There are several types of atelectasis that can occur: absorption, relaxation, adhesive, cicatricial, and round. Atelectasis causes signs of loss of lung volume such as shift of mediastinum, elevation of diaphragm, crowding of ribs, and movement of fissures and hilar structures. On imaging, atelectasis appears as a homogeneous density and causes asymmetry of the hemithorax on the affected side. The document also discusses characteristics, patterns, and radiographic findings of various cavitary lung lesions.

2. Gamal Rabie Agmy, MD, FCCP
Professor of Chest Diseases, Assiut University
ERS National Delegate of Egypt

3. The definition of atelectasis is loss of air in the alveoli;
alveoli devoid of air (not replaced).
A diagnosis of atelectasis requires the following:
1-A density, representing lung devoid of air
2-Signs indicating loss of lung volume
Atelectasis

4. 1-Absorption Atelectasis
When airways are obstructed there is no further
ventilation to the lungs and beyond. In the early
stages, blood flow continues and gradually the
oxygen and nitrogen get absorbed, resulting in
atelectasis.
Types of Atelectasis:

5. 2-Relaxation Atelectasis
The lung is held close to the chest wall because of the
negative pressure in the pleural space. Once the
negative pressure is lost the lung tends to recoil due
to elastic properties and becomes atelectatic. This
occurs in patients with pneumothorax and pleural
effusion. In this instance, the loss of negative
pressure in the pleura permits the lung to relax, due
to elastic recoil. There is common misconception that
atelectasis is due to compression.
Types of Atelectasis:

6. 3-Adhesive Atelectasis :
Surfactant reduces surface tension and keeps the
alveoli open. In conditions where there is loss of
surfactant, the alveoli collapse and become
atelectatic. In ARDS this occurs diffusely to both
lungs. In pulmonary embolism due to loss of blood
flow and lack of CO2, the integrity of surfactant
gets impaired.
Types of Atelectasis:

7. Types of Atelectasis:
4-Cicatricial Atelectasis
–Alveoli gets trapped in scar and
becomes atelectatic in fibrotic
disorders

8. .
5-Round Atelectasis
An instance where the lung gets trapped by
pleural disease and is devoid of air.
Classically encountered in asbestosis.
Types of Atelectasis:

9. Generalized
1-Shift of mediastinum: The trachea and heart gets shifted
towards the atelectatic lung.
2-Elevation of diaphragm: The diaphragm moves up and
the normal relationship between left and right side gets
altered.
3-Drooping of shoulder.
4-Crowding of ribs: The interspace between the ribs is
narrower compared to the opposite side.
Signs of Loss of Lung Volume:

10. Movement of Fissures
You need a lateral view to appreciate the movement of
oblique fissures. Forward movement of oblique fissure in
LUL atelectasis. Backward movement in lower lobe
atelectasis.
Movement of transverse fissure can be recognized in the
PA film.
Signs of Loss of Lung Volume:

11. Movement of Hilum
The right hilum is normally slightly lower than the left.
This relationship will change with lobar atelectasis.
Signs of Loss of Lung Volume:

12. Compensatory Hyperinflation
Compensatory hyperinflation as evidenced by increased
radiolucency and splaying of vessels can be seen with the
normal lobe or opposite lung.
Signs of Loss of Lung Volume:

13. Alterations in Proportion of Left and
Right Lung
The right lung is approximately 55% and left lung 45%. In
atelectasis this apportionment will change and can be a
clue to recognition of atelectasis. .
Signs of Loss of Lung Volume:

14. Hemithorax Asymmetry
In normals, the right and left hemithorax are equal in size.
The size of the hemithorax will be asymmetrical and
smaller on the side of atelectasis
Signs of Loss of Lung Volume:

