Читать книгу Respiratory Medicine - Stephen J. Bourke - Страница 114

Normal air‐filled lung does not transmit high‐frequency sound waves so that ultrasonography is not useful in assessing disease of lung parenchyma. It is helpful in assessing lesions of the pleura and is particularly useful for localising loculated pleural effusions and guiding chest tube insertion (see Chapter 16).

Figure 4.8 A cavitating lesion in the left upper lobe. A cavity appears as an area of radiolucency (black) within an opacity (white). Sputum cytology showed cells from a squamous carcinoma. Computed tomography showed left hilar and subcarinal lymphadenopathy.

Figure 4.9 Mediastinal masses. Diagram of lateral view of the chest, indicating the sites favoured by some of the more common mediastinal masses.

Figure 4.10 Mediastinal structures. Principal blood vessels and airways. Top: Heart and major blood vessels showing the aorta curling over the bifurcation of the pulmonary trunk into left and right pulmonary arteries (arrows). The horizontal lines (a)–(d) indicate the levels of the computed tomography sections illustrated in Fig. 4.10. 1, Right brachiocephalic vein; 2, left brachiocephalic vein; 3, innominate or brachiocephalic artery; 4, left common carotid artery; 5, left subclavian artery. Bottom: Structures with the heart removed. The aorta curls over the left main bronchus, which lies behind the left pulmonary artery. Pulmonary arteries are shown shaded, pulmonary veins unshaded and bronchi are shown striped. In general the arteries loop downwards, like a handlebar moustache; veins radiate towards a lower common destination – the left atrium. The veins are applied to the front of the arteries and bronchi and take a slightly different path to the respective lung segments. On the right, the order of structures from front to back is vein–artery–bronchus; on the left, the pulmonary artery loops over the left upper lobe bronchus and descends behind so that the order is vein–bronchus–artery.

Figure 4.11 Principal mediastinal structures on computed tomography. The sections (a)–(d) are at levels (a)–(d) in Fig. 4.9. The sections should be regarded as being viewed from below (i.e. the left of the thorax is on the right of the figure). (a) Section above the aortic arch. Many large vessels and an anterior sausage shape are seen; the trachea has not bifurcated (black circle). Numerals refer to Fig. 4.9 and its legend. (b) Section at the level of aortic arch. A large oblique sausage shape representing the aortic arch is seen (ao); oes, oesophagus which is visible in all the sections; svc, superior vena cava. (c) Section below the aortic arch. Both ascending (aao) and descending (dao) aortas are visible, the trachea is bifurcating and the pulmonary arteries are seen; pa, left pulmonary artery. (d) Section at the level of pulmonary veins (pv). Lower lobe intrapulmonary arteries and bronchi are not shown in the diagram.