Instrumental diagnosis of tuberculosis

Despite the abundance of diverse methods of patient research, timely diagnosis of respiratory tuberculosis remains a difficult clinical problem. Errors in the recognition of tuberculosis and other, even the most common diseases of the respiratory system are the same and characteristic. Their reasons are not so obvious, as is commonly believed. It's not just about lack of education or lack of practical skills for doctors: the diagnosis of lung diseases is a complex clinical problem due to strong objective reasons.

First of all, this is the clinical universality of the accompanying lung disease symptoms: the clinical picture of the most diverse in the genesis of diseases always consists of a combination of respiratory and intoxicating complaints. In this case, all lung diseases are very diverse in the possible variants of the course and can proceed either roughly or gradually, torpidly, which is largely due to the characteristics of the patient's body, the nature of its reactivity. Difficult to diagnose and similar mechanisms of the pathogenesis of respiratory disorders in most lung diseases. However, it is often overlooked that behind every name of the nosological form there are quite characteristic morphological manifestations of the disease - tissue reactions that determine the genesis of clinical disorders. Only when taking into account the relationship of the morphological basis of the disease and the available clinical manifestations is possible reliable diagnosis of pulmonary pathology.

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

Modern clinical diagnosis is a complex system of concepts that for a long time determines the fate of a patient with tuberculosis. 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 method of research does not give an answer to all the questions that need to be addressed at once. At the same time, there is a sequence in solving clinical problems, which causes a clear pattern of examination of the patient. Components of modern diagnosis of tuberculosis

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

Diagnosis of tuberculosis today has a wide range of research methods. This is due to the very nature of tuberculosis - a disease with a complex pathogenesis, a polymorphism of manifestations that passes through several stages in its development. Each of the methods has organizational, medical, economic and psychological constraints, so allocating only one of them as the main one can do great harm, since in this case a significant proportion of patients drop out of the doctor's field of view, for which this method is obviously ineffective.

Identification of changes in organs and tissues characteristic of tuberculosis

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

Detection of the causative agent of tuberculosis

• Indirect methods:
  • tuberculin diagnostics;
  • definition of anti-TB antibodies;
  • study of the release of interferon-γ under the influence of specific antigens 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 for all diseases, include methods based on the definition of certain changes in the body that are characteristic of the disease. For tuberculosis, direct methods of this type are morphological and radiotherapy 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, is the methods aimed at the search and identification of the pathogen. This can be either direct methods, such as the microscopy of a diagnostic material, the isolation of a culture of microorganisms, or methods that can determine its presence in the body indirectly (for example, by the presence of specific antibodies).

Obviously, the diagnostic value of indirect and direct methods is not equal. However, the scope of each of them is fully defined and meets 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 for obtaining the diagnostic material. So. The study of lavage fluid obtained by bronchoscopy can be carried out by immunological, biochemical, cytological methods; study of the biopsy of the peripheral lymph node - histological and microbiological methods, etc.

[1], [2], [3],

Stages of diagnosis of lung diseases

The purpose of the initial comprehensive examination of the patient, conducted after the detection of changes in the pulmonary 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 survey, the degree of functional disorders should also be determined and background diseases identified that can influence the choice of therapeutic tactics and / or limit the use of diagnostic techniques of the second stage. This complex of studies can be carried out both in inpatient and outpatient settings. The duration of the initial stage of the examination, taking into account the time necessary for the preparation of histological preparations of the transbronchial lung biopsy, should not exceed 10-14 days.

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

Radiation diagnosis of pulmonary tuberculosis

After the discovery of V.K. X-ray X-rays for more than 70 years, almost the only radiation method for diagnosing tuberculosis, was X-ray. Three generations of phthisiatricians, radiologists and morphologists carefully studied the clinical and radiological picture and conducted X-ray and morphological parallels in the tuberculosis of various organs and systems. Active introduction of computed tomography (CT), ultrasound, and later magnetic resonance imaging (MRI) to modern clinical practice (in the mid-1970s) and modern radionuclide diagnostics led to radiation diagnostics of all forms and stages of tuberculosis to a new qualitative stage. As a result, a new specialty was created - radiation diagnosis of tuberculosis. This was done despite that. That not all new technologies are based on the use of X-rays. To one denominator were not the different nature of X-ray radiation or ultrasound, but the medical image on the display screen. According to the WHO definition, a medical image is understood as a set of images of internal organs obtained by using electromagnetic waves or other elastic vibrations. The acquisition of this image is achieved by the most common methods of investigation - X-ray, radionuclide, ultrasound, magnetic resonance, thermographic.

