The document outlines various thoracic imaging techniques, including chest X-rays, CT scans, MRIs, and ultrasounds, detailing techniques for obtaining optimal images and identifying various anatomical structures and abnormalities. It emphasizes the importance of proper positioning and exposure to produce quality images, as well as the distinguishing characteristics of normal and abnormal findings. Additionally, it discusses the roles and limitations of advanced imaging modalities in diagnosing conditions such as pulmonary embolism, lung cancer, and other thoracic diseases.

1. IMAGING THE THORAX–
PART 1
DR. MOSES ACAN
DEPARTMENT OF RADIOLOGY

2.  Chest x-ray
 Computerised tomography
 Ultrasound
 Magnetic resonance imaging
 New advances
Thoracic Imaging

3. Chest x-ray adults:
Technique
 A Chest X-ray (CXR) is normally taken
erect and PA (posterior anterior)
 at a distance 150 or 200cm.
 anterior chest wall is against the film
cassette
 the X-ray tube behind the patient aimed
towards the film.

4. Qualities of a good PA film
(1)
 The patient should not be rotated. Look
at the anterior ends of the clavicles. They
should be equidistant from the spinous
processes.
 If the patient is rotated one side of the chest
will look paler than the other & the
mediastinum will appear abnormal

5. Qualities of a good film (2)
 The film should be taken on full inspiration.
 The top of the R diaphragm should lie below the
anterior end of the 6th
right rib.
 The left diaphragm is usually lower.
 The ribs should be sloping and not horizontal.
 If they lie horizontally, it may be that the patient was
leaning backwards and the diaphragms will
obliterate the lung bases.
 The anterior end of the first rib should lie just below
the clavicle.

6. Film should not be rotated
The distance x should be equal on the 2 sides

7. Where is the 6th
anterior rib?
Is this a good film?

8. Qualities of a good film (3)
 The scapulae should not overlay the lung fields.
 The vertebrae should be faintly visible through
the heart shadow: lesions behind or in front of
the heart will not be missed.
 The bony detail should not be visible: lungs will then
appear too dark.
 The blood vessels in the lower lobe should just be
seen through the heart.
 The whole of the lung fields should be fully
included on the film including costophrenic
angles & apices.

9. When do we need an
expiratory film
 This is taken when the patient has
breathed out.
 This may help to show bronchial
obstruction with air trapping (e.g. inhaled
foreign body in a child):

10. When do we need a lateral
film
 A lateral film should never be part of a standard chest
examination especially for medical purposes or for
follow up of a known lesion.
 The PA film should be examined. If there is an
abnormality, a lateral film may then be useful in the
following:
 If the film is too light & a lesion is suspected clinically,
 Further assessment & localisation of abnormalities seen or
suspected on the PA film.
 Earlier detection of small pleural effusions if
ultrasound is not available

11. When do we need oblique
views
 These are helpful in assessing rib lesions
& some pneumothoraces.

12. Normal chest: soft tissues
and bones
SOFT TISSUES AND BONES.
 Look at the breast shadows, ribs,
clavicles, spine and shoulders for signs
of disease

13. Diaphragms and costophrenic angles
 Diaphragms have smooth
outline and are convex
upwards.
 The right dome lies 1-2cm
higher than the left: at or
below the level of the 10th
posterior rib or 6th
anterior
rib
 The posterior ribs
differentiated from the
anterior:horizontal
 There may be a fat pad at
heart border in obese
patients.
 diaphragmatic hump
(localised bulge) is a normal
variant.
Clear C-P angles

14. Fissures: Which fissures are
shown?

15. Which fissures are shown?

16. Normal lung hilae
 The left hilum normally lies 0.5 – 1.5cm
higher than the right.
 They are of similar density and size with
concave borders.
 They are composed of the pulmonary
arteries and veins.
 Normal lymph nodes are not seen.

17. Normal mediastinum
 the trachea should be central in position.
 the subcarinal angle, (under the division of the
trachea), is normally 60-70 degrees.
 the heart size should not measure greater than
14.5/15 cm in diameter in women, or 15.5/16cm in
men. cardio-thoracic ratio (CT ratio) should not be
greater than 50%.
 In other words, the transverse diameter of the heart
should not exceed half the transverse diameter of the
thorax at the level of the diaphragms
 the heart borders should be clearly visible, the right
border should be seen to the right of the spine.
 The aorta descends just to the left of the spine and is
more or less parallel with it.

