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• Alveolar space filled
• Interstitium and
• The airway is patent
transcribes to ;
• A density corresponding
to a segment or lobe
• No significant loss of
Visualization of bronchi within parenchymal consolidation.
Branching lucencies surrounded by consolidative opacity.
Excludes a pleural or mediastinal lesion
AIR BRONCHOGRAM SIGN
BULGING FISSURES SIGN
• The bulging fissure
sign refers to
where the affected portion
of the lung is expanded.
• The most common infective
causative agents are
• An intra-thoracic radio-
opacity, if in anatomic
contact with a border of
heart , aorta or
diaphragm , will obscure
• An intra-thoracic lesion
contiguous with a border
or a normal structure will
not obliterate that border.
Right middle lobe disease
• In a small percentage of normal individual, the right
heart border may not be seen
• A depressed sternum can produce loss of the right heart
border, an appearance which mimics middle lobe
pneumonia .This is because:
(a) the depressed sternum pushes the heart posteriorly
and to the left; and
(b) bunching of the soft tissues of the deformed chest wall
causes an increase in density.
• The absence of a silhouette sign can tell you
where a shadow (consolidation or mass) is
ITS NOT JUST THE PRESENCE
RT. MIDDLE LOBE PNEUMONIA
Indistinct borders, air bronchograms, and silhouetting of the right heart border.
In collapse air is absorbed
and not replaced in
contrast to consolidation.
• The signs of lobar or pulmonary collapse can be divided
Direct signs are;
• Opacity of the affected lobe(s);
• Crowding of the vessels and bronchi within the collapsed area
• Displacement or bowing of the fissures .
Indirect signs are:
• Compensatory hyperinflation of the normal lung
• Displacement of the mediastinal structures toward the affected side
• Displacement of the ipsilateral hilum which changes shape
• Elevation of the ipsilateral hemidiaphragm
• Crowding of the ribs on the affected side
Golden S Sign:
• Seen in case of
collapse due to
a hilar mass
• The mass gives
a convexity to
Apex at hilum
are not seen
Normal or increased
No shift, or if present
Not centred at hilum
• Air–containing spaces
with thick walls that are
lined with bronchiolar
epithelium and fibrous
• Due to destruction of
alveoli and loss of acinar
• Associated with
• Usually 5-10 mm in size
LINEAR AND BAND SHADOWS
• Normal structures such
as the blood vessels
and fissures form linear
shadows within the
• However, there are
many disease processes
which may result in
• Linear shadows are
less than 5 mm wide,
• Band shadows are
greater than 5 mm thick
• Mucus-filled bronchi
• Coarse lines lying
peripherally in contact
with the pleura and
• Often left-sided and
associated with left lower
• They may develop due to
kinking of bronchi
adjacent to the collapse.
Kerley's A lines (arrows) :
• Linear opacities extending from the periphery to the hila
• Due to distention of anastomotic channels between
peripheral and central lymphatics.
Kerley's B lines (white arrowheads) :
• Short horizontal lines situated perpendicularly to the
pleural surface at the lung base
• Due to edema of the interlobular septa.
Kerley's C lines (black arrowheads): Reticular opacities at
the lung base representing superimposed Kerley's B lines.
• Small discrete
• 2-4 mm in diameter
• MC in Tuberculosis
OLD PLEURAL AND PULMONARY
• Scars are unchanged in
appearance on serial film.
• Thin linear shadow often
with associated pleural
thickening and tenting of
• Apical scarring is a
common finding with
sarcoidosis and fungal
THICKENED BRONCHIAL WALLS
• Parallel TRAMLINE
• Ring shadows on end-on
• They are common finding
• Discrete, well-marginated, rounded opacity
• Less than or equal to 3 cm in diameter
• Completely surrounded by lung parenchyma, does not
touch the hilum or mediastinum,
• Not associated with adenopathy, atelectasis, or pleural
• Lesions larger than 4 cms are treated as malignancies
until proven otherwise.
SOLITARY PULMONARY NODULES
SOLITARY PULMONARY NODULES
A right lower lobe solitary pulmonary
nodule that was later identified as a
Right lower lobe nodule later confirmed to
be primary pulmonary lymphoma
SOLITARY PULMONARY NODULES
• Intrapulmonary mass forms
an acute angle with the lung
• Extrapleural and
mediastinal masses form
obtuse angles .
