5. The right main bronchus is wider, shorter, and more
vertical than the left main bronchus
6. STRUCTURAL ANATOMY
Trachea - cartilaginous and fibro-muscular conduit for
ventilation and bronchial secretions.
Extends from C6 (cricoid cartilage) to carina
Carina - T4-T5
In adults, its length ~ 11-13 cm with 2-4 cm being extra-thoracic.
However , length is dynamic.
The trachea has 16 to 22 horseshoe bands of cartilage that
compose anterior and lateral walls of trachea. The posterior
tracheal wall lacks cartilage.
7. Coronal diameter:
Men 13 to 25 mm
Women 10 to 21 mm.
Sagittal diameter:
Men 13 to 27 mm
Women 10 to 23 mm
• Tracheal index : calculated by dividing coronal diameter by
the sagittal diameter .
Normal value is ~ 1.
8. Posterior wall appears thinner and gives a variable
contour to shape of trachea due to lack of cartilage.
It may appear flat, convex or slightly concave
depending on level of inspiration
Posterior wall of trachea either flattens or bows
slightly forward during expiration.
In normal subjects there is up to a 35% reduction in AP
tracheal lumen in forced expiration, whereas
transverse diameter decreases only by 13%
9. Axial computed tomography image shows the normal rounded configuration of the
trachea at the end of inspiration. Note the normal anterior bowing of the posterior
membranous wall of the trachea at the end of expiration
10. Congenital Tracheo-bronchial anomaly
Bronchus suis
Refers to rare congenital anomaly, whereby right
upper lobe bronchus originates directly from trachea
11. Bronchial Atresia
Developmental disorder, resulting in a segmental
or sub-segmental bronchus becoming entirely
detached from main airway.
Distal airway will continue to produce mucus while
there is no clearance from airway, leading to impaction
of mucus seen as “finger-in-glove” sign on CT
12. Most commonly in apicoposterior
segmental bronchus of the left upper lobe.
CT - central, mass like opacity with a tubular
configuration.
Distal segmental branches are dilated and
contain secretions. The peripheral lung is
hyperexpanded, with decreased attenuation
and reduced vasculature.
13. Bronchial atresia. central tubular structure with hyperlucency of the
apicoposterior segment of the left upper lobe.
14. Tracheo-esophageal fistula
Congenital malformation results from a failure of the
trachea and oesophagus to divide and grow out
separately during early development of the primitive
foregut.
Often seen in A/W other congenital anomalies, of
which the VACTERL is most commonly known
15.
16. Classification (Gross's Anatomical
Classification)
Type A: Esophageal atresia without tracheoesophageal
fistula.
Type B: Esophageal atresia with proximal
tracheoesophageal fistula.
Type C: Esophageal atresia with distal
tracheoesophageal fistula (most common type) (85%).
Type D: Esophageal atresia with proximal and distal
fistula.
Type E: Tracheoesophageal fistula without atresia.
(Not shown)
17.
18.
19. TEF. Oblique barium esophagogram demonstrates a fistula (arrow) arising from the
anterior esophagus and extending anterosuperiorly to the trachea.
20. Tracheobronchomegaly (Mounier-
kuhn disease)
Characterized by dilatation of trachea and main
bronchi owing to severe atrophy of longitudinal elastic
fibres and thinning of the muscularis mucosa.
Affected patients typically present during the third
and fourth decades with recurrent respiratory
infections.
21. Mounier-Kuhn syndrome. Dilatation of the trachea in association with bronchiectasis
(arrows). There are also multiple paraseptal bullae (curved arrow).
22. Saber sheath trachea
Associated with COPD or advanced Age
Marked coronal narrowing in the presence of accentuation of the
sagittal diameter
Sagittal:Coronal ratio of greater than 2.
Chest radiographs may show diffuse narrowing of trachea
on PA view.
CT shows inward bowing of the lateral tracheal wall, which may be
accentuated on the expiratory or dynamic CT, with the classic narrow
“saber sheath” shape.
23. Saber sheath trachea. Chest radiograph PA view demonstrating diffuse
narrowing of the trachea
CT: inward bowing of the lateral tracheal wall with elongated sagittal dimension
of trachea compared to the coronal plane is consistent with the saber sheath
configuration.
24. Relapsing Polychondritis
May be caused by a range of etiologies, including
vasculitis, amyloidosis, infectious processes.
