2nd Year OM, Topic 8: Lungs (Eng) PDF

RAY DIAGNOSTICS OF DISEASES AND DAMAGES OF LUNGS AND MEDIASTINUM METHODS OF RADIATION RESEARCH Radiation examination is an integral part of a comprehensive examination of all patients with thoracic pathology. The data obtained in this case in most cases are decisive in establishing the nature of the...

RAY DIAGNOSTICS OF DISEASES AND DAMAGES OF LUNGS AND MEDIASTINUM METHODS OF RADIATION RESEARCH Radiation examination is an integral part of a comprehensive examination of all patients with thoracic pathology. The data obtained in this case in most cases are decisive in establishing the nature of the pathological process, as well as in assessing its dynamics and the results of treatment. X-RAY METHOD To examine patients with diseases and injuries of the lungs and mediastinum, various ray methods and techniques can be used. The examination usually begins with an x-ray study. At the first stage, native, most accessible techniques are used: radiography, fluorography, fluoroscopy, linear tomography. NATIVE RADIOGRAPHICALLY METHODS Radiography of the breast irrespective of the expected pathology is performed first in the form of panoramic images in the straight (usually anterior) and lateral (respectively side of the lesion) projection with a shadow image of all the anatomical structures of this region. In the standard version, the study is performed in the patient's vertical position at the height of a deep inspiration (in order to increase the natural contrast of the lungs). Additionally, according to the indications, it is possible to take pictures in other projections (oblique), in the horizontal position of the patient, in lateroposition, in exhalation. To detail the areas of interest, you can make snapshots. Fluorography of the thoracic cavity organs is used mainly for mass screening ("preventive") studies with the purpose of early detection of various pathological processes, especially tuberculosis and lung cancer. The main advantage of this technique is the economy and high capacity, reaching 150 people per hour. A whole system of such preventive fluorography has been created in our country. Currently, fluorography due to the possibility of obtaining large-frame images have also been used as a diagnostic technique. An important advantage of radiography and fluorography is the objective documentation of the revealed changes, which allows to reliably judge their dynamics, comparing with previous or subsequent photographs. The use of fluoroscopy in the study of the organs of the breast is limited to a significant radiation burden on the patient, a lack of documentation, a lower resolving power. It should be carried out only on strict indications after the analysis of radiographs and fluorograms. The main directions of the use of fluoroscopy: polyprojection studies for the comprehensive study of various pathological changes, as well as evaluation of the organs and anatomical structures of the chest in their natural functional state (diaphragm mobility, pleural sinus opening, pulsation of the heart and aorta, mediastinum displacement, and mobility of pathological formations during breathing, swallowing, coughing). Linear tomography is currently performed in cases when it is impossible to perform CT, which has much more diagnostic information. At the same time, traditional tomography due to its availability and low cost is still used in clinical practice. The main indications for tomography of the lungs and mediastinum: - detection of destruction in inflammatory and tumor infiltrates; - detection of intrabronchial processes (tumors, foreign bodies, cicatricial stenoses); - determination of the increase in bronchopulmonary and mediastinal lymph nodes; - refinement of the structure of the lung root as it expands. Tomography is also shown when the pathological process is poor or not at all seen on radiographs, but its existence is indicated by clinical data. GENERAL SHADOW PAINTING OF THE BREAST CELL In the case of a genuine X-ray examination (radiography, fluorography, fluoroscopy), the total shadow pattern of the breast in a direct projection is composed of two light fields symmetrically located in the lateral parts of the thoracic cavity (lungs) and the middle shadow between them. From below, the thoracic cavity is separated from the abdomen by the diaphragm. A shadow of the chest wall is visible on the sides. Pulmonary fields are intersected by striped shadows of the ribs. Their posterior parts go from the spine, are arranged horizontally, convex upward, have a smaller width and greater intensity of the shadow. The anterior sections of the ribs go from the chest wall obliquely from top to bottom, the convexity is turned downward, their shadow is less intense and wider. Their ends, formed by a cartilaginous tissue that does not absorb x-rays, seem to break off at approximately the mid-clavicular level. In the elderly, these cartilages begin to calcify and become visible. In the lower part of both pulmonary fields, women determine the shadows of the mammary glands, in men - the shadows of the pectoral muscles. In