaining information about the functional state of the body, which cannot be obtained using other methods (or obtaining this information is associated with high economic costs or with a risk to the health of the patient).
2. Ability to clearly contrast(the isotope mainly accumulates in the target organ), despite the low resolution of the method.
3. Relative non-invasiveness radioisotope studies (a radioactive isotope is administered parenterally or orally).

2. What are the main disadvantages of radioisotope studies in comparison with other radiological studies.

1. Resolution of the method (1-2 cm) is lower than the resolution of other imaging methods.
2. Performing a radioisotope scan takes a long time, sometimes 1 hour or even more.
3. Exposure risk significantly higher than with magnetic resonance imaging or ultrasound scanning. However, compared with plain radiography or computed tomography, the risk of radiation exposure to patients using most methods of radioisotope scanning is not greater, and sometimes even less (exceptions are studies with the introduction of leukocytes labeled with gallium-67 or indium-Ill: in these studies, the risk of radiation exposure is 2 -4 times higher than for all other radioisotope studies). In some studies, such as the rate of gastric emptying and the time of passage of food through the esophagus, the risk of radiation exposure is less significant than the risk of radiation exposure in fluoroscopy.
4. Availability of the method is limited, since radioisotope studies require the availability of radiopharmaceuticals, as well as specialists capable of correctly interpreting the results. There are no such drugs and specialists in many treatment and diagnostic centers.

3. What radioisotope studies are the most informative when examining patients with diseases of the gastrointestinal tract?

Radioisotope studies can be used to examine patients with almost any disease gastrointestinal tract. However, the improvement and widespread use of endoscopy, manometry, pH monitoring, and other instrumental research methods somewhat limit the scope of radioisotope studies, which are used only in some specific clinical situations.

The use of radioisotope studies for the diagnosis of diseases of the gastrointestinal tract

RESEARCH METHOD	IN WHAT CASES IS IT USED
Cholescintigraphy (visualization of the liver and biliary system)	Acute cholecystitis Biliary dyskinesia Impaired patency of the common bile duct Atresia bile ducts Dysfunction of the sphincter of Oddi Infiltrative neoplasms Leakage of bile into the abdominal cavity Checking the functioning of biliodigestive anastomoses Checking the functioning of the afferent bowel loop after gastroenterostomy
Determination of gastric emptying rate	Quantification of motor activity of the stomach
Assessment of motor activity of the esophagus	Determination of transit time of food through the esophagus Detection and assessment of gastroesophageal reflux Detection of aspiration

RESEARCH METHOD	IN WHAT CASES IS IT USED
Liver/spleen scan	Volumetric lesions of the liver Accessory spleen
Scanning with the introduction of labeled erythrocytes destroyed during heat treatment	Accessory spleen
Scanning with the introduction of gallium	Staging of many malignant tumors Abdominal abscesses
	Neural crest tumors
Scanning with the introduction of 111 In-satumomab	Staging colon tumors
Scanning with the introduction of leukocytes labeled with 111 In	Identification of purulent-infectious foci and abscesses in the abdominal cavity
Scanning with the introduction of leukocytes labeled with 99m Tc-HM-PAO	Determination of the localization of the active inflammatory process in the intestine
Scanning with the introduction of erythrocytes labeled with "Tc	Determination of localization of bleeding in the gastrointestinal tract Identification of liver hemangiomas
Scanning with the introduction of pertechnetate	Identification of Meckel's diverticulum Identification of the unremoved mucous membrane of the antrum of the stomach after its resection
Scanning with the introduction of colloidal sulfur	Determining the location of bleeding in the gastrointestinal tract
Examination of the peritoneal-venous shunt	Study of the functional viability of peritoneal-venous shunts
Assessment of blood flow in the hepatic artery	Examination of the area supplied by the hepatic artery
Schilling test	Vitamin B12 malabsorption

Note. MIBG - t-iodobenzylguanidine; HM-PAO - hexamethylpropyleneamine oxime.

