Lymphadenopathy: Lymphadenopathy is usually used simply to describe enlargement of lymph nodes from various causes, synonymous with enlarged lymph nodes.
CT: Normal lymph nodes have a wide range of sizes. Mediastinal lymph nodes and hilar lymph nodes can reach 12 mm. The upper limit of mediastinal lymph nodes is currently less than 1 cm in short diameter and hilar lymph nodes less than 3 mm in short diameter in most cases, but this criterion is not very reliable in identifying benign and malignant lymph nodes.
Lymphomatoid interstitial pneumonia pathology: Lymphomatoid interstitial pneumonia is a rare disease characterized by diffuse pulmonary lymphomatoid hyperplasia involving mainly the interstitium. The disease falls within the category of interstitial pneumonia and is significantly different from diffuse lymphoma of the lung. Features include diffuse proliferation of airway-associated lymphoid tissue with diffuse infiltration of polyclonal lymphocytes around the coarctation and expansion into the interstitium. Lymphomatoid interstitial pneumonia is long associated with autoimmune disease or immunodeficiency virus infection.
CT: The main abnormality is a ground glass shadow with visible thin-walled cysts next to blood vessels. Pulmonary nodules, reticular shadows, thickening of lobular septa and bronchial bundles, and diffuse solid changes can also occur.
Cornuate Plain and CT: On chest radiographs, cornuate represents a large number of small, scattered, round pulmonary shadows (less than 3 mm in diameter), relatively uniform in size and diffusely distributed in both lungs. It is characteristic of a diffuse distribution of tuberculosis or metastatic lesions. It appears as a widespread, randomly distributed micronodule on thin-section CT.
Mosaic sign CT:This sign appears as a mosaic of different densities in patches and can be an interstitial lesion, an occlusive small airway lesion (Figure) or vascular obstructive disease. The mosaic sign has stronger diagnostic implications than mosaic-like oligemia or hypoperfusion. Air trapping due to bronchial or fine bronchial obstruction can lead to local hypodensity, which is more evident on expiratory phase CT. This sign can also be seen in interstitial lung disease and is characterized by a ground glass shadow, when high density represents an interstitial lesion and low density represents a normal lung.
Aspergillus bulb pathology: Aspergillus bulb is a mass formed by isolated hyphae intertwined, often Aspergillus-like pathogens, mucus, fibrin, cellular debris together constitute the cavity component, often launch with you on the basis of fibrous cavities (such as tuberculosis or connective tissue disease) Plain film and CT: Aspergillus bulb can change with changes in body position, some cases can be seen in the air crescent sign (Figure) CT can show sponge-like images and Foci of calcification within the varicoceles. The synonym is fungal bulb.
nodular pattern Corn-like nodular shadow This term has not been clarified how to translate well on plain film and CT: Corn-like nodular shadow is shown as numerous small round nodules on chest film with diffuse distribution, within 2~10mm of the fingertip solution (Figure). The lesion is widely but not necessarily uniformly distributed and has three anatomical distribution patterns on CT: lobular centrality, along the lymphatic vessels or random nodules Plain film and CT: nodules on the chest film appear as round high-density shadow with clear or indistinct borders and a diameter of months 3 cm.(a) Glandular alveolar nodules are round or ovoid with indistinct borders and a diameter of 5 to 10 mm, which are generally considered to be caused by solid lesions leading to solid alveoli The This use is only applicable when there are multiple foci. (b) Pseudonodules may resemble pulmonary nodules and may be rib fractures, skin lesions, body surface devices, anatomic variants or overlapping shadows. On CT, the nodule appears as a round or irregular hyperdense shadow with well-defined or indistinct borders and a diameter of less than 3 cm.(a) Lobular central nodules appear as multiple nodules several millimeters from the pleural surface, fissures, or lobular septa. They may be soft tissue dense or ground glass shadows ranging in size from a few millimeters to several centimeters, and lobular central nodules are often poorly defined. (b) Small nodules less than 3 mm in diameter.(c) Ground glass nodules (synonymous with non-solid nodules) present as faint hyperdense shadows within the lungs, allowing identification of bronchial and vascular borders. (d) Solid nodules are uniform and consistent soft tissue density (e) Partial solid nodules include both a ground glass shadow component and a soft tissue density component.
