Radiology of Mediastinal Pathologies

1. Radiological Approach to
Mediastinal Lesions
DR .FARAH JAMIL.
PG TRAINEE.

2. LINES & STRIPES

3. Anterior Junction Line
•Formed by apposition of visceral a& parietal pleura of the anteromedial
aspect of the lungs.
•Contains small amount of fat
•Seen in 25-57% of cases
•Obliteration or abnormal convexity suggest Anterior Mediastinal lesions
•Thyroid, Thymic mass, Lymphadenopathy, Tumor, or Lipomatosis

4. Anterior Junction Line
•Patient with right middle lobe lobectomy
•Note
• anterior junction line shift to right
•Volume loss

5. Posterior Junction Line
•Formed by apposition pleura of the posteromedial aspect of the lungs
posterior to esophagus and anterior to D3-D5
•Has more cranial extension than previous line (seen above clavicle)
•Seen in 32% of cases
•Bulging or abnormal convexity suggest Posterior Mediastinal lesions
•Esophageal masses, Lymphadenopathy, Aortic Disease, or Neurogenic
tumors

6. Right Paratracheal Stripe
•Formed by apposition of right upper lobe pleura in contact with right lateral
border of trachea and intervening mediastinal fat, air within right lung & trachea
•Extends from clavicle to right tracheobronchial angle at the level of azygos arch
•Seen in 97% cases
•Widening (pleural effusion /thickening) or abnormal contour seen in
•Paratracheal Lymphadenopathy, thyroid / parathyroid neoplasm, & tracheal
carcinoma / stenosis

7. Abnormal Right Paratracheal Stripe
Large ectopic parathyroid adenoma shows
•Widening of Paratracheal stripe

8. Left Paratracheal Stripe
•Formed by apposition of left upper lobe in contact with either mediastinal fat or
adjacent to left tracheal wall OR the left trachea wall itself
•Extends from aortic arch to join left subclavian artery
•Seen in 21-31% cases
•Widening (pleural effusion /thickening) or abnormal contour seen in
•Paratracheal Lymphadenopathy, neoplasm, & mediastinal haemotoma

9. Abnormal Left Paratracheal Stripe
Metastatic thyroid carcinoma shows
•Widening of Paratracheal stripe
•Mass effect on trachea
•Supraclavicular Lymphadenopathy

10. Aortic Pulmonary Stripe
•Formed by apposition of left anterior lung in contact with and tangentially
reflecting overt the mediastinal fat anterolateral to the left pulmonary artery and
aortic arch. Crosses over the aortic arch & the main pulmonary artery
•Altered in anterior mediastinal lesion
•Thyroid, Thymic mass or Prevascular Lymphadenopathy

11. Abnormal Aortic Pulmonary Stripe
Lymphoma shows
•Abnormal contour of AP stripe
•Prevascular Lymphadenopathy

12. Aortic Pulmonary Window
•Bounded superiorly by inferior wall of aortic arch, inferiorly superior wall of left
PA, anteriorly posterior wall of ascending aorta, posteriorly anterior wall of
descending aorta, medially trachea, lateral wall of left main bronchus, &
esophagus
•Convex contour is abnormal
•Contents/ disease
•Left recurrent laryngeal N, left vagus N, ligmentum arteriosum, mediastinal
fat, lymph nodes, left bronchial artery

13. Aortic Pulmonary Window
Bronchogenic carcinoma shows
•Abnormal bulge in AP window
•Thickening of right Paratracheal stripe
• left lower consolidation
•Left pleural effusion
•Lymphadenopathy

14. Right Paraspinal Line
•Formed by the right lung and pleura coming in tangential contact with
the posterior mediastinal soft tissues
•Appears straight and typically extends from the D8 to D12 vertebrae on
PA radiographs. The right paraspinal line may be displaced laterally by
osteophytes
•Abnormal contours suggest posterior mediastinal abnormality
•Mediastinal haematoma, a mass, extramedullary haematopoiesis