4. How is cholescintigraphy performed (visualization of the biliary system)? What is the normal scintigraphic picture?

The methodology for conducting a standard cholescintigraphic examination is practically the same regardless of clinical indications (see question 3). The patient is parenterally injected with preparations of imidodiacetylic acid labeled with technetium-99m. Currently, the most commonly used radiopharmaceuticals are DISHIDA, mebrofenin, and HIDA (hepato-IDA), with the latter name being generic for all of these drugs. Despite the fact that these drugs are metabolized in the same way as bilirubin, they can be used for diagnostic purposes even at very high concentrations of bilirubin in the blood (more than 200 mg / l).
After the injection of the drug, scanning begins. Each individual scan lasts 1 min, and the total duration of the study is 60 min or a little more. Normally, imidodiacetylic acid preparations are rapidly excreted by the liver. When an image of normal intensity is obtained, the activity of the blood pool in the heart weakens rather quickly and is practically not detected already 5 minutes after the injection. Long-term maintenance of blood pool activity and poor absorption of the drug by the liver indicate hepatocellular insufficiency. The left and right hepatic ducts are often, though not always, visualized within 10 minutes of drug administration, and the common bile duct and small intestine within 20 minutes. Usually the gallbladder also becomes visible by this time, and normally its image can persist for 1 hour after the administration of the drug to patients who have not eaten for 4 hours. After 1 hour, the maximum activity of the drug is recorded in the bile ducts, gallbladder and intestine , and the minimum - in the liver (the activity of the drug in the liver may not be determined at all).
If all of the above studies (see question 3) fail to image the organ of interest after 1 hour (for example, the gallbladder in acute cholecystitis, the small intestine in bile duct atresia), it is necessary to repeat the scan within 4 hours. Sometimes after the initial A 60-minute study is administered with syncalide or morphine, and then the study is continued for another 30-60 minutes.

5. How should a patient with acute cholecystitis be prepared for examination? What measures should be taken to shorten the time of the study and increase its reliability?

Traditionally acute cholecystitis is diagnosed on the basis of insufficient filling of the gallbladder (usually associated with the presence of a cystic duct stone) detected during functional cholescintigraphy at the initial 60-minute study and at a further 4-hour imaging (positive study). All preparatory procedures are performed to ensure that there is no doubt that poor visualization of the gallbladder is a true positive result, as well as to shorten the time of the study, which is sometimes extremely tiring for patients. Since food is a potential long-acting stimulator of endogenous cholecystokinin release and subsequent gallbladder contraction, Patients should abstain from eating for 4 hours before the start of the study; otherwise, the study may give false positive result. Prolonged fasting contributes to an increase in the viscosity of bile in an unchanged gallbladder, which can make it difficult to fill it with a radiopharmaceutical and cause false positive results. Most clinicians currently use fast-acting cholecystokinin analogs such as syncalide. Syncalide is administered at a dose of 0.01-0.04 μg/kg intravenously for more than 3 minutes 30 minutes before cholescintigraphy, when the patient has been fasting for more than 24 hours, when overeating or in severe disease.
Despite taking all the above measures, the gallbladder may remain unfilled even by the time the 60-minute cholescintigraphic examination is completed. If within 60 minutes the gallbladder is not visualized, but the intestine is well visualized, it is advisable to administer intravenously morphine at a dose of 0.01 mcg/kg; after the introduction of morphine, an additional study should be carried out within 30 minutes. Since morphine causes contraction of the sphincter of Oddi, when it is administered, the pressure in the biliary system increases and the functional obstruction of the cystic duct is resolved. If the image of the gallbladder does not appear after this, there is no longer any point in continuing the study, since it becomes obvious that the patient has acute cholecystitis (see figure). Some physicians believe that the simultaneous administration of syncalide and morphine can lead to perforation of the gangrenous gallbladder, but this complication has not yet been described.

Acute cholecystitis. Examination of the liver and biliary system, started 5 minutes after the injection of 99m Tc-mebrofenin, reflects the rapid uptake of the drug by the liver and its rapid excretion into the common bile duct and small intestine. Note the absence of the gallbladder (the arrow indicates the normal location of the gallbladder). After intravenous administration of 1 mg of morphine, gallbladder filling was not detected with an additional 30-minute imaging. Instead of using the described technique with the introduction of morphine, a 4-hour delayed study can be performed, but this only delays the study, which is not necessary.

6. Should liver and biliary tract scintigraphy be performed in patients with suspected acute cholecystitis?

Liver and biliary tract scintigraphy is the most exact method diagnosis of acute cholecystitis. The sensitivity and specificity of this method are 95 %. However, this method should not be used in all patients suspected of having acute cholecystitis. If, for example, the likelihood of having acute cholecystitis is low (less than 10%), then a positive result in low-risk groups (based on screening) is most likely a false positive. If the probability of having acute cholecystitis is high (more than 90%), then negative result studies in high-risk groups appear to be false negatives. When examining some patients, such as patients with acalculous cholecystitis or obesity, and those with extremely severe clinical form diseases, doctors often get false positive results, and therefore the results of scintigraphy should only be evaluated in conjunction with ultrasound data or computed tomography.

7. How is cholescintigraphy used to diagnose and treat patients with bile leakage into the abdominal cavity?

The cholescintigraphic method is characterized by high sensitivity and specificity in detecting bile leakage into the abdominal cavity (see figure). Since fluid collections outside the biliary tract often occur after surgery, the specificity of various anatomical studies is low. Cholescintigraphy has a low resolution and therefore does not allow you to accurately determine the localization of the bile outflow zone; endoscopic retrograde cholangiopancreatography (ERCP) may be required to accurately locate the bile leak. A cholescintigraphy may also be used to confirm that a bile leak has been corrected.

