from grainger and haaga

1. RADIO-IMAGING OF PLEURAL
EFFUSION AND PNEUMOTHORAX
- Yash Shah

2. ANATOMY OF THE PLEURA
Pleura is a serous membrane composed of mesothelial
cells and loose connective tissue.
:
Divided into : (a) Parietal pleura
(b) Visceral pleura
Parietal pleura is
further divided into
a) Costal;
b) Diaphragmatic;
c) Mediastinal, &
d) Cervical

3. ANATOMY OF THE PLEURA
Normally – upto 15 ml of fluid is present within the layers
of the pleura which is acellular, clear fluid that lubricates
and thus facilitates movement of the lungs in respiration
Normal thickness of the pleura including pleural space is
<0.5 mm.
The normal pleura is visualized on a PAchest radiograph
only where the visceral pleura invaginates the lung to form
fissures and where the two lungs contact each other at the
junctional lines.

4. PLEURAL EFFUSION
• Excess fluid in pleural space.
• A number of different types of fluid may
accumulate in pleural space :
i. Transudate
ii. Exudate
iii. Blood
iv. Chyle
v. Pus
• All types of pleural effusion are radiographically
identical.

5. Light’s Criteria for Defining
Exudate
•Pleural fluid protein–to–serum protein ratio
> 0.5
•Pleural fluid LDH–to–serum LDH ratio >
0.6
•Pleural fluid LDH > 2/3 times the upper
limit of normal for serum

7. BILATERAL PLEURAL EFFUSION.
• Tend to be transudate because they
develop secondary to generalized
changes that affect both pleural cavities
equally – rise in capillary pressure or fall
in blood proteins, etc.
• Bilateral effusion – exudates –
metastatic disease, lymphoma,
pulmonary embolism, rheumatoid
disease, SLE, myxoedema.

8. IMAGING DIAGNOSIS :
• CXR
Ultrasound
CT
MRI

9. •Height of the pleural
fluid is greater laterally.
•However, The true
upper limit of pleural
fluid, is usually the same
throughout the
hemithorax.
• The meniscus shape is
seen because the layer
of fluid is of insufficient
depth to cast a
perceptible shadow

14. Dependent, sickle-
shaped opacity
with a CT number
lower than that of
any adjacent pleural
thickening or mass.

15. •CT numbers do not allow a distinction
between transudate and exudate.
•However, parietal pleural thickening at
contrast-enhanced CT almost always
indicates the presence of pleural exudates.
•The fat-containing chylothorax does not
have a CT number lower than normal,
because of its protein content.

20. • Limited role
•Pleural fluid has a low signal on T1-weighted
sequences and a high signal on T2-weighted
images, with a tendency for exudates to give a
higher signal than transudates on T2-weighted
sequences.
•Chylous effusion can cause high signal intensity on
T1-weighted images similar to subcutaneous fat.
•In the subacute and chronic stage, haematomas
show bright signal intensity on T1-weighted images,
surrounded by a dark rim caused by haemosiderin.

21. CT and MRI images of pleural effusion.

22.  Radiological signs depends on
• Posture of the patient
• Distribution of the fluid (free-typical/atypical or locculated)
 FREE PLEURAL FLUID
Small amount undetectable, as it tends initially to collect
under the lower lobes.
As the amount of effusion increases, the posterior and then
the lateral CP angles become blunted, by which time a 200-
500ml effusion is present.
classical sign – homogenous opacification of lower chest
with obliteration of CP angle and hemidiaphragm.
Superior margin of opacity is concave to the lung and is
higher laterally than medially.

23. Subpulmonic or Intrapulmonary Effusions
•At times, for unknown reasons, substantial amounts
of pleural fluid (more than 1 ,000 mL) can be present
and may remain in an infrapulmonary location without
spilling into the costophrenic sulci or extending
up the chest wall.
•Decubitus examinations and USG to rule out the
possibility of a subpulmonic pleural effusion
Radiologic characteristics:
(a) apparent elevation of hemidiaphragm
(b) the apex of the apparent diaphragm is more lateral
than usual, near the junction of the middle third and the
lateral third of the diaphragm, rather than at the center
of the diaphragm

24. (c) the apparent diaphragm slopes much
more sharply toward the lateral costophrenic angle
(d) if the subpulmonic effusion is on the left side, there is
>2 cm distance b/w stomach gas bubble and apparent
hemidiaphragm.
(f) the lower lobe vessels may not be seen below the
apparent diaphragmatic border.