A doctor who has good basic training in radiology radiology will undoubtedly more effectively master the entire complex of diagnostic technologies. The process of fragmentation of specialties in the field of diagnostic radiology can lead to organizational disunity, because of which a complex rational approach to the use of all means of radiation diagnosis in different situations suffers, and consequently, the diagnosis as a whole also suffers. The clinician needs to understand that it is not necessary to use the entire available arsenal of very expensive technologies for the diagnosis and the prerogative of determining the shortest path to achieve the goal should be within the competence of the representatives of radiation diagnostics.

To identify people with suspicious for tuberculosis of respiratory organs, changes in mass population surveys until recently were used by fluorography (photographing an image from an X-ray screen onto a film). Depending on the apparatus, frames of 70x70 mm or 100x100 mm size were obtained. The method has high performance, but it has a number of technical limitations (in particular, it does not accurately display pathological formations of small dimensions). Therefore, it was impossible to establish the exact diagnosis of tuberculosis on its basis, additional radiation examination was required. With the introduction of digital fluorography, such opportunities as a wide dynamic range and high contrast sensitivity, the possibility of computer image processing, which allow reliable detection of even minor changes in biological tissues of various densities, have become available. At the same time, the radiation load on the patient decreased by 10 or more times compared with standard film fluorography and 2-3 times in comparison with large-format radiography. The effectiveness of the method is determined by the speed of the image (a few seconds), the complete absence of image rejection (with film fluorography 8-15%), the use of expensive photographic film, photo lab equipment and reagents, reliability of archiving results.

Radiography is the main primary radiation method for confirming the diagnosis of tuberculosis of the respiratory system. The method, with observance of technical requirements, differs with a high degree of standardization, allows to visually and quickly represent and reliably archive the research results. The advantage is also the relatively low cost of research with high informativeness. In some patients, the method provides information sufficient to establish a diagnosis.

To clarify the nature of the changes revealed during X-ray examination, X-ray (longitudinal) tomography is used - obtaining layered maps of lung tissue and mediastinal organs, which allows to clarify the structure of pathological changes.

On the basis of radiographic and tomographic data, an idea of a "leading radiographic syndrome" has been formed, within which differential diagnosis of various clinical forms of pulmonary tuberculosis is carried out. These same methods serve to determine the dynamics of tuberculosis changes in the background of treatment, and their results as one of the criteria for the effectiveness of the course of therapy (resorption of infiltration, closure of the decay cavity).

X-rays are not used to detect and diagnose tuberculosis of the respiratory system. However, the possibility of a polypositional and multi-projection study conducted in direct contact with the patient allowed it to retain the value of an additional method, especially when suspicions of the presence of fluid or air in the pleural cavity. The introduction of electron-optical converters, video recording devices allowed to reduce the radiation load, so the method is widely used as an auxiliary for puncture and endoscopic biopsies, as well as for the functional evaluation of respiratory organs.

CT scan

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

The method allows to establish localization, extent, complications of the tuberculosis process without increasing the radial load. In this case, the technology of spiral scanning makes it possible to build three-dimensional images of the investigated structures, including the zones hidden for classical radiology. It is possible to reliably determine the density of pathological changes with a high degree of resolution and avoid the effect of summation. The introduction of CT has led to a change in the diagnostic algorithm: in the study of the lungs are limited to the direct X-ray and CT of the chest. With the use of CT, the need to apply many complex invasive diagnostic techniques is reduced.

Indications

Indications for computed tomography in children with primary tuberculosis:

• infection with mycobacteria of tuberculosis in children at risk;
• "Small" form of tuberculosis of the intrathoracic lymph nodes for visualization of adenopathy;
• determination of 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;
• differential diagnostics;
• clarification of indications for surgery and the extent of surgical intervention.

Indications for computed tomography in adults with tuberculosis of respiratory organs:

• clarification (definition) of the clinical form of tuberculosis and its variants;
• clarification (definition) of the phase of the tuberculosis process;
• clarification (detection) of signs of activity of the tuberculosis process;
• detection of an unclear source of bacterial excretion;
• observation with drug-negative tuberculosis;
• the prevalence of the tuberculosis process and metatuberculous changes in the lungs;
• determination of bronchial condition, expediency and necessity of bronchoscopy for tuberculosis and other lung diseases;
• definition of changes in the lungs in exudative pleurisy;
• differential diagnostics between tuberculosis and other lung diseases;
• diagnostic puncture biopsy under the control of CT;
• clarification of indications for surgery and the extent of surgical intervention for pulmonary tuberculosis.