Leakage of bile into the abdominal cavity. The patient after percutaneous liver biopsy developed severe pain in the right upper quadrant of the abdomen. Ultrasound scanning did not reveal the cause of these pains. Radioisotope scanning with the introduction of 99mTc-mebrofenin revealed a thin rim of bile along the lower and lateral edges of the liver (large arrow). The early filling of the gallbladder (small arrow) and the absence of bile in the small intestine were noted.

8. On the basis of what signs is obstruction of the common bile duct diagnosed during cholescintigraphy?

Dilated bile ducts on ultrasound scan may be a non-specific finding in patients undergoing surgical operation on the biliary tract, and, conversely, acute blockage of the bile ducts (occurring less than 24-48 hours before ultrasound) may not be accompanied by their expansion. When the common bile duct is obstructed, the gallbladder and small intestine are not visualized during cholescintigraphy, the bile ducts are often not visualized even during a delayed 4-hour study. The sensitivity and specificity of this method in detecting obstruction of the common bile duct is very high (see figure). The results of cholescintigraphy are reliable even at high concentrations of bilirubin. This method can be used for differential diagnosis between mechanical and non-mechanical jaundice.

Blockage of the common bile duct. After injection of a drug that accumulates in the liver and biliary system, the intrahepatic bile ducts and small intestine are not visualized during the 10-minute (A) and 2-hour (B) studies. Ultrasound scanning did not reveal dilatation of the bile ducts and stones in the common bile duct, most common cause his blockages. The appearance of a "hot zone", visualized to the left of the liver, is due to the excretion of the drug in the urine (this is an alternative way to remove the drug from the body)

9. How can sphincter of Oddi dysfunction be detected using cholescintigraphy?

A significant number of patients complain of abdominal pain after cholescintigraphy; The cause of such pain is often dysfunction of the sphincter of Oddi. Performing manometry during ERCP is sufficient to make a diagnosis, but this study is invasive and often entails various complications. Currently, an empirical scintigraphic scale is often used, which allows quantification of bile flow and liver function. It has been proven that there is a close correlation between the results of cholescintigraphy and the results of a manometric study of the sphincter of Oddi.

10. What is the role of cholescintigraphy in the diagnosis of bile duct atresia?

Cholescintigraphy is a rather sensitive and highly specific method, which, with appropriate preparation of the patient, makes it possible to diagnose bile duct atresia. The main symptom of bile duct atresia is the presence of severe hepatitis in newborns. Ultrasound scanning in this case is uninformative: it allows you to detect the expansion of the bile ducts, but with atresia, the expansion of the ducts is usually absent. The main disadvantage of scintigraphy is the high probability of obtaining false positive results due to insufficient bile secretion in severe forms of hepatitis. To eliminate this deficiency, premedication is performed: phenobarbital is administered orally at a dose of 5 mg Dkgxday) for 5 days, which stimulates the secretion of bile. At the same time, the importance of determining the concentration of phenobarbital in the blood serum cannot be underestimated. If the small intestine is visualized on delayed cholescintigraphy, biliary atresia can be ruled out (see figure).

Hepatitis in a newborn with presumed bile duct atresia. In order to confirm this complex diagnosis, the patient is given a drug that enters the liver and biliary system. In this case, after a 5-day course of phenobarbital, the patient was parenterally injected with 99m Tc-mebrofenin. Note that 2 hours after isotope administration, blood pool activity in the heart and signs of drug excretion into the gallbladder (B) are determined, suggesting the presence of hepatocellular insufficiency and impaired excretion of the drug, which is mainly excreted in the urine. During the 4-hour study, foci of insignificant activity of the drug (arrows) in the abdominal cavity are determined, which may be due to the ingestion of the drug into the intestine or its excretion in the urine. When conducting a 24-hour study with bladder catheterization, abnormally low activity of the drug is detected in the lower left quadrant of the abdominal cavity (arrow), below and lateral to the liver (L), which indicates that the drug has entered the intestine and excludes bile duct atresia

11. In what cases is it advisable to use cholescintigraphy when examining patients with impaired patency of the gastrointestinal anastomosis?

The adductor (afferent) loop of the intestine is very difficult to examine using fluoroscopy, since it (the adductor loop) has to be filled antegradely with barium suspension. Cholescintigraphy allows, with a high degree of accuracy, to exclude a violation of the patency of the afferent loop of the intestine in the case when the activity of the drug in both the afferent and the outlet loop of the intestine is determined 1 hour after the parenteral administration of the radiopharmacological drug. Violation of the patency of gastrojejunostomy is diagnosed when accumulation of a radiopharmacological drug in the afferent loop of the intestine is detected in combination with the entry of this drug into the outlet loop after 2 hours.

12. What is gallbladder dyskinesia? How is a cholescin-tigraphic study of the evacuation function of the gallbladder performed?

