The document summarizes various patterns of lung disease and abnormalities that can be seen on a chest x-ray. It describes how interlobar fissures, lobar collapse, alveolar/interstitial diseases, lung masses/nodules, mediastinal structures, pleural/extrapleural abnormalities like effusions, pneumothorax can present on CXR through specific radiographic signs and findings. Key anatomical structures and their appearances in different lung pathologies are concisely outlined.

1. Pattern of lung disease S
on chest x ray

2. • The space between the lobes, where
the visceral pleural surfaces touch, is
called the interlobar fissure
• Because the visceral pleura is less
than 1 mm thick, the x-ray beam must
strike it parallel to its surface
• If a fissure is perpendicular to the x-ray
beam, it will not be visible..
LOBAR ANATOMY

7. The fissure normally appears as a thin white line (2 layers of pleura surrounded
by air) as in Figure 1(arrowheads). There are two exceptions. If a lobe is
consolidated,
the fissure appears as an edge, delineating that lobe.
. If pleural fluid enters a fissure, the fissure thickens. Note the thick major fissure
(arrowheads)
and normal minor fissure (arrow) i

8. Hz and oblique
fissure Azygous fissure

9. silhouette sign
 4 BASIC TYPES OF DENSITY - air , water
/soft tissues, metal /bone , fat
 Two substances of the same density, in
direct contact, cannot be differentiated from
each other on an x-ray.
 This phenomenon, the loss of the normal
radiographic silhouette (contour), due to
loss of difference in density is called the
silhouette sign.

10. 1. diaphragm is
obscured, the
disease is in the
lower lobe
2. The heart border is
blurred in rt middle
lobe and lingular
segment disease.
3. Left upper lobe
consolidation (upper
division) obliterates
the__left atrium, the
aortic knob, and the
ant & middle
mediastinum

11.  right upper lobe
consolidation
obscuring the upper
mediastinum and
ascending
aorta.

12. • positive silhouette sign is very helpful.
• A negative silhouette sign does not
ensure that a given lobe is disease-free because it
may be partially aerated an not causing a
silhouette sign.
• applied in –pneumonia,,lobar collapse,,lung
tumour,,mediastinal mass,,

13. EXCEPTIONS
 underpenetrated radiograph. If you cannot
see the spine through the heart, the film
is underpenetrated,
 Sometimes the right heart border overlies
the spine and does not protrude into the
right lung. The density of the spine hides
the lung-heart interface.
 Depressed sternum produce loss of rt
heart border.
 Pulmonary vessel and fat near heart..

15.  two silhouette signs of
the left diaphragm.
The anterior one is
due to the heart, and
the posterior one is
due to pneumonia (P)
in the left lower lobe.
 Only the middle third
of the left diaphragm
is visible (*). The
entire right diaphragm
is visible.

16. Air bronchogram sign
 Visualization of air in the intrapulmonary
bronchi on a chest roentgenogram is
called the air bronchogram sign.
 The presence of an air bronchogram
indicates abnormal lung i.e. parenchymal
lesion –not pleural – not mediastinal
 Pnuemonia , pulmonary edema,
pulmonary infarction, certain chronic lung
diseases

18. radiograph of a patient with generalized alveolar
consolidation
AIR bronchograms in both upper lobes and the right
lower lobe.

19. WHEN NOT SEEN?
 If a bronchus is obstructed or
filled with secretions ,a
pulmonary lesion would not
show an air bronchogram
 (in endobronchial CA or
collapse or FB)
 Patchy peripheral lung
consolidation or interstitial
disease usually does not
cause enough opacity to
produce an air bronchogram.
 Conditions that hyperinflate
(emphysema ) the lungs do
not cause air bronchograms.

20.  The presence of an air
bronchogram indicates
a __lung_lesion and
indicates open airways
 The absence of an air
bronchogram indicates
the lesion may be
either pulmonary or
extrapulmonary
 an air bronchogram
seen through the
cardiac shadow is the
most definitive sign of
left lower lobe
consolidation.