Pathology of nonspecific interstitial pneumonia: Nonspecific interstitial pneumonia is characterized by varying degrees of chronic inflammation or fibrosis with homogeneous involvement of the interstitium. Non-specific interstitial pneumonia can be described as idiopathic or can be seen in other diseases such as collagen vascular disease, hyper-reactive pneumonia, drug-induced lung disease, infection or immune immunosuppression (including human immunodeficiency virus) CT: Thin-section CT of non-specific interstitial pneumonia is variable, with the most common signs being ground glass shadowing with reticular shadowing, traction bronchiectasis or fine bronchiectasis, but Foveal signs are rare or absent, and the lesions are usually distributed in the basal segment or subpleural.
Pulmonary olighemia physiology: pulmonary olighemia is a decrease in pulmonary blood volume. In most cases, it is localized, but pulmonary oligemia can also be seen throughout the lung. Localized pulmonary olighemia is due to decreased blood flow to the local oligemic area.
Plain radiographs and CT: pulmonary olighemia shows reduced local or extensive pulmonary vascularization, suggesting lower than normal pulmonary blood flow. (Refer to mosaic sign and pulmonary blood redistribution.) Mechanized pneumonia pathology: The histopathology of mechanized pneumonia is characterized by loose connective tissue located in the air spaces and distal airways. Inflammation or fibrosis of the interstitium is mild or absent. Unexplained mechanized pneumonia is a relatively unusual category of idiopathic interstitial pneumonia. However, histopathologic patterns of mechanized pneumonia are seen in a variety of conditions, including pulmonary infection, hyperreactive pneumonia, and collagen vascular disease.
Plain films and CT: On plain films and CT, the predominant feature of mechanized pneumonia is solid lesions in the air-containing spaces, and in interstitial pneumonia of unknown origin, the lesions are characterized by subpleural and basal segments, sometimes in the Microsoft bronchi. Other manifestations of mechanized pneumonia include ground glass shadow, tree-bud sign and nodular shadow in alloglandular emphysema pathology: alloglandular emphysema involves all of the alveoli, with relatively uniform involvement of the secondary lung lobules. This type of emphysema is associated with antitrypsin deficiency.
CT-Total alveolar emphysema is characterized by widespread hypodensity of the lung parenchyma and a reduction in the vascular diameter of the diseased lung, and severe total alveolar emphysema may coexist and cointegrate with lobar central emphysema. The lack of characteristic hypointense shadow is difficult to distinguish from stenosing occlusive bronchiectasis. It is synonymous with total lobar emphysema.
Paraseptal emphysema pathology: Paraseptal emphysema is characterized by the involvement of mainly distal alveoli, alveolar ducts and alveolar sacs. It is characteristically separated by the pleural surface and lobular septa.
CT-This type of emphysema is characterized by hypodense areas of subpleural and parapneumonic bronchial vessels separated by lobular septa, sometimes accompanied by pulmonary macules. The synonym is distal alveolar emphysema parenchymal band Fibrous cord shadow plain film and CT: Fibrous cord shadow is a linear, high-density shadow, often 1-3 mm thick and 5 cm long, often extending into the dirty pleura (the dirty pleura is often thickly laminated and drawn), representing fibrosis of the pleura and lung parenchyma, often accompanied by drawing of the lung parenchyma. Fibrous cords are most commonly seen in asbestos-exposed patients.
Plain and CT parenchymal hyperdensity shadow: the edges of blood vessels and airway walls may or may not be blurred in the parenchymal hyperdensity shadow, and solid changes represent the loss of the edges of these structures in the hyperdensity shadow (except for the air bronchial sign). The ground glass sign suggests slightly increased density with well-defined margins of structures within it. Solid lung lesions and ground glass shadows are more widely used.
