Normal mediastinum radiograph

1. Johan Rey P. Mon
Post-Graduate Intern
MEDIASTINUM
NORMAL RADIOGRAPH

2.  Narrow, vertically oriented structure
that resides between the medial
parietal pleural layers of the lungs
 Extends from the sternum to the bodies
of the vertebrae; and from the superior
thoracic aperture to the diaphragm
 Contains the thymus gland, the
pericardial sac, the heart, the trachea
and the major arteries and veins
MEDIASTINUM

3. BOUNDARIES

4.  Boundaries
 Anterior – sternum and costal
cartilages
 Posterior – 12 thoracic vertebrae
 Superior – thoracic inlet
 Inferior – diaphragm
 Lateral – mediastinal pleura
BOUNDARIES OF THE MEDIASTINUM

5. DIVISIONS

6.  Superior mediastinum*
 Inferior mediastinum
 Anterior
- anterior to the pericardial sac and
posterior to the body of the sternum
 Middle
- contains the pericardial sac and its
contents
 Posterior
- posterior to the pericardial sac and
the diaphragm and anterior to the
bodies of the vertebrae
DIVISIONS OF THE MEDIASTINUM

8. Boundaries Contents
Anterior Mediastinum (Prevascular) Superiorly - by the thoracic inlet,
Laterally - by the pleura,
Anteriorly - by the sternum, and
Posteriorly - by the pericardium and
great vessels
Internal mammary vessels
Internal mammary ad prevascular lymph
nodes
Thymus
Middle Mediastinum (Vascular) Anteriorly - by the anterior
mediastinum
Posteriorly - by the posterior
mediastinum.
Heart and pericardium
Ascending and transverse aorta
Main and proximal right and left
pulmonary arteries
Confluence of pulmonary veins
Superior and inferior vena cava
Traches and main bronchi
Lymph nodes and fat within mediastinal
spaces
Posterior Mediastinum
(Post-vascular)
Lies behind the heart and pericardium
and extends from the level of the
thoracic inlet to the 12th thoracic
vertebra.
Descending aorta
Esophagus
Azygos and hemiazygos veins
Thoracic duct
Sympathetic ganglia and intercostal
nerves
Lymph nodes

9. MEDIASTINAL
CONTOUR

10.  Right paratracheal stripe
 seen in two thirds of normal films
 made up of right brachiocephalic vein and
SVC
 Arch of the azygous vein
 Ascending aorta
 Superior vena cava (SVC)
 Right atrium
 Inferior vena cava (IVC)
RIGHT CARDIOMEDIASTINAL CONTOUR

11.  Left paratracheal stripe
 made up of left common carotid artery,
left subclavian artery and the left
jugular vein
 Aortic arch +/- aortic nipple (left
superior intercostal vein)
 Pulmonary artery
 Auricle of left atrium
 Left ventricle
LEFT CARDIOMEDIASTINAL CONTOUR

13.  Superior mediastinum
 Great vessels
 Thymus
 Ascending aorta
 Right ventricular outflow track
 Right ventricle
ANTERIOR CARDIOMEDIASTINAL CONTOUR

14.  Left atrium and pulmonary veins
 Right atrium
 Inferior vena cava
POSTERIOR CARDIOMEDIASTINAL CONTOUR

15.  Consists of potential spaces used to describe the location of disease
processes
 Important diseases change the appearance of the aortic knuckle, the
aorto-pulmonary window and the right para-tracheal stripe
MEDIASTINAL CONTOURS

16. The aortic knuckle (red line)
represents the left lateral edge
of the aorta as it arches
backwards over the left main
bronchus, and pulmonary
vessels.
The contour of the descending
thoracic aorta (yellow line) can
be seen in continuation from
the aortic knuckle.
NORMAL AORTIC KNUCKLE

18. The aorto-pulmonary window
lies between the arch of the
aorta and the pulmonary
arteries.
Between the Aortic Knuckle (AK)
and the Left Pulmonary Artery
(LPA)
The descending aorta (DA)
marks its posterior boundary.
AORTO-PULMONARY WINDOW

20.  From the level of the clavicles to
the azygos vein the right edge of
the trachea is seen as a thin
white stripe.
 Normal: <3 mm
 Thickened: may represent
paratracheal mass or enlarged
lymph node
RIGHT PARA-TRACHEAL STRIPE

22. MEDIASTINAL MASSES

23. ANTERIOR MEDIASTINAL
MASSES

24. MIDDLE MEDIASTINAL MASSES

25. MIDDLE MEDIASTINAL MASSES

26. POSTERIOR MEDIASTINAL
MASSES

27. POSTERIOR MEDIASTINAL
MASSES

28. HILUM

29. • Junction of the lung with the
mediastinum and is composed of upper
lobe pulmonary veins and branches of
the pulmonary artery and corresponding
bronchi
• On chest radiographs, the term hilum
represents the composite shadow of the
bronchi, pulmonary arteries and veins,
and lymph nodes on the medial aspect of
each lung.
• Left hilar shadow is higher in the right in
90% of individuals
HILUM

