Transcript Slide 1

Introduction to
Chest Radiology
For medical students
Basic principles of x-ray film
X-rays reach the film and darken it, therefore the more xrays that reach an area of the film the darker the area will
be, such as the lung.
If an object is very dense, less x-rays reach the film and
the object will appear white, such as the bones.
There are five radiographic densities. In order of
increasing brightness they are; air, fat, fluid, bone and
metal.
The closer an object is to the film, the sharper the borders.
Objects further from the film will be magnified and the
borders will not be as sharp.
When two structures of the same density are next to each
other the border between them is lost.
Basic views
The standard chest examination consists of a
posterioranterior (PA) and lateral chest x-ray.
These two films are taken in the upright
position.
In ill patients who cannot assume the upright
position an AP (anteriorposterior) film by a
transportable device can be taken in their
room, hence the name “portable” film.
Posterioranterior (PA) view
The PA view is taken with the patient
six feet from the x-ray tube.
To prevent enlargement and blurring
of the heart and great vessels in the
anterior chest, these are placed
closest to the film.
The patient places their chest against
the film and the x-ray beams are shot
from the patients back, therefore
called the posterioranterior or PA view.
Hands should be placed on the hips
so the scapula will be out of the lung
fields.
Lateral view
The lateral view is taken
with the patients in profile.
Since the heart lies more
in the left chest, this side
is placed toward the film
to avoid any enlargement
or blurring.
The patient arms are
raised to move the
scapula out of the lung
fields.
Anteroposterior (AP) view
The AP view is taken with
the patient supine and 40
inches from the x-ray
tube.
Because the heart and
great vessels are further
from the film they appear
enlarged and the borders
are not as sharp.
Comparison of PA and AP view
Compare the PA and AP views
PA
AP
Decubital view
Decubital films are taken with the
patient lying on their side.
This view is helpful to assess the
volume of pleural effusion and
whether it is mobile or loculated.
If an effusion is suspected on the
right, have the patient lie with the
right side down (right lateral
decubitus view) so the fluid would
accumulate against the right chest
wall.
This view can also be used to
assess for ptx in a patient who
cannot sit upright. Place the patient
with the suspected side of the ptx
up so the air can be seen under
the chest wall.
Here is an example of a mobile,
right pleural effusion
Is the film technique adequate?
Things to assess when looking at a film:
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Inspiration
Penetration
Rotation
Motion
Inspiration
The lungs should span 9
posterior ribs to ensure
that inspiration is
adequate and a good
image was obtained.
This image is an example
of good inspiration.
If there is poor inspiration
the patient can appear to
have an abnormal CXR.
Penetration
Overpenetration: the
film appears too dark
and the vessels in the
lungs cannot be seen
Underpenetration: the
film appears too white
and the spine cannot
be visualized behind
the heart
Rotation
Rotation: make sure
the distance between
each clavicle is equal
distance from the
thoracic spinous
processes.
If there is rotation the
mediastinal contents
can appear distorted.
Notice the rotation of
the clavicles.
How to read a CXR
Always verify pt data,
compare old films and
ensure technique is
adequate.
Note the following findings:
 Trachea: midline or
deviated, caliber, mass
 Lungs: abnormal opacity
or lucency
 Pulmonary vessels:
artery or vein
enlargement
 Hila: masses or
lymphadenopathy
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Cardiothoracic ratio:
cardiomegaly, heart
borders
Mediastinal contour:
width or mass?
Pleura: effusion,
thickening, calcification
Bones: lesions or
fractures
Soft tissues: breast
shadows, mastectomy,
hematoma or subq air
ICU Films: identify
tubes / lines first; look
for ptx
How to read a CXR
It is best to develop a systemic method and follow it.
This will ensure that all areas are inspected, and that
nothing is overlooked.
Below is a recommended pattern for scanning the lung
fields.
Anatomy of the mediastinum
Specific signs
Silhouette sign
Air bronchogram
Kerly B lines
Golden S sign
Silhouette sign
When two structures that are the same density
are next to each other the border between them
is lost. This is the silhouette sign.
This is often seen when a water density process
such as pneumonia is next to a water density
structure such as the heart or diaphragm.
The location of this abnormality can help to
determine the location anatomically.
Silhouette sign and locations
The following are examples of
silhouette signs and the
associated anatomic
abnormalities, such as
collapse or pneumonia.
