2. AIR-SPACE CONSOLIDATION
• Air-space consolidation represents replacement of alveolar
air by fluid, blood, pus, cells, or other substances. Alveolar
consolidation and parenchymal consolidation are synonyms
for air-space consolidation
3. Radiographic Findings
Radiographic and computed tomography (Ct) abnormalities
indicating the presence of air-space consolidation
include the following:
• Homogeneous opacity obscuring vessels
• Air bronchograms
•Ill-defined or fluffy opacities
• "Air alveolograms"
• Patchy opacities
• "Acinar" or air-space nodules
• Preserved lung volume
• Extension to the pleural surface
• "CT angiogram" sign
4. Homogeneous Opacity Obscuring vessels
:
With complete replacement of alveolar air, homogeneous
opacification of the lung results. Vessels within the consolidated
lung are invisible.
6. AIR BRONCHOGRAM
• In patients with consolidation, air-filled bronchi are often
visible on plain radiographs or CT, appearing lucent compared
with opacified lung parenchyma . This finding is termed an air
bronchogram
• AIR BRONCHOGRAM NOT VISIABLE:
• >central bronchial obstruction, ex- cancer ,mucus
• >filling the bronchi with blood, ex-pulmonary oedema or haemorhage
• >bronchopneumonia
7. ILL DEFINED OR FLUFFY OPACITIES
• Consolidation often results in opacities with ill-defined margins in
contrast to the relatively sharp margins of a lung mass. This results
from patchy local spread of disease with variable involvement of
alveoli at the edges of the pathologic process.
9. AIR ALVEOLOGRAM
>If lung consolidation is not confluent, small focal lucencies
representing uninvolved lung may be visible.These have been termed
"air alveolograms,"
> this is a misnomer as alveoli are too small to see radiographically.
> reflect incomplete lung consolidation.
10. PATCHY OPACITIES
Variable consolidation in different lung regions
patchy areas of increased opacity.
Pulnonary vessels may be obscured or poorly defined.
Patchy consolidation visible on chest radiographs sometimes
appears to be lobular or multilobular on CT (i.e.involving individual
pulmonary lobules).
>Some lobules appear abnormally dense while adjacent lobules appear
normally aerated.
12. ACINAR OR AIR SPACE NODULE
>acinar nodule and air-space nodule are used to describe poorly
marginated rounded opacities,
>5 to 10 mm. in diameter
occur due to focal consolidation
more easily seen on high-resolution CT (HRCT') than on chest
radiographs
14. CT ANGIOGRAM SIGN
This sign is present if normal-appearing opacified vessels are visible
within the consolidated lung following the infusion of intravenous
contrast .
Although opacified vessels are sometimes seen within a lung mass,
they usually appear compressed or distorted
16. DIFFERENTIAL DIAGNOSIS OF
CONSOLIDATION: DIFFUSE OR FOCAL
• Diffuse consolidation paterns:
>perihilar bat-wing consolidation
>peripheral subpleural consolidation or reverse bat-wing
>diffuse patchy consolidation
>diffuse air space nodule
>diffuse homogenous consolidation
17. PERIHILAR BAT-WING PATTERN
>central consolidation with sparing of the lung periphery
> most typical of pulmonary edema
also may be seen with
pulmonary hemorrhage,
pneumonias (including bacteria and atypical pneumonias such as Pmumocystis jiroveci
(P. carinii ) pneumonia[PCP) and viral pneumonia),
inhalational lung injury.
In patients with pulmonary edema perihilar distribution is most often present when
rapid accumulation of fluid has occurred. Relative sparing of the lung periphery has been
attributed to better lymphatic clearance of edema fluid in this region, although the exact
mechanism is unclear.
19. Peripheral subpleural consolidation
the opposite of a bat-wing pattern (reverse bat-wing pattern)
Consolidation is seen adjacent to the chest wall, with sparing of the
perihilar regions.
>It is most often seen in a patients with a chronic lung disease .
