COLLAPSE

Navdeep Singh

COLLAPSE

Partial or complete loss of volume of a

lung

Lobar collapse due to endobronchial obstruction

• Intrinsic - Bronchogenic carcinoma, Bronchial

carcinoid - Adenoid cystic carcinoma, - Metastases, Lymphoma - Benign tumours (e.g. lipoma, hamartoma) -Miscellaneous conditions (e.g. aspirated

foreign bodies, mucus plugs, gastric contents, malpositioned endotracheal tubes)

• Extrinsic - Hilar or mediastinal lymphadenopathy - Mediastinal masses - Fibrosing mediastinitis - Aortic aneurysms

Mechanisms of collapse Relaxation or passive collapse – lung

tends to retract towards its hilum when air or increased fluid collects in the pleural space

Cicatrisation collapse – pulmonary fibrosis

Adhesive collapse - The surface tension of the alveoli is decreased by surfactant. If this mechanism is disturbed, as in the respiratory distress syndrome, collapse of alveoli occurs, although the central airways remain patent.

Resorption collapse – CA bronchus

Radiological signs of collapse

Direct signs Displacement of interlobar fissures Loss of aeration – if the collapsed lung is

adjacent to mediastinum or diaphragm, obscuration of adjacent strucutres.Increased density of a collapsed area of lung

Vascular & bronchial signs – the pulmonary vessels & bronchi become crowded together in the affected lobe and their orientation changes.

Indirect signs Compensatory hyperinflation - vessels more

widely spaced. Hilar displacement- The hilum may be

elevated in upper lobe collapse, and appears small in lower lobe collapse

Elevation of the hemidiaphragm – may be seen in lower lobe collapse.

Mediastinal displacement – in upper lobe collapse the trachea is often displaced toward the affected side, and in lower lobe collapse the heart may be displaced. Displacement of the anterior and posterior junctional line, azygo-oesophageal.

Shifting granuloma

Right upper lobe collapse

Opacity at apex of hemithorax. Elevated horizontal fissure resulting in concave

inferior margin. On lateral view, the horizontal and oblique fissure

are displaced superiorly and medially. In severe collapse the horizontal fissure parallels the

mediastinum and appear as apical cap. Overinflation of middle and lower lobe resulting

horizontal course of right bronchus and pul. Artery. The hilum is elevated.

Right upper lobe collapse. (A) PA projection. Note how lesserfissure is drawn upward, and often curved, toward the apex and mediastinum.(B) Right lateral view. Lesser fissure also displaced upward. Notesome forward displacement of greater fissure above the hilum.

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Right upper lobe collapse. Typical example of a collapsed right upper lobe demonstrating the slightly concave inferior border of the opacified lung due to the horizontal fissure

Right upper lobe collapse. An example of right upper lobe collapse mimicking an apical cap of fluid

Tight right upper lobe collapse. Note how the collapsed lobe (due to a central bronchogenic carcinoma) results in increased right paramediastinal density.

CT of right upper lobe collapse. The collapsed lobe forms a triangular wedge of soft tissue anteriorly in the right hemithorax.

Left upper lobe collapse Direction of volume lobe is anterior and medial. Veil- like opacity in affected hemithorax, greatest at

hium and gradually fades away. Loss of normal silhouette of structures adjacent to

collapse as the area is no longer aerated. Luftsichel sign On lateral view the anterior outline of ascending

aorta is seen with unusual clarity due to compensatory hyperinflation of right upper lobe.

Left main bronchus has more horizontal course. Rarely left upper lobe collapse mimics right upper

lobe collapse when apicoposterior segment is mainly involved.

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PA film shows typical upper zone haze, through which is seen the elevatedand enlarged left hilum, and vessels of the hyperinflated lower lobe.The contour of the aortic knuckle is indistinct

Lateral film shows the collapsed left upper lobe between the anteriorly displaced oblique fissure (arrow heads) and part of the hyperinflated lower lobe. (C) CT demonstration of left upper lobe collapse. Calcified lymph nodes due to previous tuberculosis are visible.

Luftsichel sign due to the overinflated superior segment of the ipsilateral lower

lobe occupying the space between the mediastinum and the medial aspect of the collapsed upper lobe, resulting in a paramediastinal translucency

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Juxtaphrenic peak sign

An useful ancillary sign of upper lobe collapse (or a combination of right upper and middle lobe collapse) is a juxtaphrenic peak of the diaphragm

The sign refers to a small triangular density at the highest point of the dome of the hemidiaphragm, due to the anterior volume loss of the affected upper lobe resulting in traction and reorientation of an inferior accessory fissure

Golden’s S sign The sign refers to the S shape (or more accurately, reverse S

on the right) of the fissure due to the combination of collapse and mass centrally resulting in a focal convexity with a concave outline peripherally

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      A right upper lobe collapse demonstrating peripheral concavity and central convexity (arrows) due to an underlying bronchogenic carcinoma resulting in a reverse S shape.