-Parabronchial interstitial anatomy: The parabronchial interstitium is a connective tissue sheath that encases the bronchi, pulmonary vessels, and lymphatics and extends from the hilum to the periphery of the lung.
-Perifollicular distribution anatomy: The perifollicular region includes the demarcated structures surrounding the secondary pulmonary lobules.
CT: This sign is characterized by the distribution of the lesion along the demarcated structures surrounding the pulmonary lobules (e.g., lobular saber, dirty pleura, and blood vessels. This term is most often applied when the lesion is located primarily on the inner surface of the secondary lung lobules (e.g., perifollicular mechanized pneumonia). This sign can resemble the atypical thickening of the lobular septa with perilymphatic distribution anatomy: this sign is characterized by the distribution of the lesion within the lung along or adjacent to the lymphatics. The lymphoid tissue is located in the bronchovascular bundles, lobular septa, large pulmonary veins, and pleura. There is no lymphoid tissue in the alveoli.
CT.- Lesions occurring along the pathways of the lymphatic system within the lung, i.e. hilar lesions, peribronchial vascular bundles, central lobular interstitial lesions, interlobular septal lesions, and subpleural lesions, are of perilymphatic distribution. Typical cases are seen in nodular disease (nodular disease) and carcinomatous lymphangitis.
Pleural spot pathology: pleural spots are fibrous hyaline, relatively acellular lesions that arise mainly from the mural layers of the pleura, especially in the supra-diaphragm and subcostal areas. Pleural spots arise almost exclusively from a long history of asbestos exposure (at least 15 years).
Plain film and CT: pleural plaques are well-defined localized pleural thickenings that appear as localized homogeneous or nodular protrusions of the pleura, often accompanied by calcifications. (Figure) Pleural plaques vary in thickness and can be less than 1 cm to 5 cm in diameter, and CT is easier to detect than plain films. Sometimes pleural plaques can resemble intrapulmonary nodules.
Pulmonary bulge pathology: Pulmonary bulge is a thin-walled inflated cavity in the lung. It is often caused by acute pneumonia, trauma, inhalation of liquid hydrocarbons, and is often transient. The mechanism is thought to be parenchymal necrosis, one-way piston formation resulting in airway obstruction.
Plain film and CT: shows a subcircular thin-walled air-containing cavity in the lung.
Mediastinal emphysema pathology: Mediastinal emphysema is the presence of gas in the mediastinal tissue outside the esophageal and tracheobronchial tree and can be caused by spontaneous rupture of the alveoli resulting in gas entering the mediastinum along the interstitial tracheal vessels. Mediastinal emphysema has a clear association with asthma, severe cough, or mechanical ventilation.
Plain film and CT: Mediastinal emphysema appears as a band of translucent shadow on chest radiographs, mostly vertical in orientation, see Fig. Some of the low signal strip shadows can outline the borders of blood vessels and bronchi (attend to pericardial emphysema) Pneumothorax and tension pneumothorax pathophysiology: Pneumothorax refers to the presence of gas in the pleural space. It includes spontaneous, traumatic, diagnostic and tension pneumothorax. Tension pneumothorax is the accumulation of gas in the pleural cavity with a certain pressure. Normally, as such, the lung will completely compress and collapse, while in a hypo-compliant lung, it can remain inflated incompletely.
Plain film and CT: On a chest film, a dirty pleural border can be seen, Figure 55, unless the amount of pneumothorax is minimal or the pleural border is not in a tangential position to the x-ray. Tension pneumothorax can present with significant mediastinal shift and/or depression of one side of the diaphragm. Some non-tension pneumothorax can also present with mediastinal shift, which is caused by intrapleural cavity pressure on the diseased side reaching atmospheric pressure while the healthy side has negative pleural cavity pressure.
