Instrumental diagnosis of tuberculosis

Despite the abundance of various methods of examining patients, timely diagnosis of tuberculosis of the respiratory organs remains a difficult clinical problem. Errors in recognizing tuberculosis and other, even the most common, diseases of the respiratory organs are uniform and characteristic. Their causes are not as obvious as is commonly believed. It is not only a matter of insufficient education or lack of practical skills among doctors: diagnosis of lung diseases is a complex clinical problem due to compelling objective reasons.

First of all, this is the clinical universality of the symptoms accompanying lung diseases: the clinical picture of the most diverse diseases in genesis always consists of a combination of respiratory and intoxication complaints. At the same time, all lung diseases are very diverse in possible course options and can proceed both rapidly and gradually, torpidly, which is largely due to the characteristics of the patient's body, the nature of his reactivity. Similar mechanisms of the pathogenesis of respiratory disorders in most lung diseases also complicate diagnosis. However, it is often overlooked that behind each name of the nosological form there are quite characteristic morphological manifestations of the disease - tissue reactions that determine the genesis of clinical disorders. Only by taking into account the relationship between the morphological basis of the disease and the existing clinical manifestations is it possible to reliably diagnose pulmonary pathology.

In this regard, it is necessary to standardize diagnostic studies and carefully monitor the full implementation of diagnostic procedures: develop principles of differential diagnostics of lung diseases based on modern research methods available to a wide range of practical phthisiology and pulmonology institutions and relying on a unified clinical and morphological approach to assessing the changes detected.

Modern clinical diagnosis is a complex system of concepts that determines the fate of a patient with tuberculosis for a long time. The diagnosis of tuberculosis performs registration-statistical, epidemiological, clinical and prognostic functions. This predetermines the complexity of the patient's examination, since even the most informative research method does not immediately answer all the questions that require a solution. At the same time, there is a sequence in solving clinical problems, which determines a clear scheme for examining the patient. Components of the modern diagnosis of tuberculosis

• nosological diagnosis.
• medical history,
• clinical form,
• localization and duration of the process,
• complications,
• functional disorders,
• background diseases,
• contagiousness of the patient (bacterial excretion).
• properties of the pathogen, primarily drug sensitivity.

Tuberculosis diagnostics today has a wide range of research methods. This is due to the very nature of tuberculosis - a disease with a complex pathogenesis, polymorphism of manifestations, passing through several stages in its development. Each of the methods has organizational, medical, economic and psychological limitations, so singling out only one of them as the main one can cause great harm, since in this case a significant portion of patients for whom this method is obviously ineffective falls out of the doctor's field of vision.

Identification of changes in organs and tissues characteristic of tuberculosis

• Indirect methods:
  • History and physical examination:
  • biochemical studies;
  • functional studies.
• Direct methods - visualization of structural changes:
  • in tissues - morphological diagnostics;
  • in organs - radiation diagnostics.

Detection of the tuberculosis pathogen

• Indirect methods:
  • tuberculin diagnostics;
  • determination of anti-tuberculosis antibodies;
  • study of the release of γ-interferon under the influence of specific antigens of M. tuberculosis.
• Direct methods:
  • bacterioscopic diagnostics;
  • bacteriological diagnostics;
  • determination of M. tuberculosis antigens;
  • molecular biological methods.

All methods of diagnosing tuberculosis can be divided into two groups. The first, common to all diseases, includes methods based on determining certain changes in the body characteristic of a given disease. For tuberculosis, direct methods of this type are morphological and radiation methods, indirect methods are classical methods of direct examination of the patient, various laboratory studies (clinical, biochemical, some immunological, etc.). methods of functional diagnostics.

The second group, used only for infectious diseases, consists of methods aimed at finding and identifying the pathogen. These can be either direct methods, such as microscopy of diagnostic material, isolation of a culture of microorganisms, or methods that allow one to determine its presence in the body indirectly (for example, by the presence of specific antibodies).

