The document provides information on the mediastinum including its definition, boundaries, and divisions. It discusses the normal lines and stripes seen on a chest radiograph. Key points include outlining the right and left paratracheal stripes, azygoesophageal recess, and aorticopulmonary window. Common conditions affecting the anterior, middle, and posterior mediastinum are listed.

1. MEDIASTINUM

2. MEDIASTINUM
 DEFINITION
 BOUNDRIES
 DIVISIONS
 NORMAL LINES & STRIPES

3. NORMAL ANATOMY

4. TECHNIQUE
 HIGH KVP TECH [120 ]--above 120
coefficient of x ray absorption of bone &
soft tissue approach each other at high kvp
& so lungs are not obscured by bones.
--better penetration of mediastnum
--short exposure-less scatter radiation ,sharp
detail outline of structure is obtained.
 WEDGE FILTER

5. Normal mediastinum on plain
radiograph
* Rt mediastinum above azygous vein is formed
by right brachiocephalic vein &s v c.
*In case of aortic or brachiocephalic artery
ectasia or unfolding either these veins will be
pushed laterally or mediastinal border is formed
by aorta or bracheocephalic artery.
*Right paratrcheal stripe-between tracheal air
column & lung . < 5 mm .
*azygous vein-outlined by air in lung at the lower
end of paratracheal stipe.

6. * Oesophageal-pleural stripe -lung posterior to
trachea contact rt wall of oesophagus.if
oesophagus at this level contain air ,rt wall of
oesophagus is seen as this stripe.
*Azygo-oesophageal recess—on rt side below
azygous arch the rt lower lobe make contact
with rt wall of esophagus & azygous vein .and
the interface is known as azygo esophageal
stripe.
---concave to rt side-normal
----convex to rt side—abnormal.subcarinal mass,
left atrial enlargement

7. Normal mediastinum
 Paraspinal lines –lymph nodes and intercostal
veins occupy this space between spine lung,
 Normal paraspinal stripe—1 to 2 mm wide.
 Aortico pulmonary window—pleura covering
the angle between mid portion of aortic arch &
main pulm artery & left pulm artery is----
Aorticopulmonary mediastinal stripe.
 Aorticopulmonary window is sensitive place to
look for lymph node enlargement.

8. The junctional lines
 Anteror junctional line –when small amount of
fat anterior to ascending aorta,two lungs may
be seperated by more than four layers of
pleura. Never extend lower than where it
envelopes rt outflow tract.
 Posterior junctional line—lungs are close
together behind the oesophagus forms this
line.line seperates to envelope the aortic arch
.
 When the lines are seen ,excludes mass or
space occupying process at junctional areas

9. DIVISIONS OF MEDIASTINUM

10. COMMON CONDITIONS

11. APPROACH
 MEDIASTNUM WIDENING OR
NORMAL
 PARENCHYMAL OR MEDIASTNAL
 ANTERIOR ,MIDDLE OR POSTEROR
COMPARTMENT
 VASCULAR OR NONVASCULAR
 ORGAN OF ORIGIN.

12. Mediastinal /parenchymal

13. Mediastinal mass
 No air bronchogram
 Margins with lung obtuse
 Mediastinal lines will be disrupted.
 Can be associated spinal ,costal or sternal
abnormalities

14. DIFF SIGN FOR
LOCALISATION
 SILHOUETTE SIGN
 HILUM OVERLAY SIGN
 HILUM CONVERGENCE SIGN
 CERVICO-THORACIC SIGN
 THORACO ABDOMINAL SIGN

15. Silhouette sign
I
 If an intrathoracic opacity is situated in
anatomic contact with a border of heart or
aorta ,will obscure that border.
A radioopacity causes obliteration of rt border of
heart , is anterior in location ,Anterior
mediastinum.
If it overlaps but does not obliterates , it lies in
posterior or middle mediastinum.

16. Silhouette sign

17. Hilum overlay sign
 Differentiates cardic enlargement from
mediastinal mass
 In mediastinal mass if Hilar vessels are seen
through the mass indicates that the mass does
not arise from hilum
 For accuracy the film should be true frontal
,slight obliquity may project normal pulmonary
artery medialy

18. Hilum overlay sign

19. Cervicothoracic sign
Well defined mass seen above the clavicle is
always situated in posterior compartment ,the
anterior compartment mass being in contact
with soft tissue rather than aerated lung is ill
defined

20. Cervicothoracic sign

21. Hilum convergence sign

22. Anterior mediastinal masses
 Displaced anterior junctional lines
 Obliterated cardiophrenic angle
 Obliterated retrosternal clear space
 Hilum overlay sign

23. ANTERIOR MEDIASTINUM
 RETROSTERNAL  PLEUROPERICARD
GOITER IAL CYST
 TORTUOS  MORGAGNI
INNOMINATE HERNIA
ARTERY
 FAT DEPOSITION
 STERNAL MASSES
 ENLARGED LYMPH
 PARATHYROID
NODES ADENOMA
 ASCENDING AORTA
ANEURYSM
 THYMOMA
 GERM CELL
TUMOUR