Right middle lobe collapse

Horizontal fissure and lower half of the oblique fissure move toward one another

Best seen in lateral projection Loss of the silhouette with right heart border. The lordotic projection brings the displaced fissure

into the line of the Xray beam, and may elegantly demonstrate right middle lobe collapse.

Right middle lobe collapse. In both projections the lesser fissure fissure is drawn downward. In the PA view (A) the fissure finally merges with the mediastinum and disappears. Note in the lateral view (B) that the lower part of the greater fissure may be displaced forward.

Right middle lobe collapse. (A) PA film shows loss of definition of the right heart border indicating loss of aeration of the middle lobe.(B) A lateral film shows partial collapse of the middle lobe evident as a wedge-shaped opacity (arrows).

Right & left lower lobe collapse

The oblique fissure is displaced posteriorly and medially, and the collapsed lobe lies in the posteromedial portion of the chest

On the frontal radiograph, the collapsed lower lobes usually form a triangular density behind the heart

The medial portion of the hemidiaphragm may be obscured as it is no longer outlined by aerated lung

On the lateral radiograph, a posterior portion of the hemidiaphragm may not be seen

The vertebral column appears progressively denser inferiorly in lower lobe collapse

CHAPTER 17 - Pulmonary Lobar Collapse: Essential Considerations from Adam: Grai...

Right lower lobe collapse. (A) Frontal view of an example of right lower lobe collapse demonstrating a triangular density which does not obscure the right hemidiaphragm silhouette. (B) The lateral radiograph shows the typical features of increased density of the posterior costophrenic angle and loss of the silhouette of the right diaphragm posteriorly.

Left lower lobe collapse. A typical appearance of left lower lobe collapse resulting in a triangular density behind the heart (arrowheads). The contour of the medial left hemidiaphragm is lost.

On the frontal radiograph the lower lobe pulmonary artery is usually not seen in lower lobe collapse as it is no longer outlined by aerated lung

There are several features involving the upper mediastinum which are sometimes helpful in diagnosing lower lobe collapse

Superior triangle sign - triangular density to the right of the mediastinum seen in right lower lobe collapse due to displacement of anterior junctional structures

      Superior triangle sign. (A) An initial image shows the normal appearances (note the lower lobe artery is clearly visible). (B) The subsequent image shows a right lower lobe collapse demonstrating the superior triangle sign (arrow) (which should not be confused with a right upper lobe collapse). The lower lobe artery can no longer be seen

‘flat waist sign’ is seen in extensive collapse of the left lower lobe and describes flattening of the contours of the aortic knuckle and main pulmonary artery due to cardiac rotation and displacement to the left

Third, the outline of the superior aortic knuckle may be lost in severe left lower lobe collapse

Whole lung collapse Complete opacification or ‘white-out’ of the

affected hemithorax. In adults, the cause is often an obstructing

neoplasm in the right or left main bronchi There is marked volume loss with

compensatory hyperinflation of the contralateral lung across the midline

The cardinal feature of volume loss can help discriminate between collapsed lung and a large pleural effusion

By comparison, the opacity of the hemithorax is more uniform on the lateral view in large pleural effusion and may be a useful discriminating feature in equivocal cases.

Combinations of lobar collapse

Collapse of the right middle and right lower lobes is often due to an obstructing lesion in the bronchus intermedius

The features are similar to right lower lobe collapse with the exception that the opacity extends laterally to the costophrenic angle on the frontal view and from the front to the back of the hemithorax on the lateral view

Collapse of the right upper and right middle lobes is more unusual as these lobes do not have a common bronchial origin which spares the lower lobe

Both bilateral lower lobe and upper lobe collapse are exceedingly rare and may occur as a result of metachronous bronchial neoplasms or mucous plugging

Rounded atelectasis This is an unusual form of pulmonary collapse which

may be misdiagnosed as a pulmonary mass. Appears on plain film as a homogeneous mass, upto

5 cm in diameter, with ill-defined edges Always pleural based & associated with pleural

thickening Vascular shadows may be seen to radiate from part

of the opacity, resembling a comet's tail. The appearance is caused by peripheral lung tissue

folding in on itself Often related to asbestos exposure, but may occur

secondary to any exudative pleural effusion It is not of any pathological significance. CT appearance is usually diagnostic, & enables

differentiation from other pulmonary masses

Rounded atelectasis in a patient with a history of asbestos exposure. (A) Chest radiograph shows en face pleural plaque on the right with calcified pleural plaques over the dome of the right diaphragm (arrowheads). There is the suggestion of a right infrahilar mass. (B) Highresolution CT demonstrates indrawing of the bronchovascular structures into a pleurally based mass. The appearances are typical of rounded atelectasis.there is widespread calcified pleural plaques