It is obvious that the diagnostic value of indirect and direct methods is not equivalent. However, the scope of application of each of them is quite defined and corresponds to certain diagnostic tasks.

It is necessary to emphasize that it is necessary to distinguish between the diagnostic methods we are talking about and the methods of obtaining diagnostic material. Thus, the study of lavage fluid obtained during bronchoscopy can be carried out by immunological, biochemical, cytological methods; the study of a biopsy of a peripheral lymph node - by histological and microbiological methods, etc.

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Stages of lung disease diagnostics

The purpose of the primary comprehensive examination of the patient, conducted after detecting changes in the lung tissue, is to establish a presumptive diagnosis or, at least, to narrow the range of differentiated diseases to two or three. At this stage of the examination, the degree of functional disorders should also be determined and background diseases that can influence the choice of treatment tactics and/or limit the use of diagnostic methods of the second stage should be identified. This set of studies can be carried out both in inpatient and outpatient settings. The duration of the primary stage of the examination, taking into account the time required to prepare histological preparations of transbronchial lung biopsy, should not exceed 10-14 days.

If diagnostic difficulties persist after the first stage of examination, it is necessary to move on to more complex technical methods that are less accessible to practical medical institutions, more expensive and often more burdensome for the patient, and therefore their use must be individualized.

Radiological diagnostics of tuberculosis of the respiratory organs

After V.K. Roentgen's discovery of X-rays, for over 70 years the only radiation method for diagnosing tuberculosis was radiological. Three generations of phthisiologists, radiologists and morphologists meticulously studied the clinical and radiological picture and drew radiological and morphological parallels in tuberculosis of various organs and systems. The active introduction into clinical practice (in the mid-1970s) of computed tomography (CT), ultrasound, and a little later magnetic resonance imaging (MRI), modern radionuclide diagnostics brought radiation diagnostics of all forms and stages of tuberculosis to a new qualitative stage. As a result, a new specialty was created - radiation diagnostics of tuberculosis. This was done despite the fact that not all new technologies are based on the use of X-rays. The different nature of X-rays or ultrasound was not reduced to a single denominator, but a medical image on a display screen. According to the WHO definition, a medical image is a set of images of internal organs obtained by using electromagnetic waves or other elastic vibrations. This image is obtained by the most common research methods - X-ray, radionuclide, ultrasound, magnetic resonance, thermographic.

A doctor with good basic training in X-ray radiology will undoubtedly be more effective in mastering the entire range of diagnostic technologies. The process of fragmentation of specialties in the field of diagnostic radiology can lead to organizational disunity, due to which the comprehensive rational approach to the use of all means of radiation diagnostics in various situations suffers, and, consequently, diagnostics as a whole suffers. The clinician must understand that it is not at all necessary to use the entire arsenal of very expensive technologies to make a diagnosis, and the prerogative of determining the shortest path to achieving the goal should be within the competence of representatives of radiation diagnostics.

Until recently, fluorography (photographing an image from an X-ray screen onto film) was used to identify individuals with suspicious changes in the respiratory system during mass population screening. Depending on the device, frames measuring 70x70 mm or 100x100 mm were obtained. The method has high productivity, but has a number of technical limitations (in particular, it does not display small pathological formations clearly enough). Therefore, it was impossible to accurately diagnose tuberculosis based on it; additional radiation examination was required. With the introduction of digital fluorography, such capabilities as a wide dynamic range and high contrast sensitivity, the possibility of computer image processing became available, allowing reliable detection of even minor changes in biological tissues of varying density. At the same time, the radiation load on the patient was reduced by 10 or more times compared to standard film fluorography and by 2-3 times compared to large-format radiography. The effectiveness of the method is determined by the speed of image acquisition (several seconds), the complete absence of image defects (8-15% with film fluorography), the exclusion of the use of expensive photographic film, photo laboratory equipment and reagents, and the reliability of archiving the results.

