Pulmonary Embolism
The CXR is often abnormal in pulmonary embolism. Atelectasis and other focal pulmonary parenchymal abnormalities are the most common findings. Pleural effusions are also common,but usually small and unilateral. Other plain film findings associated with pulmonary embolism are:
i) Westermark sign: Dilatation of the pulmonary vessels at or proximal to an embolism.
ii) Fleischner’s sign: The combination of enlargement of the pulmonary artery due to thrombus, with distal oligemia.
iii) Hampton hump: Hampton hump, a triangular or rounded pleural-based infiltrate with the apex pointed toward the hilum represents infarcted lung in pulmonary embolism.
Pericardial Effusion
The configuration of the heart in pericardial effusion depends on the volume of fluid and its distribution. It may have a globular or non-specific shape. In large effusions, there is very often a localized bulge in the left upper cardiac border. There is striking absence of abnormalities of the pulmonary vasculature. The combination of a large heart, with clear rather than congested lungs suggests a pericardial effusion. A rapid change in heart size over serial films also may be seen.
Dissection of the Aorta
The CXR may be abnormal in upto 80 per cent of patients. The abnormalities include:
i) Widened mediastinum: This is defined as a mediastinal width of more than 8 cm on the AP CXR. A tortuous aorta may be difficult to distinguish from a widened mediastinum. If in doubt, a good PA view is recommended.
ii) Abnormal aortic knob: Loss of definition or a focal widening of the mediastinal contour in the region of the aortic knuckle may be seen.
iii) Ring sign: This describes the displacement of the aorta, > 5 mm past the calcified aortic intima. The presence of this as a new finding on CXR, is considered a very specific radiographic sign.
iv) Left apical cap: This is a result of the pleural effusion that often accompanies an acute dissection.
v) Tracheal deviation and depression of left main stem bronchus or displacement of an NG tube.
Several studies have concluded that it is a combination of several of these findings that lead to suspicion of dissection.
Aneurysm of Aorta
CXR findings are an enlargement of the involved portion of the aorta. A focal dilatation may simulate a mass or adenopathy. A more generalized dilatation leads to widening of the mediastinal contours. It may be indistinguishable from an unfolded arch. In the acute situation, left pleural effusion may be present.
Pleural Effusion
Fluid has a density indistinguishable from soft tissue on a radiograph. Pleural fluid tends to accumulate in the deepest part of the posterior costophrenic angle. Small effusions are thus identified earlier on a lateral view. Ultrasonography is also capable of picking up very small effusions.
An effusion may not be recognized on a PA view until 100 to 200 ml of fluid has accumulated and has caused blunting of the costophrenic angle. Larger effusions have a fairly well defined concave upper edge (which is higher laterally than medially) and obscure the diaphragm, and later the mediastinal borders.
The CXR is often abnormal in pulmonary embolism. Atelectasis and other focal pulmonary parenchymal abnormalities are the most common findings. Pleural effusions are also common,but usually small and unilateral. Other plain film findings associated with pulmonary embolism are:
i) Westermark sign: Dilatation of the pulmonary vessels at or proximal to an embolism.
ii) Fleischner’s sign: The combination of enlargement of the pulmonary artery due to thrombus, with distal oligemia.
iii) Hampton hump: Hampton hump, a triangular or rounded pleural-based infiltrate with the apex pointed toward the hilum represents infarcted lung in pulmonary embolism.
Pericardial Effusion
The configuration of the heart in pericardial effusion depends on the volume of fluid and its distribution. It may have a globular or non-specific shape. In large effusions, there is very often a localized bulge in the left upper cardiac border. There is striking absence of abnormalities of the pulmonary vasculature. The combination of a large heart, with clear rather than congested lungs suggests a pericardial effusion. A rapid change in heart size over serial films also may be seen.
Dissection of the Aorta
The CXR may be abnormal in upto 80 per cent of patients. The abnormalities include:
i) Widened mediastinum: This is defined as a mediastinal width of more than 8 cm on the AP CXR. A tortuous aorta may be difficult to distinguish from a widened mediastinum. If in doubt, a good PA view is recommended.
ii) Abnormal aortic knob: Loss of definition or a focal widening of the mediastinal contour in the region of the aortic knuckle may be seen.
iii) Ring sign: This describes the displacement of the aorta, > 5 mm past the calcified aortic intima. The presence of this as a new finding on CXR, is considered a very specific radiographic sign.
iv) Left apical cap: This is a result of the pleural effusion that often accompanies an acute dissection.
v) Tracheal deviation and depression of left main stem bronchus or displacement of an NG tube.
Several studies have concluded that it is a combination of several of these findings that lead to suspicion of dissection.
Aneurysm of Aorta
CXR findings are an enlargement of the involved portion of the aorta. A focal dilatation may simulate a mass or adenopathy. A more generalized dilatation leads to widening of the mediastinal contours. It may be indistinguishable from an unfolded arch. In the acute situation, left pleural effusion may be present.
Pleural Effusion
Fluid has a density indistinguishable from soft tissue on a radiograph. Pleural fluid tends to accumulate in the deepest part of the posterior costophrenic angle. Small effusions are thus identified earlier on a lateral view. Ultrasonography is also capable of picking up very small effusions.
An effusion may not be recognized on a PA view until 100 to 200 ml of fluid has accumulated and has caused blunting of the costophrenic angle. Larger effusions have a fairly well defined concave upper edge (which is higher laterally than medially) and obscure the diaphragm, and later the mediastinal borders.
Atypical Distribution of Pleural Fluid
i)Lamellar effusion: These are shallow collections of fluid between the chest wall and the lung surface.
ii) Subpulmonic effusion: Fluid accumulating between the lung and the diaphragm will cause the contour of the “diaphragm” to be altered, its apex being more lateral than expected. There may be associated blunting of the CP angle. On the left side, a subpulmonic effusion may result in an increased distance between the fundic air bubble and the lung base.
iii) Loculated effusion: Fluid may be loculated along the lung periphery due to fusion of the visceral and parietal pleura. These collections often have a biconvex shape and when viewed in profile have a sharp outline, with tapered margins forming an obtuse angle with the chest wall. Fluid may be loculated in the interlobar fissures, most commonly seen in heart failure.Fluid in the horizontal fissure is well defined and more easily recognized to be an interlobar
effusion. In the major fissure, PA and lateral views may be necessary to make the diagnosis. Typically, these collections disappear rapidly after treatment for heart failure, and are known as pseudo or vanishing tumours.
effusion. In the major fissure, PA and lateral views may be necessary to make the diagnosis. Typically, these collections disappear rapidly after treatment for heart failure, and are known as pseudo or vanishing tumours.
Pneumothorax
Air in the pleural cavity manifests in a number of ways on the CXR, depending on the volume of air and position of the patient. The typical findings of a pneumothorax are an area of marked radiolucency, with absent vascular markings, and visibility of the adjacent lung margin. On an erect film, a small pneumothorax would be identified at the lung apex. Larger pneumothoraces are easily identified by their radiolucency and the adjacent collapsed lung. A tension
pneumothorax would increase the volume of the ipsilateral thoracic cavity by flattening the diaphragm, widening the rib interspaces, displacing the mediastinum to the opposite side and causing complete collapse of the lung.
pneumothorax would increase the volume of the ipsilateral thoracic cavity by flattening the diaphragm, widening the rib interspaces, displacing the mediastinum to the opposite side and causing complete collapse of the lung.
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