18. Normal lungs and lung
markings
 Normal lung markings (lines or shadows seen across the
lungs) are due to, pulmonary vessels or fissures
 Bronchi are normally only visible near the hilae :bronchus
should only be 1mm or less in thickness.
 Bronchi seen end-on near the hilae should roughly be the
same diameter as a vessel.
 Bronchi are hollow ring shadows & vessels are solid grey discs.
 In the erect film lower zone vessels are larger than those in the
upper lobe.
 In the supine chest X-ray, upper lobe vessels are the same size
as the lower lobe vessels.
 The lungs should be of equal transradiancy.

19. Tricky or review areas
 lesions lying in some areas on chest X-ray
are more likely to be overlooked than
others.
 These are called the “review areas” and
are: the apices, mediastinum, hilae,
retrocardiac & retrodiaphragmatic
areas & the bones

20. Lung Anatomy
(1) aortic arch
(2) pulmonary trunk
(3) left atrial appendage
(4) left ventricle
(5) right atrium
(6) superior vena cava
(7 & 8) diaphragm
(9) transverse fissure

21. Lung Anatomy
(1) oblique fissure
(2) transverse fissure
(3) retrocardiac space
(4) retrosternal space

22. Correct CXR
 Name
 Date of birth
 Date
 Left and right, marker/stomach
Chest x-ray viewing guide

23.  PA, AP, lateral or decubitus view
 Rotation – Sternal end clavicles equal
from vertebral body
 If AP what position
Patient Position

24.  How dark or light a film is
 Should faintly see vertebral bodies
through heart
Exposure

25.  Breast shadows
 Air in tissues
 Tissue folds in obese
 Medical equipment
Soft Tissues

26. Breast
shadows

27.  Ribs
 Scapulae
 Clavicles
 Vertebrae
Bony Structures

28.  Deviated
 Carina
 Artificial airway
Trachea

29.  Deviated
 Hilar shadows
 Aortic arch
Mediastinum

30. Size
 No larger than half width of chest
Position
 Two thirds on the left
Borders
 Clear
Mediastinum - Heart

31.  Shape
 Height: right –6rib ant, left – 7 ant
 Cardiophrenic angle
 Costophrenic angle
Diaphragm

32.  Black with lung markings
 Other opacity indicated pathology
 Fissures
 Zones
 Air bronchograms
 Consolidation
Lung Fields

33. normal

34. OTHER IMAGING
MODALITIES FOR THE CHEST

35. Radionuclide scanning
 This is of most value in the diagnosis of pulmonary embolus.
If the scan is perfectly normal this virtually excludes it. The
major drawback is the lack of specificity and a report can only
be made when a recent chest X-ray and a ventilation scan are
available. The main indications are:
 1. Pulmonary embolus
 2. Evaluation of emphysema
 3. To determine the extent of parenchymal disease
 Monitoring therapy

36. Perfusion scan & ventilation
scan
A lung perfusion scan. There are multiple
wedge-shaped defects in the lungs. A
ventilation scan should also be performed to
see if the defects match or are seen only on the
perfusion scan. If so, they are due to
pulmonary emboli
A ventilation lung scan performed
on the same patient. This shows
no defects, the lungs showing
even uptake of the isotope.
This confirms the diagnosis of pulmonary
emboli.

37. Computed tomography of the thorax
 Computed tomography is being
increasingly used for examining the
chest despite its high radiation dose.
 The newer spiral CT machines allow
coverage of the entire thorax with
one breath hold.

38. The main indications for computed
tomography of the thorax:
 1. Staging of lung cancer and other
malignant tumours
 2. Diffuse lung disease – high resolution CT
 3. Pleural disease e.g. fluid versus malignant
tumour; empyema versus lung abscess
 4. Mediastinal disease: masses, aortic
dissection
 5. Conditions which are may be incoclusive at
CXR eg subtle signs of a pneumonia

39. CT used to study small nodular
disease and the medistinum

40. Magnetic resonance imaging of the
chest
 The role of MRI is not yet clearly defined. It
is good for vessels and lesions in the
mediastinal and hilar regions.
 A major disadvantage is respiratory and
cardiac motion. It is unable to visualise the
small pulmonary vessels and bronchi and
lung parenchyma.
 It is unable to provide the same anatomic
detail as high resolution computed
tomography and CT is the procedure of
choice for most diseases of the thorax.