their center often seen more dense shadows of the nipples. In the upper parts of the lateral walls of the chest, outside the pulmonary fields, the intensity of the shade of the scapula is seen to be weak. The tops of the lungs are intersected by the clavicles. The median shadow in a direct projection forms mainly the heart, the aorta and the spine. From the parts of the sternum in this projection, only its handle with the sternoclavicular joint is visible. Thoracic vertebrae in a direct projection in the study using "hard" X-rays (more than 100kV) are visible all over, and at a voltage of less than 100k the shadows of only a few upper thoracic vertebrae are clearly defined. On "hard" x-ray images in the mediastinum, in addition to a separate shadow image of dense structures, a trachea lumen is also visible in the upper part of the median line, which divides at the level of the V thoracic vertebra into the right and left main bronchi. In the paramediastinal zones of the pulmonary fields between the anterior ends of the IIIV ribs there are shadows formed by the roots of the lungs. Large blood vessels, central parts of the bronchial tree, lymph nodes, fiber are involved in their formation. Normally, the image of the roots of the lungs is structured. Throughout the rest of the pulmonary fields, a so-called pulmonary pattern emerges. Its anatomic substrate is normally the intrapulmonary vessels. They are displayed on the roentgenograms on the basis of their spatial arrangement in relation to the X-ray path. In the longitudinal section, the vessels have the form of linear shadows, fan-shapedly diverging from the roots of the lungs to the periphery, dichotomically dividing, gradually becoming thinner and disappearing at a distance of 1-1.5 cm from the visceral pleura. In the transverse (orthogonal) section, the vessels have the form of rounded or oval shadows with smooth, well defined contours. Bronchi do not normally give a shadow image and do not participate in the formation of a pulmonary pattern. In the lateral projection, the images of both halves of the thoracic layer overlap, so there is only one common pulmonary field. Heart, thoracic aorta, spine, sternum give a separate image. In the center of the chest cavity, crossing it in the upper part from the top down and deviating somewhat posteriorly, the air gleams of the trachea, the main and lobar bronchi are visible. From the spine to the sternum, the ribs of both halves of the thorax go obliquely downward and forward. The lobes of the lungs are separated by interspecies gaps, which can not be seen on radiographs. The boundaries between them become discernible when infiltrating pulmonary tissue in the border areas with the pleura, or with the thickening of the interlobar pleura. In a direct projection, the lobes of the lungs largely overlap each other. The boundaries of the shares are simpler and more precisely defined in lateral projections. The main interlobar crevices extend from the III thoracic vertebra to the point between the middle and anterior third of the diaphragm canopy. A small interlobar slot is located horizontally from the middle of the main slit to the sternum (Figure 1). Fig. 1. Chest radiographs in the straight (a), right (b) and left (in) lateral projections with the designation of intersecting slits Lobes of the lungs consist of smaller anatomical units - segments. They are parts of the lung tissue with a separate system of ventilation and arterial blood supply. In the right lung there are 10 bronchopulmonary segments, in the left - 9. Segmental structure of the lungs is shown in Table. 1. Table 1. Segmental structure of the lungs Segments have no shells, so the boundaries between them are normally not distinguishable. They begin to differentiate only when the lung tissue is compressed. Each segment is projected on radiographs in a direct and lateral projection in a specific location, which allows X-ray diagnostically to establish the segmental localization of the pathological process (Fig. 2). Fig. 2. Diagrams of segments of the lungs in the straight line (a), right (b) and left (c) lateral projections SPECIAL X-RAY-CONTRAST METHODS Radiography, fluorography, fluoroscopy give a fairly large amount of information about the state of the lungs and mediastinum, but it is often required to determine the nature and details of pathological processes. In such cases, special radiopaque methods of examination are additionally used: bronchography, angiopulmonography, pneumomediastinography, pleurography, fistulography. Bronchography allows you to obtain an image of the whole bronchial tree when you insert the RCC (Figure 3). For these purposes, usually use either oil or water-soluble iodine-containing drugs. Bronchography is performed, as a rule, under local anesthesia. General anesthesia is necessary mainly in patients with respiratory failure and in preschool children. Indications for bronchography are suspicions of bronchiectasis, anomalies and malformations of the bronchi, cicatrical narrowing, intrabronchial tumors, internal bronchial fistulas. Despite the high information