A significant number of patients in whom no changes in the gallbladder are detected during clinical and instrumental studies suffer from pain associated with dysfunction of the gallbladder. The severity of symptoms in these patients improves after cholecystectomy. The origin of these pains may be based on several yet insufficiently studied pathological conditions, which are commonly combined under common name"biliary dyskinesia". It is believed that the basis of biliary dyskinesia is a violation of the coordination of contractions of the gallbladder and cystic duct. As a result of this violation, pain occurs. It has been established that with biliary dyskinesia, an abnormally small amount of bile is secreted when stimulated with cholecystokinin (syncalide).
After filling the gallbladder, in order to stimulate its contraction, syncalide is administered at a dose of 0.01 μg/kg for 30-45 minutes. The amount of bile excreted gallbladder in 30 min is the ejection fraction of the gallbladder. This fraction is normally 35-40% of the capacity of the gallbladder. Cholescintigraphy with the introduction of syncalide is a highly informative method that allows you to determine the ejection fraction of the gallbladder and, accordingly, to identify functional disorders.

13. What radioisotope method is used to determine the rate of gastric emptying?

It is possible to determine the rate of evacuation from the stomach of both liquid and solid contents using radioisotope studies. The rate of evacuation of fluid from the stomach is usually determined in children. A solution of colloidal sulfur labeled with technetium-99t is given to a child with milk or during a normal meal. Scanning is performed every 15 minutes for 1 hour, then the half-life of the drug is calculated. In adults, the rate of evacuation of solid food from the stomach is usually determined after an overnight fast. The patient eats scrambled eggs with sulfur labeled with technetium-99t, along with normal food, then in the anterior and posterior projections, scanning is performed every 15 minutes for 1.5 hours, followed by calculation of the percentage of the excreted drug. There are no standard diets, the results of the study depend on the composition of the breakfast. The patient is usually offered breakfast, energy value which is 300 calories. Breakfast includes scrambled eggs, bread and butter; while gastric emptying is 63% in 1 hour (± 11%).

14. In what clinical situations is it advisable to determine the rate of gastric emptying using radioisotope methods?

WITH symptoms associated with impaired gastric motility are rather non-specific, and X-ray examination using a barium suspension does not allow a quantitative assessment of the rate of gastric emptying; moreover, this study is non-physiological. Methods for determining the rate of gastric emptying are semi-quantitative, which greatly complicates the interpretation of the results. In addition, these techniques are not standardized. However, the determination of gastric emptying rate in certain groups of patients (for example, patients with diabetes mellitus and patients undergoing gastrectomy) can be very useful, as this method allows you to find out the origin of non-specific clinical symptoms (see figure).

Picture of normal gastric emptying. A. Initial image in the anterior (A) and posterior (P) projections after the patient has taken colloidal sulfur labeled with "Tc" with scrambled eggs and steak. Accumulation of the drug in the fundus of the stomach (F) in the posterior projection is detected, followed by its entry into the antral part of the stomach (an) B. After 90 minutes, a small amount of the drug remains in the fundus of the stomach, a significant amount of it accumulates in antrum stomach (an); in addition, the accumulation of the drug in small intestine(S). C. After 84.5 minutes, 50% of the food leaves the stomach (the norm is 35-60% for this food)

15. What radioisotope methods of examination of the esophagus exist and when should they be used?

IN clinical practice three radioisotope methods for examining the esophagus are used: the study of esophageal motility, the study of gastroesophageal reflux and the detection of pulmonary aspiration.
Study of esophageal motility. While the patient is swallowing water containing colloidal 99m Tc, the doctor is taking a series of sequential images of the esophagus. This study is quite accurate and allows you to quantify the indicators that reflect the functional state of the esophagus. The advantage of X-ray examination using a barium suspension is that it makes it possible to differentiate structural and functional disorders with high accuracy. However, radioisotope study of esophageal motility has its advantages - it is easy to perform and allows a non-invasive way to evaluate the effectiveness of treatment for disorders of esophageal motility and achalasia.
Examination of gastroesophageal reflux. This study takes a series of sequential images of the esophagus after the patient drinks orange juice containing colloidal Tc. The patient's abdomen is compressed with a special inflatable bandage. Although this method is less sensitive than 24-hour esophageal pH monitoring, its sensitivity is higher, than the sensitivity of fluoroscopy using barium suspension.This method is useful for screening patients or to evaluate the effectiveness of treatment for already established gastroesophageal reflux. Detection of pulmonary aspiration. This study is a visualization chest after the introduction per os colloidal 99mTc with water. Aspiration is diagnosed by detecting the activity of the drug in the projection of the lungs. Although the sensitivity of this method is rather low, it is still higher than the sensitivity of X-ray methods using contrast agents. In addition, the advantage of the radioisotope method is the ease of obtaining a series of consecutive images, which makes it possible to detect intermittent aspiration.

