Transcript Chest X Ray Tutorial

CXR
Chest X Ray Tutorial
The Retro look
This tutorial was created by Dr I Runcie, Princess
Royal Hospital, Haywards Heath. It was originally
created in 1993 in HyperCard which was just
about the first programme to effectively use text
hyperlinks. It was monochrome in ‘93 and used
the metaphor of file cards rather than slides. The
look of the original has been retained along with
the rather crude diagrams, poorly reproduced
films (digital camera on a viewing box!) and
ancient references. Originally the films were
separate but they were later photographed and
incorporated. The films were everyday examples,
some were copies and one is badly scratched.
The tutorial is interpretation orientated rather than
disease orientated. It was designed for use by
anaesthetists but others may find it useful. The
lateral features heavily but this is, of course, now
largely replaced by CT.
Contents
basics
collapse
basics
Chest X Ray Tutorial
Pulmonary shadows
Disease in the different anatomical divisions of the
lung give rise to different appearances and it is
necessary to distinguish between Interstitial
change, air space shadowing (often called
consolidation) and pleural abnormalities. All of
these frequently co-exist, as in pneumonia & LVF
but one type of shadowing will usually dominate. It
is then necessary to match up the clinical history
with the type and distribution of the shadowing.
Basics
Chest X Ray Tutorial
A PA view is preferable to a AP view because
the lung fields are less obscured by the
magnified heart and by the projected scapulae.
The further away the source the more these
advantages will apply. A portable film will always
be AP with a short tube- film distance.
Basics
Chest X Ray Tutorial
Take a look at the films
Basics
Chest X Ray Tutorial
Film 1 is PA and film 2 is a AP view of the
same patient. Note the difference in the
size and shape of the heart shadow and
the position of the scapulae. In clinical
practice you cannot be sure of the
projection unless the radiographer has
marked the film. All portable films will be
AP.
Basics
Chest X Ray Tutorial
Basics
Centring is checked by comparing the medial end of the clavicles with the spinous processes (see inset).
As a rule the side to which the patient is rotated becomes more translucent (black). But there are
frequent exceptions, often due to failure of precise lateral centering which can give a false impression of
rotation. The great majority of cases of unilateral hypertransradient lung are due to technical factors. (ref.
Joseph et al Clinical Radiology 1978 29 125-131 )
Film 3
Film 4
Chest X Ray Tutorial
Basics
Films 3 & 4 are of the same patient. Film 3 is rotated and there is a difference between the
distances between the clavicles compared with the spinous process of T3. The distance on the
right side is 4 cms and on the left 2.2 cms. There was a minimal difference in density between
the two sides on the original film, but this is not easy to see on your copy films. Note therefore
that quite noticeable degrees of rotation are required to produce significant changes. Film 4 is
very rotated and even on the copy films the left lung appears darker. The left clavicle has rotated
so far to the right that it is overlying the spinous process. This film therefore demonstrates that
the side to which the patient is rotated becomes hypertransradient. If a film demonstrates the
opposite situation there is probably some pathology present. For a technical explanation see
Joseph et al Clinical Radiology 1978 29 125-131. Below is an enlargement of film 4. The
arrows point to the medial ends of the clavicles
Chest X Ray Tutorial
Basics
Looking at the film Everyone should develop their own system. I leave the lung fields until last.
The bones come first, from outside in, ie humeri and scapulae, then the ribs. I look at the
posterior ends of the ribs remembering to look straight through the heart to where the ribs meet
the spine. I run my eyes down each chest wall and then view the anterior end of each rib. As I do
all this I am comparing the two sides. Many radiologists prefer to examine each rib as a whole.
The soft tissues come next ie the mediastinal shadows and the diaphragm. Then the lung fields,
comparing the two sides by mentally dividing them into; upper, mid and lower zones and looking;
rt upper, lft. upper, rt. mid etc. Finally I go back to the difficult areas ; apices, costophrenic
angles, hila and through the the heart. There is a lot of lung behind the heart.
Try looking at some of the previous films again.
Anatomy
Chest X Ray Tutorial
Anatomy 1
Consideration of the
secondary pulmonary
lobule assists
interpretation of the
various types of lung
shadowing. This is an
area of lung surrounded to
a
variable extent by a
connective tissue
septum (CTS). Thickening
of the CTS produces
the honeycombing pattern
of some interstitial
diseases. The lobules vary
in size from 1.2 to 2.5
cms. (for key see following
cards.)
Basics
Secondary Pulmonary Nodule
Chest X Ray Tutorial
Pulmonary veins and
lymphatics (v+l) run within
the CTS and engorgement
produces the interstitial
changes seen in oedema.