> classically associated with eosinophilic lung diseases, particularly
eosinophilic pneumonia
may also occur with organizing pneumonia, sarcoidosis, radiation
pneumonitis, lung contusion, or bronchioloalveolar carcinoma.
Peripheral consolidation need not always appear peripheral on the frontal
radiograph; it may be peripheral in the anterior or posterior lung and
overlie the parahilar regions.
23. Diffuse air-space nodular opacities
prominent feature is typical of endobronchial spread of disease
seen in patients with endobronchial spread
of infection such as tuberculosis (TB) or Mycobacterium avium complex
(MAC), bacterial bronchopneumonia, viral pneumonia endobronchial
spread of bronchioloalveolar carcinoma, pulmonary haemorrhage, or
sometimes aspiration
25. Diffuse homogeneous consolidation
>most typical in patients with pulmonary edema, ARDS, pulmonary
haemorrhage . pneumonias (including viral and PCP), alveolar
proteinosis , and extensive atelectasis.
26. DIFFERENTIAL DIAGNOSIS OF FOCAL
CONSOLIDATION
>lobar consolidation
>round or spherical consolidation
>segmental or subsegmental consolidation
>focal patchy consolidation
27. LOBAR CONSOLIDATION
> most typical of pneumonia(including S. pneumoniae, Klebsiella ,
Legionella, and TB) and abnormalities associated with bronchial
obstruction.
>occurs because of inter alveolar spread of disease via the pores of
Kohn (small holes in the alveolar walls)
> spread continues until a fissure or pleural surface is reached.
Organisms spread via the pores of Kohn are characterized by thin
secretions.
>The presence of an incomplete fissure may lead to a lobar pneumonia
becoming bilobar (or trilobar)
28. LOBAR CONSOLIDATION
interalveolar spread - seen with lymphoma and bronchioloalveolar
carcinoma
lepidic growth- local interalveolar spread of tumors such as
bronchioloalveolar carcinoma, using alveolar walls as a scaffold.
Bronchial obstruction with postobstructive pneumonia or atelectasis
also commonly results in lobar consolidation
Lobar expansion in association with lobar consolidation suggests
infection, particularly by Klebsiella or Pneumococcus, TB, bronchial
obstruction with postobstructive pneumonia, or consolidation
associated with neoplasm
30. Round or spherical consolidation
>Most typical of bronchioloalveolar carcinoma, lymphoma or
lymphoproliferative disease, or round pneumonia.
>A round or spherical pneumonia is typical of organisms that spread via
the pores of Kohn and canals of lambert and progress to being lobar,
such as S. pneumoniae, Klebsiella, Legionella, or TB.
> Occurs mostly in children because of poorly form pores of kohn and
canals of lambert
32. Segmental (or subsegmental) consolidation
> a wedge-shaped opacity of more than a few centimeters in size
>apex of the wedge pointing toward the hilum .
> abnonnality in segmental bronchus or artery.
Focal patchy consolidation
> typical of pneumonias, endobronchial spread of TB, or
endobronchial spread of tumor such as bronchioloalveolar carcinoma
>Patchy consolidation is typical of bronchopneumonia.
>Pneumonias of(Staphylococcus,Haemophilus, Pseudomonas) are
characterized by thick and tenacious secretions and spread via airways rather
than the pores of Kohn.
34. Rapidly appearing consolidation (a few hours) :
Suggests atelectasis with drowned lung, aspiration, pulmonary edema,
pulmonary hemorrhage, infarction, or rapidly progressing pneumonia,
particularly in an immunocompromised host. Occasionally a
lymphoproliferative neoplasm progresses within hours.
Longstanding(chronic) consolidation ( 4 to 6weeks): eosinophilic
pneumonia, BOOP, bronchioloalveolar carcinoma, lymphoma, lipoid
pneumonia, or some indolent pneumonias such. as fungal infections.