16. What role do radioisotope diagnostic methods play in the examination of patients with large liver masses?

Traditional scanning of the liver and spleen, during which a drug is injected intravenously that is captured by Kupffer cells, or a colloidal solution of sulfur or albumin labeled with 99mTc, can be replaced by ultrasound scanning or computed tomography, since these research methods have a higher resolution and allow assessing the condition of nearby organs and tissues. However, if it is impossible to make an accurate diagnosis, for example, in patients with fatty liver (see figure), it is advisable to perform a radioisotope functional scan.

Examination of volumetric formation in the liver. A. Computed tomography of the liver using a radiopaque substance revealed diffuse fatty infiltration liver and two areas with relatively normal view(circled), in a patient with colon cancer after treatment with 5-fluorouracil. Differential diagnosis should be made between nodular regeneration and liver metastases. C. When visualizing these pathological lesions in close-up in the anterior projection during cholescintigraphy, metastases appear as light filling defects (arrow). If such defects are not detected, then the detected volumetric formations are regeneration nodes. Focal nodular hyperplasia in traditional radioisotope scanning of the liver and spleen, it looks like an accumulation of "warm" or "hot" foci, since Kupffer cells predominate in the nodes, and looks like an accumulation of "cold" foci during functional cholescintigraphy, since there is an insufficient number of hepatocytes in the nodes. Focal nodular hyperplasia of the liver is characterized by a combination of these features. And vice versa, when liver adenomas, which mainly consist of hepatocytes, the identified masses appear "warm" or "hot" during cholescintigraphy and "cold" during traditional radioisotope scanning of the liver and spleen. This combination is also quite specific. Hepatomas also look "warm" or "cold" (but not "hot") on cholescintigraphy. The cells of the overwhelming majority of hepatomas have a high affinity for gallium-67 and actively accumulate it. This combination can also be considered highly specific, if we do not take into account the rare metastases of various tumors in the liver, which have an affinity for gallium (see table).

Differential diagnosis of volumetric formations of the liver, detected during radioisotope studies

	COLLOID SULFUR LABELED 99mTc	DELAYED IMAGING USED CALLING DRUGS TROPIC TO HEPATOCITES	ERYTHROCYTES LABELED 99mTc	GALLIUM-67
Adenoma	"Cold" lesions or reduced drug accumulation		Norm
Hepatoma	"Cold" spots	Decreased, normal, or increased drug accumulation	Decreased or normal drug accumulation	Normal or increased accumulation of the drug; a significant increase is a characteristic diagnostic sign *
Hemangiomga	"Cold" spots	"Cold" spots	A significant increase in the accumulation of the drug is a characteristic diagnostic sign	"Cold" spots
Metastases	"Cold" spots	"Cold" spots	Normal or slightly reduced accumulation of the drug	Decreased, normal or slightly increased accumulation of the drug
Focal nodular hyperplasia	Normal or increased drug accumulation	Decreased or normal drug accumulation	Norm	Norm

* An exception is liver metastases, which have an affinity for gallium.

17. What methods of radioisotope scanning allow diagnosing liver hemangiomas?

With the help of computed tomography, magnetic resonance imaging and ultrasound scanning, it is not always possible to diagnose liver hemangiomas. Delayed single-photon emission computed tomography (SPECT, a three-dimensional scintigraphic imaging, similar in many respects to CT), during which hemangiomas are filled with Tc-labeled red blood cells, is the most sensitive and specific method for diagnosing hemangiomas larger than 2.5 cm (see Fig. The probability of detecting small hemangiomas (less than 1 cm) during SPECT is also very high. This is due to the very high selectivity of drug accumulation in hemangiomas. Delayed SPECT is the method of choice in the diagnosis of liver hemangiomas. However, if hemangiomas are located near blood vessels, it can be difficult distinguish hemangiomas from vessels, in which case other imaging modalities should be used.Rarely, thrombosed hemangiomas and hemangiomas undergoing fibrotic degeneration are also very difficult to detect using SPECT.

Liver hemangioma. A. An ultrasound scan reveals a 3-cm hypoechoic mass, the appearance of which is characteristic of a hemangioma, but not specific enough. C. After 2 hours, during SPECT with the introduction of erythrocytes labeled with 99m Tc, a focus of increased accumulation of the radioisotope is determined in the lower parts of the right lobe of the liver during the reconstruction of sections in the axial and coronal planes (arrows). C. When performing contrast computed tomography, centripetal (afferent) filling of the nodes (arrow) is revealed, which allows confirming the diagnosis established during the study with the introduction of erythrocytes labeled with 99m Tc