The acinus (ac) (5-6 mm)
arises from the terminal
bronchiole (tb) and tends
to act as a pathological
unit. It is rare for only part
of an acinus to be
consolidated.
Consolidated acini
adjacent to non
consolidated ones give
rise to the "fluffy"
appearances at the edge
of an area of air space
shadowing.
Basics
Secondary Pulmonary Nodule
Chest X Ray Tutorial
The primary lobule arises
from
the last respiratory
bronchiole (rb) and
appears similar to the
terminal respiratory unit
(tru) mentioned in some
anaesthetic text books.
art=pulm. artery (travel
with bronchial tree)
ven= venules
pok= pores of Kohn
ad=alveolar duct
alv=alveolus
Basics
Secondary Pulmonary Nodule
Chest X Ray Tutorial
Knowledge of the anatomy
as seen on the 'lateral' is
the key to accurate
interpretation of the frontal
view. Note the position of
the fissures.
It is worthwhile
persevering with the next
5 cards in order to gain an
understanding of
principles which will allow
a logical approach to
interpretation of difficult
films.
Basics
spine
spine
Chest X Ray Tutorial
A Normal PA and lateral. Think about the position of
the various lobes and segments.
Basics
Chest X Ray Tutorial
On the lateral note that the lung is darkest
posteriorly just above the diaphragm.If this is not the
case there is probably some basal pathology. Note
also the position of the two oblique fissures running
from about T6 posteriorly to almost the anterior end
of the diaphragm just behind the main bulk of the
hila in the centre of the film.
Note the shadows of the humeri, glenoids and
scapulae which can occasionally be misinterpreted.
The scapulae can be seen running downwards just
anterior to the vertebral bodies. Look at the
diaphragms. Note that you can see almost the
whole length of them but not the anterior end of one
of them. -Why not and which diaphragm is it? What
is the nearly vertical line coming upwards from the
middle of the lower diaphragm? Yes its the IVC- but
why cant you see the front of it? You will be able to
work all of this out if you read on
Basics
Chest X Ray Tutorial
To help you. 1. oblique fissure 2. humerus 3. soft
tissue of arm 4. scapulae 5. IVC
Basics
Chest X Ray Tutorial
On the frontal view segments overlap
and their positions only become clear
when they are consolidated.
Basics
Chest X Ray Tutorial
Film 7 shows consolidation adjacent to the upper left
heart border but the heart border remains visible.
This means that the consolidation must be posterior.
Now look at the next card.
Basics
Chest X Ray Tutorial
The lateral view shows the consolidation to be very
posterior, overlying the vertebral bodies . The
consolidated segment is below the level of the
horizontal fissure, which can just be made out, and
therefore must be in the apical segment of the lower
lobe. If it were above the oblique fissure it would be
in the posterior segment of the upper lobe. Sorry
about the scratch.
Basics
Film 7A
silhouette sign
Chest X Ray Tutorial
Basics
The silhouette sign
Described by Benjamin Felson this observation was a revelation at the time although it now
seems obvious. He observed that the reason that the borders of the mediasinum and the
diaphragm are seen on the CXR is that there is air alongside them. Compare this with the viscera
on an abdominal film which are just not identified except for those outlined by fat. The inside of the
bowel wall may be outlined by the gas in the lumen, but only if there is a large pneumoperitoneum
is the outside of the bowel wall seen. Note that not all of the diaphragm is seen on the CXR. The
part touching the heart is not visible, either on the frontal view or on the lateral. (This is the best
way to identify which hemi- diaphragm is which on the lateral). Another example is a cardiophrenic
fat pad which may obscure the heart border and mimic consolidation. The silhouette sign can be
used to identify and localise consolidation and masses without a lateral view. Obliteration of the
heart border will be due to opacification of the middle lobe on the right and the lingula on the left.
Conversely, consolidation seen through the heart but with the heart borders visible will be in the
posterior segments. ref. Felson "Chest roentgenology"W. B. Saunders 1973
Chest X Ray Tutorial
Basics
Films
8 &
8a
Film 8 shows consolidation bounded above by the horizontal fissure
but without loss of the right heart border.The lateral 8A shows
consolidation adjacent to the heart. Try to work this out before
clicking here to see the answer.
The consolidation is only in the lateral segment of the
middle lobe which is not in contact with the heart border.
