14Pulmonary Lobar Collapse:

Essential Considerations

• FIGURE 14-1 Total left lung ■collapse. (A) Frontal and (B) lateral chest radiographs. The cause of the collapse is a bronchogenic carcinoma; the endobronchial component is visible as an abrupt cutoff of the left main bronchus. Note the marked displacement of the right lung anteriorly and posteriorly across the midline (arrows). Note the marked anterior hyperlucency of the thorax on the lateral view (B).

• FIGURE 14-2 Total right lung collapse in a ■neonate. The patient was ventilated for respiratory distress syndrome and the cause of the total lung collapse was a mucus plug.

• FIGURE 14-3 Shifting ■granuloma sign. (A) Before and (B) after right lower lobe collapse.

• FIGURE 14-4 ■Luftsichel sign. (A) A left upper lobe collapse demonstrating paramediastinal lucency (arrow). (B) CT shows interposition of aerated lung between the collapse and the mediastinum (arrow). There is also a large right paratracheal node causing some distortion of the SVC.

• FIGURE 14-5 Juxtaphrenic peak sign. A ■small triangular density (arrow) is seen in a left upper lobe collapse. The sign is due to reorientation of an inferior accessory fissure.

• FIGURE 14-6 Golden’s S sign. A right upper lobe ■collapse demonstrating peripheral concavity and central convexity (arrows) due to an underlying bronchogenic carcinoma resulting in a reverse S shape.

• FIGURE 14-7 Air bronchograms in a collapsed and ■consolidated right lower lobe. The sign can be helpful in excluding a central obstructing mass and in this case the cause was a bacterial pneumonia.

• FIGURE 14-8 Enhancement of ■atelectatic lung versus pneumonia. (A) Axial intravenous contrast enhanced CT in a patient with passive atelectasis of the right lower lobe due to a large pleural effusion. Note the dense homogeneous enhancement of the collapsed right lower lobe. (B) Axial intravenous contrast enhanced CT of a patient with right upper lobe pneumonia, right pleural effusion and pericardial effusion. Note the relative lack of enhancement of the posterior right upper lobe (arrow) resulting in less clear differentiation of pulmonary parenchyma from pleural fluid than demonstrated in (A).

• FIGURE 14-9 CT of a ■collapsed right upper lobe due to a squamous cell carcinoma. Note the peripheral air bronchograms (arrow) in (A) despite a central obstructing mass with amorphous calcification (B). There is a convex border of the collapsed lobe (arrows) (B) which is the CT equivalent of Golden’s S sign.

• FIGURE 14-10 CT of right upper lobe collapse due to ■bronchogenic carcinoma. Note how the attenuation of the necrotic tumour is lower than the adjacent collapsed lung which enhances with intravenous contrast medium.

• FIGURE 14-11 Left lung ■collapse. (A, B) Contrast enhanced CT sections of whole lung collapse due to a squamous cell carcinoma in the left main bronchus (arrow in A). There is also a left pleural effusion and a small pericardial effusion. Note the low attenuation areas relative to the densely enhancing left lower lobe parenchyma (B) which represent mucus filled airways—the CT mucous bronchogram sign.

• FIGURE 14-12 Left lower lobe collapse. Contrast ■enhanced CT showing a tight left lower lobe collapse. Normal mediastinal structures (particularly left sided) may cause a focal bulge in the contour of a lobar collapse (in this case by the well opacified descending thoracic aorta) and should not be confused with a Golden’s S sign due to tumour.

• FIGURE 14-13 Resolution of ■left lower lobe collapse. (A) An initial high resolution CT of a young female patient with symptoms of recurrent respiratory tract infections shows a collapsed left lower lobe with possible bronchiectatic airways, raising the possibility of chronicity. (B) Follow up conventional CT at the same level several months later shows complete resolution of the left lower lobe collapse and normal airways. This case illustrates the difficulty in making an accurate assessment of the airways in patients with lobar collapse.

• FIGURE 14-14 Ultrasound demonstrating a ■linear collapsed lower lobe with a large pleural effusion. The asterisks demonstrate the distance between the collapsed lung and hemidiaphragm.