Cartilaginous part of the airway progressively
destroyed due to an autoimmune process of recurrent
inflammation.
It results in significant airflow obstruction due to
collapse of the trachea and main bronchi during
expiration
25. At expiration, 90% or more patients show
signs of collapse (malacia) with or without air
trapping.
Calcifications in the airway walls may be seen
in approximately 40% of patients.
.
26. CT scan: diffuse thickening of tracheal wall with abnormal calcification
and narrowing of the tracheal lumen. (B) CT scan just below level of canna
shows identical abnormalities extending into both main bronchi.
27. Relapsing polychondritis - characteristic thickening of the anterior cartilaginous
wall of the trachea (arrow). The posterior membranous wall is uninvolved.
28. Tracheobronchial stenosis
Defined as focal or diffuse narrowing of the tracheal
lumen and may occur secondary to a wide variety of
benign and malignant causes.
31. Post-intubation tracheal stenosis. A: Coronal and B: sagittal volume-
rendered reconstructions demonstrate a 3-cm area of narrowing in the
trachea above the thoracic inlet.
32. Tracheo-bronchial malacia
Tracheobronchomalacia refers to weakness of the
airway walls and/or supporting cartilage and is
characterized by excessive expiratory collapse
Tracheobronchomalacia may be either congenital or
acquired
33. Risk Factors for Acquired Tracheomalacia
COPD
Posttraumatic and iatrogenic factors
Postintubation
Posttracheostomy
Radiation therapy
Post lung transplantation
Relapsing polychondritis
Chronic external compression of the trachea
Paratracheal neoplasms
goiter
congenital cyst
34. Variable degree of collapse of airway during
expiration
On CT scans. A “frownlike” tracheal
configuration, due to the marked anterior
bowing of the posterior membranous wall
forming a crescenteric configuration, has
been described as Characteristic of
tracheomalacia
Main imaging finding
35. End inspiratory and end expiratory axial computed tomography scan shows
excessive collapse of the posterior wall of the trachea in expiration.
Note the extensive changes consistent with emphysema in both lungs.
36. Tracheal neoplasms
Uncommon, with 90% being malignant.
Two major types of tracheal carcinomas
Squamous cell (55%)
Adenocystic (18%)..
Rare hematogenous metastases from melanoma or breast
Malignant neoplasms :
CT as an eccentric irregular soft tissue mass within lumen,
most typically arising from posterior and lateral wall
42. TYPES
Cylindrical (tubular) uniform mild dilatation
with loss of normal tapering of bronchi
Varicose greater dilatation with irregular caliber
due to areas of expansion and narrowing.
Cystic (saccular) marked dilatation with peripheral
ballooning.
43. Chest radiographs:
Tram tracks parallel line opacities
Ring opacities
Tubular structures.
Chest radiographs lack sensitivity for detecting mild or
even moderate disease.
44. X ray photo
Multiple ring shadowTramline shadow visuble through heart
45. CT is more sensitive.
Characterized by lack of bronchial tapering
Bronchi visible in peripheral 1 cm of lungs
Increased bronchoarterial ratio producing the
so-called signet-ring sign.
46. Cylindric Bronchiectasis
Diagnostic criteria bronchial diameter >
accompanying artery (signet ring sign)
Lack of bronchial tapering.
Identification of a bronchus within 1 cm of costal
pleura or abutting the mediastinal pleura.
55. ABPA. Coronal reformation CT image demonstrates
impacted bronchi in the left upper lobe producing a
“gloved finger” appearance.
56. Impaction of bronchiectatic airways -tubular opacities
with a Y- or V-shaped configuration, often mimicking a
“gloved finger”
Impaction of a single bronchus may mimic a
parenchymal mass, but careful inspection typically
reveals a tubular rather than round configuration
scrolling through a series of axial images
or assessment with MPR can be helpful.
57. Bronchial impaction. A, Axial CT image shows a tubular structure (arrow) in the
superior segment of the right lower lobe with no visible aerated bronchus. B, Axial CT
image following expectoration of a large mucus plug shows underlying bronchiectasis
58. EMPHYSEMA
Chronic condition characterized by progressive irreversible
enlargement of airspaces distal to the terminal bronchiole with
destruction of the alveolar walls and no obvious fibrosis
Types of emphysema
Centrilobular
Panlobular
Paraseptal
Paracicatricial
59. respiratory bronchioles and the adjacent alveolar spaces, which are located in the
central
portion of the secondary pulmonary lobule, are progressively enlarged and destroyed.