Chest X Ray Tutorial
Basics
Oblique fissure
Examples of the sillhouette sign as
applied to the lateral. Consolidation
seen above the hilum on the PA
view without obliteration of the
mediastinal border may be in the
apical segment of the lower lobe
(point Y on the diagram) or in the
posterior segment of the upper lobe
(Point X)
heart
consolidation
Rt diaphragm lost posteriorly
due to contact with
consolidated posterior basal
segment
Left diaphragm lost anteriorly due
to contact with the heart. Rt
diaphragm is seen through the heart
shadow as it is in contact with air.
Chest X Ray Tutorial
Basics
Film
9
Film 9 shows consolidation in the rt. mid zone. It was on
both sides of the horizontal fissure and therefore not in
the anterior segment of the upper lobe or the middle
lobe. It could be in the apical segment of the lower lobe
or the posterior segment of the upper lobe.
Film 9A shows it to be in the upper lobe, bounded
inferiorly by the horizontal fissure. Consolidation in the
apical lower would be bounded superiorly by the fissure.
Film 9A
Chest X Ray Tutorial
Basics
The silhouette sign 3
The aortic knuckle lies alongside the
apicoposterior seg. of the left upper lobe and
is therefore lost when this area is opacified.
The 'apex' of the lung lies posteriorly and
masses which are clearly defined above the
level of the clavicle must lie posteriorly. An
anterior mass above the clavicle, in contact
with soft tissue, may be seen as an increased
density but will not be well defined.
Film 10 is slightly rotated to the left. There is
an apparent mass to the left of the trachea
above the medial end of the clavicle. This is
due to tortuous vessels made more
prominent by the rotation. That the shadow is
anterior is evidenced by the lack of a
definable lateral edge.
Film 10
Chest X Ray Tutorial
Basics
Film 10A is a more striking
example. The lateral border of
the tortuous vessels on the right
is well seen inferiorly but
suddenly disapears superiorly,
just above the clavicle, where
they are no longer in contact with
lung. A similar but less obvious
appearance is seen on the left.
Film 10A
Chest X Ray Tutorial
Basics
10 B shows a mass situated
more posteriorly on the
right.Above the clavicle the
edge of the mass could just be
made out against the lung. The
appearances in this case are
subtle and it is possible to see
posterior masses much more
clearly outlined in the apex than
this, but life (and radiology) is
not always simple. By now it
should not be necessary for me
to point out the secondary
deposit.
Film 10B
Chest X Ray Tutorial
Basics
Well all right then. It’s here
Film 10B
Collapse
Chest X Ray Tutorial
Collapse
Collapse or atelectasis is reduction in volume of an area of lung.
The signs of lobar or segmental collapse are discussed under three categories.
1. Changes in densityA. The collapsing area may appear more dense due to approximation of the vessels within it. This is
usually only seen when there is considerable loss of volume.
B. There may be compensatory emphysema in the surrounding lung.
2. Changes in position- the hilum & mediastinum may shift towards the side of the collapse. Fissures
show characteristic movement depending on which lobe is involved.
3. The silhouette sign may apply to borders adjacent to collapsed airless lung.
Consideration of the lateral is the keyto understanding
collapse
Chest X Ray Tutorial
The following descriptions are of classical lobar
collapse. Actually this hardly ever happens. There is
usually some associated consolidation or preexisting disease which alter appearances. Lung
fibrosis particularly restricts the movement of fissures
etc. Knowledge of the classical appearances are a
guide to interpretation in practice.
Total collapse of a lung gives a whiteout on the
affected side due to the mediastinum and hemidiaphragm moving over to fill the spac. Ribs on the
affected side move closer together. The other lung
shows compensatory emphysema and may "herniate'
across the midline anteriorly. Compensatory
emphysema is usually identified by increased spaces
between vessels rather than an obvious decrese in
density.
Ref ‘Pulmonary collapse’ Seminars in Roentgenology
1980 Vol 15
Collapse
Other causes of unilateral whiteout
causes
signs
pneumonectomy sternal clips or deformed
or missing ribs.
conslidation
central mediastinum
pleural effusion
mediastinum may be shifted
(massive)
away (but beware of
associated collapse)
Chest X Ray Tutorial
Rt. upper lobe collapse
The horizontal fissure pivots on the hilum. Its lateral
end moesg upwards and medially and its anterior end
moves upwards. The upper half of the oblique fissure
moves anteriorly and, in severe collapse, the two
meet up against the superior mediastinum.
Cont-
Collapse
Chest X Ray Tutorial
Rt. upper lobe collapse
Signs
1.A Vessels in the Rt. upper zone (RUZ)
get closer together and just before total
collapse a density appears alongside
the superior mediastinum. B. There may
be increased lucency in the mid & lower
zones (RMZ&RLZ).
2. Fissures move as shown. The
trachea moves to the rt. The hilum is
elevated and becomes more prominent.