41. Ultrasound imaging in the chest
 The acoustic mismatch between the chest wall
and the aerated lung results in almost total
reflection of the ultrasound beam
 Therefore ultrasound is little used for lung
pathology except for diagnosis and localisation
of effusions or other collections.
 Pleural fluid appears as an echofree area outlining
the pleural space.
 Internal echoes may be due to blood or pus, with
septa indicating loculation and a thick wall
suggesting an empyema.
 Pleural based masses are usually of low
echogenicity and pleural thickening is easily
identified.

42. LUNG ABNORMALITIES:

43. The abnormal chest
 overlying soft tissues or rib cage,
 lung disease
 disease of the pleura
 heart
 Other Mediastinal structures
 hilar areas
 diaphragm

44. OPACITY DUE TO OVERLYING SOFT
TISSUES OR RIB ABNORMALITIES
 Masses in the breast or other soft tissues of the thorax: can
be mistaken for pulmonary disease.
 structures superimposed on each other can mimic lung
disease e.g scapula overlying a posterior rib.
 Buttons or other fasteners on patients clothes may cast
confusing shadows & buttons may look like pulmonary
deposits.
 it is important not to assume that an opacity is on the
clothing. This should be confirmed by repeat PA film without
clothes.
 A lateral film is sometimes necessary.
 Rib fractures or deposits in the ribs commonly show a
peripheral opacity related to the rib.

45. LUNG SHADOWING/OPACITIES
 The fine network of the lungs is made up of: a) the alveoli or
air spaces b) the interstitium (i.e. the soft tissues between
the alveoli in which the bronchi & blood vessels lie)
 Disease processes may involve the alveoli, the interstitium,
or both.
 It is important but difficult to differentiate alveolar from
interstitial shadowing.
 There are 2 important signs, which help to interpret lung
shadowing.
 The silhouette sign
 The air bronchogram

48. In these two conditions, bronchi are
visible, which are the two conditions?
What conditions cause bronchial walls to thickening?, what is the
Explanation for the bronchus to be seen clearly when there is
Alveolar consolidation?

49. ALVEOLAR SHADOWING
(AIRSPACE
OPACITIES/DENSITIES)

50. ALVEOLAR SHADOWING (AIRSPACE
OPACITIES/DENSITIES)
 If the alveoli are involved in a disease process,
they fill with fluid or solid tissue.
 In the very early stages it may be that the alveoli
show as small separate rounded 6mm opacities
 small opacities rapidly become confluent
shadowing with fluffy ill defined margins.
 The vessels are obscured and there may
sometimes be an air bronchogram.
 There may also be a silhouette sign.
 When the alveoli fill with fluid or other
substances, it is called consolidation.

51. Signs of alveolar shadowing
 In the early stages it may present as a faint homogenous
haze or “ground glass” appearance
 Shadowing may be homogenous, patchy or blotchy in
appearance
 Fluffy, ill defined areas of opacification
 Areas of shadowing tend to coalesce and become
consolidation
 2 patterns of distribution occur: 1. Segmental or lobar 2.
“batswing”.
 Bats wing occurs typically in pulmonary oedema. It is non-
segmental.
 Air bronchograms may be visible.

52. Describe what is shown on these
pts with alveolar shadowing!

53. Pathogenesis of alveolar
shadowing (1)
 Note that all produce the same appearance on the CXR:
only differentiated by the distribution and the clinical
features.
 TRANSUDATE:
 the alveoli become filled with a clear transudate of low
protein content and this occurs in e.g. pulmonary
oedema, which may be of cardiogenic or non cardiogenic
origin.
 EXUDATE
 alveoli become filled with fluid of a high protein content and
the commonest cause is infection. Other less common
causes are acute Respiratory Distress Syndrome (ARDS),
pulmonary oesinophilia, and alveolar proteinosis.
 HAEMORRHAGE:
 alveoli fill with blood and this may occur in trauma, lung

54. Causes of alveoar
shadowing (2)
 INFILTRATION:
 the alveoli become filled with solid tissue
such as lymphoma, alveolar cell
carcinoma or carcinomatosis
 MISCELLANEOUS:
 Aspiration of gastric contents is an
important cause. Other causes are
inhaled foreign body, oesophageal leak,
oesophageal stricture due to carcinoma
or corrosive, radiation therapy and in
babies hyaline membrane disease.