Pneumonia pathology: Pneumonia is an inflammation of the lung parenchyma and/or interstitium (e.g., infection, bacterial pneumonia). Infectious pneumonia is characterized by exudative lesions leading to solid changes. This term is also used to refer to a range of non-infectious syndromes of the lung parenchyma characterized by varying degrees of inflammation and fibrosis (e.g., nonspecific interstitial pneumonia) – Pericardial emphysema pathology: Pericardial emphysema is the presence of gas in the pericardial cavity. It is usually medical in origin, surgical in nature and commonly seen in adults.
Plain film and CT: Pericardial emphysema can be differentiated from mediastinal emphysema because the gas causes translucency that does not extend beyond the pericardial cavity.
Progressive extensive pulmonary fibrosis pathology: the disease arises from chronic accumulation of dust and collagen hyperplasia following patient exposure to inorganic dust (mainly seen in coal workers) Plain film and CT: a mass-like lesion, often bilateral, occurs in the upper lobe (Figure 56). Nodular background density abnormalities suggest pneumoconiosis, with or without emphysematous destruction adjacent to extensive fibrosis. Lesions similar to progressive extensive fibrosis can also be seen in nodular disease and talipes.
Pseudocavitation CT – Pseudocavitations appear as round or ovoid hypointense within a pulmonary nodule, mass, or solid shadow, reflecting relatively normal lung parenchyma, or dilated bronchi, or localized emphysema, rather than a cavity. Pseudocavities are usually less than 1 cm in diameter and can be seen in adenocarcinomas (Figure), fine bronchoalveolar carcinomas, and benign lesions such as infectious pneumonia.
Pseudopleural plaques CT: Pseudopleural plaques are high intrapulmonary densities that are continuous with the dirty pleura and are formed by small nodules fusing with each other. This sign is most commonly seen in nodular disease, (Figure), silicosis, and coal workers’ pneumoconiosis.
Pulmonary blood redistribution pathophysiology: Pulmonary blood redistribution is a change in the normal distribution pattern of pulmonary blood due to increased pulmonary vascular resistance in the pulmonary vascular bed. Plain film and CT: Signs suggestive of pulmonary blood redistribution are a decrease in the diameter or number of pulmonary vessels in one or more areas with a corresponding increase in the diameter or number of pulmonary vessels in other parts of the lung. The redistribution of pulmonary blood in the upper lobe of patients with mitral valve lesions is an example of primitive (archetypal example) pulmonary blood redistribution.
Respiratory bronchiolitisCinterstitial lungdisease, or RB-ILDPathology: Respiratory bronchiolitis-interstitial lung disease is a group of smoking-related lesions characterized by respiratory bronchiolitis or bronchiolitis. Respiratory bronchitis-interstitial lung disease is a group of smoking-related lesions characterized by inflammation of the respiratory or peribronchial alveoli, primarily by macrophage infiltration, sometimes with nonspecific or desquamative interstitial pneumonitis. (Figure 60), with or without fine fibrosis. This is often accompanied by thickening of the bronchial wall and lobar centrilobular emphysema. Areas of air retention represent partial lesions of the fine bronchi.
Reticular shadowing on plain radiographs and CT. – On chest radiographs, reticular shadowing is a large collection of fine thread-like shadows that, in short, form a web-like appearance. (Figure) This sign generally represents interstitial lung disease. Thin-section CT shows a much clearer component of the reticular shadow, which can be a thickening of the lobular septa, intralobular lines, or the cystic wall of the honeycomb sign. Note that reticular shadow and foveal sign are not synonymous.
Reticular nodular shadow plain film and CT: It is a reticular shadow and nodular shadow overlapping together. This sign is often a small nodular shadow formed when a large number of linear shadows cross each other. The size and number of nodules depend on the size and number of linear shadows. On CT images, this sign appears as both reticular and nodular shadows. Small nodules can be located in the center of the reticular shadow (e.g. lobular central nodules) or nodules on a linear density shadow (spaced nodules).
Anticoronal sign CT.-The anticoronal sign is a confined rounded ground glass shadow surrounded by a relatively intact annular solid shadow, Fig. This sign is rare and was first reported in unexplained mechanized pneumonia and also seen with paracoccidioidomycosis.