18. Is it possible to detect ectopic gastric mucosa using radioisotope scanning methods?

It is the main source of gastrointestinal bleeding in children Meckel's diverticulum almost always contains the lining of the stomach. Since 99m Tc-pertechnetate selectively accumulates in the gastric mucosa, this drug is ideal for localizing sources of bleeding that are very difficult to detect using conventional X-ray contrast studies with the introduction of contrast agents. The research includes intravenous administration pertechnetate to the patient and scanning of the abdominal cavity after 45 minutes. Usually, the ectopic gastric mucosa is visualized simultaneously with the stomach and does not move during the study. The sensitivity of the method for detecting a bleeding Meckel's diverticulum is 85%. To increase the sensitivity of the method, cimetidine (to block the excretion of pertechnetate into the intestinal lumen) and / or glucagon (to suppress gastrointestinal motility and prevent washout of the drug) can be pre-administered to the patient. The same scanning technique can be used to detect unremoved mucous membrane of the antrum of the stomach after surgical intervention about chronic stomach ulcers; in this case, the sensitivity of the method is 73%, and the specificity is 100%.

19. How is the vitamin B12 absorption test (Schilling test) performed and when is it used?

The Schilling test allows you to examine the body's ability to absorb and excrete vitamin B 42. Since there are many causes of vitamin B 12 malabsorption, the study is carried out in stages, at each stage the most likely causes of vitamin B 12 deficiency are identified (or excluded). Although some clinicians in the treatment of patients with vitamin B 12 deficiency do not determine the cause of its development, determining the etiology of the disease is very important for many patients, as comorbidities or disorders that were not expected may be found.

There is no need (and even undesirable) to prescribe to a patient with severe vitamin B 12 deficiency his preparations before the Schilling test. At the first and all subsequent stages of the study, the patient is given regular (not radiolabeled) vitamin B 12, 1 mg intramuscularly to “bind” the corresponding receptors, and 2 hours after that, the patient takes vitamin B 12 labeled with radioactive cobalt with food. The necessary conditions for a successful study are the abstinence of the patient from eating for 3 hours before and after taking a radioactive preparation of vitamin B 12 (to avoid the binding of labeled vitamin B 12 with food) and the collection of all excreted urine within 24-48 hours after the administration of the drug. The concentration of creatinine in the urine and daily diuresis are determined. Decreased creatinine content in the daily volume of urine may indicate improper collection of urine for analysis, which artificially reduces the amount of vitamin B 12 excreted in the urine. In the collected urine, radioactive cobalt is detected. Normally, less than 10% of the dose of radioactive cobalt taken orally is excreted in 24 hours. If the release of the vitamin IN 12 within 24 hours is within the normal range, which indicates its normal absorption in the gastrointestinal tract.
If any pathology is detected at the first stage of the study, they proceed to the second stage. At the second stage of the study, the same actions are performed as at the first, except that, together with a radioactive preparation of vitamin B 12, the patient takes internal factor. The third stage has several modifications. The choice of modification depends on the etiology of malabsorption of vitamin B 12 assumed on the basis of clinical data (see figure). The detection of normal release of vitamin B 12 at the second stage in the presence of changes detected at the first stage indicates the presence of pernicious anemia.

Algorithm for determining the etiology of vitamin B12 deficiency

20. Can an accessory spleen be detected using radioisotope scanning methods?

The ineffectiveness of splenectomy performed in connection with idiopathic thrombocytopenia may be due to the fact that the patient has an accessory spleen.
Such an undetected accessory spleen may be the cause of abdominal pain. To establish the localization of small areas of the splenic tissue, it is most advisable to perform scanning with the introduction of labeled 99m Ts erythrocytes, which have been subjected to heat treatment, since damaged red blood cells selectively accumulate in the tissue of the spleen. This scanning technique is the method of choice, especially when performing SPECT. However, special heat treatment of erythrocytes can be performed only in specialized laboratories, and therefore this method is not used in every diagnostic and treatment center. As a method of primary examination, as a rule, traditional scanning of the liver and spleen is used. If an accessory spleen is found, appropriate therapy is performed (see figure). If an additional spleen is not detected during scanning of the liver and spleen, a study is performed with the introduction of radiolabeled erythrocytes subjected to heat treatment.

Accessory spleen in a patient who underwent splenectomy for idiopathic thrombocytopenic purpura. The extremely high degree of contrast achieved with the introduction of colloidal sulfur labeled with 99m Tc makes it possible to visualize even small areas of the spleen tissue (arrow) and remove them in the future. Shown are images obtained by scanning in the left anterior oblique (LAO) and posterior (PST) projections. If a negative result is obtained during a study with the introduction of colloidal sulfur labeled with radioactive technetium, it is advisable to conduct a high-contrast special study, for example, a scan with the introduction of labeled erythrocytes subjected to heat treatment, which selectively accumulate mainly in the spleen, which allows in most cases to establish the presence of an additional spleen

21. What radioisotope scanning methods can be used to examine patients with inflammatory bowel diseases and abdominal abscesses?