55. Common causes of alveolar
shadowing: Lobar/segmental pattern
 Infection
 Pulmonary infarct
 Alveolar cell carcinoma
 Contusion
 Note: Alveolar shadowing, which is purely lobar will be
bounded by the fissures and depending on the segments
may produce a sharp outline of one border next to a
fissure.

56. Segmental/alveolar shadows:
In what part of the lung is this located, what radiological signs can you see? Why is the
® hemi diaphragm still clear? Name the lung lobes and segments! What do you see on
a PA and lat CXR when you have consolidation in each of the lobes/ segments

57. Alveolar consolidation of the
“bats –wing pattern”
 a) acute:
 - Pulmonary oedema
 b) chronic:
 - Lymphoma/leukaemia
 - Sarcoidosis but the interstitial form
is much commoner
 - Pulmonary alveolar proteinosis
 - Alveolar cell carcinoma but the
localised form is much commoner

59. Alveolar consolidation: bats
wing

60. Alveolar pneumonia not fitting in with
segmental or bats wing patterns.
 Alveolar shadowing may not fit into any
of the above patterns e.g.
 - Bronchopneumonia as in
staphylococcal septicaemia or pulmonary
tuberculosis.
 - Fat embolism (occurs 1-2 days
following major trauma, particularly
fractures of the large bones of the lower
limbs)
 Eosinophilic pneumonia

62. INTERSTITIAL
OPACITIES/SHADOWING

63. INTERSTITIAL SHADOWING:
 This is due to disease in the interstitium
i.e. the tissue in which the blood vessels
and bronchi lie within the lungs.
 This leads to a non homogenous pattern
of shadowing which may take many
forms.
 The alveoli are still aerated: no air
bronchogram or silhouette sign.
 blood vessels become ill defined or
obscured.

64. Causes of interstitial
shadowing.
 These diseases often look identical on CXR
regardless of the cause but distribution is
important.
 Some are characteristically more predominant in
the lower zones and others in the upper zones.
 Interstitial disease is better imaged by high
resolution CT for DDX, but some may need lung
biopsy for DX.
 clinical features help in DDX
 Diseases may also be classified on the basis of
whether acute or chronic as well as the
distribution in the lungs.

65. Interstitial disease:
common patterns
 Linear
 Miliary
 Reticulo-nodular
 Honeycomb
 Nodular

66. Linear Pattern
 abnormal network of fine lines running through the lungs
due to thickened connective tissue septae. The most
common are:
 Kerley A lines: long thin lines in the upper lobes, seen in
both PA & lateral views(under the sternum in the latter)
 Kerley B lines: short thin lines predominantly in the
periphery of the lower zones extending 1-2cm horizontally
inwards from the lung surface.
 Kerley C lines: diffuse linear pattern through the entire lung:
these can be difficult to recognise.
 Causes of Kerly lines are interstitial pulmonary oedema and
lymphangitis carcinomatosis.

67. Interstitial shadows: linear
pattern

68. Interstitial shadows: nodular
pattern
 interstitial nodules are small (1-
5mm), well defined, and not
associated with air bronchograms.
 often very numerous and
distributed evenly through the
lungs.
 if low in density may be difficult to
appreciate in the early stages

69. Interstitial shadows: causes
of nodullar pattern
 ACUTE:
 Infections such as tuberculosis, chickenpox
 Pulmonary oedema
 Acute extrinsic allergic alveolitis
 Fat emboli
 LESS ACUTE
 Carcinomatosis – especially thyroid carcinoma,
chorionepithelioma, breast.
 CHRONIC
 Sarcoidosis – predominantly mid zones.
 Coal miners pneumoconiosis, silicosis
 Fibrosing alveolitis

70. Interstitial shadows: nodular
pattern

71. Interstitial shadows: reticulo-
nodular pattern:
 this due to very fine nodular opacities
superimposed on a fine network of
short lines.
 This may be seen in TB, silicosis,
rheumatoid lung disease and
fibrosing alveolitis as well as drug
induced lung changes.
 It is usually more obvious at the
bases.