• A nodule is assessed for its
size, shape and outline and
for the presence of
calcification or cavitation. .
• Carcinomas often have irregular, spiculated or notched
• Calcification favours a benign lesion although a
carcinoma may arise coincidentally at the site of an old
• Calcified metastases are rare, the primary tumour being
usually an osteogenic or chondrosarcoma.
• Granulomas frequently calcify and are usually well
defined and lobulated.
SOLITARY PULMONARY NODULES
Calcified mets in
MULTIPLE PULMONARY NODULES
• Multiple small nodules 2-4
mm are called miliary
• Mostly metastases or
• Calcified nodules are
generally benign except for
metastases from bone or
Posteroanterior view of the chest showing multiplediffuse pulmonary nodules.
• These are variable in
• Usually wedge shaped
with base towards the
• Resolve slowly over
months decreasing in
size (MELTING SIGN)
CAVITATING LESIONS AND CYSTS
• It’s a gas filled space surrounded by a complete wall which
is 3 mm or greater in thickness.
• Thinner walled cavities are called CYSTS or ring shadows.
• Requires a patent airway to communicate with necrotic area
• Common cavitating processes are tuberculosis,
staphylococcal infections and carcinoma
Common sites of the Lesion
• Tuberculous cavities : Upper zone and apical segments
of the lower lobes.
• Lung abscesses following aspiration : Rightsided and
lower zone(patient position dependant)
• Traumatic lung cysts : Subpleural
• Amoebic abscesses : Right base ,infection extending
from the liver.
• Pulmonary infarcts : Usually in lower lobes
Thick walled cavity
• Fluid levels are common
in primary tumors , and
irregular masses of blood
clot or necrotic tumor
may be present.
• Fluid levels are
uncommon in cavitating
tuberculous cavities .
AIR CRESCENT SIGN
within a parenchymal
consolidation or nodular
Air fills the space between the
devitalized tissue and
Opaque rim of hemorrhagic
tissue peripheral to the
Common in Aspergilloma
WATER LILY SIGN
cysts with daughter
cysts floating within
• Other intracavitory lesions include inspissated pus,blood
clot and cavernoliths.
• Blood clot may form within cavitating neoplasms,
tuberculosis and pulmonary infarcts
• Calcification is most easily recognized with low kVp
• In the elderly , calcification of the tracheal and bronchial
cartilage is common.
• Tuberculosis is the commonest calcifying pulmonary
process usually upper zone.
• Chickenpox foci are smaller (1-3 mm), regular in size
and widely distributed.
Apical pleural thickening/Pleural Cap
• It is crescent shaped density
• It may represent old pleural thickening
• Also seen in Pancoast tumor – assess the ribs for
• Commom site for Tb , fungal infection like
histoplasmosis , coccidioidomycosis, aspergillosis etc
• Comparision of lungs should reveal any focal or
generalized abnormality of transradiancy.
• Look for signs of obstructive or compensatory
emphysema such as
o splaying of the ribs
o separation of the vascular markings
o mediastinal displacement
o depression of the hemidiaphragm
• Most common causes : Patient rotation and scoliosis
• With rotation to the left, the left side becomes more
• Mastectomy is another important cause. An abnormal
axillary fold is seen following a radical mastectomy.
• Fluid in the pleural
• Erect CXR- commonest
appearance is an opaque
meniscus at costophrenic
• If the effusion is very
large entire hemithorax
may be opaque and heart
may be pushed to the
Features on CXR:
• Blunting of the costophrenic angle
• Blunting of the cardiophrenic angle
• Fluid within the horizontal or oblique fissures
• A meniscus will be seen, on frontal films seen laterally and
gently sloping medially
• With large volume effusions, mediastinal shift occurs away
from the effusion
Approximately 200 ml of fluid are needed to
detect an effusion in the frontal film vs.
approximately 75ml for the lateral
• LAMELLAR EFFUSION: Shallow collections between
the lung surface and the visceral pleura sometimes
sparing the costophrenic angle.
