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.
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
11. APPROACH
MEDIASTNUM WIDENING OR
NORMAL
PARENCHYMAL OR MEDIASTNAL
ANTERIOR ,MIDDLE OR POSTEROR
COMPARTMENT
VASCULAR OR NONVASCULAR
ORGAN OF ORIGIN.
13. Mediastinal mass
No air bronchogram
Margins with lung obtuse
Mediastinal lines will be disrupted.
Can be associated spinal ,costal or sternal
abnormalities
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.
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
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
31. Middle mediastinal masses
Widened paratrcheal stripes
Displaced azygo oesophageal recess on right
side
Mass on posterior trachea
Lateral 'doughnut '
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
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
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
65. EMPHYSEMA
Abnormal permanent enlargement of air
spaces distal to terminal bronchioles with
destruction of alveolar walls without obvious
fibrosis
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.
75.
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.
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.
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.
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.
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.
94.
95.
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.
98.
99. HONEYCOMBING
Interstitial fibrosis (IPF, RA, scleroderma,
drug reaction, asbestosis, end stage
hypersensitivity pneumonitis)
End stage sarcoidosis
Images are usually displayed using "lung windows," in which air appears black, aerated lung dark grey, and other structures white
This image of normal left lung shows central, branching pulmonary arteries and bronchi. The bronchovascular bundles are made up of these paired structures and their surrounding interstitium (connective tissue). In cross section, the bronchus is a thin-walled, white circle with central air (black), and the adjacent artery appears as a solid, white circle. More peripherally, numerous small "dots" and a few branching lines represent small pulmonary arteries and veins. Throughout, arteries branch at acute angles, and veins branch at 90° angles. The pleura of the major interlobar fissure is a thin, horizontal line traversing the lung. The peripheral pleural surface, which cannot be seen, is smooth.
This image shows complete opacification of most of the left upper lobe. Vessels are not visible in this area. When the bronchi remain aerated, they are seen as branching lucencies called air-bronchograms, which are present in this image. This image represents infectious pneumonia, which is limited by the major fissure, resulting in a sharp border. The advancing anteromedial margin shows ground-glass opacity
This image shows patchy ground-glass opacities throughout both lungs. Note that in the regions of ground-glass, one can see the vessels.
