Helpful Radiologic Signs in Chest X-ray

1. Helpful Radiological Signs
in CXR
A. Almasi MD
Iran University of Medical Sciences
Department of Radiology

2. Mass vs Infiltrate/ Consolidation
1.
2.
3.
•
•
•
First of all, you should be able to detect an abnormality
Then you should describe your findings
Putting together your different findings you can come to a diagnosis
In each of the cases below, there is an abnormal opacity in the left upper lobe (1)
In the case on the left, the opacity would best be described as well-defined. The
case on the right has an opacity that is poorly defined (2)
Therefore the left radiograph depicts a mass and the one on the right is an air
space disease (3)

3. Silouhette Sign
• By studying the borders of the heart,
diaphragm and the aorta we can determine
the anteroposterior position of a lesion on a
frontal CXR.
• The border of the anatomic organ is obscured
only if it is in contact with the lesion (i.e. in
the same anteroposterior position).

4. Silhouette Sign
• For the heart, the silhouette
sign can be caused by an
opacity in the RML, lingula,
anterior segment of the upper
lobe, anterior mediastinum,
and anterior portion of the
pleural cavity
• This contrasts with an opacity
in the posterior pleural cavity,
posterior mediastinum, of
lower lobes which cause an
overlap
and
not
an
obliteration of the heart
border

5. Silhouette sign in an anteriorly
located mass
(bronchogenic carcinoma)

6. Silhuette sign in a posteriorly located lesion (lower
lobe pneumonia); not obscuring the right heart border

7. Silhouette sign in an anterior lesion
obscuring the PA but not the aortic knob

8. Air Bronchogram
• Visible air-filled bronchus in a background
of airless parenchyma
• Most commonly seen in pneumonia and
pulmonary edema
• Its presence confirms the intrapulmonary
location of the lesion

9. Air bronchogram in pneumonia

10. Air Bronchogram

11. Causes of an air-bronchogram
Common
• Expiratory film
• Consolidation (air space
disease)
• Cardiogenic pulmonary
edema
• Hyaline membrane disease
Rare
•
•
•
•
•
•
•
Lymphoma
Alveolar cell carcinoma
Sarcoidosis
Fibrosing alveolitis
Alveolar proteinosis
ARDS
Radiation fibrosis

12. Air-space (acinar/alveolar) pattern or
consolidation or infiltration
• Acinus is the functional unit of the lung and is defined
as all the airways located distal to a terminal bronchiole.
• Acinar pattern appears when the distal airways and the
alveoli are filled with fluid (transudate, exudate or
blood).
• Fluid-filled acini form nodular shadows 4-8mm in
diameter (acinar shadows).
• An air-filled acinus surrounded by fluid-filled acini
produces air-acinogram
• These acinar shadows can coalesce into larger illdefined homogenous or patchy opacities which are
well-defined adjacent to the fissures.
• Vascular markings are usually obscured.
• Air-bronchogram is characteristic

13. Air-space pattern characteristics
• Ill-defined nodular shadows 4-8mm in
diameter
• Coalescence of these acinar nodules
• Ill-defined borders of larger opacities except
where limited to a fissure
• Air-bronchogram
• Air-acinogram

14. Acinar nodules in a case of diffuse
TB (bronchial spread)

15. Coalescing acinar nodules in
pulmonary contusion (hemorrhage)

16. Alveolar filling pattern in a case of
diffuse TB

17. Sharp border of an alveolar shadow confined to
the minor fissure in RUL pneumonia

18. Typical air-space pattern in
pneumonia

19. Common causes of an air-space
pattern (Consolidation)
•
•
•
•
Pulmonary edema: cardiogenic/noncardiogenic
Pneumonia/pneumonitis
Aspiration
Hemorrhage

20. Pulmonary edema
• Two basic types:
– cardogenic edema: increased hydrostatic
pulmonary capillary pressure
– noncardogenic edema: either altered
capillary membrane permeability or
decreased plasma oncotic pressure.

21. Cardiogenic Pulmonary Edema
• Would you favor pneumonia or CHF in this patient? Why?
What pattern is shown?

22. Fat Embolism (ARDS)
• Mostly
peripheral
distribution of the
opacities contrasts
with the central bat
wing pattern seen in
cardiogenic
pulmonary edema
• Normal heart size is
another suggestive
evidence

23. Pulmonary Hemorrhage

24. Congestive Heart Failure
• Cardiomegaly: the earliest CXR finding
• Cephalization: when the pulmonary capillary wedge
pressure (PCWP) 12-18 mmHg
pulmonary venous
hypertension (PVH) grade I
• Interstitial edema: PCWP 18-24 mmHg, Kerley lines and
peribronchial cuffing (thickening), PVH grade II
• Alveolar edema: PCWP > 24 mmHg, PVH grade III
often in a classic perihilar bat wing pattern of density.
Pleural effusions also often occur.
• CXR is important in evaluating patients with CHF for
development of pulmonary edema and evaluating response
to therapy as well.