Radiography is the main primary radiation method for confirming the diagnosis of tuberculosis of the respiratory organs. The method, if the technical requirements are met, is highly standardized, allows for visual and quick presentation and reliable archiving of the results of the study. Another advantage is the relative cheapness of the study with high information content. In some patients, the method provides information sufficient to establish a diagnosis.

To clarify the nature of the changes revealed by radiography, X-ray (longitudinal) tomography is used - obtaining layer-by-layer images of lung tissue and mediastinal organs, which allows for a more precise definition of the structure of pathological changes.

Based on radiographic and tomographic data, a concept of the "leading radiographic syndrome" has been formed, within which differential diagnostics of various clinical forms of respiratory tuberculosis is carried out. These same methods serve to determine the dynamics of tuberculosis changes during treatment, and their results are one of the criteria for the effectiveness of the course of therapy (resorption of infiltration, closure of the decay cavity).

X-ray is not used to detect and diagnose tuberculosis of the respiratory organs. However, the possibility of multi-position and multi-projection examination, carried out in direct contact with the patient, allowed it to retain the value of an additional method, especially when there is a suspicion of fluid or air in the pleural cavity. The introduction of electron-optical converters, video recording devices made it possible to reduce the radiation load, so the method is widely used as an auxiliary method in puncture and endoscopic biopsies, as well as for the functional assessment of the respiratory organs.

Computer tomography

The rapid development of CT allows us to talk about a new stage in X-ray diagnostics of tuberculosis of all localizations. Computer tomography is a fundamental method of radiation diagnostics of respiratory diseases, especially in recognizing fine morphological structures. CT is given an important and in many cases the main place in the complex diagnostics of tuberculosis of the chest organs.

The method allows to establish the localization, extent, and complications of the tuberculosis process without increasing the radiation load. At the same time, the spiral scanning technology makes it possible to construct three-dimensional images of the structures being examined, including areas hidden from classical radiology. It is possible to reliably determine the density of pathological changes with a high degree of resolution and avoid the summation effect. The introduction of CT has led to a change in the diagnostic algorithm: when examining the lungs, they are limited to a direct radiograph and CT of the chest. When using CT, the need for many complex invasive diagnostic techniques is reduced.

Indications

Indications for computed tomography in children with primary tuberculosis:

• infection of children at risk with Mycobacterium tuberculosis;
• "minor" form of tuberculosis of the intrathoracic lymph nodes for the purpose of visualizing adenopathy;
• determination of the localization of the process, prevalence, structure of nodes, condition of surrounding tissues;
• clarification of signs of activity of the primary tuberculosis complex and tuberculosis of the intrathoracic lymph nodes;
• drug-negative tuberculosis of the intrathoracic lymph nodes and primary tuberculosis complex;
• conducting differential diagnostics;
• clarification of indications for surgery and the scope of surgical intervention.

Indications for computed tomography in adult patients with tuberculosis of the respiratory organs:

• clarification (definition) of the clinical form of tuberculosis and its variants;
• clarification (determination) of the phase of the tuberculosis process;
• clarification (identification) of signs of tuberculosis process activity;
• identification of an unclear source of bacterial excretion;
• observation of drug-negative tuberculosis;
• determination of the prevalence of the tuberculosis process and post-tuberculous changes in the lungs;
• determination of the condition of the bronchi, the appropriateness and necessity of bronchoscopy for tuberculosis and other lung diseases;
• determination of changes in the lungs with exudative pleurisy;
• conducting differential diagnostics between tuberculosis and other lung diseases;
• diagnostic CT-guided puncture biopsy;
• clarification of indications for surgery and the scope of surgical intervention in pulmonary tuberculosis.

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Interpretation of results

The use of CT in tuberculosis of the respiratory organs corresponds to modern practice of improving X-ray diagnostics of diseases of the respiratory organs.