content, the use of this technique is currently severely limited due to its invasiveness on the one hand and the large diagnostic capabilities of CT on the other. Fig. 3. Bronchograms of the right lung in the straight (a) and lateral (b) projections Angiopulmonography - radiocontrast study of small blood vessels. Usually it is performed by catheterization of the femoral vein by Seldinger, followed by a catheter through the lower vena cava, right atrium and right ventricle into the common pulmonary artery trunk into which a water-soluble iodine-containing contrast agent is administered. The serially executed images sequentially display both phases of blood flow: arterial and venous (Figure 4). The use of this technique is shown for the reliable establishment and detailed characterization of pulmonary vascular lesions: aneurysms, constrictions, congenital developmental disorders, thromboembolism, and also for the purpose of specifying the degree of lesion of the trunk and main branches of the pulmonary artery in central lung cancer and malignant mediastinal tumors. Fig. 4. Angiopulmonograms in arterial (a) and venous (b) phases Pneumomediastinography is performed with preliminary introduction into the mediastinum of gas, which allows to establish authentically the topographic-tomical location (in the lung or mediastinum) of neoplasms located in the border pulmonary-mediastinal zone (see Fig. 5). Fig. 5. Chest radiographs in a direct projection: a) native (widening of the "heart" shadow to the left); b) pneumomediastinogram (the gas introduced into the mediastinum exfoliated from the heart a tumor originating from the left thymus gland) Pleurography is the artificial contrasting of the pleural cavity with the introduction into it of puncture or through the drainage tube of water-soluble or oily PKC. This technique is used mainly for encapsulated pleural empyema, when it is necessary to establish the exact localization, size and shape of the cavity, as well as the possible bronchopleural fistulas (Fig. 6). Fig. 6. Pleurogram in the left lateral projection. Impaired empyema of the pleura Fistulography is used for external fistula of the chest to establish their type, direction, extent, connection with the bronchial tree, determine the source of the purulent process. Despite the high information content, the use of special techniques is now severely limited due to their invasiveness on the one hand and the large CT diagnostic capabilities on the other. X-RAYHENOLOGICAL SYNDROMES OF LUNG DISEASES X-ray manifestations of pathological processes in the lungs are very diverse, but they are based on only 4 phenomena: shading of lung fields, enlightenment of pulmonary fields, changes in pulmonary pattern, changes in the roots of the lungs. Shadowing of the lungs is most often caused by the accumulation in the alveoli of inflammatory exudate or edematous fluid, a decrease in the airyness of the lungs due to a violation of bronchial patency or in connection with the compression of the lungs, replacement of the pulmonary parenchyma with pathological tissues. It should be borne in mind that this phenomenon can give and extrapulmonary processes: neoplasms of the thoracic wall, diaphragm and mediastinum, which go into pulmonary fields; fluid accumulation in the pleural cavities. Enlightenment is caused by a decrease in the mass of tissues per unit volume of the lung. This happens when the whole lung or part of it is airy, or when air cavities are formed in the lung parenchyma. In addition, the enlightenment of the pulmonary field may be due to the accumulation of gas in the pleural cavity. Change in the pulmonary pattern occurs in connection with either the interstitial component, or with a violation of blood and lymph flow in the lungs. The change in the radiographic pattern of the roots of the lungs is due to the damage to their structural elements: vessels, bronchi, cellulose, lymph nodes. These skiological phenomena can be detailed depending on their extent, shape, structure, outlines. There are 9 radiologic syndromes, reflecting practically the whole multifaceted pathology of the lungs (Figure 7). Fig. 7. Schemes of X-ray syndromes of lung diseases: 1. Extensive shading of the pulmonary field 2. Limited shading 3. Round Shadow 4. Foci and limited focal dissemination 5. Extensive focal dissemination 6. Extensive enlightenment 7. Limited Enlightenment 8. Changing the pulmonary picture An analysis of the x-ray picture of the lungs should begin with a distinction between "norm" and "pathology." In the presence of pathological changes, it should be determined by what kind of radiological syndrome they are manifested, which immediately significantly reduces the range of possible diseases and facilitates differential diagnosis. The next stage is intrasyndrome diagnosis with the definition of the general nature of the pathological process and the specific nosological form of the disease. Syndrome of extensive shading of the pulmonary field. The pathological process displayed by this syndrome is determined by the position of the mediastinum and the nature of the shading (Figure 8-10). Fig. 8. The total homogeneous shading of the left hemithorax with a shift of the mediastinum towards the shading (atelectasis of the left lung) Fig. 9. The total non-uniform shading of the left hemithorax with a shift of the mediastinum towards the shading (cirrhosis of the left lung) Fig. 10. Total homogeneous shading of the left hemithorax with displacement of the mediastinum in the opposite direction (left-sided total hydrothorax) The position of the mediastinum and the nature of the shading for various diseases are shown in Table. 