21.  The crowded air
bronchograms
suggest this is non
obstructive
atelectasis

27.  Rt & lt lower lobe
collapse—
◦ Triangular density
over heart
◦ Hilum depressed
◦ Lower lobe pul.
Artery not
visualized
◦ Medial aspect of
diaphragm
obscure.
◦ Lateral margin of
vertebra effaced.
◦ Over expantion of
remaining lung.
Middle lobe collapse—
◦ Hz fissure move inferior.
◦ Blurring of heart border.
◦ On lat.xray slice of cake
apperance.wedge shape
oppacity.
 Rt upper lobe
collapse
◦ Hz fissure move
superior.
◦ Elevated hilum
◦ Dense collapse lung
◦ Golden s sign
 Lt upper lobe
collapse
◦ Veil like oppacity
cover most of lf
thorax.
◦ Heart border
obscure.
◦ .hilum elevation

31. •Loss of volume
on left side
•i/l shift of
trachea and
mediastinum
•Compensatory
hyperinflation of
right lung
•Raised left
hemidiaphragm
with tenting
•Haziness over
the aortic
knuckle
(silhoutte sign)

32.  In Figure there is
collapse of the _rt
upper _ lobe. The
sharp inferior
margin is caused by
the _minor fissure_.
It is [elevated] in
position

33.  five basic mechanisms that cause volume
loss:
 (1) resorption of air - obstruction of a
bronchus;
 (2) compression -air or fluid in the pleural
space;
 (3) scarring, causing lung contraction;
 (4) decreased surfactant reducing lung
distensibility (adhesive atelectasis); and
 (5) hypoventilation as a result of central
nervous system depression or pain. after
general anesthesia or heavy sedation.
involves the lung base.

34. Alveolar & intersitial disease
 air sacs are called
__alveoli__ they
contain air, and they
are radiolucent on x-
ray.
 If fluid or tissue (e.g., blood,
edema, mucus, tumor) fills
the air sacs, the lungs
become [radiodense]
 The interstitial markings are
[less] visible within the
alveolar consolidation.
 The lungs appear
homogeneously white. They
are not aerated.

35.  Supporting the alveoli are
vessels, lymphatics bronchi,
and connective tissue. This
support known as the
__interstitium of the lung.

 On a normal chest x-ray, the
branching pulmonary arteries
and veins are our only look at the
interstitium.
 They appear white. They branch
and taper and become invisible
in the outer third of the lung
because they are ___beyond the
resolution of the x-ray _
 If a disease affects only
the interstitium, the
interstitial tissue around
the small vessels or
interlobular septa
thicken and they
become [more visible]
at the periphery of the
lung. Because the air in
the alveoli is hardly
affected, the lung still
appears well aerated.

36.  Most lung diseases result in increased
radiodensity of the lung. If the interstitium
thickens, it can be seen more peripherally
on the x-ray . .
 If the alveoli fill with fluid, the fluid-filled
area becomes radiodense, and the
interstitium is enveloped in the dense
white lung and is not visible
•With the interstitial pattern, the lungs
appear well [aerated]
the lung markings are __thick more
prominant.
• with the alveolar pattern, the
individual lung markings are
___invisible__ because the surrounding
lung is airless.

37.  If the interstitial
thickening is
generalized, the
pattern is linear
(reticular)
 If the thickening is
discrete, it forms
multiple nodules

39.  In general, acute and chronic interstitial lung
diseases look similar.
 If the markings are hazy (ill defined) and not
distorted (i.e., normal branching pattern), the
disease is probably acute – viral n interstitial
pneumonia , pulmonary edema – focal or
diffuse
 If the lung markings are sharp (well defined)
and distorted (i.e., angular, irregular, bowed),
the disease is probably [chronic - fibrosis -
diffuse
 The most reliable method of distinguishing
acute from chronic is by viewing past films
or,taking a history.