15. Right Paraspinal Line
Traumatic Injury shows
•Mediastinal Haematoma

16. Left Paraspinal Line
•Formed by tangential contact of the left lung and pleura with the
posterior mediastinal fat, left paraspinal muscles, and adjacent soft
tissues
•Extends from aortic arch to diaphragm & typically lies medial to lateral
wall of descending aorta
•Osteophytes & abnormal mediastinal fat can change contour however
posterior mediastinal abnormalities are main culprit
•Mediastinal haematoma, a mass, extramedullary haematopoiesis
&esophageal varices

17. Left Paraspinal Line
Liver Cirrhosis case shows
•Esophageal varices

18. Posterior tracheal Stripe
•Formed by air within the trachea &right lung outlining the posterior
tracheal wall & intervening soft tissues
•2.5 mm in thickness
•It forms anterior border of Raider triangle
•Most common abnormalities are aortic arch congenital anomalies
•Other include
•Vascular lesions, esophageal lesions, lymphomatus malformations,
mediastinits, traumatic haematoma

19. Posterior tracheal Stripe
Patient with achalasia shows
•Widened tracheobronchial stripe

20. Azygo-Esophageal Recess
•Formed by difference in density between Mediastinum & the
posteromedial portion of the right lower lobe
•Space lies posterior to esophagus and extend from anterior turn of
azygos vein to aortic hiatus inferior inferiorly
•Most common abnormalities are
•Lymphadenopathy, Hiatus hernia, Broncho-pulmonary malformations,
Esophageal neoplasm, left atrial enlargement

21. Azygo-Esophageal Recess
Patient with Hiatus hernia shows
•Abnormal contour and right lateral convexity

22. Posterior wall of Bronchus Intermedius
•Formed when lung within the azygo-esophageal recess outlines posterior
wall
•When abnormal band like or lobulated appearance
•Mostly see in
•Pulmonary edema, primary lung neoplasm, lymphadenopathy from
lymphoma, TB, sarcoidosis

23. Posterior wall of Bronchus

24. • Lines typically measure less than 1 mm in width and are formed by air,
typically within the lung, outlining thin intervening tissue on both sides
• Visible on 21%–31% of PA chest radiographs, the left paratracheal
stripe is seen less frequently than the right paratracheal stripe, since it
may be obscured by contact between the left lung and either the
proximal left common carotid artery anteriorly or the left subclavian
artery posteriorly
• Because of their similar names, the AP window is often confused with
the aortico-pulmonary stripe. The AP window actually lies posterior to
the aortic-pulmonary stripe.
Important Points

25. • Like the right, the left paraspinal line actually represents a
lung-mediastinum interface and is associated with a positive
Mach band phenomenon, having the appearance of a line
etched in white.
• Reported on 41% of PA radiographs, the left paraspinal line is
seen more frequently than the right paraspinal line due to the
presence of the descending thoracic aorta on the left, which
promotes the tangential contact of the left lung necessary to
produce the lung mediastinum interface
Important Points

26. • The posterior tracheal stripe forms the anterior border of the
retrotracheal space (Raider or retrotracheal triangle), with the
remaining borders being the spine posteriorly, the aortic arch
inferiorly, and the thoracic inlet superiorly.
Important Points

27. Mediastinal Masses

28. Mediastinum
• Anatomist divide mediastinum into 4 parts
– Superior
– Inferior
• Inferior is further divided into 3 parts
– Anterior
– Middle
– Posterior
• We will use modified anatomic classification with no
superior compartment separately

30. Anterior Mediastinum
Normal contents include
•Thymus
•Lymph nodes
•Adipose tissue
•Internal mammary vessels

31. Anterior Mediastinum Mass
1. Lymph adenopathy
2. Retrosternal Goiter
3. Thymic lesion i.e. thymoma,
cacinoma, hyperplasia, cysts,
thymolipoma
4. Germ Cell tumors
•Epicardiac fat pad
•Diaphragmatic Hump
•Morgagni Hernia
•Pleuropericardial Cysts
•Lymph Nodes
1. Lymphomatus
malformations
2. haemangioma
Pre Vascular Pre Cardiac