72. Interstitial shadows:
reticulonodular pattern.

73. Interstitial shadows: the
honey-comb pattern
 represents the end stage of many interstitial
processes and implies extensive destruction of
pulmonary tissue.
 lung parenchyma replaced by cysts, which range
in size from tiny up to 2 cm diameter. These are
separated by coarse linear interstitial markings.
 cysts have very thin walls
 normal pulmonary vasculature cannot be seen
 may be complicated by pneumothorax.
 Examples are: Chronic heart failure, Rheumatoid,
Scleroderma, Fibrosing alveolitis, & Histiocytosis.

74. BRONCHIECTASIS
 Usually occurs secondary to infection.
 postnasal drop in chronic sinusitis, pertussis, TB,
pneumonia of any kind and any cause of segmental
atelectasis.
 The bronchi become infected, dilate peripherally and
develop thick walls visible on chest X-rays.
 Commonly seen in the lower zones, the bronchi appear as
thick lines enclosing the aerated lumen.
 If seen in cross section the bronchi look dilated surrounded
by a white cuff, which represents the thickened wall.
 super-added inflammatory changes appearing as alveolar
shadowing may co-exist.
 involve any lobe, segment or complete lung.

75. Interstitial shadows:
Bilateral lower zone
bronchiectasis

76. Interstitial shadowing: diseases
causing milliary shadows.
 multiple small opacities less than 5mm in diameter are:
1. Tuberculosis
2. Miliary metastases – any primary site but especially thyroid
& chorion epithelioma
3. Chickenpox
4. Pneumocystis Carinii pneumonia, Cytomegalic infection
5. Sarcoidosis
6. Dust inhalation – pneumoconioses
7. Haemosiderosis
8. Extrinsic allergic alveolitis, eosinophilia
 Fibrosing alveolitis

77. Interstitial shadows: acute diseases which
cause linear patterns.
 Pulmonary oedema – cardiac, non
cardiac causes
 Infections – particularly viruses,
pneumocystis, measles, malaria &
tuberculosis (less often)

78. Interstitial shadows: chronic
diseases that give a linear pattern
 Linear interstitial shadowing due to long standing
pulmonary oedema with Kerley B lines
 Lymphangitis Carcinomatosis – may be unilateral. Often
associated hilar adenopathy
 Sarcoidosis
 Early silicosis & asbestosis
 Allergic alveolitis & pulmonary oesinophilia
 Drugs & inhaled irritants such as chlorine or tear gas
 Connective disorders: Rheumatoid arthritis, scleroderma,
systemic lupus,graulomatosis
 Miscellaneous: histiocytosis, tuberous sclerosis
 Bronchiectasis: usually a mixed alveolar/interstitial pattern

79. PULMONARY COLAPSE

80. PULMONARY COLLAPSE:
• A cause of opacity on chest X-ray
• features to distinguish it from
alveolar/interstitial shadowing are:
-The loss of lung volume may affect the
position of adjacent structures such as the
diaphragm, hilum, mediastinum and fissures.
-There may be a silhouette sign but no air
bronchogram unless associated with
consolidation

81. Collapse: causes of collapse
• Obstruction of a bronchus by a foreign
body, tumour, mucus plug, aspiration,
or a stricture
• Compressive collapse due to air or fluid
in the pleural cavity.
• Cicatrization. This is commonly seen
following pulmonary tuberculosis

82. Collapse: what part of lung is
involved
• Collapse may involve the whole lung,
• lobe of the lung (lobar collapse) or it
may involve just
• part of a lobe such as a segment or
subsegment.
• Subsegmental collapse is often called
“plate atelectasis” because of its
appearance.

83. SIGNS OF COLLAPSE:
• Whole lung collapse:
• complete opacity of the hemithorax
• displacement of the mediastinum to
the side of the opacity
• silhouette sign with loss of
diaphragm and mediastinal outlines.
• herniation of the unaffected lung across
the midline

84. Collapse
Describe these changes, what other pathology causes homogenous Opacities?
What are the causes of collapse?, How does the pt. present and and what are the
CXR signs

85. Collapse: lobar collapse
• Lobar collapse
• The lobes collapse in characteristic
fashion:
• The upper lobes collapse upwards,
medially and anteriorly
• The middle lobe goes downwards and
medially
• The lower lobes collapse posteriorly,
medially and downwards.