Lung tissue in the periphery of the lobule is spared initially but may become involved in
the hater stages of the disease.
60. Panlobular Emphysema
Also K/as panacinar or diffuse emphysema)
Affects entire SPL producing diffuse destruction and
enlarged airspaces throughout the lung
Lower lobe predominance in most cases,
presumably due to the greater blood flow in this
region especially in chronic bronchitis
alfa -1-antitrypsin deficiency.
61. Main radiological sign :
Hyperinflation of lung
Decrease pulmonary vascularity peripherally
Retrosterrnal air space depth
Heart appears long and narrow
`Barrel chest'
62. chest radiographs, postero-anterior and lateral views, show hyperinflation of the lungs
(flattened diaphragm and widened retrosternal space), increased translucency in the upper
lungs with vascular attenuation and distorted arborization
64. Lower-lung predominance, and vascular attenuation are better shown by the coronal
minimum intensity projection and maximum intensity projection images .
65. Centriobular Emphysema
(also called centriacinar or proximal acinar emphysema)
Selective process characterized by destruction & dilatation of
respiratory bronchioles.
Emphysematous spaces lie near the center of SPL and the
lung tissue distal to the emphysematous spaces is often
normal . alveolar ducts, sacs and alveoli are spared until a late
stage.
Upper zones tend to be more severely involved than the
lung bases.
It is usually found in smokers, frequently in association with
chronic bronchitis.
66. Centrilobular emphysema. large irregular areas of lucency, without any definable walls, with a
paucity of pulmonary vessels
67. Paraseptal Emphysema
Also referred to as distal acinar or localized
Involves the distal portion of the lobule.
Characteristically adjacent to the visceral pleura and
interlobular septa, within otherwise normal lung
When these paraseptal cysts exceed 1 cm in size,
with an exceedingly thin wall, they may be termed
bullae.
69. Paracicatrieial Emphysema
also referred to as irregular or scar emphysema
Distension and destruction of terminal air spaces adjacent
to fibrotic lesions.
Causes
Tuberculosis (MC),
silicosis.
Often associated traction bronchiectasis and honeycomb
lung.
70. (PCE) from progressive massive fibrosis caused by silicosis: conglomerate masses with
surrounding low attenuation (arrows) indicating PCE
71. Bulla
Bullae- usually A/W some form of emphysema
Common - paraseptal emphysema.
Their walls may be visible as a smooth, curved,
hairline shadow.
If the walls are not visible, displacement of vessels
around a radiolucent area may indicate a huIlous area.
72. ‘Both upper zones are occupied by large bullae which are compressing upper
lobes. No evidence of generalised emphysema or air trapping. The level and
shape of the diaphragm are normal
73. coronal computed tomography multiplanar reformation and maximum intensity
projection images show a large bulla in the right upper lobe with atelectasis of the adjacent
lung
74. A giant bulla A bulla that takes up a third or more of
the space in and around the affected lung is called a
giant bulla.
D/D- Loculated Pneumothorax
CT may be necessary to demonstrate the wall of the
bulla or thin strands of lung tissue crossing it.
75. Large bullae can compress adjacent more compliant
lung, producing atelectatic pseudomasses
Predispose to pneumothorax and can reach a very
large size.
76. Atelectatic pseudomass. Computed tomography demonstrates a right paraspinal
mass (arrow) with central air bronchograms. A very large bulla almost
completely fills the right hemithorax. The mass represented collapsed normal
lung that re-expanded following resection of the bulla.
77. ASTHMA
Clinical syndrome result from hyper-reactivity of
larger airways to a variety of stimuli, causing
narrowing of the bronchi, wheezing and often
dyspnoea
Extrinsic or atopic asthma is usually associated with a
history of allergy and raised plasma IgE.
Intrinsic or non-atopic asthma may be precipitated by a
variety of factors such as exercise, emotion and
infection.
78. The role of radiology in Asthma
Normal chest X-ray during remissions.
During attack the chest X-ray may show:
Signs of hyperinflation with depression of the
diaphragm and expansion of the retrosternal air space.