Tenting may occur (next)
3. In severe collapse the upper
mediastinal border may be lost.
Collapse
Chest X Ray Tutorial
Films11 & 12
(1)There is crowding of
vessels in the Rt. upper
lobe plus some increase in
density which the lateral
shows to be due to
associated consolidation
immediately superior to the
oblique fissure in the
posterior segment. The
anterior segment is not
consolidated. (2.)The
consolidation demonstrates
the anterior position of the
oblique fissure. The
normally positioned left
fissure can be seen more
posteriorly.
On the PA it can be seen
that the hila are at the
same level. Normally the rt
hilum is positioned
slightly below the Lft.
Collapse
If they are at the same level either the rt is higher or the left is depressed. Frequently in
upper lobe collapse the hilum may also be rotated so that the normal pattern of the arteries
leaving the hilum is disturbed and the hilum appears to be an unusual shape. In this case
there is a mass in the upper half of the hilum. Mediastinal shift and compensatory
emphysema are not evident.The rt. hemi diaphragm may be elevated but comparison with
previous films would be necessary to be sure.
Incidentally the thoracic vertebral bodies are osteoporotic and are beginning to wedge.
Chest X Ray Tutorial
Tenting' of the diaphragm is usually
noted as a feature of long standing
upper lobe collapse or fibrosis,
particularly following TB. If seen as a
new feature it may be diagnostic of
upper lobe collapse. It is due to the
elevation of the hilum pulling on the
pulmonary ligament and accessory
fissures. The pulmonary ligament is a
strand of fibrous tissue between the
hilum and the diaphragm.
Collapse
Chest X Ray Tutorial
film 13 shows loss of volume in the
RUL, probably long standing, as
evidenced by the peribronchial
thickening and some
emphysematous change suggesting
chronic airways obstruction. There is
also apical pleural thickening ( black
arrow) by far the commonest cause
of this is chronic bronchitis.
The horizontal fissure (white arrow)
is elevated as is the right hilum the
normal position of which is lower
than the left because of the anatomy
of the pulmonary arteries. There is
also a small tent on both hemi
diaphragms. Tenting can sometimes
be much more gross than this
especially in cases of coarse upper
zone fibrosis such as occurs in TB.
Collapse
Chest X Ray Tutorial
Left Upper Lobe Collapse
On the lateral, the oblique fissure
moves bodily forwards (straight
arrows) and comes to lie close to the
anterior chest wall. In severe
collapse the anterior part of the lobe
moves backwards away from the
chest wall. The lower lobe then
comes over the top of the collapsed
lobe (curved arrow) and comes to lie
against the anterior chest wall. On
the frontal view the fissure is not
seen but the collapsed lung may
become evident against the upper
mediastinum.
Collapse
Chest X Ray Tutorial
Left Upper Lobe Collapse
1.A On the frontal view the vessels in
the LUL approximate and a density
appears around the position of the
aortic knuckle. On the lateral the
anterior part of the chest becomes
increasingly more dense. B There
may be compensatory emphysema
in the LLL.
2. The fissure moves as shown on
the Lat. The Trachea moves to the
left. As the LLL expands the
diaphragm and the L hilum may
elevate & tenting may occur.
3 As the lobe collapses it comes up
against the aortic knuckle which lies
anteriorly. As it loses air and
becomes more dense the aortic
knuckle disappears (silhouette sign).
Collapse
But when it collapses enough to retract from the
anterior chest wall, the LLL comes round and lies
against the knuckle which then becomes visible again.
The density of the collapsed lung continues to be
evident adjacent to the knuckle and the hilum.
Chest X Ray Tutorial
Film 14 is an excellent example of
well advanced LUL collapse. The
collapsed lobe is closing down onto
the hilum and becoming denser
causing the veil like shadowing
around the hilum. Note that there is
no shift of the mediastinum, trachea,
hemi diaphragm or hilum. Nor is
there any obvious compensatory
emphysema. This is because there is
no pre existing lung disease and the
lower lobe is large enough and
flexible enough to fill the available
space. In fact it is large enough to
have come round medial to and
above the collapsing lobe causing
the luscency around the aortic
knuckle and allowing this structure to
be clearly seen.
Collapse
Chest X Ray Tutorial
Film 15 is the lateral. The oblique
fissure is seen anterior to the hilar
shadows and has moved bodily
forwards. The luscency immediately
behind the sternum may be due to
the enveloping lower lobe.
Collapse
Chest X Ray Tutorial
Rt Middle Lobe Collapse
The horizontal & lower half of the
oblique fissure move towards each
other. The collapsed lobe comes to
lie against the heart border.The
horizontal fissure is the more mobile.