Right paratracheal band anatomy and plain radiograph: The right paratracheal band is a vertical linear soft tissue density, less than 4 mm wide, corresponding to the right tracheal wall and the adjacent mediastinal tissue and adjacent pleura. On the orthopantomogram, this band of density is 3-4 cm high and continues roughly from the level of the medial end of the clavicle to the right tracheobronchial angle. It can be seen with 94% of adults and can be widened or queued in cases with abundant mediastinal fat. Widening, distortion, or disappearance of the right parabronchial band is most commonly due to enlargement of the paratracheal lymph nodes.
Pathology of rounded atelectasis: Rounded atelectasis is a circular collapse of lung tissue associated with fibrous pleural reflexion and thickened fibrosis of the lobular septa. In most cases, it is the result of asbestos-induced exudative pleural effusion secondary to pleural scar formation, and can also occur from other causes of pleural fibrosis.
Plain film and CT: On chest radiographs, rounded pulmonary atelectasis appears as a mass shadow protruding from the pleural surface, . It is usually located in the posterior part of the lower lobe. The vessels are twisted and displaced in an arc and clustered on the surface and inside the mass (comet’s tail sign). The degree of lobe atrophy depends on the lung volume of the minister. This sign is often combined with other signs of pulmonary fibrosis (e.g., blunted septal angle), and CT is more sensitive in demonstrating the features of rounded pulmonary atelectasis (Figure). Another characteristic of rounded atelectasis is homogeneous enhancement.
Marginal signs silhouette sign plain radiograph: Marginal signs are indistinct soft tissue interfaces of anatomic structures due to solid or/and adjacent pulmonary tissue, masses, or adjacent pleural effusions (Figure). Marginal signs are caused by adjacent structures with similar density. This sign actually refers to marginal indistinctness and does not necessarily refer to disease (e.g. unexplained loss of cardiac margins can be associated with funnel chest and is sometimes seen in normal individuals.
Subpleural curve CT – This sign is a thin curve-like density, 1-3 mm thick, less than 1 cm from the pleura, parallel to the pleural wall, (Figure). If seen in the lower posterior portion of the lung of a patient examined in the prone position, it can be a normal lung that is not dilated and can disappear when the patient is examined on CT in the prone position. It can also be seen in patients with pulmonary edema, or pulmonary fibrosis (seen as other signs). Although asbestosis has been described, it is not a specific sign of asbestosis.
Dilated bronchi or fine bronchial dilatation CT: Dilated bronchi and fine bronchial dilatation are irregular dilatations of the bronchi and fine bronchi due to the pull of peripheral pulmonary fibrosis. The dilated airways can be either cystic (bronchi) or small cystic (fine bronchi) as shown in the figure. Multiple cystic airway deformations are difficult to distinguish from the honeycomb sign due to simple fibrosis.
Dendritic sign CT – The dendritic sign represents the central branching structures of the lobules in the form of sprouting dendrites. This sign represents a class of lesions in and around the fine bronchi, including mucus embolism, inflammation, and/or fibrosis (Figure). It is more pronounced with the peripheral portion of the lung and is often accompanied by abnormalities of the airways. Particularly common are diffuse total bronchial inflammation, intra-airway dissemination of mycobacteria, and cystic fibrosis.
Generalized interstitial pneumonia pathology: generalized interstitial pneumonia is a histopathologic feature of pulmonary fibrosis with temporal and spatial heterogeneity, with pulmonary fibrosis and cellular signs scattered between normal lungs. The key signs of the disease include fibrogenic lesions, fibrous destruction of lung structures, and honeycomb signs. Fibrosis occurs first with the periphery of the lung. Idiopathic interstitial fibrosis is usually seen, but can also occur in other conditions, such as hyperreactive pneumonia.
Plain radiographs and CT: The foveal sign at the base of the lung and under the pleura is diagnostically specific, but some biopsy-proven cases of generalized interstitial fibrosis may also be without this characteristic lesion.