15. Signs of Loss of Lung Volume:
Generalized
Shift of mediastinum: The trachea and heart gets shifted towards the atelectatic lung.
Elevation of diaphragm: The diaphragm moves up and the normal relationship between left
and right side gets altered.
Drooping of shoulder.
Crowding of ribs: The interspace between the ribs is narrower compared to the opposite side.
Movement of Fissures
You need a lateral view to appreciate the movement of oblique fissures. Forward movement of
oblique fissure in LUL atelectasis. Backward movement in lower lobe atelectasis.
Movement of transverse fissure can be recognized in the PA film.
Movement of Hilum
The right hilum is normally slightly lower than the left. This relationship will change with lobar
atelectasis.
Compensatory Hyperinflation
Compensatory hyperinflation as evidenced by increased radiolucency and splaying of vessels
can be seen with the normal lobe or opposite lung.
Alterations in Proportion of Left and Right Lung
The right lung is approximately 55% and left lung 45%. In atelectasis this apportionment will
change and can be a clue to recognition of atelectasis.
Hemithorax Asymmetry
In normals, the right and left hemithorax are equal in size. The size of the hemithorax will be
asymmetrical and smaller on the side of atelectasis

16. Atelectasis Right Lung
Homogenous density right hemithorax
Mediastinal shift to right
Right hemithorax smaller
Right heart and diaphragmatic silhouette are not identifiable

17. Atelectasis Left Lung
Homogenous density left hemithorax
Mediastinal shift to left
Left hemithorax smaller
Diaphragm and heart silhouette are not identifiable

18. Left Lower Lobe Atelectasis
• Inhomogeneous cardiac density
• Left hilum pulled down
• Non-visualization of left diaphragm
• Triangular retrocardiac atelectatic LLL

19. Atelectasis Left Lower Lobe
Double density over heart
Inhomogenous cardiac density
 Triangular retrocardiac density
Left hilum pulled down
Other findings include:
Pneumomediastinum

20. Atelectasis Left
Upper Lobe
Mediastinal shift to left
Density left upper lung field
Loss of aortic knob and left hilar
silhouettes
Herniation of right lung
Atelectatic left upper lobe
Forward movement of left
oblique fissure "Bowing sign"

21. Atelectasis Left Upper
Lobe
Hazy density over left
upper lung field
Loss of left heart
silhouette
Tracheal shift to left
Lateral
A: Forward movement of
oblique fissure
B: Herniated right lung
C: Atelectatic LUL

22. Lateral
Movement of oblique and transverse
fissures
Atelectasis Right Upper Lobe
Homogenous density right upper lung
field
Mediastinal shift to right
Loss of silhouette of ascending aorta

23. Lateral
Movement of oblique and transverse
fissures
Atelectasis Right Upper Lobe
Homogenous density right upper lung field
Mediastinal shift to right
Loss of silhouette of ascending aorta

24. RML Atelectasis
Vague density in right lower lung field, almost normal
RML atelectasis in lateral view, not evident in PA view

25. Vague density in right lower lung field (almost a normal film).
Dramatic RML atelectasis in lateral view, not evident in PA view. Movement of
transverse fissure.
Other findings include: Azygous lobe

26. Atelectasis Right Lower Lobe
Density in right lower lung field
Indistinct right diaphragm
Right heart silhouette retained
Transverse fissure moved down
Right hilum moved down

27. Adhesive Atelectasis
Alveoli are kept open by the integrity of surfactant. When there is loss
of surfactant, alveoli collapse. ARDS is an example of diffuse alveolar
atelectasis.
Plate-like atelectasis is an example of focal loss of surfactant.

28. Relaxation Atelectasis
The lung is held in apposition to the chest wall because of negative pressure
in the pleura. When the negative pressure is lost, as in pneumothorax or
pleural effusion, the lung relaxes to its atelectatic position. The atelectasis is
a secondary event. The pleural problem is primary and dictates other
radiological findings.