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Right heart= RML
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Left heart border= lingula
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Right hemidiaphragm=RLL
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Left hemidiaphragm= LLL
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Aortic knob/Descending
aorta=LUL
Silhouette sign
On this film the right
heart border is lost, or
silhouetted out.
This indicates
pathology of the Right
middle lobe.
Air Bronchogram
Normally the thin walls of
the bronchi are not visible
because they are filled
with air and surrounded
by air.
If the alveoli are
surrounded by fluid then
the air in the bronchi can
be seen. This is called
an air bronchogram.
This is a non-specific
finding and can indicate
pus, blood or fluid.
Kerly B sign
Kerly B lines are small
horizontal lines that are
seen in the periphery of
the lung and always
extend to the pleura.
They are seen when
there is increased fluid
density in the interlobular
septa.
This often results from
pulmonary edema seen in
CHF.
Golden S sign
This sign is often seen in
RUL collapse and resembles
a reverse S sign. It is also
called “the reverse S sign of
Golden”.
RUL collapse causes the
minor fissure to assume this
reverse S shape, with a
lateral concavity and
medical convexity.
Note the convexity
(arrowhead) from the mass
and the concavity (arrow) of
the minor fissure.
Most common Abnormalities on CXR
Atelectasis
Pulmonary edema
Pneumonia
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Bacterial, viral and atypical
PCP, Tb, other opportunistic infections
Pneumothorax
Pulmonary embolism
Emphysema
Pulmonary embolism
Pleural effusion
Interstitial pulmonary fibrosis
Emphysema
Lung nodules/mass
Enlarged cardiac silhouette
Pericardial effusion
Atelectasis
Atelectasis or “collapse” refers
to volume loss.
The affected area appears
white because of the loss of
air.
When a portion of lung
collapses it pulls its adjacent
fissure with it.
This is an example of RUL
atelectasis with superior
displacement of the minor
fissure.
Atelectasis is due to:
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Obstruction-air cannot fill the alveoli.
Compression-air pushed out of lung.
Traction-scarring contracts the lung
and distorts the alveoli.
Pulmonary Edema
There are 2 types of Pulmonary Edema, cardiogenic and noncardiogenic.
Cardiogenic pulmonary edema is due to pump failure and increased
hydrostatic pressure.
Noncardiac pulmonary edema is due to altered permeability or
decreased oncotic pressure. Etiologies include NOTCARDIAC
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Near drowning
Oxygen therapy
Transfusion, trauma
CNS disorder
ARDS, Altitude sickness
Renal disease-most common cause
Drugs
Inhaled toxins
Allergic
Contusion, Contrast (IV)
Cardiogenic Pulmonary Edema
On CXR this can appear as
cephalization of the
pulmonary vessels, Kerly B
lines, peribronchial cuffing,
or “bat wing” pattern and
cardiomegaly.
Here is an example of “bat
wing” pattern in a patient
with pulmonary edema.
Pneumonia
Pneumonia can present as a focal opacity or diffuse
interstitial disease.
Bacterial or pyogenic pneumonia often causes silhouette
or air bronchogram signs. It may involve part or all of a
lobe and is often caused by bacterial infection.
Diffuse pneumonia is often bilateral and appears as
multiple white lines. It is mainly caused by viruses and
atypical bacteria.
Tuberculosis is another type of pneumonia and can
either be a primary, secondary or miliary TB.
Pneumonia can also be due to opportunistic organisms
such as Pneumocystis.
Bacterial pneumonia
Bacterial pneumonia
is a focal area of
opacity.
This is an example of
RUL pneumonia.
Viral and atypical pneumonia
Diffuse interstitial
pneumonia is usually
viral or atypical in
etiology.
It is often bilateral and
appears as multiple
white lines.
Tuberculosis
Primary TB infection usually results in air
space disease of the lower lobes with hilar
lymph node enlargement.
Secondary TB occurs weeks to years later
and tends to occur in the upper lobes.
Miliary TB can occur during both primary
or secondary and looks like very small
pellets involving both lungs.
Primary TB
Primary TB is represented by
consolidation, adenopathy
and pleural effusion.
A Ghon focus is an area of
focal consolidation that
occurs in the mid and lower
lungs.
A Ghon complex is the
addition of calcified hilar
lymphadenopathy.
Secondary TB
Secondary TB is often
represented by fibrosis,
cavitation and
calcification primarily in
the upper lobes.