79. During an asthmatic attack the lungs are
hyperinflated, the diaphragms being and flattened
During remission the chest normal
80. Chest radiographs: to exclude complications and
associations with asthma
Consolidation
Atelectasis with mucoid impaction,
Pneumothorax,
Pneumomediastinum,
ABPA.
81. Role of HRCT
Characteristic CT findings
Bronchial dilatation
Bronchial wall thickening
Mucoid impaction
Cylindric bronchiectasis
Centrilobular bronchiolar abnormalities such as tree-in-bud
Patchy areas of mosaic perfusion
Regional areas of air-trapping on expiratory scans
82. mild bronchial thickening
and dilatation
HRCT during expiration demonstrates a
mosaic pattern of lung attenuation in a
patient with asthma.
83. Chronic bronchitis
Traditionally defined when cough and sputum
expectoration occurs on most days for at least 3 months of
the year and for at least 2 consecutive years
cigarette smoking is responsible for 85% to 90%.
complications :
Pulmonary emphysema
superimposed infection or possibly bronchiectasis.
cor pulmonale.
84. Chronic bronchitis Small poorly defined opacities are present throughout both
lungs, producing the 'dirty chest
85. Bronchiolitis
Current pathologic classification includes three main
categories of bronchiolitis:
Cellular bronchiolitis,
Bronchiolitis obliterans with intraluminal polyps,
Constrictive (obliterative) bronchiolitis
87. Poorly defined centrilobular nodules and/or
a combination of linear and nodular
branching opacities (tree-in-bud sign).
Presence of poorly defined ground-glass
centrilobular nodules
88. Axial CT image demonstrates diffuse centrilobular nodular and branching
opacities (arrows) with tree-in-bud configuration.
90. Axial end-inspiratory HRCT scan is normal. B, Axial end-expiratory HRCT image shows
multiple lobular foci of air-trapping . Coronal end-inspiratory (C) and end-expiratory (D)
images provide better appreciation of the extent of air-trapping .
91. Collapse
Partial or complete loss of volume of a lung is referred
to as collapse or atlectasis.
92. Mechanism of collapse
Relaxation or passive collapse:
When air or increased fluid collected in pleural space ,
lung tends to retract towards hilum.
Cicatrisation collapse
Pulmonary fibrosis: Lung is abnormally stiff, lung
compliance is decreased and the volume of the
affected lung is reduced.
93. Adhesive collapse Respiratory distress syndrome
surface tension of alveoli is decreased by surfactant. If
this mechanism is disturbed, collapse of alveoli occurs,
although the central airways remain patent
Resorption collapse
In acute bronchial obstruction the gases in the alveoli are
steadily taken up by the blood in the pulmonary
capillaries and are not replenished, causing alveolar
collapse.
Collapse seen in carcinoma of the bronchus.
94. Abrupt cut-off of the left main bronchus
marked displacement of the right lung anteriorly and posteriorly
across the midline
95. Total right lung collapse in a neonate. The patient was ventilated
for respiratory distress syndrome and the cause of the total lung
collapse was a mucus plug
96. Direct signs of collapse
Displacement of interlobar fissures
Loss of aeration
Vascular and bronchial signs
97. Indirect sign of collapse
Elevation of hemidiaphragm
Mediastinal displacement
Hilar displacement
Compensatory hyperinflation
98. Right Upper Lobe Collapse
Volume loss of the right upper lobe.
Right upper zone has become dense due to lobar
collapse.
The volume loss has displaced the trachea which
is PULLED to the right, and the horizontal fissure
(arrow) has been PULLED upwards
99.
100. Right upper lobe collapse. An example of right upper lobe collapse
mimicking an apical cap of fluid (arrow).
101. Tight right upper lobe collapse. Note how the collapsed lobe (due to a
central bronchogenic carcinoma) results in increased right
paramediastinal density
102. On CT, the collapsed RUL is seen as a sharply defined
triangular density bordered by the minor fissure
laterally and the major fissure posteriorly
103. On computed tomography, the collapsed lobe appears as a triangular,
enhancing structure, sharply marginated laterally by the minor fissure (solid
arrows) and posteriorly by the major fissure (open arrow). B: On a more
caudal image, the obstruction (arrow) of the lobar bronchus is demonstrated.