To detect infectious-purulent foci in the abdominal cavity, scanning is used with the introduction of gallium-67, leukocytes labeled with 99m Tc-HMPAO, and leukocytes labeled with indium-111.
Gallium-67 normally excreted into the intestine, a small amount of 99m Tc-HMPAO from leukocytes also enters the intestine; therefore, these drugs are less effective in detecting inflammatory foci in the abdominal cavity. When scanning with the introduction of gallium-67, it may be necessary to perform similar studies during the week to assess intestinal motility. In this case, foci of inflammation in the abdominal cavity can be identified quite clearly. The disadvantages of scanning with the introduction of gallium-67 are offset by the relatively low cost of this study. Despite the high radiation exposure (equivalent to radiation exposure when performing 2-4 computed tomography of the abdominal cavity), this method is used quite often. Studies with the introduction of leukocytes labeled with 99m Tc-HMPAO and 111 In are more expensive and require special equipment.
Scanning with the introduction of leukocytes labeled 111 In, which normally accumulate only in the liver, spleen and bone marrow, is the method of choice when establishing localization purulent-infectious foci in the abdominal cavity in cases where computed tomography, magnetic resonance imaging and ultrasound scanning do not allow a diagnosis. Normally, leukocytes are also absorbed by the liver and spleen, therefore, to obtain a clear picture, an isotope scan is additionally performed with the introduction of colloidal sulfur labeled with "Tc (traditional scan of the liver and spleen). Abscesses of the liver and spleen look like "cold" foci on conventional scanning of the liver and spleen and the appearance of "hot" foci when scanning with the introduction of leukocytes labeled with 111 In The disadvantage of the method is also the need for a delayed scan after 24 hours to obtain the most reliable picture.Within 1 hour after parenteral administration of leukocytes labeled with 99m Tc-HMPAO, the scan data are clearly correlate with the severity of the inflammatory process. inflammation in the intestine coincides with the localization of these foci, determined during other visualization studies. Therefore, this scanning method can be used for non-invasive monitoring. It is preferable to use 111 In-labeled leukocytes as a radiopharmacological preparation because this method is the most sensitive and its use is associated with the lowest radiation exposure.

22. Is it advisable to use radioisotope scanning methods when placing catheters for arterial perfusion?

Placement of arterial catheters providing hepatic perfusion is often difficult due to the inadvertent discovery of undiagnosed systemic shunts, catheter displacement, and the inevitable concomitant perfusion of areas in which it is undesirable to create a high concentration of highly toxic chemotherapeutic drugs. The introduction of macroaggregated albumin (MAA) labeled with 99m Tc into the catheter causes microembolization at the level of arterioles and makes it possible to obtain an image that can be used to judge the area of the perfusion site, especially when using SPECT. Using this technique, it is impossible to obtain reliable results when using a radiopaque substance, since it is rapidly diluted at the level of arterioles.

23. Is it advisable to use radioisotope scanning methods when establishing the localization of the source of gastrointestinal bleeding, or is simpler methods sufficient in this case?

Scanning with the introduction of erythrocytes labeled with 99m Tc, in detecting transient bleeding, is in most cases more sensitive than angiography (see figure). Previously, there was a rule that identification of the source of gastrointestinal bleeding using radioisotope scanning methods should always be performed as a screening method and precede angiography. At present, this rule is not always followed. However, when establishing the localization of the source of bleeding, radioisotope scanning can be useful in many cases. Knowing the advantages and disadvantages of all methods, a specialist can choose the most appropriate study in each case.

Bleeding from the small intestine. After an unsuccessful endoscopic examination against the background of ongoing bleeding, the patient underwent a radioisotope scan with the introduction of Tc-labeled erythrocytes, as a result of which it was possible to detect the source of bleeding, visualized near the spleen (large arrow). small intestine (small arrows) towards the lower right quadrant of the abdomen These findings confirmed that the source of bleeding was in the small intestine During surgery, the source of bleeding was found to be a low ulcer duodenum. (B - bladder; AC - ascending colon)

24. What radioisotope scanning methods should be used to identify the source of bleeding from the lower gastrointestinal tract?

