Computed tomography of the thorax is normal
Last reviewed: 23.04.2024
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Normal anatomy
CT sections of the chest also go and are displayed from the bottom. Therefore, the left lung is visualized on the right side of the image and vice versa. It is necessary to know well the trunk vessels originating from the arch of the aorta. From the front to the subclavian artery, the left common carotid artery and the brachiocephalic trunk adjoin. More to the right and to the front are seen the brachiocephalic veins, which after merging on the slices form the upper hollow vein. In the axillary tissue, it is often possible to recognize normal lymph nodes by their characteristic form with a fat-density gate. Depending on the angle of the section, lymph nodes on the cut, the gate of reduced density is visualized in the center or along the edge. The normal lymph nodes of the axillary region are clearly delineated from the surrounding tissues and do not exceed 1 cm in diameter.
Behind the trachea, near the esophagus, an unpaired vein is visualized. Forming an arch over the right main bronchus, it passes forward and falls into the upper hollow vein. Examining the cavernous space, one should not confuse an unpaired vein, a semi- unpaired vein or an additional semi-unpaired vein with paraaortic lymph nodes.
Directly under the arch of the aorta is located the pulmonary trunk, which is divided into the right and left pulmonary arteries. It is also necessary to check the area under the bifurcation of the trachea between the two major bronchi next to the pulmonary vessels - there you can find enlarged lymph nodes or malignant neoplasms. Near the internal pectoral (mammar) vessels pass the lymphatic ducts from the internal parts of the mammary glands, while the lymphatic ducts from the external sections of the mammary glands pass in the direction of the axillary lymph nodes.
The left atrium is the back chamber of the heart. In the center of the heart is the output tract of the left ventricle, passing into the ascending aorta. On the right side is the right atrium, and the right ventricle is in front, just behind the sternum. In the soft tissue window, only large branches of pulmonary vessels are visualized. About small, peripheral branches of pulmonary vessels it is better to judge by a pulmonary window (here it is not visible).
The lower hollow vein is visualized on more caudal sections, and finally, the dome of the diaphragm appears together with the upper pole of the liver. If you suspect a bronchial cancer, many radiologists are expanding the caudal zone of interest to include the entire liver, because lung cancer often metastasizes to the liver and adrenal glands. In the peripheral parts of the lungs near the diaphragm, the diameter of the pulmonary vessels is so small that they are not visible in the soft tissue window, as in the presented images. Therefore, the vascular pattern of the lungs must be evaluated in the pulmonary window, which includes negative values of the density of the Hounsfield scale. Only after this assessment of the chest cavity is complete.
Variants of normal anatomy
Among the many variants of normal chest anatomy in carrying out computed tomography of the chest, the atypical location of the unpaired vein is relatively common. Leaning from the posterior mediastinum to the superior vena cava, it can pass through the upper lobe of the right lung. Located inside the pleural fold, the proportion of the unpaired vein is separated from the rest of the upper right lobe. This feature has no clinical significance, and it is usually detected accidentally with traditional chest radiography.
Atypical location and branching of the vessels of the arch of the aorta is infrequent. For the pathological formation of the superior mediastinum, the right subclavian artery, known as the "artery of the lucuria," should not be taken.
Note that normal breast tissue surrounded by fatty tissue can have very uneven contours. When you view an image in the pulmonary window, you need to pay attention not only to focal formations and inflammatory infiltration, but also to impoverishment or even the absence of a vascular pattern of the lungs.
Reducing the number of vessels in the lung tissue when performing a computed tomography of the chest is not always a sign of emphysema. After the removal of part of the lung, the asymmetry of the distribution of blood vessels and bronchi develops.
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