29. Round Atelectasis
Mass like density
Pleural based
Base of lungs
Blunting of costophrenic angle
Pleural thickening
Pulmonary vasculature curving
into the density
Esophageal surgical clips

30. Round Atelectasis
Mass like density
Pleural based
Base of lungs
Blunting of costophrenic angle, pleural thickening
Pulmonary vasculature curving into the density

31. RML Lateral Segment Atelectasis

32. Sub-segmental Atelectasis

33. Atelectasis
Segmental
Anterior sub-segment of RUL
"Bronchial wedge"

34. Hilar Displacement

39. Bronchiectasis
Left lung atelectasis due to mucus plugging
Mucus plugs suctioned with bronchoscopy
Bronchogram done after bronchoscopy
Saccular bronchiectasis in bronchogram below

40. Bronchogram
Bronchograms are rarely done nowadays. The need for it
disappeared with the invention of the fiberoptic
bronchoscopy and high resolution CT scan. View these
images to get a greater understanding of a three
dimensional view of a bronchial tree..

41. Bronchogram
Bronchograms are rarely done nowadays. The need for it disappeared with the
invention of the fiberoptic bronchoscopy and high resolution CT scan.

42. Calcification
Focal lung lesion: Ghon's complex
Miliary lung calcification:
Histoplasmosis
Tuberculosis
Alveolar microlithiasis
Chicken pox pneumonia
Solitary pulmonary nodule :
Central / Granuloma
Lamellar / Histoplasmosis
Pop corn / Hamartoma
Eccentric / Scar Cancer

43. Calcification
Nodes:
Homogenous / TB
Clumpy / Histoplasmosis
Egg shell / Silicosis, Sarcoidosis
Tracheal cartilage : Aging
Tumor:
Mediastinal mass / Teratoma
Healed lymphoma / Metstasis

44. Calcification
Vascular:
Aortic calcification
Pulmonary artery calcification
Pulmonary hypertension
Pleural:
Visceral / Hemothorax, TB, Empyema
Parietal / Asbestosis
Subcutaneous calcification:
Cysticercus

45. Broncholith
Subsegmental atelectasis
Calcified node
Broncholith obstructing bronchus

47. Silicosis
Egg shell calcification of lymph nodes
Other findings include:
Diaphragmatic pleural calcification
Multiple cavities with fluid levels

48. Histoplasmosis
Calcified nodes
Clumpy calcification Calcified nodules in lungs

49. Hamartoma
Popcorn calcification

50. Pleural Calcification
Visceral pleural
calcification
Parietal pleura appears
black because it is
sandwiched between
bony densities

51. Pleural Calcification
Visceral pleura
Old TB

52. Visceral pleural calcification
Open drainage with air fluid levels in pleural space

53. Subcutaneous calcification

54. Cavitary Lung Lesions

55. Number:
Multiple bilateral cavities would raise
suspicion for either bronchiogenous or
hematogenous process. You should consider:
Aspiration lung abscess
Septic emboli
Metastatic lesions
Vasculitis (Wegener's)
Coccidioidomycosis, tuberculosis

56. Location:
• Classical locations for aspiration lung abscess
are superior segment of the lower lobes
posterior segments of upper lobes.
• Tuberculous cavities are common in superior
segments of upper and lower lobes or posterior
segments of upper lobes.
• When a cavity in anterior segment is
encountered, a strong suspicion for lung cancer
should be raised. TB and aspiration lung
abscess are rare in anterior segments. Cancer
lung can occur in any segment.

57. Wall Thickness:
• Thick walls are seen in:
– Lung abscess
– Necrotizing squamous cell lung cancer
– Wegener's granulomatosis
– Blastomycosis

58. Wall Thickness:
• Thin walled cavities are seen in:
• Coccidioidomycosis
• Metastatic cavitating squamous cell
carcinoma from the cervix
• M. Kansasii infection
• Congenital or acquired bullae
• Post-traumatic cysts
• Open negative TB

59. Contents:
• The most common cause for air fluid level is
lung abscess. Air fluid levels can rarely be
seen in malignancy and in tuberculous
cavities from rupture of Rasmussen's
aneurysm.
• A fungous ball should make you consider
aspergillosis. A blood clot and fibrin ball will
have the same appearance.
• Floating Water Lily: The collapsed membrane
of a ruptured echinococcal cyst, floats giving
this appearance.