C: Even more caudal, the collapsed lobe is flattened against the mediastinum
104. Left Upper Lobe Collapse
Left lower lobe has increased in volume to compensate
volume loss and can be seen wrapping round the
medial side of the collapsed upper lobe. This is known
as the 'Luftsichel' (air crescent) sign .
105. PA and lateral chest radiographs in a patient with tight left upper lobe collapse
and hyperexpansion of the left lower lobe. There is resulting hyperlucency
(“luftsichel” sign) adjacent to the thoracic aorta.
Left Upper Lobe
Collapse
107. Juxtaphrenic peak sign. A small triangular density
(arrow) is seen in a left upper lobe collapse. The sign is
due to reorientation of an inferior accessory fissure
Left Upper Lobe Collapse
108. Atypical left upper lobe collapse. The frontal radiograph
demonstrates the inferior concave border of the collapsed lobe and
resembles a right upper lobe collapse
109. On CT, the atelectatic LUL appears as a triangular or
V-shaped soft tissue density structure that abuts the
chest wall anterolaterally with the apex of the V
merging with the pulmonary hilum
110.
111. Right Middle Lobe Collapse
Minor fissure and lower half of the major fissure move
close together.
Lordotic AP projection brings the displaced fissure into
the line of the Xray beam, and may elegantly
demonstrate right middle lobe collapse.
Since the volume of this lobe is relatively small,
indirect signs of volume loss are rarely present.
112.
113. On CT scans, the collapsed lobe is triangular or
trapezoidal, and is demarcated by the minor fissure
anteriorly
114. Middle lobe collapse. Collapsed lobe seen as a wedge-shaped structure,
bordered by the minor (long arrows) and major (short arrows) fissures.
115. Lower Lobe Collapse
The pattern of collapse is similar for both lower lobes,
which collapse caudally, posteriorly, and medially toward
the spine.
On CT, the collapsed lower lobe appears as a wedged-
shaped soft tissue attenuation structure adjacent to the
spine.
Major fissure, which forms the lateral border of the lobe, is
displaced
116. chest x-ray of RLL collapse
Tracheal deviation to the right
overall volume loss of the right hemithorax, compared
with the left.
The mediastinum is therefore PULLED to the right.
118. Left lower lobe collapse
The tracheal deviation to left.
classical appearance of a 'double left heart border,' or a
'sail sign' (orange). The second heart border (curved
arrow) is due to the dense edge of the collapsed left
lower lobe, which has been squashed into a triangle or
sail shape.
119.
120. PA (right) and lateral (left) chest radiographs in a patient with tight left
lower lobe collapse. Note the triangular white opacity (black arrows)
behind the heart obscuring the posteromedial left hemidiaphragm.
Left lower lobe collapse.
121. Lower lobe atelectasis. CECT demonstrates marked enhancement of the collapsed
left lower lobe (arrowheads) and posterior basal segment of the right lower lobe
(arrow) in a postabdominal surgery patient suspected of having pulmonary
embolism
122. Rounded Atelectasis
Symphysis of the visceral and parietal pleura, and
resultant infolding and entrapment of a peripheral
portion of the underlying lung
3 to 5 cm in diameter
Most commonly located in the paraspinal region
Composed of a swirl of atelectatic parenchyma
adjacent to thickened pleura
124. CT findings
Rounded or wedge-shaped mass that forms an acute angle with
thickened pleura
Pleura is usually thickest at its contact with the contiguous mass
vessels swirling around and converging in a curvilinear fashion
into lower border of mass (comet tail sign)
Air bronchograms in the central portion of the mass
Homogeneous contrast enhancement of the atelectatic lung
125. Axial enhanced CT scan of the chest shows a nodular-area of increased density (blue arrow),
associated with pleural thickening and pleural plaques (yellow arrows) consistent with
asbestos-related pleural disease. Red arrow point to "comet tail" density that surrounds
rounded atelectasis
Round atelactasis
131. Distinguish Giant Bulla from Pneumothorax
Important for treatment plan
Differentiation can be difficult on conventional radiography;
they can coexist
Expiratory chest radiograph may help delineating a visceral
pleural line of pneumothorax
CT scan is the most accurate mean to differentiate the two
diagnoses
"Double wall" sign described in cases with ruptured bulla
causing pneumothorax (air outlining both sides of the bulla
wall parallel to the chest wall)