The use of CT in the clinic of tuberculosis in children shows that the use of planar radiography in the diagnosis of tuberculosis of the intrathoracic lymph nodes leads to significant diagnostic errors. Hyperdiagnosis of tuberculosis of the intrathoracic lymph nodes is noted in 66-70% of patients, mainly when examining children with "minor" variants diagnosed by indirect radiographic signs. Errors in preliminary clinical diagnoses are the result of a subjective assessment of the radiographic picture of the structures of the roots of the lungs, dynamic blurring of the vessels, the thymus gland. False diagnosis of adenopathy includes incorrect interpretation of normal and abnormal vascular structures of the roots of the lungs, non-tuberculous pathology in the form of tumors and cysts of the mediastinum, tumors of the pleura.

An example of hyperdiagnosis in children infected with tuberculosis mycobacteria with a "minor" form of tuberculosis of the intrathoracic lymph nodes can be a single calcification in the area of the aortic window, assessed in planar radiography as a calcified lymph node of the arterial (Botallo's) duct. In CT, the calcification is represented by calcification of the arterial ligament - a strip-shaped or irregularly shaped formation located between the descending aorta and the pulmonary artery.

CT has made it possible to diagnose the tuberculosis process at the earliest stage - in the form of pulmonary manifestations without affection of the lymph nodes. Incomplete primary complex is manifested by small single, often subpleural foci, sometimes accompanied by pleurisy.

In the diagnosis of intrathoracic adenopathy, the contribution of CT to the analysis of affected lymph nodes is the identification of lymph nodes of all groups, their precise localization and size. CT allows characterizing lymph nodes based on their density, identifying them as homogeneous, necrotic, calcified, and determining the morphology of lymph nodes. CT visualizes lymph nodes measuring 3 mm, and calcified ones - 1 mm.

CT uses an anatomical classification of intrathoracic lymph nodes, including 13 groups: retrosternal, paravasal, paratracheal, retrocaval, paraaortic, aortic window, bifurcation, paraesophageal, tracheobronchial, peribronchial, pulmonary, paracostal, and inferior diaphragmatic. In tuberculosis of the intrathoracic lymph nodes, the paravasal, retrocaval, and tracheobronchial groups of lymph nodes are most often affected.

According to CT data, in case of tuberculosis of the intrathoracic lymph nodes, the altered lymph nodes can be determined in one group or in several, up to 13 groups of nodes. The size of individual nodes ranges from 1 to 18 mm, conglomerates of lymph nodes - up to 40 mm. In most children, the size of the affected lymph nodes ranges from 4 to 10 mm.

In CT, differentiation between normal nodes and soft tissue density adenopathy is performed by the multiplicity of lymph nodes in one group, lesions of several groups, abnormalities in the structure of nodes and perinodular tissue.

An objective assessment of adenopathy using CT allows us to characterize variants of tuberculosis of the intrathoracic lymph nodes by the size of the nodes:

• pronounced adenopathy - the size of the nodes is more than 10 mm or multiple conglomerates of small (less than 10 mm) lymph nodes; the nodes are fresh, infiltrative, caseated;
• mild adenopathy - node size from 5 to 10 mm; nodes are fresh, infiltrative, or with compacted caseous matter, or partially or completely calcified.

Nodes smaller than 5 mm, i.e. within normal values, conglomerates and multiple groups of nodes are assessed as micropolyadenopathy. In CT, along with soft tissue homogeneous nodes, soft tissue nodes with point compactions, with foci of calcification and completely calcified are visualized.

Pronounced small adenopathy and micropolyadenopathy represent an active tuberculous process. Micropolyadenopathy in the form of small, multiple soft tissue, homogeneous lymph nodes in one or several groups does not exclude a non-specific process. With ineffective chemoprophylaxis, micropolyadenopathy may transform into tuberculosis of the intrathoracic lymph nodes. Intrathoracic micropolyadenopathy in a child infected with tuberculosis mycobacteria is considered an objective reflection of latent tuberculosis infection. Detection of micropolyadenopathy by CT facilitates early diagnosis of tuberculosis in children and adequate chemotherapy.