40. It is chronic because
the markings are
[distorted] and
[distinct]
form of fibrosis is
“honeycombing.” The
fibrosis forms multiple
small
cysts, often stacked up
one on another, just
beneath the pleura

41.  1. “Pulmonary
markings” are [more]
visible.
 2. The lung appears
[aerated].
 3. An air bronchogram is
not visible.
 4. The silhouette sign is
not] visible.
 5. signs of chronic
disease include
distortion,
honeycombing,sharp
margins,
alveolar filling disease
/airspace consolidation:
 1. Vessels are [less]
visible in the area of
disease.
 2. The diseased lung
appears [not aerated].
 3. An air bronchogram
[may be] visible.
 4. A silhouette sign
[may be] visible.
INTERSTITIAL DISEASE VS CONSOLIDATION

46. •If a very
focal area
of
consolidati
on has
well-
defined
border
•greater
than 3 cm
mass
• less than
3 cm,
“nodule.”

47. SPOT ON THE LUNG
 In young patients,
chronic alveolar
consolidation,
nodules, and masses
are most often due
to indolent infection
or inflammatory
lung disease.
 In patients older
than age 40, cancer
becomes a major
concern.

48.  Mass-- >3 cm
 Nodule-- <3 cm
 Milliary shadow--,2 mm
 Bulla—thin wall,>1 cm
 Cavity—thick wall ,>3 mm

50. THE MEDIASTINUM
.

51.  The most frequent sign of mediastinal
disease is mediastinal widening.
 Most masses -focal widening. Infiltrating
diseases, -hemorrhage or infection -
generalized
 A mediastinal mass displaces the medial
pleura toward the lung. The interface with
the lung is usually [sharp] And convex
toward the lung.
 Secondary signs of mediastinal disease is
displacement, compression, silhouette sign
invasion .

54. Division of mediastinum into three
compartments
based on the lateral chest x-ray.
 line separates the
anterior (I) and
middle mediastinum
(II).The line sits in
front of the trachea
but behind the heart.
 A second line, 1 cm
back from the
anterior edge of the
vertebral bodies,
separates the middle
mediastinum from
the posterior
mediastinum.

55. The lateral radiograph is often
helpful in assigning disease to
one of the mediastinal
compartments.
 the mass sits in the
anterior mediastinum.
It fills the retrosternal
clear space
 the five T’s are named
Thyroid,
Thymus,Teratoma,
Thoracic aorta
(ascending), and
Terrible lymphoma and
heart

56.  The major middle
mediastinal organs
are esophagus,
trachea,and aorta
(arch and
descending). , LN
 Enlarged lymph
nodes are the most
frequent cause of a
middle mediastinal
mass. –
 SARCOIDOSIS
(young)
 LUNG CANCER ( old)

58. an aneurysmal aortic
arch projects as a
mass. Note the
calcified
(atherosclerotic)
intima of the aortic
arch (upper arrow).
tortuous descending
aorta (arrow)
overlapping the
spine.

59. Posterior mediastinum Most posterior
mediastinal masses
are from the nerve
or their coverings
(NF or
meningocoele) in
young patients
 Multiple myeloma
and metastatic
spine disease are
more common in
old patients

61. THE PLEURAL AND
EXTRAPLEURAL SPACES
 The pleural cavity is a true space between
the visceral and parietal pleura.
 The extrapleural space, a potential space,
lies between the rib cage and the
adherent parietal pleura.
 The [posterior] costophrenic angle is
deepest and seen only on the lateral
radiograph.

65. subpulmonic fluid
 subpulmonic fluid
because it so closely
simulates an elevated
Hemidiaphragm
 . On the left, the
stomach bubble is
normally separated
from the lung base by
only the thin
diaphragm.
 In Figure with left
subpulmonic fluid, the
gas bubble lies [farther
from]the lung base.
 This is known as the
“stomach bubble sign.”

66.  There is no stomach bubble on
the right. We often have to rely
on the change of shape of the
right “diaphragm” with apex
shifted laterally ( normally in line
with MCL) to diagnose
subpulmonic effusion.
 Lateral decubitus view –
affected side down--best to

67.  supine position, the
fluid gravitates
[posteriorly] and
causes the affected
hemithorax to
appear [more]
radiodense.
 The supine view is
less sensitive than
the erect view in
detecting effusion.