24. Ant mediastinal mass--lymphoma

25. Retrosternal goiter

26. Retrosternal goiter

27. ASCENDING AORTA ANEURYSM

28. Thymoma

29. Thymoma

30. Benign teratoma

31. Middle mediastinal masses
 Widened paratrcheal stripes
 Displaced azygo oesophageal recess on right
side
 Mass on posterior trachea
 Lateral 'doughnut '

32. MIDDLE MEDIASTINUM
 LYMPH NODE  TRACHEAL
ENLARGEMENT LESIONS
 AORTIC ARCH  CARDIAC
ANEURYSM TUMOURS
 ENLARGED PULM
ARTERY
 DILATATION OF
SVC
 BRONCHOGENSTIC

33. Anterior and middle mediastinal
lymph node enlargement

34. Tuberculosis

35. Pulm hypertension / sarcoidosis

36. Thoracic aorta aneurysm

37. Recurrent bronchogenic cyst

38. Esophageal duplication cyst

39. POSTERIOR MEDIASTINUM
 NEUROGENIC  PARAVETEBRAL
TUMORS MASSES
 PHARYNGO  NEUREENTERIC
ESOPHAGEAL CYSTS
POUCH  BOCHDALEK
 HIATUS HERNIA HERNIA
 DESCENDING  PANCREATIC
AORTA PSEUDOCYST
ANEURYSM  ABCESSES ,
 OESOPHAGEAL FIBROSIS
DIALATION

40. Neuroenteric cyst

41. Neuroenteric cyst

42. Bochdalek's hernia

43. More than one compartment
 Since no tissue plane in diff compartments in
some conditions multiple comp are involved
 Enlarged lymph nodes.
 Mediastinitis
 Hematomas
 Vascular entities
 Bronchogenic cancer
 Metastates
 lymphangiomas

44. Characterization of mass on C T
 Does it contain fat
 Does it contain fluid?
 Does it enhance following the
administration of i v contrast

45. Thank you

46. Cystic hygroma
TECHNIQUE
 Transverse images of thin
slices of lung (1 to 1.5 mm
thick) are obtained at non-
contiguous intervals,
 In routine CT, slices 3 to 10 mm thickcm apart,
usually 1 to 2 are obtained
throughout.
contiguously, imaging 100% of the lung

47. HRCT
 Mediastinal window: C/W = 35/350
 Lung window: C/W = -450/1350
 Bone window: C/W = 500/1800

48. NORMAL ANATOMY

49. The junctional lines

50. Cystic hygroma

51. Germ cell tumour

52. Thymic cyst

53. NORMAL VARIANT
 Azygous Lobe:-
Area of lung medial to the azygous fissure

54. BronchoPulmonarySegments
Right Lung 10 Segments
 Upper Lobe :- apical
anterior
 posterior
 Middle Lobe :- medial
lateral
 Lower Lobe :- superior
anterior basal
medial basal
lateral basal
posterior basal

55. BronchoPulmonarySegments
Lef superior
inferior
 Lower lobe :- superior
anterior basal
lateral basal

56. VASCULAR ANATOMY

57.  The bronchial arteries provide systemic blood
to the lung tissue
 Arising from the aorta; supply nearly all lung
tissue
 The alveoli are supplied by the pulmonary
circulation

58. Secondary Pulmonary Lobule

59. INDICATIONS OF HRCT

60. Descending aorta aneurysm

61. Consolidation

62. Posterior mediastinum

64. BRONCHIECTASIS

65. EMPHYSEMA
 Abnormal permanent enlargement of air
spaces distal to terminal bronchioles with
destruction of alveolar walls without obvious
fibrosis

66. EMPHYSEMA
 Types
 Centilobular
 Panacinar
 Paraseptal or subpleural

67. EMPHYSEMA

68. EMPHYSEMA

69. INTERLOBULAR SEPTAL
THICKENING
 Seen in patients with interstitial lung disease.
 Types :- smooth
nodular / irregular

70. INTERLOBULAR SEPTAL
THICKENING

71. SEPTAL THICKENING
(SMOOTH)
 Pulmonary edema
 Lymphangitic spread of carcinoma
 Amyloidosis

72. SEPTAL THICKENING
(NODULAR/IRREGULAR)
 Lymphangitic spread of carcinoma
 Pulmonary Fibrosis
 Rare: amyloidosis & asbestosis
 Sarcoidosis

73. NODULES
 Smallest diameter detected 1-2 mm
 Classification
Appearance - well-defined (likely interstitial)
ill-defined (likely air-space)
Distribution - centrilobular perilymphatic, or
random

74. CENTRILOBAR
MICRONODULES
 Centrilobular nodules can be identified in close
association to pulmonary artery branches
 Centrilobular nodules are often centered 5-10 mm
from the pleural surface
 Centrilobular nodules are usually of similar size and
spaced at regular distances from each other.