26.  LOCULATED PLEURAL FLUID
• Fluid can loculate between visceral and parietal pleural
layers in fissures or between visceral and parietal layers,
usually against the chest wall.
• Both ultrasound and CT can be used to distinguish
loculated fluid from solid lesions.

27.  LAMELLAR EFFUSION
• Vertical band shadow of soft tissue density
b/w lung and chest wall
• collections between the lung and the visceral
pleura So NOT a true pleural effusion
• Represent interstitial pulmonary fluid commonly in
heart failure

28.  In the supine patient, pleural fluid layers out
posteriorly and the meniscus effect, present from front
to back, is not appreciated because of the projection.
The main radiographic finding is a hazy opacity like a
veil affecting the whole or the lower part of the
hemithorax, with preserved vascular opacities in the
overlying lung.
 Additional signs include haziness of the diaphragmatic
margin, blunting of CP angle, a pleural cap to the lung
apex

30. PNEUMOTHORAX
Presence of air in pleural cavity.
When air and liquid are present the nomenclature
depends on their relative volumes and the type of
liquid. Small amounts of liquid are disregarded and the
condition is still called a pneumothorax; otherwise, the
prefix hydro-, haemo-, pyo- or chylo- is added,
depending on the nature of the liquid.

31. Air enters through a defect in either
the parietal orvisceral pleura. Such
defects are the result of :
- Lung pathology : spontaneous
pneumothorax
- Trauma :traumatic pneumothorax
- Deliberate introduction of air : artificial
pneumothorax
If pleural adhesions are present the
pneumothorax maybe localized ,
otherwise it may be generalized

32. If air can move freely in and out of pleural space
during repiration – open pneumothorax
If no movement of air occours – closed
pneumothorax
If air enters the pleural space on inspiration, but
does not leave on expiration – valvular
pneumothorax. As intrapleural pressure increases
tension pneumothorax develops

33. Primary spontaneous pneumothorax
Iatrogenic causes - primary spontaneus pneumothorax
(PSP)
Pneumothorax occouring without an obvious
precipitating event is spontaneous, and if the patient has
essentially normal lungs , it is in addition primary.
Predominantly in young adults
Five times more common in men
Nearly always caused by the rupture of an apical pleural
bleb

34. • Spontaneous, Primary
• Spontaneous, Secondary
• Airflow obstruction: Asthma,Chronic obstructive
pulmonary disease,Cystic fibrosis
• Pulmonary infection: Cavitary
pneumonia,Tuberculosis,Fungal disease,AIDS,
Pneumatocele
• Pulmonary infarction
• Neoplasm: Metastatic sarcoma
• Diffuse lung disease: Histiocytosis
X,Lymphangioleiomyomatosis,Fibrosing
alveolitis,Other diffuse fibroses
• Hereditable disorders of fibrous connective tissue:
Marfan’s syndrome
• Endometriosis (catamenial pneumothorax)

35. • Traumatic, Non-iatrogenic :Ruptured
oesophagus/trachea,Closed chest trauma (±
rib fracture),Penetrating chest trauma
• Traumatic, Iatrogenic:
Thoracotomy/thoracocentesis,Percutaneous
biopsy,Tracheostomy,Central venous
catheterisation

36.  TYPICAL SIGNS:
• Seen on erect radiographs –pleural air rises to the
lung apex. visceral pleural line at the apex becomes
separated from the chest wall by a transradiant zone
devoid of vessels
• difficulties of interpretation can arise with avascular
lung apices, as in bullous disease and when linear
shadows are created by clothing or dressing
artefacts, tubes and skin folds. Skin folds cause
problems particularly in neonates and in old people
radiographed slumped against a cassette in the AP
projection