It is well known that the localization of the source of acute bleeding from the lower gastrointestinal tract is associated with significant difficulties. Precise definition the cause of the bleeding is often irrelevant to the production medical tactics, since treatment in any case involves resection of a section of the colon. Even acute and intense bleeding is often transient and therefore often not detected during angiography; in such cases, bleeding is diagnosed by the presence of blood in the lumen of the intestine, detected during endoscopic examination. It is quite difficult to identify the source of bleeding, localized in distal parts the small intestine, inaccessible to the endoscope.
Currently, two methods are used to localize the source of bleeding from the gastrointestinal tract: short-term scanning after the introduction of a colloid labeled with 99m Tc, and long-term scanning after the administration of erythrocytes labeled with 99m Tc Despite the theoretical advantages of using a colloid solution with 99m Tc in detecting small bleeding, this method has a limitation characteristic of angiography associated with the residence time of the drug in the bloodstream (several minutes). Scanning with the introduction of erythrocytes labeled with 99m Tc is a more preferable method, since the injected drug remains in the bloodstream for a long time (this time is determined by the half-life of the radioactive isotope), which, during long-term scanning, makes it possible to detect accumulations of radioactive blood in the intestinal lumen.
This technique has become widely used since in vitro technetium-99t-labeled erythrocytes were obtained. Development of a method for obtaining labeled cells in vitro was of great importance, because inadequate labeling of erythrocytes in vivo may be the cause of artifacts associated with the release of red blood cells through the stomach and urine. The patient is injected with labeled radioactive isotopes erythrocytes, after which a series of sequential computer images are obtained. The study takes 90 minutes or more. When using a computer, the sensitivity of this method in determining the localization of the source of bleeding is higher than when using a kinetoscope.

25. How to assess the functional viability of a peritoneal-venous shunt using radioisotope scanning methods?

When increasing the volume of the abdomen in patients with a peritoneal-venous shunt (LeVeen or Denver), first of all, the functional viability of the shunt should be assessed, since the amount of fluid in the abdominal cavity may increase as a result of a violation of the patency of the shunt. If the shunt is made of X-ray negative material, radiographic studies cannot be used, and in any case, the shunt should be catheterized to perform such studies. Since the fluid flows through the shunt in only one direction, it is very difficult to assess the functional viability of the shunt with retrograde administration of a contrast agent. The integrity of the shunt can be assessed with intraperitoneal injection of 99m Tc-MAA followed by a chest scan 30 min later. At the same time, the shunt itself may not be visualized, but the penetration of 99m Tc-MAA into the arterioles of the lungs is determined, which indicates the patency of the shunt.

There are "blind" areas around the liver and spleen This method does not allow to localize the source of transient bleeding without numerous repeated injections

Scanning with the introduction of erythrocytes labeled99m Tc

The most sensitive method in identifying sources of transient bleeding This method allows you to perform several scans during the day

Relatively non-invasive method

The process of labeling erythrocytes is long (20-45 minutes) Repeated scanning does not allow to accurately determine the localization of the source of bleeding, since the blood in the intestinal lumen moves quickly There are "blind" areas around the liver and spleen

Angiography

This method can be used for treatment (administration of vasopressin, Gelfoam)

The method is insensitive if the bleeding is not intense during the administration of the contrast agent Invasive method

26. Is it possible to detect malignant neoplasms in the abdominal cavity using radioisotope scanning methods?

Gallium-67 is traditionally considered a non-specific marker of neoplasms and infectious foci. This isotope is used when the presence of malignant tumor. This method does not allow to determine the stage of tumor development, but it is useful in cases where it is necessary to find out if there have been recurrences of hepatoma, Hodgkin's and non-Hodgkin's lymphomas, since it is quite difficult to distinguish necrosis and cicatricial changes from tumor recurrence during anatomical studies. Difficulties in using this method are due to varying degrees of absorption of the drug by tumors and the release of the drug into the lumen of the colon. The main difficulty lies in differentiating the manifestations of the functional activity of the unchanged intestine from the manifestations of the functional activity of tumor cells. For this, SPECT is used, and studies are carried out within a week (during this time, gallium-67 is removed from the intestinal lumen).
The recently developed 111 In-pentreotide and 131 I-MIBG preparations for imaging of neural crest tumors open up new possibilities for studying these tumors, which are extremely difficult to detect. Scanning with the introduction of 131 I-MIBG, which is an analogue of dopamine, is especially informative as an adjunct to computed tomography and magnetic resonance imaging in the detection of carcinoid tumors, neuroblastomas, paraganglia and pheochromocytoma. Scanning with the introduction of 111 In-octreotide, which is an analog of somatostatin, is also highly sensitive and specific for the detection of neural crest tumors. When using this method, latent pathology is often detected that is not diagnosed using other imaging methods, a preliminary diagnosis based on computed tomography and magnetic resonance imaging is often confirmed, gastrinoma, glucagonoma, paraganglioma, pheochromocytoma, carcinoid, Hodgkins and non-Hodgkins are diagnosed. lymphomas.
Recently received radiolabeled antibodies 111 In-satumomab. Their use has proved to be extremely effective in examining patients with elevated levels of carcinoembryonic antigen and colon cancer, which is not detected using other methods; patients who have a tumor recurrence; Patients with questionable results during routine testing. Scanning with 111 In-satumomab often reveals hidden diseases. In addition, the data obtained using this method greatly influence the treatment of most patients with primary colon tumors and their recurrences.