• FIGURE 14-15 Intravenous contrast enhanced ■CT demonstrating right middle lobe collapse (A). Image from a CT PET study at the same level (B) shows increased uptake of radioisotope within the collapse. A targeted ultrasound guided biopsy was performed (C), and bronchogenic carcinoma confirmed. Continued

• FIGURE 14-15 Intravenous contrast enhanced ■ CT demonstrating right middle lobe collapse (A). Image from a CT PET study at the same level (B) shows increased uptake of radioisotope within the collapse. A targeted ultrasoundguided biopsy was performed (C), and bronchogenic carcinoma confirmed.

• FIGURE 14-16 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.

• FIGURE 14-17 ■Right upper lobe collapse. An example of right upper lobe collapse mimicking an apical cap of fluid (arrow).

• FIGURE 14-18 Tight right upper lobe ■collapse. Note how the collapsed lobe (due to a central bronchogenic carcinoma) results in increased right paramediastinal density.

• FIGURE 14-19 CT of right upper lobe collapse. ■The collapsed lobe forms a triangular wedge of soft tissue anteriorly in the right hemithorax.

• FIGURE 14-20 Left upper lobe ■collapse. (A) A typical example of left upper lobe collapse demonstrating increased angulation between the left main bronchus and the lower lobe bronchus arrow) on the frontal view. The aortic knuckle is visible in this example due to compensatory hyperinflation of the left lower lobe. (B) The lateral view demonstrates anterior displacement of the oblique fissure. Note the increased retrosternal lucency (see Fig. 14.21).

• FIGURE 14-21 Left upper lobe collapse. Intravenous ■contrast enhanced CT of left upper lobe collapse shows increased wedge shaped density of the left upper lobe adjacent to the mediastinum. Note the displacement of the right lung across the midline anteriorly, resulting in retrosternal hyperlucency and increased clarity of the anterior ascending thoracic aorta on the lateral view (see Fig. 14.20).

• FIGURE 14-22 Atypical left upper lobe collapse. (A) The ■frontal radiograph demonstrates the inferior concave border of the collapsed lobe and resembles a right upper lobe collapse. (B, C) CT images show increased triangular density to the left of the mediastinum (B), which does not extend along the left heart border (C), a feature usually seen in left upper lobe collapse. The appearance is due to sparing of the lingular segments.

• FIGURE 14-22 Atypical left upper lobe collapse. (A) The frontal ■radiograph demonstrates the inferior concave border of the collapsed lobe and resembles a right upper lobe collapse. (B, C) CT images show increased triangular density to the left of the mediastinum (B), which does not extend along the left heart border (C), a feature usually seen in left upper lobe collapse. The appearance is due to sparing of the lingular segments.

• FIGURE 14-23 Lingular collapse. (A) Frontal view of ■isolated collapse of the lingular segments of the left upper lobe showing loss of clarity of the left heart border and a raised hemidiaphragm. (B) The similarity to a right middle lobe collapse can be appreciated on the lateral view.

• FIGURE 14-24 Right middle lobe collapse. ■(A) Frontal view of a typical example showing loss of clarity of the right heart border. (B) The lateral view shows the wedge shaped density extending anteriorly from the hilum.

• FIGURE 14-25 Right middle lobe collapse. An ■example showing a triangular shaped density adjacent to the right heart border.

• FIGURE 14-26 Middle lobe syndrome. High ■resolution CT showing right middle lobe collapse and bronchiectasis due to previous tuberculous infection.

• FIGURE 14-27 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.

• FIGURE 14-28 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.

• FIGURE 14-29 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.

• FIGURE 14-30 ■Schematic appearances of the various lobar collapses on frontal and lateral radiographs. RUL, right upper lobe; RML, right middle lobe; RLL, right lower lobe; LUL, left upper lobe; LLL, left lower lobe.

• FIGURE 14-31 Combined right middle and right lower lobe collapse. (A) On ■the frontal view the increased density extends to the right costophrenic angle. (B) On the lateral view the increased density also extends from the anterior to the posterior chest wall. The cause in this case was a bronchogenic carcinoma obstructing the bronchus intermedius.

• FIGURE 14-32 Bilateral lower lobe collapse. Bilateral ■triangular densities are seen with obscuration of the medial portions of the hemidiaphragms. The cause was mucus plugging.