[4], [5], [6], [7], [8]

Interpretation of results

The use of CT in respiratory tuberculosis responds to modern practice of improving the radiographic diagnosis of respiratory diseases.

The use of CT in a tuberculosis clinic in children shows that the use of planar radiography in the diagnosis of tuberculosis of the intrathoracic lymph nodes leads to significant diagnostic errors. Hyperdiagnostics of tuberculosis of the intrathoracic lymph nodes is noted in 66-70% of patients, mainly when examining children with "small" variants diagnosed by indirect radiographic signs. Errors of preliminary clinical diagnoses are the result of a subjective assessment of the radiographic picture of the structures of the roots of the lungs, the dynamic blur 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, a non-tuberculous pathology in the form of tumors and cysts of the mediastinum, pleural tumors.

An example of overdiagnosis in infants infected with Mycobacterium tuberculosis in children with a "small" form of tuberculosis of the intrathoracic lymph nodes can be a single calcification in the aortic window region, regarded as a plane radiography as a calcified lymph node of the arterial (botallova) duct. In CT, calcinate is represented by calcification of the arterial ligament - formation of a strip-shaped or irregular shape, located between the descending aorta and the pulmonary artery.

With CT, it became possible to diagnose the tuberculosis process at the earliest stage - in the form of pulmonary manifestations without affecting the lymph nodes. An incomplete primary complex is manifested by small single, more often subpleural foci, sometimes accompanied by pleurisy.

In the diagnosis of intrathoracic adenopathy, the contribution of CT to the analysis of the affected lymph nodes is to identify the lymph nodes of all groups, their precise localization and magnitude. CT allows us to characterize lymph nodes based on their density, identify them as homogeneous, necrotic, calcified, determine the morphology of the lymph nodes. At CT, lymph nodes with a size of 3 mm are visualized, and calcified ones - 1 mm.

In CT, an anatomical classification of the intrathoracic lymph nodes is used, which includes 13 groups: retinal, paravasal, paratracheal, retrovascular, para-aortic, aortic window, bifurcation, parasideal, tracheobronchial, peribronchial, pulmonary, paracostal, inferior diaphragmatic. When tuberculosis VGLU is more often affected paravazalnaya, retrokavalnaya and tracheobronchial groups of lymph nodes.

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

In CT, the differentiation between normal nodes and adenopathies of soft tissue density is carried out by multiplicity of lymph nodes in one group, damage to several groups, anomalies in the structure of nodes and perinodular tissue.

An objective assessment of adenopathies in CT allows characterizing the variants of tuberculosis of the intrathoracic lymph nodes in terms of the size of the nodes:

• expressed adenopathy - the size of the nodes is more than 10 mm or multiple conglomerates of small (less than 10 mm) lymph nodes; nodes fresh infiltrative, caseified;
• little expressed adenopathy - the size of nodes from 5 to 10 mm; nodes fresh infiltrative or with compacted casein or calcified partially or completely.

Nodes with a value of less than 5 mm, i.е. Within the limits of normal values, conglomerates and multiplicity of groups of nodes are evaluated as micro-polyadenopathy. In CT, along with soft tissue homogeneous nodes, soft tissue assemblies with dot seals, calcification centers and fully calcified are visualized.

Severe adenopathy and micropolyadenopathy are an active tuberculosis process. Micropoliadenopathy in the form of small, multiple soft-tissue, homogeneous lymph nodes in one or more groups does not exclude a nonspecific process. With ineffective chemoprophylaxis, the transition of micro-polyadenopathy to tuberculosis of the intrathoracic lymph nodes is possible. Intramuscular micro-polyadenopathy in a tuberculosis infected with mycobacteria is considered as an objective reflection of a latent tuberculosis infection. Detection of micro-polyadenopathy in CT helps early diagnosis of tuberculosis in children and the conduct of adequate chemotherapy.

Disseminated pulmonary tuberculosis is distinguished by a wide variety of clinical and morphological manifestations. By 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 for diagnosis. Most patients are referred for examination with "dissemination of an unclear genesis," sarcoidosis, cancer lymphangitis, bilateral pneumonia. Disseminated tuberculosis of lymphogenous-hematogenous origin is morphologically characterized by the defeat of various degrees of parenchyma and interstitial tissue.

The interstitial variant of disseminated tuberculosis is characterized by a different structural rearrangement of the interstitial component. The main computer-tomographic marker is the bilateral diffuse interstitial lung lesion with the macrostructure of the reticular or reticular-nodular character. The level of lesions is characterized by infiltration of inter-, intralobular and peribronchovascular interstitium.