32. a. Anterior Junction Line
Anterior Mediastinum

33. Anterior mediastinal mass in the Prevascular region can
obliterate anterior junction line
_______________________________________
Hilum overlay sign is present when normal structures
project through mass
_______________________________________
Lesions in diaphragmatic contact include epicardial fat
pad, pleuropericardial cysts & Morgagni hernia

34. Epicardial fat pad obliterate cardiac silhouette & are of relatively
low density
_______________________________________
Bowel gas in mediastinal mass suggest Morgagni hernia
_______________________________________
Thyroid can disrupt middle and posterior mediastinal lines
For thyroid assess its lateral margins
_______________________________________
Anterior masses above the level of clavicle do not have an
interface with lung so not exhibit sharp, well defined margins

35. • The mass is cystic but has solid enhancing septa.
This finding is very specific for a germ cell
tumor.Now many think that germ cell tumors
contain fat and if a lesion does not contain fat, it
cannot be a germ cell tumor.
• only about 60 % of germ cell tumors contain fat,
so absence of fat does not exclude a germ cell
tumor from the differential diagnosis.
The more solid components a germ cell tumor has,
the more likely the tumor is to be malignant.

36. GERM CELL TUMOUR

37. Hilum Overlay Sign
Mass can be anterior or posterior but descending aorta is clearly seen
suggesting mass is not posterior

38. Hilum Overlay Sign

39. Thyroid Mass
Margins above the clavicle are not sharp, obliterated right paratracheal
stripe, tracheal deviation, obliterated anterior junction line

40. Epicardial Fat Pad
Loss of cardiac silhouette, Low density

41. Middle Mediastinum
Normal contents include
•Heart & pericardium
•Ascending & transverse aorta
•SVC
•IVC
•Brachiocephalic Vessels,
•Trachea & main bronchi
•Lymph nodes
•Phrenic, Vagus & Left Rec Nvs

42. – Lymphadenopathy
– Aortic arch aneurysm
– Enlarged PA
– Foregut Duplication Cysts
• Bronchogenic, Esophageal, Neuroenteric
– Pericardial Cyst
– Tracheal Lesions
Middle Mediastinum

43. a. Right / Left Paratracehal Stripe
b. Aortico-Pulmonary Window
Middle Mediastinum

44. Middle Mediastinum
Right paratrcheal stripe can be widened from
abnormality of any of its components from tracheal
mucosa to pleural space
___________________________________________
AP Window contains lymph nodes , left Rec N, Left
bronchial arteries , ligmentum arteriosum and Fat
___________________________________________
AP window can be distorted by lymphadenopathy,
abnormal fat or aortic arch aneurysm
___________________________________________

45. Middle Mediastinum
Pitfalls
Right sided artic arch may mimic paratracheal
lymphadenopathy however absence of aortic knuckle helps
___________________________________________
Left sided SVC may create additional mediastinal line lateral
to aortic arch but this variant is anterior to hilum
___________________________________________
Azygos continuation of IVC will show an enlarged azygos
vein may be mistaken for lymphadeopahty
___________________________________________

46. Right paratrcheal stripe

47. Absent Right paratracheal stripe
Obliterated air-soft tissue interface between right lung &
tracheal wall
Right Paratracheal Lymphadenopathy

48. AP Window Lymphadenopathy
Abnormal convexity of AP window

49. Aortic arch aneurysm
AP window with convex border
Lateral aneurysm

50. Right sided aortic
arch
Left sided SVC
Azygos

51. Posterior Mediastinum
Normal contents include
•Esophagus
•Descending aorta
•Azygos & Hemiazygos veins
•Thoracic Duct
•Vagus & Splanchnic N
•Lymph Nodes
•Fat

