This document provides information on the anatomy and structural abnormalities of the trachea and bronchi. It begins with a description of the normal anatomy of the trachea including its length, diameter, cartilage structure, and changes during inspiration and expiration. It then discusses various congenital anomalies such as bronchus suis, bronchial atresia, and tracheoesophageal fistula. Acquired conditions of the trachea and bronchi are also summarized such as tracheobronchomegaly, saber sheath trachea, relapsing polychondritis, stenosis, malacia, and neoplasms. Common lung diseases like bronchiectasis, emphysema, asthma, and chronic bronchitis are briefly explained as well.

1. MODERATOR: DR. KANCHAN
DHUNGEL
PRESENTER: DR ABHISHEK

2. • ANATOMY
• CONGENITAL TRACHEO-BRONCHIAL ANOMALY
• BRONCHIECTASIS
• EMPHYSEMA
• BRONCHIAL ASTHMA
• CHRONIC BRONCHITIS
• BRONCHIOLITIS
• COLLAPSE OF LUNG

3. STRUCTURAL ANATOMY

4. STRUCTURAL ANATOMY

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

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)

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.

29.  Iatrogenic
Postintubation
Lung transplantation
 Infection
Laryngotracheal papillomatosis[*]
Rhinoscleroma
Tuberculosis
 Tracheal neoplasm
 Systemic diseases
Amyloidosis
Inflammatory bowel disease
Relapsing polychondritis
Sarcoidosis
Wegener granulomatosis

30. Subglottic stenosis resulted from
prolonged intubation.

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

37. Squamous cell carcinoma of trachea.

38.  Benign tracheal tumors
Squamous papilloma (young children),
Pleomorphic adenoma
Mesenchymal hamartomathose of cartilaginous origin.
 Well circumscribed/smoothly marginated/< 2 cm in
diameter.

39. Bronchiectasis
Irreversible localized or diffuse dilatation of
cartilage containing airways or bronchi.
Resulting from
 Chronic infection
 Proximal airway obstruction
 Congenital bronchial abnormality

40. Causes of Bronchiectasis
 Infection – bacteria, mycobacteria, fungus, virus
 Acquired bronchial obstruction (neoplasm, foreign body,
bronchholith)
 Extrinsic bronchial obstruction (lymph node enlargement, neoplasm)
 Inherited molecular and cellular defects(cystic fibrosis, a1 antitrypsin
deficiency)
 Inherited bronchial structural deficiencies(bronchial
atresia,congenictal tracheobronchomegaly, Williams-campell
syndrome)
 Primary ciliary dyskinesia (Kartagener syndrome)
 Pulmonary fibrosis(results in traction bronchiectasis)

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.

47. signet ring sign

48. Normal bronchus cylindric bronchiectasis with lack
tapering
Cylindrical bronchiectasis

49. varicoid bronchiectasis
Varicoid bronchiectasis is characterized by a beaded
appearance, mimicking a “string of pearls” .

50. Cystic bronchiectasis
Cystic bronchiectasis is characterized by thin-walled cystic
spaces that connect with proximal airways, with or without

52. Cystic bronchiectasis is characterized by thin-walled cystic
spaces with fluid levels

54. Atypical mycobacterial infection:Cylindrcal broncheactasis &
centrilobular nodule in middle lobe & lingula

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

63. High-resolution computed tomography images through the lung apices and
bases demonstrate lower lobe predominate emphysema

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.

68. Paraseptal emphysema. A and B, HRCT show extensive emphysema in
the subpleural regions.

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

86. Causes of Cellular 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.

89. Causes of Constrictive Bronchiolitis

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

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

106. 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

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.

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.

117. RLL collapse

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.

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

123. Round atelactasis

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

126. THANK YOU

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)