25. Kerley B lines
•
•
These are horizontal lines less than 2cm long, commonly found in the lower
zone periphery. These lines are the thickened, edematous interlobular septa.
They are found in interstitial pulmonary edema, but are also seen in
lymphangitis carcinomatosa, lymphoma and other diseases too.

26. PVH grade I

27. PVH grade II
Peribronchial
cuffing

28. PVH grade III

29. Solitary Pulmonary Nodule
•
•
•
•
•
•
•
A solitary nodule in the lung can be totally innocuous or potentially a fatal
lung cancer
Rule out presence of multiple nodules first
After detection, the initial step in analysis is to compare the film with prior
films if available. A nodule that is unchanged for two years is almost certainly
benign
If the nodule is completely calcified or has central or stippled calcium it is
benign
If the nodule is indeterminate after considering old films and calcification,
subsequent steps in the work-up include ordering a CT to find subtle
calcification
Nodules with irregular calcifications or those that are off center should be
considered suspicious, and need to be worked up further with a PET scan or
biopsy
The patient may choose to have an indeterminate nodule removed if there is no
evidence of spread on CT as this would diagnose and treat a cancer if present

30. Solitary Pulmonary Nodule
• This patient clearly has a solitary lung nodule present on chest xray. Can you tell which lobe it's in?

31. Solitary Pulmonary Nodule
• PA and Lateral of a subtle right lower lobe
cancer. Can you find it in the frontal projection?

32. Interestitial lung disease
• Correlation between the CXR and severity
of the symptoms is poor
• HRCT can detect interstitial changes in
earlier stages
• Different patterns on CXR:
–
–
–
–
–
Miliary
Ground-glass
Reticular
Reticulonodular
Honeycomb

33. Different patterns of interestitial
involvement of the lungs
• Miliary pattern: 2-4mm well-defined nodules most
often seen with TB
• Ground-glass opacity: low density opacity which
does not obscure the vascular pattern of the lungs. It
may be due to either an interestitial disease or mild
alveolar filling
• Reticular pattern: fine irregular network of lines
unlike vessels which bifurcate
• Reticulonodular pattern: presenting as reticulations
plus nodules <1cm in between
• Honey combing: a network made of thin-walled cysts
measuring less than one centimeter in diameter and
implying end-stage lung fibrosis

34. The most common causes of miliary
pattern
1)
2)
3)
4)
5)
TB
Silicosis
Coal worker’s pneumoconiosis
Metastases
Sarcoidosis

35. Miliary pattern in TB

36. Ground glass density/opacity in
usual interstitial pneumonitis

37. Reticulonodular pattern in idiopathic
pulmonary fibrosis

38. Honeycomb pattern in longstanding
RA with reumatoid nodules

39. Atelectasis/Collapse/Volume Loss
• Passive collapse: due to pleural effusion or
thickening or pneumothorax
• Cicatrisation collapse: due to fibrosis (e.g. IPF,
TB)
• Adhesive collapse: due to lack of surfactant
• Resorption collapse: due to bronchial obstruction.
This has a lobar pattern

40. Anatomy of the Fissures

41. Radiological Signs of Atelectasis
• Direct signs
– Displacement of interlobar fissures
– Loss of aeration
– Vascular and bronchial signs (crowding of vascular
markings, airbronchogram)
• Indirect signs
–
–
–
–
Elevation of a hemidiaphragm
Mediastinal displacement
Hilar displacement
Compensatory hyperinflation

42. Adhesive Atelectasis due to RDS

43. Passive Atelectasis due to
Pneumothorax

44. Cicatrisation Atelectasis due to TB

45. RUL Atelectasis

47. RUL Atelectasis

48. RUL Atelectasis

49. RUL Consolidation
• Lobar consolidation
usually indicates
bacterial pneumonia

50. RUL Consolidation

51. Thymus Sail Sign

52. Left Upper Lobe Atelectasis

53. LUL Atelectasis

54. LUL Consolidation

55. LUL Atelectasis

56. LUL Atelectasis

57. Middle Lobe Atelectasis
•
Right middle lobe atelectasis may cause minimal changes on the frontal chest
film. A loss of definition of the right heart border is the key finding. Right
middle lobe collapse is usually more easily seen in the lateral view. The
horizontal and lower portion of the major fissures start to approximate with
increasing opacity leading to a wedge of opacity pointing to the hilum. Like
other cases of atelectasis, this collapse may by confused with right middle lobe
pneumonia.