52. 1. Esophageal lesions, hiatal hernia
2. Descending aortic aneurysm
3. Foregut duplication cyst
4. Neurogenic tumor
5. Paraspinal abscess
6. Lateral meningocele
7. Extramedullary hematopoiesis
Posterior Mediastinum

53. a. Posterior Junction Line
b. Paraspinal Line
c. Azygoesophageal recess
Posterior Mediastinum

54. Posterior Mediastinum
Azygo-esophageal recess reflection is prevertebral structure &
is disrupted by preverbal disease
_____________________________________________________
In subcarinal region, left atrial enlargement, subcarinal
Lymphadenopathy, Esophageal disease & bronchogenic cysts
may cause deviation of azygoesophageal recess
_____________________________________________________
Inferiorly this line is disrupted by esophageal disease & hiatus
hernia
_____________________________________________________

55. Posterior Mediastinum
Superior to aortic arch prevertebral disease can
obliterate Posterior Junction Line and have sharp well
defined margins
___________________________________________
Paraspinal lines are obliterated by paraverterbral
disease including disk, vertebrae & Neurogenic tumors
___________________________________________

56. Cervicothoracic sign

57. Cervicothoracic sign
• Therefore, when a mass extends above the
superior clavicle, it is located either in the
neck or in the posterior mediastinum.
When lung tissue comes between the mass
and the neck, the mass is probably in the
posterior mediastinum.

58. Bronchogenic Cyst
Splaying of carina, abnormal azygoesophageal line

59. Bronchogenic Cyst
Obliteration of posterior junction line
Lesion above the clavicle
Well demarcated outline

60. Left / Right Paraspinal Lines

61. Para Spinal Abscess
Effacement of left paraspinal line
Separate wall of descending aorta

62. Aortic Aneurysm

63. Neurogenic tumor
Disruption of left paraspinal line

64. MOST IMPORTANT
• Most masses (> 60%) are:
– Thymomas
– Neurogenic Tumors
– Benign Cysts
– Lymphadenopathy (LAD)
• In children the most common (> 80%) are:
– Neurogenic tumors
– Germ cell tumors
– Foregut cysts

65. Fat containing masses
• The differential diagnosis of fat containing mediastinal
masses is:
• Thymolipoma
• Teratoma (Germ cell tumors)
• Esophageal lipoma
• Fat deposition
• Lipoma
• Lipoblastoma
• Liposarcoma
• Extramedullary hematopoiesis

66. Enhancing masses
• Hyperenhancing lymph nodes
• Thyroid tissue
• Paragangliomas
• Hemangiomas
• Vascular Etiologies

67. Fluid containing masses
• Thymic Cyst
• Thymoma
• Teratoma
• Pericardial Cyst
• Foregut Duplication
• Meningocoele
• Neuroenteric Cyst
• Cystic Lymphadenopathy
• Lymphangioma

68. The hilum overlay sign is present when the normal hilar structures project
through a mass, such that the mass can be understood as being either anterior
or posterior to the hilum.
The azygoesophageal recess reflection is a prevertebral structure and is,
therefore, disrupted by prevertebral disease. It has an interface with the middle
mediastinum; thus, the resulting line seen at radiography can be interrupted by
abnormalities in both the middle and posterior compartments.
The paraspinal lines are disrupted by paravertebral disease—which commonly
includes diseases originating in the intervertebral disks and vertebrae—and by
Neurogenic tumors.
A convex border between the AP window and the lung is considered abnormal.
A right paratracheal stripe 5 mm or more in width is considered widened.
IMPORTANT POINTS

69. REFERENCES
• kstr.radiology.or.kr/weekly/index2.php - 22k
- Cached
www.radiologyassistant.nl/en/4620a193b67
9d - 47k - Cached
• kstr.radiology.or.kr/chest/2002

70. Thanks