Disseminated pulmonary tuberculosis is characterized by a wide variety of clinical and morphological manifestations. Due to the similarity of the clinical and radiological picture with a number of nosologies united in the group of interstitial lung diseases, the interstitial variant of disseminated tuberculosis is the most difficult to diagnose. Most patients are referred for examination with "dissemination of unknown genesis", sarcoidosis, cancerous lymphangitis, bilateral pneumonia. Disseminated tuberculosis of lymphogenous-hematogenous origin is morphologically characterized by varying degrees of damage to the parenchyma and interstitial tissue.

The interstitial variant of disseminated tuberculosis is characterized by various structural reorganizations of the interstitial component. The main computed tomographic marker is bilateral diffuse interstitial lung damage with a reticular or reticular-nodular macrostructure. The level of damage is characterized by infiltration of the inter-, intralobular and peribronchovascular interstitium.

The interstitial variant of disseminated tuberculosis with a predominance of damage to the interlobular interstitium occurs predominantly with a clinical picture of subacute dissemination. This localization of damage is characterized by a large mesh structure caused by infiltration of the interlobular or septal interstitium.

Among patients, the predominant lesion is of the intralobular interstitial structures, corresponding to disseminated tuberculosis of chronic course with a productive inflammatory reaction. In CT, its characteristic feature is the fine-mesh structure of the thickened intralobular interstitium.

The interstitial variant of disseminated tuberculosis with predominant damage to the peribronchovascular interstitium is manifested by a large-loop and mesh-linear structure as a consequence of inflammation of the interstitial-parenchymatous structures. In these cases, along with interstitial inflammation, one can observe a CT picture characteristic of bronchial tuberculosis, peribronchial acinous foci, foci of broncholobular pneumonia, sometimes with decay and cavernization.

Under the influence of anti-tuberculosis therapy, the initial sign of recovery, determined by CT, is the elimination of infiltration of the intralobular periacinar interstitium. This sign, recorded by CT after a month of treatment, can be used to assess the effectiveness of therapy.

Focal tuberculosis in CT is manifested by intralobular, lobular (exudative or productive) bronchogenic foci or interstitial inflammation with isolated tubercles. "Fresh", newly detected focal tuberculosis in CT is characterized by intralobular foci and bronchiolocoele, reflecting caseous damage to the bronchioles.

Chronic focal tuberculosis (fibrofocal) is represented by encapsulated, clearly demarcated caseous foci or conglomerates of foci, partially calcified and/or fibrotic, bronchiectasis and emphysema on CT. The most common signs of active focal tuberculosis, both newly diagnosed and in chronic relapse, on CT were intralobular foci and bronchoceles.

The CT picture of infiltrative tuberculosis is characterized by significant polymorphism, determined by the level of participation in the pathological process of damage to parenchymatous, interstitial and bronchial structures.

The parenchymatous variant of infiltrative tuberculosis is associated with bronchogenic spread of tuberculosis infection. In CT, this form of tuberculous bronchopneumonia is formed by compactions from lobular to lobar extension. It occurs mainly with an exudative inflammatory reaction.

In the interstitial variant of infiltrative tuberculosis, the CT picture is dominated by inflammatory compaction of the interstitium at the level from intralobular to large peribronchovascular structures. The predominantly productive type of inflammatory reaction and torpid course are characteristic.

The selection of variants of infiltrative tuberculosis involves a differentiated approach to chemotherapy. Caseous pneumonia on CT is formed by acinous, lobular and lobar consolidations of the type of extensive lobar and large-volume lesions. Caseous-pneumonic pulmonary changes on CT are distinguished by structures of different density, caused by caseosis in different phases of its transformation and exudative inflammation.

The use of CT in the diagnosis of tuberculomas brought CT semiotics closer to the pathological understanding of this form of tuberculosis. Computer tomographic semiotics of tuberculomas fits into the morphological concept of homogeneous, layered and conglomerate, which allows them to be differentiated from false tuberculomas of the infiltrative-pneumonic type. Changes in the surrounding tissue, which are detected in CT in 99% of cases, are of great importance for the diagnosis of tuberculomas.