Note that the TB has
caused a pneumothorax
on the right.
Opportunistic pneumonias
Pneumocystis Pneumonia
(PCP) is the most common
opportunistic pneumonia in
immunocompromised patients.
Often presents with diffuse,
symmetric finely
granular/reticular interstitial
infiltrates with a central
location.
It can also present with a
normal CXR.
Pneumothorax
Pneumothorax is air inside the
thoracic cavity.
It can be idiopathic or due to
asthma, COPD, infections,
neoplasm or iatrogenic.
On CXR you will see air
without lung markings and a
pleural line.
If it is large there can be a shift
in the mediastinum – tension
ptx.
This is an example of tension
ptx with mediastinal shift.
Pulmonary Embolism
The CXR is usually normal in patients with
pulmonary embolism.
The main purpose of the CXR is to rule out
other causes of dyspnea or hypoxia.
There are two signs that can be seen with
a pulmonary embolism
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Westermark’s sign
Hampton’s Hump
Westermark’s sign
Westermark’s sign is a
focal, hyperlucent,
wedge-shaped area.
This sign is due to lack
of blood filling the
vessels distal to the
embolism.
Hampton’s Hump
Hampton’s hump is a
white, wedge-shaped
area of infarction.
Pleural effusion
On an upright film a pleural effusion will cause blunting
of the costophrenic angles.
The posterior costophrenic angle is the deepest, and
fluid can collect here undetectable behind the dome of
the diaphram. On the PA view approximately 200 cc of
fluid must be present to be detected.
The lateral view is superior to the PA view when
assessing for an effusion. Approximately 75 cc of fluid
are needed to detect an effusion.
On the supine view the effusion layers out and will
appear as a graded haze that is denser at the base.
When in doubt a lateral decubitus will visualize an
effusion. As little as 5-10cc can be seen on this view.
Pleural effusions
Here is an example of bilateral pleural
effusions. Note the blunting of the
costophrenic angles.
Interstitial pulmonary fibrosis (IPF)
On CXR IPF appears as a reticular or linear opacification
with volume loss.
Interstitial pulmonary fibrosis has many etiologies
including:
 Idiopathic >50% of causes
 Collagen vascular disease
 Cytotoxic agents
 Pneumoconiosis
 Radiation
 Sarcoidosis
Emphysema
Emphysema is loss of elastic recoil of the
lung with destruction of alveolar septa.
This is primarily due to smoking, but is
also seen in alpha-1 antitrypsin deficiency.
CXR finding are hyperinflation, flattened
diaphragms, increased retrosternal space,
bullae and enlargement of pulmonary
vasculature.
Emphysema
Example of hyperinflation
and flattened diaphragms
Example of increased
retrosternal air space
Solitary pulmonary nodule
A nodule is a lesion that is less
than 3 cm.
After detection compare lesion to
prior films.
If the nodule does not change for
2 years it is usually benign.
If the nodule is completely
calcified or has central
calcification it is usually benign.
If the nodule has irregular
calcifications it must be worked up
further.
Benign nodules usually have a
smooth edge opposed to the
spiculated borders of malignant
lesions.
Any lesion greater than 3 cm is
considered a mass.
Enlarged cardiac silhouette
The simplest method of
measuring the heart is the
cardiothoracic ratio.
This is the transverse diameter of
the heart divided by the
transverse diameter of the chest.
If the ratio is >50% the heart is
abnormally enlarged.
This is only true for PA views
since the AP projection will
magnify the heart.
Enlarged cardiac silhouette can
be due to cardiomegaly or
pericardial effusion.
Pericardial effusion
Pericardial effusion causes a globular enlargement of the
heart shadow.
A “fat pad” sign is a soft tissue strip >2mm between the
epicardial fat and the anterior mediastinum.
Approximately 400-500 cc of fluid must be present to
detect changes on the CXR.
Notice that in cardiomegaly the hila structures are
pushed outward, opposed to a pericardial effusion where
the hila is hidden behind the fluid/heart shadow. This is
one way to determine the etiology of an enlarged heart
shadow.
Pericardial effusion
Large, globular heart
“Fat pad” sign
Quiz #1
If there is silhouetting of the descending
aorta, what lobe of the lung is involved?
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Right Middle Lobe
Left Upper Lobe
Lingula
Left Lower Lobe
Quiz
If there is silhouetting of the descending
aorta, what lobe of the lung is involved?