Recurrent processes (e.g., recurrent pulmonary edema, pulmonary
hemorrhage, or aspiration) may appear to be chronic if radiographs are
obtained only during the acute episodes
35. SILHOUETTE SIGN
The borders of soft tissue structures such as the mediastinum, hila,
and hemidiaphragms are visible on chest radiographs because they are
outlined by adjacent air-containing lung. When consolidated lung (or a
soft tissue mass) contacts one of these structures, its border becomes
invisible or is poorly marginated. This is termed the "silhouette sign.
36. SILHOUETTE SIGNS( FRONTAL RADIOGRAPH)
Right superior mediastinum (i.e., superior vena cava[SVC]) =right upper lobe
Right heart border = right middle lobe (common) or medial right lower lobe
(less common)
Right hemidiaphragm =right lower lobe
Left superior mediastinum (e.g., aortic arch) = left upper lobe
Left heart border= lingular segments of left upper lobe
Left hemidiaphragm or descending aorta= left lower lobe
Caveat: The diaphragmatic contour seen on the frontal (PA or AP) radiograph
represents the dome, or the highest point, of the diaphragm. The
diaphragmatic dome is relatively anterior, and lower lobe consolidation may
be posterior to it ; in this case, the hemidiaphragm may remain visible.
37. SILHOUETTE SIGNS (LATERAL RADIOGRAPH)
>Posterior margin of the heart or posterior left hemidiaphragm =left
lower lobe; hiatal hernia may mimic this.
>Anterior right hemidiaphragm = right middle lobe
>Posterior right hemidiaphragm = right lower lobe
38. The silhouette sign in right upper lobe
pneumonia. Consolidation of the right
upper lobe obscures (i.e.silhouettes) the
border of the right superior
mediastinum and superior venacava.
The upper part of the right hilum is also
invisible
39. Anatomic relationships used
with the silhouette sign. Obscuration of the
borders shown in this diagram are associated
with consolidation of the listed lobes.
RUL, right upper lobe; RML, right middle
lobe; RLL, right lower lobe; LUL, left upper
lobe; LLL, left lower lobe.
40. The silhouette sign in right middle lobe
pneumonia. On frontal view - Consolidation of the right middle
lobe., obscures (silhouettes") the right heart border
. In contrast, the left heart border is sharply marginated. 'The
right hemidiaphragm appears sharply marginated. The
pneumonia is marginated by the minor fissure {arrow).
: On the lateral view, middle lobe consolidation is visible,
marginated above by the minor fissure (large arrows);
inferiorly, it is marginated by the major fissure (small arrow)
41. The silhouette sign in right lower lobe pneumonia. : frontal view shows right
lower lobe consolidation with obscuration of the diaphragm, right heart border (arrow)
remains visible as an edge.
On the lateral view, complete right lower lobe consolidation is visible,
outlined anteriorly by the major fissure (white arrow). The right hemidiaphragm (large blade
arrows) is sharply marginated anterior to the consolidated lobe but is invisible posteriorly.
posterior left heart border and left hemidiaphragm are sharply marginated (small blade arrow).