According to CT data, the cavern is represented by a cavity formed as a result of the destruction of lung tissue, with dimensions of 3 mm or more. CT visualization of the macrostructure of caverns at the stage of their formation and reparation, taking into account the morphological features of cavernous tuberculosis, allows us to differentiate the cavern as acute (unformed), formed and chronic.

An acute cavity in an infiltrative-pneumonic compaction is considered as a phase of cavernization of infiltrative tuberculosis. A cavity with a formed wall in the presence of significant focal and infiltrative changes is considered as cavernous tuberculosis in the infiltration phase.

Chronic cavernous tuberculosis in CT is represented by variants with a predominant bronchosclerotic component, predominant fibrosis of the peribronchovascular interstitium, or as a polycavernous type of destroyed lung.

CT scan during antibacterial therapy provides an idea of the dynamics of reparative processes in the cavern.

Cirrhosis of the lungs as a form of cirrhotic tuberculosis is assessed by the presence of tuberculous changes (calcified foci, slit-like cavern, calcified lymph nodes). The most reliable CT signs of cirrhotic tuberculosis activity are considered to be the presence of bronchogenic disseminations.

In the clinical sense, bronchial tuberculosis is usually referred to as tuberculosis of large bronchial branches accessible for endoscopic diagnostics. In this regard, improving the X-ray method of bronchial tuberculosis diagnostics is an urgent need for the clinic, especially for pediatric tuberculosis clinics with limited capabilities for bronchofibroscopy.

In CT, bronchial tuberculosis is diagnosed as a process accompanying tuberculous lung lesions and intraluminal lymph nodes or as an isolated process leading to secondary changes. CT diagnostics of bronchial tuberculosis is based on a set of data on the density and contours of the bronchial wall, the state of its lumen, the presence of intraluminal inclusions, and the state of the surrounding lung tissue and mediastinum.

With the use of spiral CT, it became possible to apply methods of volumetric image transformation - two-dimensional and volumetric. The programs allow performing virtual visualization techniques, in particular virtual bronchoscopy, which allows assessing the spatial relationships of the bronchial walls, intraluminal and peribronchial structures.

Radionuclide diagnostics of tuberculosis

Radionuclide diagnostics of tuberculosis allows to identify functional and anatomical disorders in various pathological conditions at the initial stages, when it is difficult to do using other methods. Traditional clinical, radiological and functional methods of research do not always allow to clarify the pathogenesis of ventilation-perfusion disorders, to characterize in detail the microcirculation in the lungs, to evaluate the mucociliary clearance of the bronchi and the function of the intracranial lymph nodes. To solve these problems, radionuclide-labeled drugs are used. Radiometric equipment (scanners and scintillation gamma cameras) is used. Gamma cameras allow to obtain not only static, but also dynamic data on the function of the organ being examined. The devices are equipped with video recording and computer analysis systems, with the help of which changes in the organs are visualized and dynamic characteristics of the organ being examined are obtained in the form of a graphic image. The duration of the study depends on the goals (1-15 min).

The severity of respiratory dysfunction and the scintigraphic picture depend on the morphological changes, prevalence and duration of the pathological process. Disorders detected by scintigraphy may be more pronounced than radiologically determined changes in the lungs.

Regional blood flow and ventilation of the lungs are assessed using an analog image of the organ, as well as by quantitatively recording radioactive radiation in each lung and specifically in "zones of interest" using computer data processing. Computer programs allow for more accurate interpretation of the data obtained.

The physiological nature of radionuclide studies, their relative simplicity and the possibility of conducting repeated studies during the treatment of a patient allow the methods to be used in the diagnosis of extrapulmonary forms of tuberculosis.