31.  On a true lateral radiograph, the right
and left hilar shadows are not
completely superimposed and
comprise a combination of the right
and left pulmonary arteries and the
superior pulmonary veins
 Inferior hilar window
- An avascular aspect of the composite
hilar shadow, inferior to the shadow of
the right pulmonary artery and veins and
anterior to the descending left
pulmonary artery and left superior vein
LEFT LATERAL VIEW OF THE HILUM

32. HILAR MASS

33.  RUL bronchus is seen in
approximately 50% of
individuals as an end-on, round
lucency at the upper margin of
the composite hilar shadow
 Recognition of this bronchus,
when not visible on prior
radiographs, should suggest a
mass or lymph node
enlargement about the bronchus
LEFT LATERAL VIEW OF THE HILUM

34. HEART

35. • It lies primarily in the anterior left
hemithorax, with the LV lying on the
left hemidiaphragm
• The RA extends to the right of
midline as it receives systemic
blood from the SVC, IVC, and
coronary sinus
• The RA and RV lie primarily anterior
to the planes of the LA and LV
• The RV is the most anterior
chamber and abuts the sternum
• The LA is subcarinal and midline in
the thorax
HEART

36. HEART

37. CARDIOMEDIASTINAL
ANATOMY
(PA VIEW)
1. Superior vena cava
2. Right atrium
3. Inferior vena cava
4. Aortic arch
5. Main pulmonary artery
6. Left atrial appendage
7. Left ventricle

38. CARDIOMEDIASTINAL
ANATOMY
(LATERAL VIEW)
1. Left atrium
2. Left ventricle
3. Inferior vena cava
4. Right ventricle
5. Right pulmonary artery
6. Left pulmonary artery
7. Aorta

39.  Refer to the bulges of
the cardiomediastinal contour on
frontal chest radiographs.*
 Right cardiomediastinal border:
 the right atrium is the only
normal bulge
MOGULS OF THE
HEART

40.  Left cardiomediastinal border:
 1st mogul
- uppermost, located paratracheally above
the carina, and formed by the aortic arch
(aortic knuckle or knob)
 2nd mogul
- located just above the left main bronchus
and represents the main pulmonary artery
segment
 3rd mogul
- NEVER NORMAL
 if present, it lies below the left main
bronchus and is usually formed by
prominent left atrial appendage,
which is commonly seen in rheumatic
heart disease
MOGULS OF THE
HEART

42.  4th mogul
- bulge just above the diaphragm formed
by the left ventricular margin or cardiac
apex
 5th mogul
- bulge at the cardiophrenic angle
- may be caused by prominent pericardial
fat pad, pericardial cyst, or adenopathy
MOGULS OF THE
HEART

44.  Right cardiac borders:
1. Superior vena cava
2. Inferior vena cava
3. Right atrium
CARDIAC BORDERS

45.  Left cardiac borders:
1. Aortic knob
2. Main pulmonary trunk
3. Left ventricle
CARDIAC BORDERS

46. RA LV
RV
LA
LV
HEART CHAMBERS

47.  Heart size is assessed as the
cardiothoracic ratio (CTR)
 Determines the relation of the heart to
the width of the chest at its widest part
near the level of the diaphragm
 Cardiac size is measured by dropping
parallel lines down both sides of the
heart, at the most lateral points on
each side, and measuring between
them.
 Thoracic width is measured by
dropping parallel lines down the inner
aspect of the widest points of the rib
cage, and measuring between these.
 CTR =
Maximum cardiac diameter
Macimum intrathoracic diameter
CARDIOTHORACIC RATIO

48. Adult
PA view = 0.50
AP view = 0.55
Pedia
Age (wks) Range
0-3 0.60-0.50
4-7 0.64-0.52
8-15 0.62-0.51
16-23 0.62-0.51
24-31 0.61-0.50
32-39 0.61-0.51
40-47 0.60-0.49
48-55 0.57-0.49
Age (yrs)Range
0-1 0.65-0.39
1-2 0.60-0.39
2-3 0.50-0.39
3-4 0.52-0.40
4-5 0.52-0.40
5-6 0.50-0.40
7 0.49-0.43
8 0.49-0.42
9 0.49-0.41
10 0.49-0.43
11 0.49-0.43
12 0.46-0.40
CARDIOTHORACIC RATIO NORMAL VALUES

49. THANK YOU!!!