2. Table 2. The position of the mediastinum and the nature of shading in various diseases Limited shading can give both changes in the lungs and extrapulmonary processes. When decoding this syndrome, first of all it is necessary to establish anatomical localization of the pathological process: the chest wall, the diaphragm, the mediastinum, the lungs. In most cases, this can be achieved in the simplest possible way - using a multi-projection X-ray study. The processes emanating from the chest wall are widely adjacent to it and are displaced when breathing in one direction with the ribs. The processes originating from the diaphragm are naturally closely related to it. The mediastinal neoplasms that protrude into the pulmonary fields are mostly located in the middle shadow, do not move when breathing, push and squeeze out one or the other anatomical structures of the mediastinum. On the unconditionally intrapulmonary localization of the pathological process is its location within the pulmonary field in all projections (the only exception is the fluid in the interlobar slot) and the displacement of the pathologically altered area during breathing and coughing together with the elements of the lung. Most often such a syndrome displays inflammatory infiltrations of pulmonary tissue of various etiologies, segmental atelectasis, local pneumosclerosis (Figure 11, 12). Fig. 11. Limited shading of the right lung - atelectasis of the upper lobe Fig. 12. Limited right shading of the right lung - segmental pneumonia Round shadow syndrome - limited shading, in all projections retaining the shape of a circle, semicircle, oval more than 12 mm. In this case, it is also necessary first of all to establish the localization of the pathological process: it is located outside or intrapulmonarily. From the intrapulmonary processes most often give a round shadow of the tumor, cysts, tuberculosis (infiltrative, tuberculoma), vascular aneurysms, lung sequestration. Carrying out the differentiation of these processes, we must pay attention to the number of shadows, their contours and structure, the dynamics of the x-ray picture. Despite the differences in the image of the pathological processes of the globular shape, their demarcation remains a challenge. Nevertheless, sometimes it is possible to assume with a high degree of probability the morphological substrate of the round shadow: a single formation and enlarged lymph nodes of the lung root - peripheral cancer; multiple formations - metastases; single formation with massive chaotic or mottled calcification - hamartoma; formation with an independent pulsation - vascular aneurysm (Figure 13). Fig. 13. Syndrome of a round shadow – hamartoma Foci and limited focal disseminations are rounded, polygonal or irregularly shaped shadows up to 12 mm in size, the anatomical base of which is the lobe of the lung. Several foci, located side by side, are designated as a group of foci. Limited dissemination is the multiple foci detected on the roentgenogram, localized within no more than two segments. Most often this syndrome shows focal tuberculosis, peripheral cancer, metastasis, lobular atelectasis, aspiration pneumonia (Figure 14). Fig. 14. Limited focal dissemination in the upper lobe of the right lung (focal tuberculosis) The syndrome of extensive focal dissemination - lesions of the lungs, the length of which exceeds two segments (widespread dissemination), and lesions of both lungs (diffuse dissemination). Four types of rashes are distinguished by the size of the foci: miliary (focal size - up to 2 mm), finely confined (3-4 mm), medium-focal (5-8 mm), large-focal (9-12 mm). The most common syndrome of extensive focal dissemination is disseminated tuberculosis, sarcoidosis, carcinomatosis, pneumoconiosis, and alveolar pulmonary edema (Fig. 15). Fig. 15. Diffuse two-sided miliary dissemination of the lungs Syndrome of extensive enlightenment of the pulmonary field. Out of extrapulmonary pathological processes, this syndrome displays total pneumothorax (Figure 16). With intrasyndromic differentiation of intrapulmonary pathological processes, it is first of all necessary to estimate their prevalence. There are 3 variants of extensive enlightenment: total two-sided, total one-sided, subtotal one-sided. Fig. 16. Total unilateral enlightenment Total bilateral enlightenment most often gives emphysema of the lungs and hypovolemia of the small circle of blood circulation with some congenital heart defects (tetralogy of Fallot, isolated pulmonary artery stenosis). Total unilateral