Collapse
Chest X Ray Tutorial
Rt Middle Lobe Collapse
signs
1 Because the lobe is small,
compensatory emphysema is rarely
seen. There may be a vague density
against the heart border best seen
on the Lateral.
2 Fissure movement as described.
Best seen on the lateral. On the
frontal view if the Horizontal fissure is
not seen the other changes may be
difficult to spot.
3 In the late stages the rt. heart
border may be lost.
Collapse
Chest X Ray Tutorial
Collapse
Rt Middle Lobe Collapse
16.
There is loss of the right heart
border. The horizontal fissure
cannot be seen.
!7.
The horizontal fissure and the
oblique fissure have
approximated to each other
leaving the middle lobe as a
linear density overlying the
heart shadow (arrowed).
Film 16
Film 17
Chest X Ray Tutorial
Lower Lobe Collapse
The pattern is similar on both
sides. The oblique fissure
moves backwards and also
medially so that the fully
collapsed lobe becomes a
wedge of tissue lying up
against the posterior
mediastinum. The middle and
upper lobes expand to fill the
space lateral and anterior to the
collapsing lobe.
Collapse
Chest X Ray Tutorial
Lower Lobe Collapse
signs
1A As the lobe moves posteriorly it becomes
more and more dense on the Lat. On the AP
view it may
be seen as a wedge shape through the heart
shadow.
B Compensatory emphysema may be noted
when vessel density is compared with the
other side.
2 The oblique fissure moves back. On the rt
the horizontal fissure moves in a similar way
to RML collapse but the lung underneath it
becomes less rather than more dense. There
is movement of the heart shadow towards
the side of the collapse and the hemidiaphragm may elevate especially if there is
pre-existing lung disease limiting the
compensatory emphysema. The hilum
becomes depressed.
Collapse
PA
Lat
3 The silhouette sign operates in reverse ie
there is a shadow behind the heart but the heart
shadow is still seen. The part of the diaphragm
in contact with the dense lung may be lost
(curved arrows).
Chest X Ray Tutorial
Lower Lobe Collapse
Film 18 .
1.There is a hint of a triangular opacity behind the
heart on the left.
Compensatory emphysema can be identified on the
left by comparing the number of vessels on the two
sides.
2 The heart shadow has moved to the left.
The left hilum is depressed as can be seen by the
angle of the left main bronchus seen through the
heart shadow.
Collapse
Chest X Ray Tutorial
Lower Lobe Collapse
Film 19
Little in the way of density change can be identified.
One oblique fissure has moved backwards slightly
and can be seen behind the hilum. The other can
still be seen in front of the hilum. There is an
excellent example of the silhouette sign. The
posterior part of the left diaphragm cannot be
identified although the stomach bubble shows you
where it should be. Its anterior part can be identified
in front of the little diaphragmatic "tent" near to the
inferior insertion of the oblique fissure. The right
hemi-diaphragm can be clearly seen. This must
mean that there is a considerable increase in the
density of the collapsing lung possibly with some
associated consolidation.
Collapse
Chest X Ray Tutorial
Lingular collapse
Often involved in upper lobe collapse, but
occaisionally the lingula may collapse on its own.
Features are identical to RML collapse except that
the horizontal fissure is not there to help you. On the
frontal view the only evidence may be a subtle loss
of the Lft. heart border.
Collapse
Chest X Ray Tutorial
Plate atelectasis or Linear collapse. Areas of
subsegmental collapse appearing as lines, usually
horizontal, of variable thickness. Often long standing
and fibrotic. May be referred to as scarring.
Common.
Round atelectasis Of little pathological interest and
rare, but may be mistaken for a mass. An area of
lung rolled up like a Swiss Roll containing rolled up
vascular structures. Always touching pleura and
associated with pleural thickening. About 5cm in
diameter. Diagnosed by CT.
Collapse
Chest X Ray Tutorial
Film 20 shows a vertical band shadow at the right base, film
20A taken a few days later shows that it has disappeared and
was therefore an area of subsegmental collapse. Such band
shadows are often horizontal. They may be associated with
infection or embolus and are not uncommon in post op.
patients due to poor aeration. Permanent bands are usually
due to areas of fibrotic scarring.
Collapse
Similar shadows may be seen due to fluid filled
bronchi and thickened fissures often due to pleural
effusions.
Ref Heitzman E. R. “The Lung. Radiologicpathologic correlation.” 1974, Mosby
Pulmonary collapse ‘Seminars in Roentgenology”
1980 Vol 15