42. The left heart border is obscured
because of lingular consolidation. 'The
left superior mediastinum remains
sharply marginated because
the medial portions of the anterior and
apical segments of the left upper lobe
remain aerated
43. The silhouette sign in left lower lobe pneumonia.
Frontal view: The left hemidiaphragm is partially obscured by left lower
lobe consolidation (arrows). On the lateral view, a portion
of the left hemidiaphragm (arrow) also is obscured
44. ATELECTASIS
It is used to indicate loss of volume of lung tissue associated
with a decrease in the amount of air it contains. It is synonymous
with collapse
TYPES OF ATELECTASIS
Four different types or mechanisms of atelectasis are recognized
a)resorption (obstructive) b) relaxation(passive)
c)adhesive d)cicatricial
45. TYPES OF ATELECTASIS
RESORPTION ATELECTASIS
>Caused by airway obstruction with
resorption of alveolar gas
>Occurs within 24 hours
>More rapid when breathing pure oxygen
>May result in drowned lung with little
volume loss
>Collateral ventilation may prevent collapse
with large airway obstruction,
airbronchograms are often absent
RELAXATION ATELECTASIS
Atelectasis due to pleural effusion,
pneumothorax, or mass
Lung density need not be increase
ADHESIVE ATELECTASIS
Atelectasis caused by loss of lung surfactant
Typical of respiratory distress syndrome of
the newborn,
acute respiratory distress syndrome,
radiation pneumonitis
CICATRICIAL ATELECTASIS
Atelectasis caused by lung fibrosis
46. RESORPTION(OBSTRUCTIVE) ATELECTASIS
>alveolar gas is absorbed by circulating blood and not replaced by inspired
air.
>Occurs in the presence of airway obstruction
>obstructed airway may be the trachea. main bronchus, lobar bronchi or
multiple small bronchi or bronchioles.
>common after surgery and general anesthesia
>airless in 24 hrs of obstruction
>occurs more quickly in case of a) breathing pure oxygen b)one way valve
endobronchial lesion
>drowned lung : rapid transudation of fluid in alveoli and interstitium with
out significant volume loss
>airbronchogram absent( large airway involvement)
47. RELAXATION AND COMPRESSION ATELECTASIS
>Relaxation atelectasis or passive atelectasis:
The presence of pneumothorax. pleural effusion, or a mass lesion
allows the lung to decrease in volume or relax to its natural size, which
is smaller than the thoracic cavity.
>compressive atelectasis:
it implies a reduction in lung volume beyond its normal relaxed
state.
49. ADHESIVE ATELECTASIS
> Surfactant reduces the surface tension of alveolar fluid and
tends to prevent lung collapse as the alveoli decrease in volume
with expiration.
>Deficiency of surfactant allows alveoli to collapse. so-called adhesive
atelectasis.
>This is most typical of respiratory distress syndrome of the newborn
but is also seen in patients with ARDS, acute radiation pneumonitis, or
hypoxemia, and in the postoperative period
50. CICATRICIAL ATELECTASIS
> to loss of lung volume occurring in the presence
of lung fibrosis.
It may be focal, lobar or diffuse, depending on the disease
responsible.
Findings of fibrosis are typically present
52. RADIOGRAPHIC FINDINGS OF ATELECTASIS
DIRECT SIGNS: >due to lobar volume loss
>Displacement of fissures
>Crowding of vessels
INDIRECT SIGNS: >secondary to volume loss
>Diaphragmatic elevation
>Mediastinal shift
>Compensatory overinflation of normal lung
>Hilar displacement
>Reorientation of the hilum or bronchi
>Approximation of the ribs
>Increased lung opacity
>Absence of air bronchograms
>Shifting granuloma sign
53. lndired Signs Seen With Specific Types
of Atelectasis
Golden's S sign: right upper lobe atelectasis
Juxtaphrenic peak: upper lobe atelectasis
Luftsichel sign: upper lobe atelectasis (usually the left upper
lobe)
Flat waist sign: left lower lobe atelectasis
Comet-tail sign: rounded atelectasis
54. ATELECFASIS OF AN ENTIRE LUNG
Lung atelectasis usually results from
>obstruction of a main bronchus by an endobronchial lesion (or
intubation of the opposite main bronchus),
>obstruction of small peripheral bronchi by secretions,
>large ipsilateral pneumothorax or pleural effusion.
55. Bronchial Obstruction With Lung Collapse
> the ipsilateral diaphragm is elevated,
>shift of both the upper and lower mediastinum to the side of
atelectasis is present
the ipsilateral ribs crowding
and the lung is increased in density in comparison to the opposite
side .
Absence of air bronchograms suggests a central obstruction
visible air bronchograms suggest peripheral small airway
obstruction.