86. Collapse: sign of lobar
collapse
  increased density due to loss of aeration
  crowding of the blood vessels
  displacement of the hilum – upwards or downwards
  displacement of a fissure which may be bowed
  shift of the mediastinum, trachea towards the collapsed part
of the lung
  elevation of the diaphragm
  silhouette sign
  the remainder of the lung may be overexpanded &
hypertranslucent with fewer vessels showing.
• rib crowding may occur in children or with long standing
collapse

87. Collapse: R upper lobe
• movement of the horizontal fissure
upwards,
• The collapsed lung assumes an
increased density at the R apex, it’s
lower border being sharply defined by
the horizontal fissure,
• Horizontal fissure may be bowed.
• The hilum is usually distorted & pulled
up.

88. Collapse lung A
Describe the changes in these CXRs and give a differential diagnosis. What are
the radiological features of: lung, lobar, segmental and subsegmental collapse?
What are the radiological changes in upper lobe, mid and lower lobe collapse?
What may cause collapse of these lobes?

89. Collapse middle lobe
• relatively small lobe so collapse
produces only minor changes on the PA
film.
• There is increased density lateral to the
R heart border & blurring of the outline.
• On the lateral view it shows as a
triangular opacity anteriorly.

90. Collapse lower lobe A
• The oblique fissure moves backwards
maintaining the same slope.
• On the PA view, left lower lobe collapse
shows as a triangular opacity projected
through the heart shadow.
• on the right, it may be accompanied by
collapse of the middle lobe leading to a larger
opacity
• Complete collapse of the lower lobes is often
difficult to detect as the lobe comes to lie
against the mediastinum on the PA view &
may be invisible.

91. Collapse of lobes
What do these diagrams represent?, what would one see on the
CXRs?

92. Collapse lower lobes
B
• the L hilum is pulled downwards & hidden by the
cardiac shadow normally should lie above the R
hilum.
• The mediastinum is displaced to the L & the L heart
border straightened.
• The L diaphragm is may lie higher than the R
though.
• As the collapse increases the collapsed lobe overlies
the spine on the lateral view and is no longer visible
in this projection. The only clue is that the spine
appears of even density throughout whereas
normally it looks darker in the lower part of the chest

93. Collapse lower lobe 3 (right
lower lobe)
• R lower lobe collapse produces shadowing adjacent to the R
heart border.
• There is usually a well -defined lateral boundary.
• The R hilum disappears as it is pulled downwards towards the
heart.
• In combined collapse of the R middle & lower lobe the
shadowing is greater and more obvious
• The lesser fissure may be bowed inferiorly.
• There is a silhouette sign of the R heart border & diaphragm.
• The upper border is bounded by the lesser fissure indicating
that the middle lobe is involved.
• The heart may be displaced a little to the R.

94. Patterns of collapse cont.
What part of the lung has collapsed in these pictures? How
would this appear on CXR?

95. Collapse L upper lobe
• This behaves differently than collapse of
the R upper lobe because of the lingular
segment,
• The lingular is equivalent to the middle
lobe on the R, but is part of the L upper
lobe.
• The oblique fissure moves forwards & the
collapsed lobe lies anteriorly against the
chest wall.
• This produces hazy ill -defined opacity in
the L upper & mid zones on the PA film
with a
• silhouette sign affecting the L

96. collapse
Describe the changes on the CXRs. Give differential diagnosis/
How do the CXR changes in lobar collapse of the right lung differ
From the left? What cause slund collapse on the left side?

97. Collapse left lower lobe B
• Lateral view may showing bowing
backwards of the oblique fissure.
• The anterior boundary of the collapsed
lobe may be difficult to identify
because the lobe lies against the
mediastinum.
• The posterior edge is usually visible
because it is bounded by the oblique
fissure.

98. Segmental & subsegmental
collapse
• Only a segment or subsegment of a
lobe may collapse.
• Small linear subsegmental atelectatic
shadows at the lung bases are called
“plate atelectasis” and are due to poor
aeration or perfusion.

99. Causes of segmental or
subsegmental collapse
• post abdominal surgery
• abdominal distension due to tumour or
ascites
• post MI (myocardial infarction)
• mucous plugs (asthma)
• pulmonary infarct
• segmental collapse may occur secondary to
• infection or distal to a small tumour.
• common in children with bronchiolitis

100. Subsegmental collapse
Describe the changes. Give a differential diagnosis. What are the
Causes of subsegmental collapse? What are myocardial infarction,
pulmonary embolism, Pulmonary infarction, asthma and bronchiolitis
and how do these conditions present clinically and at CXR?