This document provides an overview of the radiological anatomy of the thorax as seen on various imaging modalities like plain X-ray, CT, MRI, ultrasound and nuclear medicine. It describes the lungs, mediastinum, bony cage and soft tissues of the thorax. It also discusses the anatomy of specific structures like the heart, lungs, bronchial tree, pulmonary arteries and veins. Standard views used for chest X-rays and important lines and stripes seen are explained. CT windows and segmental anatomy of the lungs are outlined as well.

2. Radiological Anatomy of the Thorax
Modalities
Plain X-Ray
Computed Tomography (CT)
Magnetic Resonance Imaging (MRI)
Ultrasound
Nuclear Medicine
Angiography

3. Radiological Anatomy of the Thorax
• LUNGS
• MEDIASTINUM
• BONY CAGE
• SOFT TISSUE COMPONENT

4. OVER
ADEQUATE
UNDER
o Exposure
o Position
o Inspiration
Radiological Anatomy of the Thorax

5. AP PA LATERAL
•Erect/standing posture.
•Scapula seen in the periphery of
thorax.
•Clavicles project over the lung
fields.
•Posterior ribs distinct.
•Heart magnification: nil
•Cardio-thoracic ratio- 1:2
•Diaphragm: lower level
•Gastric air/fluid seen.
•Supine/ sitting posture.
•Scapula seen over the lung
fields.
•Clavicles above the apex
of lung fields.
•Anterior ribs are distinct.
•Heart magnification:
significant.
•Cardio-thoracic ratio-
increased.
•Diaphragm : higher level
•Gastric air/fluid not seen.
LATERAL
DECUBITUS
OBLIQUE
APICAL
LORDIC VIEW

6. UPPER
MIDDLE
LOWER
UPPER
LOWER

7. LUNG LOBES AND FISSURES
RIGHT LUNG:
• Three lobes ( upper, middle & lower)
• Two fissures (horizontal and oblique)
LEFT LUNG:
Two lobes (upper & lower)
One fissure (major oblique)

8. LOBAR ANATOMY
Upper Lobe
Lower Lobe
Major Fissure
Major Fissure
Minor Fissure
Upper Lobe
Middle Lobe
Lower Lobe
R
L
RIGHT LUNG
LEFT LUNG

9. Radiological Anatomy of the Chest

10. Radiological Anatomy of the Thorax

11. Radiological Anatomy of the Thorax

14. CHEST X RAY- LINES AND STRIPES
• Chest x-ray lines and stripes are important to recognize on chest
radiographs.
• Lines are usually less than 1 mm in width and are comprised of tissue outlined on
either side by air and typically represent pleural-covered structures within the
superior and middle mediastinum.
• Stripes, on the other hand, are thicker than lines, and are seen when these
thicker anatomical structures are outlined by air.
• A third important part of chest x-ray lines and stripes are the interfaces, although
confusingly some are known as 'lines/stripes', which are the borders of solid
structures with air.
• Recognition of any abnormality in the various lines and stripes on chest x-ray is
invaluable in ensuring the appropriateness in further investigation with CT.

15. • Anterior Junction Line
• Posterior Junction Line
• Right Paratracheal Stripe
• Left Paratracheal Stripe
• Posterior Tracheal Stripe
• Right Paraspinal Line
• Left Paraspinal Line
• Aortopulmonary Stripe
• Aortopulmonary Window
CHEST X RAY- LINES AND STRIPES

17. Cardiomegaly
• Occupies most of the mediastinum (2/3 on left and 1/3 on right side)
Trans-cardiac : Trans-thoracic diameter= 1:2
If >1:2- cardiomegaly

18. RULE OF THUMB:
• On lateral chest Xray,
there should not be
any abrupt change in
the density across the
shadow of the heart, if
present…suspect
superimposed
pulmonary pathology.

19. Mach Effect

21. CT Anatomy of the Thorax
Sagittal Axial Coronal
• HRCT –Thin sections 0.5-
1.5mm is essential for
optimal study
• Radiation Dose
PA CXR - 0.05 mSv
MD-HRCT - 4 to 7 mSv
(60-80 CXR)

22. Lung Window (-600 to –700 HU)
Mediastinal Window
(40-50/350-450 HU)

23. LUNG ANATOMY
WEIBEL’S MODEL OF
AIRWAY GENERATIONS
• Model for branching pattern
of tracheo-bronchial tree.
• 23 Airway Generations
• Divided into….
1-Conducting zone (gen 0-16)
2-Respiratory zone (gen 17-
23)

24. • Functional divisions of the lung.
• Each segment is supplied by…
Specific bronchial segment
Own vascular supply
Own lymphatic drainage
• Arteries run through the center of
the segment.
• Veins and lymphatic vessels
drain along the edges of the
segment.
BRONCHO-PULMONARY SEGEMENTS

25. Segmental Anatomy of the Lungs

26. Radiological Anatomy of the Bronchial System
Lung Window (-600 to –700 HU)

27. Radiological Anatomy of the Chest

28. Radiological Anatomy of the Chest

29. Radiological Anatomy of the Chest

30. Radiological Anatomy of the Chest

31. Radiological Anatomy of the Chest

32. Radiological Anatomy of the Chest

33. Radiological Anatomy of the Chest

34. Radiological Anatomy of the Chest

35. Radiological Anatomy of the Chest

36. MEDIASTINUM
The mediastinum is a space in the thorax that contains a group of organs, vessels,
nerves, lymphatics and their surrounding connective tissue. It lies in the midline of
the chest between the pleura of each lung and extends from the sternum to

37. Radiological Anatomy of the Mediastinum
ANTERIOR
MIDDLE
POSTERIOR
Thymus.
Lymph nodes.
Mediastinal fat.
Left brachiocephalic
vein.
Heart, superior vena cava [SVC],
ascending thoracic aorta, aortic arch,
descending thoracic aorta,
intrapericardial pulmonary arteries,
and thoracic duct.
trachea, oesophagus, and lymph nodes.
# Extrapericardial pulmonary arteries and veins are considered to be pulmonary and
not mediastinal structures
Thoracic spine
Paravertebral soft
tissues

38. Radiological Anatomy of the Mediastinum
T-12

39. Radiological Anatomy of the Mediastinum

40. Radiological Anatomy of the Mediastinum
T-10

41. Radiological Anatomy of the Mediastinum
LOW CARDIAC LEVEL

43. HIGH CARDIAC LEVEL

44. Radiological Anatomy of the Mediastinum
T- 6

45. MAIN PULMONARY ARTERY LEVEL

46. LEVEL OF AORTO-PULMONARY WINDOW
T- 5

47. AORTIC ARCH LEVEL
T- 4

48. FIVE VESSEL VIEW
T- 3

50. T- 1

51. L
Y
M
P
H
A
T
I
C
S

52. HEART

54. HEART CHAMBERS

56. Arterial Supply

57. Right Coronary Artery Left Coronary Artery

58. Venous Supply

61. THANK YOU