enlightenment most often displays a valve disruption of the main bronchus, compensatory hyperpneumatosis of one lung with atelectasis or absence of another lung, thromboembolism and agenesis of one of the main branches of the pulmonary artery. Subtotal unilateral enlightenment is observed with valvular disruption of the patency of the lobar bronchus due to its partial mechanical obturation with a tumor or foreign body; with compensatory hyperpneumatosis of the part of the lung due to atelectasis or the removal of another lobe of the same lung; with thromboembolism of the lobe branch of the pulmonary artery; with congenital lobar emphysema. The syndrome of limited bleaching is a local increase in the transparency of the pulmonary field, which may have an annular or irregular shape. The most frequent intrapulmonary processes displayed by such a picture are true and false cysts, cystic hypoplasia, emphysematous bullae, abscesses, destructive forms of tuberculosis, and the cavity form of peripheral cancer. Out of extrapulmonary processes, this syndrome most often manifests limited pneumothorax, diaphragmatic hernia, conditions after plasty of the esophagus by the stomach or intestine (Figure 17). Fig. 17. Limited bleaching of the left pulmonary field (limited pneumothorax) The syndrome of limited lightening of the lungs can imitate a variety of pathological changes in the ribs: congenital deformities, adhesions of neighboring ribs, tumors, inflammatory processes (osteomyelitis, tuberculosis). Syndrome of changes in the pulmonary pattern - all deviations from the x-ray pattern of the normal pulmonary pattern, which are manifested by amplification, depletion or deformation. Strengthening the pulmonary pattern is an increase in the number and caliber of its elements per unit area of the pulmonary field. This is due either to the fullness of the lungs with certain congenital and acquired heart defects, or excessive development of connective tissue. The depletion of the pulmonary pattern, on the contrary, is manifested by a decrease in the number and caliber of its elements per unit area of the pulmonary field. This is observed with hypovolemia of a small circle of circulation in congenital heart defects with stenosis of the pulmonary artery; swelling of the lung tissue with valvular stenosis of the bronchus and hyperpneumatism; with emphysema. Deformation is a change in the normal course, shape and unevenness of the contours of the elements of the pulmonary pattern, as well as the change that determines its mesh, taut appearance. A similar pattern is often observed in chronic bronchitis, pneumoconiosis, pneumosclerosis (Figure 18). Fig. 18. Diffuse amplification and deformation of the pulmonary pattern, most pronounced in the basal parts of the lungs Fig. 19. Tomogram of the breast in a straight projection. Two-sided expansion of the roots of the lungs, due to the increase in lymph nodes The syndromic approach to radiographic diagnosis of respiratory diseases is quite fruitful. A detailed analysis of the features of the X-ray picture in many cases provides a correct definition of the nature of bronchopulmonary pathology. The data obtained by X-ray examination also serve as the basis for a rational further examination of patients using other ray imaging methods: X-ray CT, MRI, ultrasound and radionuclide methods. Table 8.3. Change in the roots of the lung for various diseases X-RAY COMPUTER TOMOGRAPHY CT is the most informative method of radiation diagnosis of respiratory diseases. For clinical indications and accessibility, CT should be performed instead of linear tomography and before any ren-radiopaque studies. At the same time CT of lungs and mediastinum is expedient to spend after careful studying of results of traditional native X-ray examination (roentgenography, fluoroscopy). The role of CT in negative results of conventional radiographic examination of patients with disturbing clinical data is extremely important: progressive unmotivated dyspnea, hemoptysis, detection of atypical cells or mycobacterium tuberculosis in sputum. The primary standard CT scan is to obtain a series of contiguous tomographic sections from the tops of the lungs to the bottom of the posterior rib-diaphragmatic sinuses under natural contrast conditions (native CT) at the height of the retarded inspiration. The best visualization of intrapulmonary structures is achieved with CT examination in the so-called pulmonary electronic window (-700...