68.  The erect PA requires greater than 175
mL; the erect lateral, 75 mL;the
decubitus, greater than 5 mL; the supine,
more than several hundred milliliters.
 When one hemithorax is totally opaque, is
it usually due to consolidation and
atelectasis, or is it due to a large pleural
effusion

69. Loculated fluid
 The borders of an
encapsulation
 are generally convex
toward the lung.
 The margin forms an
obtuse angle with
the chest wall when
seen in profile
(arrows).
 d/t adhesions –
preexisting or dev
after

70. Intrafissural effusion
(“pseudotumor”)
“Pseudotumors” are most commonly encountered in congestive
heart failure. As the congestive heart failure resolves, the loculated
fluid
disappears (“vanishing tumor”).

71. Hilum
 Lf hilum never
lower than rt hilum.
 If lower than
◦ Lf Lower lobe &rt
upper lobe collapse
◦ Enlarge rt hilum
 Enlarge hilum
◦ LN,,tumour,,enlarge
artery
◦ Artery always emerge
from mass,,smoth
margine,,outer 13
arteries
disproportionaty
smaller than hilum.
◦ LN have lumpy
bumpy outline..

72. Hyperinflation.
The diaphragms are normally at the
9th-10 th posterior rib.

73. Pneumothorax
 Air in the pleural
space is [more]
radiolucent than the
lung.
 With a
pneumothorax, the
visceral pleura is
seen as a thin white
line between air in
the lung and air in
the plural space.

74. tension pneumothorax
 Occasionally, air
enters the pleural
space with each
breath but cannot
escape, increasing
the intrapleural
pressure.
 The increased
pressure [depresses]
the diaphragm,
collapses the lung,
and shifts the
mediastinum [away
from] the
pneumothorax.

75. Extrapleural lesion.
 Lesions that arise in
 structures within or
bordering the extrapleural
space (e.g., ribs, muscle,
connective tissue) may lift
the adjacent [parietal] pleura
and push it toward the lung.
 The convex margin facing
the lung is sharp, and the
borders are tapered (obtuse
angle with chest wall).
 The lesion looks similar to
encapsulated fluid..
 it may be difficult to
separate the two.
 Most extrapleural lesions are
due to rib fractures and rib
metastasis

76. Cardiovascular Disease
 The normal cardiothoracic ratio is less than
0.5
 patient, an increase of greater than 1 cm in
cardiac diameter from a prior film is a more
reliable index of cardiac enlargement than
the cardiothoracic ratio.
 The “heart” may be enlarged because of
intrinsic cardiac disease ( Lung changes seen
) or appear enlarged by surrounding
pericardial fluid.
 If the left atrium enlarges, it protrudes
[laterally in PA and [posteriorly – IN
LATERAL VIEW. On the frontal view, its
margin becomes [convex]

77. With left ventricular enlargement on the frontal view, the left
heart border
moves laterally, and the cardiac apex moves inferolaterally.
On the lateral view,
the left heart border moves inferoposteriorly.

78.  In the frontal
projection, the normal
right heart protrudes
slightly to the right of
the spine,
 In the lateral
projection,the right
heart enlarges
anteriorly and
superiorly.
 The normal right heart
contacts the lower one
third of the sternum,
whereas the enlarged
right heart contacts the
lower one half.

79. cephalization or vascular
redistribution
 Cephalization, not
heart size, is the key
to diagnosing
elevated left heart
pressure. Left heart
failure and mitral
valve stenosis are the
most frequent causes
of redistribution or
cephalization.
 A shunt (e.g., atrial
or ventricular septal
defect) causes all
vessels to enlarge.

80.  left heart failure, the
cardiac silhouette often
enlarges.
 A. In mild failure, there
iscephalization _ of the
vessels but no edema.
 B. Moderate failure
causes indistinct vessel
margins as a result of
interstitial] edema.
interstitial; Kerley B
lines and pleural
effusions may be
present.
 C. Severe failure
causes [alveolar]
edema
 Fluid thickens the
interlobular septa,
causing short lines
perpendicular to the
pleural surface. These
are “Kerley B” lines
indicating interstitial
edema..

81. Kerley B line
 Determining
cardiomegaly and
cephalization is
unreliable on supine
films.