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Right Middle Lobe
Left Upper Lobe
Lingula
Left Lower Lobe
Quiz
Recall the following examples
of silhouette signs and the
associated anatomic
abnormalities.
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Right heart= RML
pneumonia
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Left heart border= lingula
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Right hemidiaphragm=RLL
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Left hemidiaphragm= LLL
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Descending aorta=LUL
Quiz #2
This sign is called the
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Luftsichel sign
Golden S sign
Kerly B sign
Hilum overlay sign
Quiz
This sign is called the
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Luftsichel sign
Golden S sign
Kerly B sign
Hilum overlay sign
Quiz #3
When is the Golden S sign seen?
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RLL collapse
RML collapse
RUL collapse
LLL collapse
LUL collapse
Quiz
When is the Golden S sign seen?
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RLL collapse
RML collapse
RUL collapse
LLL collapse
LUL collapse
Quiz
Recall that this sign is
often seen with RUL
collapse and resembles
a reverse S sign. It is
also called “the reverse
S sign of Golden”.
Quiz #4
The most common cause of pulmonary
fibrosis (IPF) is
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Cytotoxic
Collagen vascular disease
Radiation
Idiopathic
Pneumoconiosis
Sarcoidosis
Quiz
The most common cause of interstitial
pulmonary fibrosis (IPF) is
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Cytotoxic
Collagen vascular disease
Radiation
Idiopathic
Pneumoconiosis
Sarcoidosis
Quiz #5
This normal CXR is
not technically
adequate because
there is
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Overpenetration
Underpenetration
Rotation
Poor inspiration
Quiz
This normal CXR is
not techinically
adequate because
there is
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Overpenetration
Underpenetration
Rotation
Poor inspiration
Quiz
Recall that the film
appears too white and the
spine cannot be visualized
behind the heart in
underpenetration.
Overpenetration: the
film appears too dark
and the vessels in the
lungs cannot be seen
Quiz #6
This is an example of
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Bacterial pneumonia
Viral pneumonia
Tuberculosis
Pulmonary embolism
Quiz
This is an example of
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Bacterial pneumonia
Viral pneumonia
Tuberculosis
Pulmonary embolism
Quiz
Bacterial pneumonia
is a focal area of
opacity.
This case is an
example of RUL
pneumonia.
Quiz #7
This is an example of
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Air bronchograms
Hampton’s Hump
Pneumothorax
Westermark’s sign
Quiz
This is an example of
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Air bronchograms
Hampton’s Hump
Pneumothorax
Westermark’s sign
Quiz
Westermark’s sign is a
focal, hyperlucent,
wedge-shaped area.
This sign is due to lack
of blood filling the
vessels distal a
pulmonary embolism.
Quiz #8
Which of the following is most commonly
seen on CXR of a patient with pulmonary
embolism?
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Westermark’s sign
Hampton’s hump
None of the above
Quiz
Which of the following is most commonly
seen on CXR of a patient with pulmonary
embolism?
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Westermark’s sign
Hampton’s hump
None of the above
The most common finding is a
normal CXR.
Quiz #9
What is this sign
called?
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Atelectasis
Kerly B
Air bronchogram
Hampton’s Hump
Quiz
What is this sign
called?
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Atelectasis
Kerly B
Air bronchogram
Hampton’s Hump
Quiz
Air bronchograms as
seen when alveoli are
surrounded by fluid.
Normally the thin walls of
the bronchi are not visible
because they are filled
with air and surrounded
by air.
This is a non-specific
finding and can indicate
pus, blood or fluid.
Quiz #10
The CXR of this
patient is indicative of
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Atelectasis
Pulmonary edema
Bilateral pneumonia
Pneumothorax
Quiz
The CXR of this
patient is indicative of
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Atelectasis
Pulmonary edema
Bilateral pneumonia
Pneumothorax
Quiz
This is an example of a
“bat wing” pattern in a
patient with pulmonary
edema due to congestive
heart failure.
On CXR this can appear
as cephalization of the
pulmonary vessels, Kerly
B lines, peribronchial
cuffing, or “bat wing”
pattern and cardiomegaly.
Resources
Novelline, Robert. Squire’s Fundamentals
of Radiology, 5th edition
Brant, W., Helms, C. Fundamentals of
Diagnostic Radiology.
Ouelletts, H., Tetreault, P., Clinical
Radiology made ridiculously simple.
http://radiology.rsnajnls.org