- 800 HU). In this case, the lungs are displayed as dark gray fields against the background of which the longitudinal and cross sections of the blood vessels forming the pulmonary pattern are visible, as well as the lumens of the bronchi up to the subsegmental inclusions. In the subpleural departments, individual elements of the pulmonary lobules are distinguished: the transverse or longitudinal section of the intra-lobular arteries and veins, the interlobular septa. The pulmonary tissue within the lobules is homogeneous, homogeneous. Its densitometric parameters are normally relatively stable and are in the range of 700... -900 HU (Figure 20). The organs and anatomical structures of the mediastinum receive a distinct separate image when using a soft tissue electron window (+40 HU) (Figure 21). Fig. 20. Computer tomography of the breast in the pulmonary window Fig. 21. Computed tomography of the breast in the soft tissue window The thoracic wall on computer tomograms, unlike the X-rays, receives a differentiated map of the anatomical structures: the pleura, muscles, fatty interlayers. The edges on the axial sections are shown fragmentarily, since their arrangement does not correspond to the scanning plane. If there are no changes, the study can be completed at this stage. If any pathological changes are detected, their location is determined, anatomical and densitometric analysis is performed. To clarify the nature of pathological processes, special CT techniques can be used: high-resolution CT, contrast imaging, CT angiography, dynamic and expiratory CT, polypositional study. High-resolution CT is mandatory in the study of patients with disseminated processes, emphysema, bronchiectasis. The method of contrast enhancement of the image is shown mainly for the detection of purulent-necrotic changes. In their zone there is no vascular network, therefore densitometric parameters after intravenous administration of RKS do not increase. The CT-angiography technique is a priority in the diagnosis of pulmonary embolism, anomalies and vascular malformations, in addressing the spread of the malignant tumor process of the lungs and mediastinum to the aorta, pulmonary artery, hollow veins, heart; in the evaluation of bronchopulmonary and mediastinal lymph nodes. Dynamic CT, which consists in performing after the intravenous introduction of the RCC series of tomograms at the same level, is used in the differential diagnosis of circular pathological formations in the lungs. Expiratory CT is based on comparison of anatomical changes and densitometric parameters of lung tissue on inspiration and expiration. The main purpose of this study is to detect obstructive lesions of small bronchi. Polypositional CT is a study in a different position of the patient (usually on the back and stomach). It can be used to distinguish between physiological hypoventilation and pathologic compaction of lung tissue, because as a result of the redistribution of the gravitational effect that occurs, the hypoventilation of the posterior parts of the lung restores its airiness, and the compaction of the lung tissue remains regardless of the position of the patient's body. Additional information on the state of the anatomical structures of the chest is provided by the technologies of multiplanar reformation and three-dimensional transformations. The multiplanar reformation is most important in CT examination of blood vessels and bronchi. The program of volumetric transformation of shaded surfaces (SSD) provides the most visibility of images of ribs, intrapulmonary vessels surrounded by airborne lung tissue, trachea and bronchi containing air, as well as contrasted mediastinal vessels (Figure 22). The maximum intensity program (Max IP) has become most widespread in the diagnosis of the pathology of the chest vessels (Figure 23). Fig. 22. Computer tomogram of the breast with the construction of the image of shaded surfaces (SSD) Fig. 23. Computer tomography of the breast with the construction of images of the maximum intensity projection (MIP) in the frontal plane MAGNETIC RESONANCE IMAGING To diagnose diseases of the respiratory and mediastinal organs, MRI is currently not widely used. Priority is given to X-ray CT. However, MRI has some advantages. So, it is preferable to CT in evaluating the roots of the lungs, pleura, chest wall. In MR-mediastinal examination, it is possible to differentiate between tissue and fluid-containing structures, including vascular structures, by the difference in relaxation characteristics. The effectiveness of MRI increases under conditions of contrast enhancement, which makes it possible to detect malignant tumor infiltration of the pleura, thoracic wall, and major vessels. It is also possible to determine active tumor tissue after chemoradiotherapy, establish necrosis in tumors, and find signs of hypervascularization. Possible reliable recognition of thromboembolism of the trunk and main branches of the pulmonary artery. Methods for inhalation of lung contrast are being developed. ULTRASONIC METHOD With the ultrasound of the breast for visualization, the thoracic wall, the rib and diaphragm pleura, the lining region of the lungs, the heart, the thoracic aorta and its branches, the hollow veins, the trunk and the main branches of the pulmonary artery, the fork gland, the mediastinal lymph nodes, the dome of the diaphragm, diaphragmatic sinuses. Scanning of intrathoracic anatomical structures is performed mainly from intercostal, subcostal, parasternal, suprasternal access. On echograms of the chest wall from the intercostal spaces, soft tissues (skin, subcutaneous fatty tissue, muscles), ribs, and the surface of the lung are successively displayed. The ribs have the appearance of hyperechoic