60. Lining of Wall:
The wall lining is irregular and nodular in
lung cancer or shaggy in lung abscess

61. Evolution of Lesion:
Many times review of old films to assess the
evolution of the radiological appearance of
the lesion extremely helpful. Examples
• Infected bullae
• Aspergilloma
• Sub acute necrotizing aspergillosis
• Bleeding from Rasmussen's aneurysm in a
tuberculous cavity

62. Associated Features:
Ipsilateral lymph nodes or lytic
lesions of the bone is seen
with malignancy

63. Bulla
<1mmwall
>1cmsize
Pneumatocele
<1mmwall
staph.infection
Honeycombing
<1cmsize
multipleequal
Cyst
1-3mmwall
1-10cmsize
Cavity
>3mmwall
Anysize
Cavitarylesionsoflung

64. Bulla
Definition
•Thin-walled–less than 1 mm
•Air-filled space
•In the lung> 1 cm in size and up to 75% of lung
•Walls may be formed by pleura, septa,
or compressed lung tissue.
•Results from destruction, dilatation and
confluence of airspaces distal to terminal
bronchioles.

65. •Bullous disease may be primary or associated
with emphysema or interstitial lung disease.
• Primary bullous lung disease may be familial
and has been associated with Marfan's, Ehler's
Danlos, IV drug users, HIV infection, and
vanishing lung syndrome.
•Bullae may occasionally become very large
and compromise respiratory function. Thus
has been referred as vanishing lung syndrome,
and may be seen in young men.

66. Upper lobe Bulla

67. Lower lobe Bulla

68. A: Xray shows bilateral bulla.
B: CT shows bilateral bulla.
C: CT after bullectomy.

70. Pneumatocele is a benign air containing cyst of lung, with
thin wall < 1mm as bulla but with different mechanism 
Infection with staph aureus is the commonest cause ( less
common causes are, trauma, barotrauma) lead to necrosis
and liquefaction followed by air leak and subpleural
dissection forming a thin walled cyst.

71. •Honeycombing is defined as multiple cysts < 1cm in diameter,with
well defined walls, in a background of fibrosis, tend to form
clusters and is considered as end stage lung .
•It is formed by extensive interstitial fibrosis of lung with residual
cystic areas.

73. A cyst is a ring
shadow > 1 cm in
diameter and up to
10 cm with wall
thickness from 1-3
mm.

75. Thin walled cysts of LAM

76. A cavity is > 1cm
in diameter, and its
wall thickness is
more than 3 mm.

77. •A central portion  necrosis and communicate to bronchus.
•The draining bronchus is visible (arrow). CT (2 mm slice thickness)
shows discrete air bronchograms in the consolidated area.
Mechanism

78. 1. Site

79. A cavity in apicoposterior segment of left upper lobe

80. 2.Number
Multiple cavities:
1. Aspiration.
2. TB
3. Fungal.
4. Metastatic.
5. Septic emboli.
6.Wegners granulomatosis

81. Multiple cysts of metastasis
from squamous cell
carcinoma.
Multiple thick wall cavities from
adenocarcinoma of right lung

84. Irregular , nodular inner lining of thick wall abscess
Malignant cavity.
3. Thickness and
irregularity

85. 4. eccentric
Malignant

86. 5. Relation to lymph
node enlargement

87. 6. Contents

88. •Arrow head  Crescent sign.
•Black arrows  Fibrotic bands surrounding cavity
(Fibrocavitary TB).

90. Primary Lung Cancer
• Thick wall
• Shaggy lumen
• Eccentric cavitation

91. |
Squamous Cell Carcinoma Lung
LUL mass
Thick walled cavity
Eccentric location of cavity

92. Fungous Ball
Long standing cavity
Containing round density (A)
Mobile density
Adjacent pleural reaction (B) - characteristic of aspergilloma

93. Cavitating Metastasis
MultipleThin Walled Cavities
Cancer Cervix