76. CENTRILOBAR
MICRONODULES
 Endobronchial tuberculosis
 Any bronchopneumonia
 Endobronchial spread of timor
 Silicosis or Coal workers’ pneumoconiosis

77. PERILYMPHATIC NODULES
 Perilymphatic nodules are usually well-defined
and occur in relation to the lymphatics. They
often affect the pleural surfaces and the
peribronchovascular, interlobular septa, and
centrilobular interstitial components.

79. PERILYMPHATIC
MICRONODULES
 Sarcoidosis
 Lymphangitic spread of carcinoma
 Silicosis & coal workers’ pneumoconiosis
 Lymphoid interstitial pneumonitis (rare)
 Amyloidosis (rare)


80. RANDOMLY DISTRIBUTED
NODULES
 Random nodules are usually well-defined and
appear diffuse, but uniform in distribution.

82. RANDOMLY DISTRIBUTED
MICRONODULES
 Miliary tuberculosis
 Fungal infections
 Hematogenous metastasis
 Sarcoidosis (when diffuse)

83. TREE-IN-BUD
 "Tree-in-bud" appearance represents dilated and
fluid-filled (i.e. pus, mucus, or inflammatory
exudate) centrilobular bronchioles.
 Abnormal "tree-in-bud" bronchioles appear more
irregular , lack of tapering or knobby/bulbous
appearance at the tip of their branches.

85. TREE-IN-BUD
 Infection: Tuberculosis, mycobacterium avium
intracellulare complex (MAC), bacterial,
fungal
 Airway disease (i.e. cystic fibrosis or
bronchiectasis)
 Allergic bronchopulmonary aspergilosis (rare)

86. Ground-glass Opacity
 Ground-glass , increased hazy opacity within
the lungs that is not associated with obscured
underlying vessels .
 Minimal thickening of the septal or alveolar
interstitium, thickening of alveolar walls, or
the presense of cells or fluid filling the alveolar
spaces.

88. GROUND GLASS OPACITY
(ACUTE)
 Pulmonary edema
 Hemorrhage
 Pneumocystic pneumonia (PCP)
 Acute interstitial pneumonia
 Hypersensitivity pneumonia
 Early idiopathic pulmonary fibrosis (IPF)

89. GROUND GLASS OPACITY
(CHRONIC)
 Desquamative interstitial pneumonitis
 Idiopathic pulmonary fibrosis
 Alveolar proteinosis
 Hypersensitivity pneumonitis - chronic
 Sarcoidosis
 Lipoid pneumonia
 Bronchoalveolar carcinoma

90. MOSAIC ATTENUATION
 Decreased attenuation which results from regional
differences in lung perfusion secondary to airway
disease or pulmonary vascular disease.
 Distribution is often patch, hence the designation
"mosaic."
 Pulmonary arteries will be reduced in size in the
lucent lung fields thus allowing mosaic perfusion to
be distinguished from ground-glass opacities.

92. MOSAIC ATTENUATION
 Bronchiolitis Obliterans
 Cystic fibrosis
 Chronic PE

93. AIR TRAPPING
 Abnormal retention of gas within the lung
following expiration.
 On HRCT, the lung parencyhma remains
lucent on expiration, while normal lung areas
show increased attenuation.
 Inspiration scans can be completely normal in
air trapping.

96. AIR TRAPPING
 Obliterative bronchiolitis
 Asthma
 Hypersensitivity pneumonitis
 Normal variant (seen in superior segement of
left lobe, middle lobe or lingula)

97. HONEYCOMBING
 Honeycombing
extensive lung fibrosis
alveolar destruction
cystic appearance on gross pathology.
Honeycombing
presence of thich-walled, air-filled cysts,
usually between the size of 3mm to 1cm in
diameter.

99. HONEYCOMBING
 Interstitial fibrosis (IPF, RA, scleroderma,
drug reaction, asbestosis, end stage
hypersensitivity pneumonitis)
 End stage sarcoidosis

100. APPROACH TO DIAGNOSIS
An acute appearance suggests pulmonary edema
or pneumonia

101. APPROACH TO DIAGNOSIS
Reticulonodular lower lung predominant
distribution with decreased lung volumes
suggests: (APC)
1. Asbestosis
2. Aspiration (chronic)
3. Pulmonary fibrosis (idiopathic)
4. Collagen vascular disease

102. APPROACH TO DIAGNOSIS
 A middle or upper lung predominant
distribution suggests:
1. Mycobacterial or fungal disease
2. Silicosis
3. Sarcoidosis
4. Langerhans Cell Histiocytosis

103. APPROACH TO DIAGNOSIS
Associated lymphadenopathy suggests :
1. Sarcoidosis
2. Neoplasm (lymphangitic carcinomatosis,
lymphoma, metastases)
3. Infection (viral, mycobacterial, or fungal)
4. Silicosis

104. APPROACH TO DIAGNOSIS
 Associated pleural thickening and/or
calcification suggest asbestosis.

105. APPROACH TO DIAGNOSIS
Associated pleural effusion suggests :
1. Pulmonary edema
2. Lymphangitic carcinomatosis
3. Lymphoma
4. Collagen vascular disease

106. 