37. • Features that help identify artefacts and skin folds include --
extension of the ‘pneumothorax’ line beyond the margin of the
chest cavity, laterally located vessels and an orientation of a line that
is inconsistent with the edge of a slightly collapsed lung. In addition,
the margin of skin folds tends to be much wider than the normally
thin visceral pleural line.
• In indeterminate circumstances a repeat chest radiograph, an
expiratory radiograph or one taken with the patient decubitus may
clarify the situation
• CT is helpful in distinguishing between bullae and pneumothorax

38. ATYPICAL SIGNS :
Arise when patient is SUPINE or the pleural space is
partly obliterated
In supine position, pleural air rises and collects anteriorly
particularly medially and basally and may not extend far
enough posteriorly to separate lung from chest wall at the
apex or laterally. Signs that suggest a pneumothorax
under these conditions are
i. Ipsilateral transradiancy, generalized or hypochondrial
ii. A deep, finger like costophrenic sulcus laterally
iii. A visible anterior costophrenic recess seen as an
oblique line or interface in the hypochondrium ; when

39. iv.A transradiant band parallel to diaphragm and/or
mediastinum with undue clarity of mediastinal border.
v.Visualization of the undersurface of the heart, and of the
cardiac fat pads as rounded opacities suggesting masses.
vi. Diaphragm depression.
• A large pneumothorax may lead to complete relaxation and
retraction of the lung, with some mediastinal shift towards the
normal side, which increases on expiration.
 in a patient who can not stand, the presence of
pneumothorax can be confirmed with lateral decubitus view.
 When the pleural space is partly obliterated , pneumothorax
may be loculated , and must be differentiated from other
localized transradiencies (cysts , bullae, pneumatocoeles,
pneumomediastinum and local emphysema)
 Can be differentiated by CT.

41. TENSION PNEUMOTHORAX
Life threatening complication. Occurs when intrapleural
pressure becomes positive relative to atmospheric
pressure for a significant part of the respiratory cycle.
Diagnosis is usually made clinically.
Chest radiograph shows contralateral mediastinal shift
and ipsilateral diaphragm depression.
Mild degree of contralateral mediastinal shift is not
unusual with a non tension pneumothorax because of
negative pressure in normal pleural space. Moderate or
gross mediastinal shift , however should be taken as
indicating tension , particularly if ipsilateral
hemidiaphragm is depressed.

42. Empyema
1 Definition :
-Infected purulent and often loculated pleural effusion and
is a cause of a large unilateral pleural collection
2 Stages :
-Stage 1 : Exudative
-Stage 2 : Fibrinopurulent
-Stage 3 : Fibrinous
3 Causes :
a) Postinfection (parapneumonic) , 60%
b) Postsurgical , 20%
c) Posttraumatic , 20%

43. a) Plain Radiography :
-Can resemble a pleural effusion and can mimic a
peripheral pulmonary abscess
-Pleural fluid is typically unilateral or markedly
asymmetric
-Form an obtuse angle with the chest wall
-The lenticular shape (bi-convex) is also
suggestive of the diagnosis, as transudative /
sterile pleural effusions tend to be cresentic in
shape (i.e. concave towards the lung)

45. (A)CXR shows pleural-
based opacity (arrow) with
tapering obtuse margins
in left hemithorax
(B)CT+C shows loculated
collection (arrowhead)
with peripherally
enhancing thick walls

46. b) CT :
-Typically appears as a fluid density collection in the
pleural space , sometimes with locules of gas (due to
gas forming organisms)
-They form obtuse angles with the adjacent lung which
is displaced and compressed
-The pleura is thickened due to fibrin deposition and in-
growth of vessels
-Pleural enhancement
-At the margins of the empyema , the pleura can be
seen dividing into parietal and visceral layers , the so-
called split pleura sign which is the most sensitive
and specific sign on CT

49. Chylothorax
1-Definition :
-Presence of chylous fluid in pleural space often as
a result of obstruction or disruption to thoracic
duct or seepage from collaterals
Indistinguishable on CXR or CT
Low trauma ---- right chylothorax
High trauma ---- left chylothorax
No lymphography

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