58. RML Atelectasis
• Right middle lobe collapse can be difficult to detect in the PA
film.
• The right heart border is indistinct on the PA film.
• The lateral CXR shows a marked decrease in the distance
between the horizontal and oblique fissures.

59. Middle Lobe Consolidation

60. RML Consolidation vs Collapse

61. Left Lower Lobe Collapse

62. Left Lower Lobe Collapse

63. Left Lower Lobe Consolidation

64. Right Lower Lobe Collapse

65. Right Lower Lobe Collapse

66. Right Lower Lobe Consolidation

67. Pleural Diseases
•
•
•
•
•
•
Pleural Effusion
Subpulmonic Effusion
Pleural Thickening
Pleural Calcification
Pneumothorax
bronchopleural fistula

68. Normal Pleural Space
• Visceral pleura is adherent to the lung
• Space between visceral and parietal
pleura is a potential space
• Infoldings of visceral pleura form
fissures.
• Normally there are 2-10 cc of fluid in the
pleural space.

69. Appearances of Pleural Effusions
• Blunting of
Costophrenic angle
• Meniscus sign
• Subpulmonic
effusion
• Layering
• Loculated
• Laminar effusion
• Opacified
hemithorax
• Air-fluid levels

70. Blunting of Costophrenic Angle
• Normally there are 2-10cc of fluid in the
pleural space
• When >75cc accumulate, the posterior
costophrenic (CP) sulci, seen on the
lateral film, become blunted
• When 200-300cc accumulate, the CP
sulci on the frontal film become blunted

71. Blunting of the CP Angle
Normal Rt costophrenic angle
Blunted Lt costophrenic angle
• When 200-300cc of fluid accumulate in pleural space, the
usually acute costophrenic angle becomes blunted

72. Meniscus Sign
• Pleural fluid tends to rise higher along its
edge producing a meniscus shape medially
and laterally.
• Usually only lateral meniscus can be seen
• The meniscus is a good indicator of the
presence of a pleural effusion.

73. Meniscus Sign
• Fluid rises higher
along the edge of a
pleural
effusion
producing an upside
down “U” or meniscus
shape.

74. Loculated Effusion
• Occurs secondary to adhesions which form
between visceral and parietal pleura.
• Adhesions more common with blood
(hemothorax) and pus (empyema).
• Loculated effusions have unusual shapes or
positions in thorax e.g. remain at apex on
erect films.

75. Loculated Effusion
• A loculated effusion
has an unusual shape
(lentiform) or position
in the thoracic cavity
• This is a loculated
empyema

76. Laminar Effusion
• A laminar effusion collects in the loose
connective tissue between the lung and the
visceral pleura.
• It is not usually free-flowing.
• It usually occurs with CHF or lymphangitic
spread of malignancy

77. Laminar Effusion
• A laminar effusion collects
between the lung and the
visceral pleura in the loose
connective tissue of the
subpleural space
• Laminar
effusions
are
usually seen with CHF or
lymphangitic
spread
of
tumor

78. Effect of Position - Layering
Erect
Supine
• In the supine position, the fluid layers out posteriorly and
produces a haziness, especially near the bases.
• In the erect position, the fluid falls to the bases.

79. Lateralized Diaphragmatic Dome in
Subpulmonic Effusion
Subpulmonic PE
Normal

80. Right Lateral Decubitus

81. Subpulmonic Effusion presenting as
increased distance between stomach gas
and diaphragm

82. Subpulmonic PE
Previously Normal Film

83. Deep Sulcus Sign

84. Pneumothorax

85. Hydropneumothorax
• If both a pneumothorax and a pleural
effusion occur together, it is called a
hydropneumothorax.
• A hydropneumothorax is usually due to
trauma, surgery or bronchopleural fistula
• It is characterized by an air-fluid level in
the hemithorax.

86. Hydropneumothorax
• A straight edge, indicative of a
fluid interface, in this case an airfluid interface, is seen on the
right.
• In
order
to
have
an
air-fluid
level
in
the
pleural
space,
there
must be a pneumothorax present.

87. Y=4.2+[4.7 x (A+B+C)]

88. Barotrauma

89. Unilateral White Hemithorax