arched lines with conically divergent acoustic shadows. On modern scanners due to their high resolution, differentiation of the costal pleura and lung is possible. On the inner surface of the intercostal muscles, a fixed, fine hyperechoic line appears, which is a reflection of the parietal pleura. Deeper than this, a broader and brighter hyperechogenic line of the airway surface is determined, which shifts synchronously with breathing along the chest wall. A pleural sine with a physiological amount of fluid can be identified as a thin, slit-like anechogenous space in which a mobile hyperecho-genic, angularshaped lung is determined during respiration. With subcostal scanning, in addition, the liver, spleen and dome of the diaphragm are visualized, having the appearance of a thin echogenic line 5 mm thick, which is displaced by breathing. From the para- and suprasternal approaches, the mediastinum organs are located. His fatty tissue gives an echospositive homogeneous image, against a background which can be seen echonegative large blood vessels. Unchanged lymph nodes are oval in length along the major axis up to 10 mm with smooth, well defined contours. In general, when examining patients with respiratory organs, the ultrasonic method is quite informative for: - determining the presence, volume, location and nature of the fluid in the pleural cavities; - diagnosis of neoplasms of the chest wall and pleura; - differentiation of tissue, cystic and vascular neoplasms of the mediastinum;- выявления патологических процессов (воспалительные инфильтраты, опухоли, абсцессы, ателектазы, пневмосклерозы) в субплевральных отделах легких; - Evaluation of mediastinal lymph nodes; - diagnosis of thromboembolism of the trunk and main branches of the pulmonary artery. RADIONUCLIDE METHOD Radionuclide studies of the lung and mediastinum are currently performed using methods of planar scintigraphy, SPECT, PET. Main directions: - study of physiological processes that form the basis of external respiration: alveolar ventilation, alveolar-capillary diffusion, capillary blood flow (perfusion) of the system of a small circle of blood circulation; - Diagnosis of pulmonary embolism; - Diagnosis of malignant neoplasms of the lungs; - Definition of tumor lesion of lymph nodes of the mediastinum; - Diagnosis of mediastinal goiter. To assess the alveolar ventilation and bronchial patency, a technique of inhalation (ventilation) scintigraphy is used. Patients are allowed to inhale a gas mixture containing a radioactive nuclide. The most common inert gas is xenon-133 (133Xe) and aerosol of microspheres of human serum albumin (MCA) labeled with technetium-99 m (99mTc). The resulting scintigraphic image provides information on the flow of gas into various parts of the lungs. Places of reduced accumulation of RFP correspond to sites of disturbed ventilation. This is observed with any bronchopulmonary diseases, accompanied by violation of bronchial patency, alveolar ventilation, alveolar-capillary diffusion (tumor and scar bronchial stenoses, obstructive bronchitis, bronchial asthma, pulmonary emphysema, pneumosclerosis). The state of blood flow in a small circle of blood circulation is estimated using perfusion scintigraphy. Intravenously injected solution containing macroaggregates or microspheres of human serum albumin labeled with 99mTc (99mTc-MAA or 99mTc-MCA). These particles enter the small circle of the circulation, where, in connection with their They are retained in the capillary bed for a short time. Emitted by the radionuclide γ-quanta are detected by a γ-chamber (Fig. 24). Fig. 24. A series of perfusion single-photon emission computer tomograms of the lungs in the frontal (a), sagittal (b) and axial (in) planes When lung vessels are damaged, macroaggregates (microspheres) do not penetrate into the capillary network of pathologically altered areas of the lungs, which on scintigrams will be displayed as defects in the accumulation of the radionuclide. These violations of pulmonary blood flow can be caused by a variety of diseases and therefore are nonspecific. Radionuclide examination of patients with suspected PE includes a one-step perfusion and ventilation scintigraphy. For maximum reliability, the analysis of scintigrams must be combined with radiographic data. The projection coincidence of perfusion defects with the areas of light shading on X-rays significantly increases the probability of PE. To detect malignant neoplasms in the lungs and tumoral lesions of the mediastinal lymph nodes, scintigraphy with tumorotropic RFPs (most often 99mTc-MIBI, 99mTc-tetrafosmin, 201Tl) and PET with RFP based on ultrashort-free positron-irradiating radionuclides (most preferably FDG-fluoride -oxy-glucose). According to diagnostic information, these radionuclide techniques exceed CT scans. Diagnostically optimal combination of PET and CT (see Figure 8.25 on the color insert). For the diagnosis of mediastinal goiter scintigraphy is best performed with RFP 123Isodium iodide or 99mTc-pertechnetate. The diagnosis confirms the accumulation of radioactive iodine below the sternum.