Target

Radionuclide diagnostic methods are used to clarify the pathogenesis of ventilation-perfusion disorders, to assess mucociliary clearance, microcirculation in the lungs and the function of the mediastinal lymph nodes.

Radionuclide methods allow studying the functional state of the kidneys (tubular secretion, glomerular filtration, urodynamics, the state of the vascular bed and parenchyma), their topography, the contractile ability of the ureters; they are used to monitor the effectiveness of patient treatment.

Bone tissue examination is performed to identify the structure of bone tissue and foci of its destruction, assess the prevalence of the pathological process, and restore bone tissue after fractures and radical restorative surgeries.

Indications

The methods are used to clarify the prevalence, localization and degree of activity of the pathological process, to identify areas of organ dysfunction during the diagnosis of tuberculosis, to determine indications for surgical treatment, and to dynamically assess the effectiveness of treatment and the results of surgery.

Contraindications

Hemoptysis, pulmonary hemorrhage, high body temperature, acute psychosis, pregnancy, infancy (up to one year).

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Methodology and interpretation of results

Ventilation scintigraphy of the lungs with radioactive ¹³³ Xe.

The gas is injected inflationally using a rubber mouthpiece connected to a spirograph (a closed patient-spirograph system). The patency of the tracheobronchial tract is determined, the time of filling, mixing and half-life of gaseous ¹³³ Xe from the tracheobronchial space is studied. The radiation load on the lungs does not exceed 0.06 mSv, the energy of gamma-quanta radiation is 81 keV, the half-life is 5.27 days, the biological half-life is about one minute.

Lung perfusion scintigraphy

An aqueous solution of ¹³³ Xe is administered intravenously, the study is conducted during breath holding on a deep inhalation. The method allows to characterize the rate of "diffusion" - penetration of the radiopharmaceutical drug (RPD) through the membranes of the capillary bed into the alveoli of the lung and trachea. Based on the data, perfusion of the capillary bed of the lung is assessed, hidden forms of pulmonary emphysema are detected, and its localization is established. The physicochemical characteristics of an aqueous solution of ¹³³ Xe are the same as those of gaseous xenon.

Regional pulmonary blood flow scintigraphy

Short-lived drugs are used: technetium ( ^99m Tc) or indium ( ^113m In). The technique is based on "microembolization" of the capillary bed of the lungs and is designed to determine the localization, prevalence and degree of activity of microcirculation disorders in the lungs. Radiation load on the lungs is 0.057 mSv. The radiation energy of gamma quanta ^99m Tc is 140 keV, half-life is 6 hours. The energy of ^113m In is 393 keV, half-life is 1.7 hours, radiation load is 0.005 mSv.

The use of albumin aggregate labeled with iodine ( ¹³¹ I) requires a "blockade" of the thyroid gland, since radioactive iodine is split off from albumin and, getting into the thyroid gland, has a significant radiation effect on it. Two days before the study and for a week after it, the patient takes Lugol's solution 4-5 drops twice a day. The radiation energy of ¹³¹ I is 360 keV, the half-life is 8.2 days. The radiation load is 1.8 mSv, and the resolving power is less than when using other radioactive isotopes.

Aerosol scintigraphy of the bronchi with macroparticles labeled with ^99m Tc

The study is conducted to examine the mucociliary clearance of the bronchi, assess the effectiveness of treatment and determine indications for surgical intervention on the lungs and bronchi. The drug is administered using an ultrasonic inhaler (particle size from 10 to 50 μm). During one inhalation, 2-3 ml of the radiopharmaceutical suspension with an activity of 300-400 MBq is administered.

The study allows us to identify two types of mucociliary clearance disorders in acute or chronic course of the process. Compensation phase: normal values (uniform distribution of the drug in the tracheobronchial tree and its almost complete elimination within 1 hour). In the decompensation phase, zones of decreased drug inclusion along the bronchial tree are recorded.

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Complications

Radionuclide diagnostics of tuberculosis is fraught with various allergic reactions to radiopharmaceuticals.

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