• LOCULATED EFFUSION: Effusion within the fissures.
• Effusions accumulate between the diaphragm and
undersurface of a lung.
The following features are helpful :
• Right: peak of the hemidiaphragm is shifted laterally
• Left: increased distance between lower lobe air and
gastric air bubble
• Plaques are focal areas of
thickening of parietal pleura due
to previous exposure to asbestosis.
• Characteristically appear as
scattered islands of well
circumscribed pleural densities.
• Most commonly seen posteriorly
and laterally, predominantly
affecting the lower third of the
• Do not involve the CP angles .
• May be calcified.
• Calcified pleural plaques from
asbestos exposure : typically has
sparing of costophernic angles
• Infection involving the pleura -
e.g pyothorax / empyema
• Tuberculous pleuritis
• extra skeletal osteosarcomaof
• Refers to the presence of gas in the pleural space.
• Open Pneumothorax: If air can move in and out of
pleural space during respiration
• Closed Penumothorax: No movement of air occurs
• Valvular : Air enters pleural space on inspiration but
doesnot leave on expiration
• When this collection is constantly enlarging with
resulting compression of mediastinal structures it is
known as a tension pneumothorax.
DEEP SULCUS SIGN
• This sign refers to a deep
collection of intrapleural
air (pneumothorax) in the
costophrenic sulcus as
seen on the supine chest
• Visible visceral pleural edge
see as a very thin, sharp white
• No lung markings are seen
peripheral to this line
• The peripheral space is
radiolucent compared to
• The lung may completely
• No mediastinal shift unless
a tension pneumothorax is
• It is the concurrent
presence of a
pneumothorax as well as
a hydrothorax in the
• On an erect chest
seen as an air-fluid level.
• Fibrosis within the pleural space
• Occurs secondary to the inflammatory response
• Seen in
• Superior margin of left hilum is normally higher than
• Whenever a left hilum appears lower than right – check
whether there is other evidence suggestive of collapse of
either left lower lobe or of right upper lobe ; or
enlargement of right hilum(eg; tumor or nodes)
• Bilateral hilar enlargement -Enlarged lymph nodes, or
• Unilateral enlargement : MC due to neoplasm or infections
such as tuberculosis and whooping cough.
• Nodes affected by lymphoma are often asymmetrically
• Bilateral involvement occurs with sarcoidosis, silicosis and
• Used to discern the anterior or posterior location of a lesion in
the superior mediastinum on frontal chest radiographs.
• The anterior mediastinum stops at the level of the superior
• Thus when a mass extends above the superior clavicle, it is
located either in the neck or in the posterior mediastinum.
• When lung tissue comes between the mass and the neck, the
mass is probably in the posterior mediastinum.
A mass extending above the
level of the clavicle and
there is lung tissue in front
of it, so this must be a mass
in the posterior
ANTERIOR MEDIASTINAL MASS
T cell lymphoma
Anterior mediastinal masses consist of the 4 "T's" (Terrible lymphoma, Thymic tumors,
Teratoma, Thyroid mass) and aortic aneurysm, pericardial cyst, epicardial fat pad.
• Retrosternal goitre
The plain chest film
shows a large
mass narrowing the
MIDDLE MEDIASTINAL MASS
due to metastases
or primary tumor.
Esophageal duplication cyst
Mass is detected by a pleural margin search along the superomedial part of right lung.
The interface is interrupted.
Neurenteric cyst or
• Lymphadenopathy is
the next most frequent
cause of a mediastinal
may occur in any of the
and it is often possible
to diagnose enlarged
lymph nodes from their
and the multiple
Superior mediastinal lymph node
enlargement. Note the bilateral
HILUM OVERLAY SIGN
• This sign is used to distinguish between cardiac
enlargement and an anterior mediastinal mass, as
• Hilum lateral to the lateral border of the “mass”–
• Hilum medial to the lateral border of mass”–
HILUM CONVERGENCE SIGN
• Used to distinguish between a prominent hilum and
an enlarged pulmonary artery.
• If the pulmonary arteries converge into the lateral
border of a hilar mass, the mass represents an
enlarged pulmonary artery.