The interstitial variant of disseminated tuberculosis with prevalence of interlobular interstitial lesion proceeds mainly with the clinical picture of subacute dissemination. For such a lesion localization, a large-scale structure characterized by infiltration of interlobular or septal interstitium is characteristic.

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

The interstitial variant of disseminated tuberculosis with the predominant lesion of peribronchovascular interstitium is manifested by large-branched and net-linear structure as a consequence of inflammation of the interstitial-parenchymal structures. In these cases, along with interstitial inflammation, it is possible to observe a CT picture typical of bronchial tuberculosis, peribronchial acinous foci, foci of bronchopulmonary pneumonia, sometimes with decay and cavernization.

Under the influence of antituberculous therapy, the initial sign of cure, determined with the help of CT. Is the elimination of infiltration of intralobular periacinar interstitium. This symptom, fixed at CT after a month of treatment, can be used to evaluate the effectiveness of therapy.

Focal tuberculosis with CT is manifested by intra-lobular, lobular (exudative or productive) bronchogenic foci or interstitial inflammation with individual tubercles. "Fresh", newly diagnosed focal tuberculosis in CT is characterized by intralobular foci and bronchiolocele, reflecting caseous bronchioles.

Chronic focal tuberculosis (fibro-focal) in CT is represented by encapsulated, clearly delimited caseous foci or conglomerates of foci, partially calcified and / or fibrotic, bronchiectasis and emphysema. The most common signs of active focal tuberculosis, both newly diagnosed and relapsed chronic, with CT were intralobular foci and bronchocoel.

CT scan of infiltrative tuberculosis is characterized by significant polymorphism. Caused by the level of participation in the pathological process of lesion of parenchymal, interstitial and bronchial structures.

The parenchymal variant of infiltrative tuberculosis is associated with bronchogenic spread of tuberculosis infection. With CT, this form of tuberculosis bronchopneumonia is formed by seals from lobular to lobar extent. It mainly flows with exudative inflammatory reaction.

In the interstitial variant of infiltrative tuberculosis, an inflammatory compaction of interstitium predominates in the CT picture at the level from the interlobular to the large peribronchovascular structures. The predominantly productive type of inflammatory reaction and torpid current are characteristic.

The selection of variants of infiltrative tuberculosis presupposes a differentiated approach to chemotherapy. Caseous pneumonia in CT is formed by acinous, lobular and lobar seals according to the type of extensive fractional and large lesions. Caseous-pneumonic pulmonary changes at CT are distinguished by structures of different density, caused by caseous disease in different phases of its transformation and exudative inflammation.

The use of CT in the diagnosis of tuberculosis brought the CT-semiotics closer to a pathoanatomical understanding of this form of tuberculosis. Computer-tomographic semiotics tuberculosis fits into the morphological concept of homogeneous, layered and conglomerate, which allows them to differentiate from infiltrative-pneumonic types that are not true to tuberculosis. For the diagnosis of tuberculosis, changes in the surrounding tissue are of great importance, which in CT detection in 99% of cases.

According to CT, the cavity is a cavity formed as a result of destruction of the lung tissue, with dimensions from 3 mm or more. CT imaging of the cavern macrostructure at the stage of their formation and repair, taking into account the morphological features of cavernous tuberculosis, makes it possible to differentiate the cavern as acute (unformed), formed and chronic.

The acute cavity in the infiltrative-pneumonic compaction is considered as the phase of the infiltrative tuberculosis cavernization. A cavern 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 with CT is represented by variants with a predominant bronchosclerotic component, preferential fibrosis of peribronchovascular interstitium, or as polycavernous according to the type of the destroyed lung.

CT on the background of antibiotic therapy gives an idea of the dynamics of reparative processes in the cavity.

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 the presence of bronchogenic dissemination.

In the clinical sense, bronchial tuberculosis is commonly referred to as tuberculosis of large bronchial branches, which are available for endoscopic diagnosis. In connection with this, the improvement of the radiographic method for diagnosing bronchial tuberculosis is an acute need of the clinic, especially the clinic of children's tuberculosis with limited capabilities for bronchoconstriction.

With CT, bronchus tuberculosis is diagnosed as concomitant with tuberculosis lesions of the lungs and VGLU process or as an isolated process leading to secondary changes. CT scan of bronchial tuberculosis is based on a complex of data on the density and contours of the bronchus wall, the state of its lumen, the presence of intraluminal inclusions, the state of the surrounding lung and mediastinal tissues.