57. Right Upper Lobe Atelectasis
Frontal radiograph
>ill defined increase in opacity in the upper thorax
>Apparent right mediastinal widening
>Silhouetting of the right upper mediastinum
>Tracheal shift to the right
>Upward bowing and displacement of the minor fissure
>Golden's S sign
>Elevation of the hilum
>Outward rotation of the hilum or bronchus
>Right-sided juxtaphrenic peak
Lateral radiograph
>Upward displacement and bowing of the minor fissure
>Anterior displacement and bowing of the upper major fissure
59. Left Upper Lobe Atelectasis
Frontal radiograph
>Ill-defined increase in opacity in the upper thorax
(decreasing with increased collapse)
>Silhouetting of the left upper mediastinum
>Tracheal shift to the left
>Luftsichel sign
>Apical cap
>Elevation of the hilum
>Outward rotation of the hilum or bronchus
>Juxtaphrenic peak
Lateral radiograph
>Anterior bowing and displacement of the major fissure
61. Right Middle Lobe Atelectasis
Frontal radiograph
>Minor fissure is invisible
>increased lung opacity (decreasing with increased collapse)
>Silhouetting of the right heart border
Lateral radiograph
>Downward bowing and displacement of the minor fissure
>Anterior bowing and displacement of the inferior major fissure
>Wedge of consolidated lung anchored at the hilum
63. Lower Lobe Atelectasis
Frontal radiograph
>Major fissure becomes visible (upper portion best seen)
>Triangular opacity
>Downward bowing of the minor fissure (right lower lobe atelectasis)
>Downward displacement of the hilum
>Invisibility of the interlobar pulmonary artery
>Obscuration of the diaphragm
>Shift of the heart
>Flat-waist sign (left lower lobe atelectasis)
Lateral radiograph
>Obscuration of the posterior diaphragm
>Posterior bowing of the major fissure (lateral radiograph)
65. Combined Collapse of Right Middle and Lower
Lobes
occurs in patients with obstruction of the bronchus intermedius.
On the frontal and lateral radiographs, both the displaced major and
minor fissures may be variably visible, outlining the consolidated lung.
On the frontal view, both the right heart border and diaphragm often
appear obscured . This appearance may closely
mimic that of right lower lobe collapse associated with an
elevated hemidiaphragm or subpulmonic pleural effusion.
67. Combined Collapse of Right Middle and Upper
Lobes
>double lesion sign:
most commonly occurs when lung cancer involves the hilum,
with invasion of both the upper and middle lobe bronchi
while the lower lobe bronchus remains patent;
>it may also be
seen with multiple isolated bronchial lesions, as in a patient
with mucous plugging.
>On the frontal radiograph, right upper lobe opacification
obscures the right superior mediastinum while right
middle lobe opacification obscures the right heart border
69. ROUNDED ATELECTASIS
Round or elliptical opacity
>Associated with an ipsilateral pleural abnormality
>Peripheral in location
>Extensive contact with the abnormal pleural surface
>Comet-tail sign
>Volume loss
>Posterior, paravertebral lower lobe in patients with effusion
>Atypical appearances when associated with pleural fibrosis
>Dense opacification on CT after contrast infusion
71. PLATELIKE OR DISCOID ATELECTASIS
>Linear areas of atelectasis,
>a few millimeters to 1 c.m thick and at least several centimeters in length
>commonly occur in patients with decreased depth of breathing or
diminished diaphragmatic excursions
>they tend to occur at the lung bases, several centimeters above and parallel
to the diaphragm .
>they cross segmental boundaries.
>They may also occur in the medial infrahilar regions.
>typically angled upward from the mediastium at about a 45-degree angle.
73. Segmental (or subsegmental) atelectasis
secondary to obstruction of segmental (or subsegmental} bronchi by
tumor, mucus, or inflammatory disease
wedge-shaped opacities are seen radiating outward :from the hilum
or involving the peripheral lungs with the base of the wedge touching
the pleural surface.