• If the convergence appears behind the abnormality or
arises from the heart, a mediastinal mass is more
• To localize the LOWER MEDIASTINAL MASS on frontal CXR
• It is the presence of extraluminal gas within
• Blunt chest trauma
• Secondary to chest, neck, or retroperitoneal surgery
• Esophageal perforation :
– Boerhaave syndrome
– Endoscopic intervention
– Esophageal carcinoma
• Air around the pulmonary artery produces a black ring
• Air around the arteries arising from the aortic arch
appears as a black rings and often referred to as the
“ring around the artery sign”.
• Angel wing sign – represents the normal thymus
surrounded by mediastinal air.
CONTINUOUS DIAPHRAGM SIGN
Continuous lucency outlining
the base of the heart,
• Air in the mediastinum
between the heart and
• Pneumopericardium can
have a similar appearance
but will show air
CAUSES OF A UNILATERAL ELEVATED DIAPHRAGM
• Above diaphragm: phrenic nerve palsy; infiltration from
bronchial carcinoma or mediastinal tumour.
• Diaphragm: eventration, more common on the left and results
from deficiency or atrophy of muscle.
• Below diaphragm: right diaphragm elevation; liver or
subphrenic abscess, liver secondary deposits.
• A congenital defect in the
diaphragm, more common
on the left, allows bowel
protrusion into the thoracic
Eg: Hiatus Hernia
EVENTRATION OF THE DIAPHRAGM
• This is a congenital
condition in which the
diaphragm lacks muscle
and becomes a thin
• The eventration may only
involve part of one
in a smooth 'hump
Localized eventration of the diaphragm.
There is a smooth localized elevation of the
medial half of the right hemidiaphragm
• Old healed fractures are frequent findings.
• Erosion of the outer ends of the clavicles is associated
with rheumatoid arthritis and hyperparathyroidism.
• Hypoplastic clavicles are seen with the Holt-Oram
syndrome and cleido cranial dysostosis
CHEST WALL ABNORMALITIES
• Sternal fractures are often due to a steering wheel
• Associated with congenital heart disease: Sternal
agenesis, premature obliteration of the ossification
centres and pigeon chest which are found
with ventricular septal defects.
• Depressed sternum(Pectus Excavatum) - Atrial septal
defects and Marfan's syndrome.
• Delayed epiphyseal fusion is a feature of cretinism
• Double ossification centres in the manubrium commonly
occur in Down's syndrome
• It may affect the superior or
inferior surface and can be U/L or
• Superior notching : Rheumatoid
neurofibromatosis and in
paraplegics and polio victims.
• Inferior notching develops as a
result of hypertrophy of the
intercostal vessels or with
neurogenic tumours .
• A cervical rib in humans
is a supernumerary rib
which arises from the
seventh cervical vertebra.
• Congenital rib anomalies
such as hypoplasia,
bridging and bifid ribs
• The sixth to ninth ribs line are the
common sites for cough fractures.
• Stress fractures usually affect the
• Pathological fractures may be due
to senile osteoporosis, myeloma,
Cushing's disease and other
endocrine disorders, steroid
therapy and diffuse metastases.
• Cushing's disease is associated
with abundant callus formation
• Check for abnormal curvature or alignment , bone and disc
destruction, sclerosis, paravertebral soft-tissue masses and
congenital lesions such as butterfly vertebrae
• Anterior erosion of vertebral bodies sparing the disc spaces is
noted with aneurysm of descending aorta, vascular tumors
• A single dense vertebra , the ivory vetebra, - classical
appearance of lymphoma, but also – pagets disease and
• Destruction of pedicle is typical of METASTASIS .
• Destruction of the disc with adjacent bony
involvement is characteristic of an INFECTIVE
• Disc calcification occurs in ochronosis and ankylosing
SOFT TISSUE ABNORMALITIES
• Skin lesions including
naevi and lipomas may
simulate lung tumours.
• Multiple nodules occur
with neurofibromatosis .
• Mastectomy is one of the
commonest causes of a
• Poland’s syndrome;
There is a congenital absence of pectoralis major
and minor, associated with syndactyly and rib
SOFT TISSUE ABNORMALITIES