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

Radionuclide Diagnosis of Tuberculosis

Radionuclide diagnosis of tuberculosis allows us to identify functional and anatomical disorders in various pathological states in the initial stages, when it is difficult to implement with the help of other methods. Traditional clinical, radiologic and functional methods of investigation do not always allow us to clarify the pathogenesis of ventilation-perfusion disorders, to characterize microcirculation in the lungs in detail, to evaluate mucociliary clearance of the bronchi and the function of VGLU. To solve these problems radionuclide-labeled drugs are used. Use radiometric equipment (scanners and scintillation gamma cameras). Gamma cameras allow you to get not only static. But also dynamic data on the function of the organ under investigation. The devices are equipped with video recording and computer analysis systems that visualize changes in organs and obtain a dynamic characteristic of the organ under investigation in the form of a graphic image. The duration of the study depends on the goals (1-15 min).

The severity of violations of respiratory functions and the scintigraphic picture depend on the morphological changes, prevalence and duration of the pathological process. Disturbances detected by scintigraphy may be more pronounced than radiological changes in the lungs.

Evaluation of regional blood flow and ventilation of the lungs is carried out with the help of an analog image of the organ, as well as by quantitative recording of radioactive radiation in each lung and targeted in "areas of interest" by computer data processing. Computer programs allow you to more accurately interpret the data.

The physiology of radionuclide studies, the relative simplicity and the possibility of carrying out repeated studies during the treatment of a patient allow the use of methods in the diagnosis of extrapulmonary forms of tuberculosis.

Goal

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 lymph nodes of the mediastinum.

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

The study of bone tissue is carried out to identify the structure of bone tissue and foci of its destruction, assess the prevalence of the pathological process, restore bone tissue after fractures and radical-recovery operations.

Indications

Methods are used to clarify the prevalence, localization and degree of activity of the pathological process, identify areas of organ failure in the diagnosis of tuberculosis, to determine indications for surgical treatment, to dynamically evaluate the effectiveness of treatment and the results of surgery.

Contraindications

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

[9], [10], [11], [12], [13], [14], [15], [16],

Methods of conducting and interpreting the results

Ventilating scintigraphy of lungs with radioactive ¹³³ Xe.

Gas is injected with inflation using a rubber mouthpiece connected to a spirograph (closed system "patient-spirograph"). Determine the patency of the tracheobronchial pathways, study the filling, mixing and half-life of gaseous ¹³³ Xe from the tracheobronchial space. The radiation load on the lungs does not exceed 0.06 mSv, the gamma radiation energy is 81 keV, the half-life is 5.27 days, the biological half-life is about one minute.

Perfusion lung scintigraphy

An aqueous solution of ¹³³ Xe is administered intravenously, the test is carried out during a delay in breathing at a deep inspiration. The method makes it possible to characterize the rate of "diffusion" - the penetration of a radio-pharmaceutical preparation (RFP) through the membranes of the capillary bed into the lung alveoli and the trachea. On the basis of the data, the perfusion of the capillary bed of the lung is assessed, the hidden forms of emphysema of the lungs are revealed, and its localization is established. Physico-chemical characteristics of the aqueous solution of ¹³³ Xe are the same as for gaseous xenon.

Scintigraphy of regional pulmonary blood flow

Use short-lived drugs: 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 microcirculatory disturbances in the lungs. Radiation load on the lungs is 0.057 mSv. The gamma radiation energy is ^99m Tc - 140 keV, the half-life is 6 hours. The energy is ^113m In-393 keV, the half-life is 1.7 hours, the radiation load is 0.005 mSv.

The use of an albumin unit labeled with iodine ( ¹³¹ I) requires a "blockade" of the thyroid gland, since radioactive iodine is cleaved from albumin and, having got into the thyroid gland, has a significant radiation effect on it. 2 days prior to the study and within a week after it, the patient takes Lugol's solution of 4-5 drops twice a day. The radiation energy is ¹³¹ I - 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 bronchial tubes with macromolecules labeled with ^99m Tc

The study is conducted to study mucociliary clearance of the bronchi, evaluate the effectiveness of treatment and determine the indications for surgery on the lungs and bronchi. The drug is administered by an ultrasonic inhaler (particle size from 10 to 50 μm). During one inhalation, 2-3 ml of suspended soluble RFP activity of 300-400 MBq are administered.

The study makes it possible to distinguish two types of mucociliary clearance disorders in acute or chronic course of the process. Compensation phase: normal indices (uniform distribution of the drug in the tracheobronchial tree and almost complete excretion within 1 h). In the phase of decompensation, the zones of reduced inclusion of the preparation are fixed during the course of the bronchial tree.

[17], [18], [19], [20], [21], [22]

Complications

Radionuclide diagnosis of tuberculosis is fraught with various allergic reactions to RFP.

[23], [24], [25], [26], [27], [28],