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Thoracic Radiographic Anatomy

Thoracic Radiographic Anatomy. Einav Shochat MS4 Visiting Medical Student. PA and Lateral Chest Radiograph. Lobar Anatomy. There are three lobes in the right lung and two in the left Lobes are divided into anatomic segments; each is supplied by its own bronchus and blood vessels.

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Thoracic Radiographic Anatomy

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  1. Thoracic Radiographic Anatomy Einav Shochat MS4 Visiting Medical Student

  2. PA and Lateral Chest Radiograph

  3. Lobar Anatomy • There are three lobes in the right lung and two in the left • Lobes are divided into anatomic segments; each is supplied by its own bronchus and blood vessels

  4. Lobar Anatomy: Right upper & right middle lobes RUL RUL RML borders the right atrium and much of the dome of the diaphragm. Indistinct borders of these areas suggest RML pathology. RML RML

  5. Lobar Anatomy: Right lower lobe Consolidations of the lower lobes are largely behind the diaphragm dome, hence the diaphragm border will still appear sharp on the PA film. RLL RLL

  6. Lobar Anatomy: Left upper lobe LUL LUL LUL borders the left atrium, left ventricle and much of the dome of the diaphragm. Indistinct borders of these areas suggest LUL pathology.

  7. Lobar Anatomy: Left lower lobe Most of the LLL is posterior to the left border of the heart and the dome of the diaphragm. Distinct borders of these areas with surrounding opacity is seen with LUL consolidations. LLL LLL

  8. Can you find the source of this patient’s fever and cough?

  9. Can you find the source of this patient’s fever and cough? Left Lower Lobe pneumonia Distinct borders Note the abnormal opacification of the lower vertebrae in the lateral view. Normally there is less soft tissue around the inferior thoracic vertebrae making them appear darker than the more superior vertebrae. See next slide for comparison.

  10. On the right is the same radiograph from the previous slide with a normal one for comparison. Normally, inferior vertebrae appear darker Note the general opacification of the lower lobe in the image on the right. Look particularly at the vertebral bodies and posterior border of the heart.

  11. Lobar Anatomy • The lobes of the lungs are lined by visceral pleura, which normally is not visualized except along the interlobar fissures • Fissure anatomy may have many anatomic variations and may not be complete

  12. On the right there are two fissures, the oblique (major) fissure and the horizontal (minor) fissure. The left lung contains an oblique fissure only. minor minor major

  13. It is uncommon to see distinct fissures. If opacified there may be thickening of or fluid between the pleura. This patient has congestive heart failure and subsequent subpleural thickening. Can you identify the oblique fissures?

  14. It is uncommon to see distinct fissures. If opacified there may be thickening of or fluid between the pleura. This patient has congestive heart failure and subsequent subpleural thickening. Can you identify the oblique fissures?

  15. Here there is fluid trapped between the pleura within the fissures.

  16. Occasionally accessory fissures can be found. For example, the azygos fissure, a normal variant, can form during the embryonic migration of the azygos vein through the apical pleura.

  17. Knowing the normal position of the interlobar fissures helps us diagnose pulmonary volume changes. For example when a lobe collapses the fissure is displaced and seen as a sharp interface between opacified (collapsed) and aerated lung. Can you identify the pleural lining of the collapse lung?

  18. Knowing the normal position of the interlobar fissures helps us diagnose pulmonary volume changes. For example when a lobe collapses the fissure is displaced and seen as an interface between two densities (e.g., opacified/collapsed and aerated lung) Can you identify the pleural lining of the collapse lung? scapulae Left pulmonary artery: vasculature are pulled inferiorly by the collapsed LLL Inferior vertebrae opacified by LLL atelectasis Left hemidiaphragm becomes indistinct when adjacent to collapsed LLL Major fissure not normally seen on the PA film because it runs parallel to the radiation beams

  19. What’s happened here?

  20. What’s happened here? Right upper lobe collapse

  21. We can use the pleura to identify whether a mass is within the lung parenchyma or in the extrapleural space. Is this mass intrapleural or extrapleural? How can you tell?

  22. We can use the pleura to identify whether a mass is within the lung parenchyma or in the extrapleural space. Is this mass intrapleural or extrapleural? How can you tell? Extrapleural The medial border of the mass is draped by pleura and is distinct where it is adjacent to aerated lung. The lateral border is next to bone and soft tissue of more similar density.

  23. The pleura is often involved in inflammatory and traumatic insults to the chest. These may result in areas of thickening or distortion of the pleural lining, which may be appreciated in the normally sharp costophrenic & cardiophrenic angles/sulci. Cardiophrenic angle Posterior costophrenic angle Lateral costophrenic angle Lateral costophrenic angle

  24. Pleural effusions can be identified by: blunting of the lateral and posterior costophrenic sulci, a meniscus sign, opacification of a hemithorax, and/or fluid in the fissures. Small free-flowing pleural effusions are best identified on the lateral radiograph as this view captures the most dependent region of the thoracic cavity, the posterior costophrenic angles.

  25. Mediastinum • Many structures can be identified within the mediastium; we will start with the heart and blood vessels…

  26. How many structures can you identify?

  27. Aortic pulmonary recess Vascular pedicle SVC Aortic arch pulmonary Right pulmonary artery Left Aorta artery LA Right pulmonary artery (lower lobe) RA LV RV

  28. How many structures can you identify?

  29. Brachiocephalic vessels Trachea Scapula Manubrium Aorta Right upper lobe bronchus LPA RPA Retrosternal space Left upper lobe bronchus Pulmonary outflow tract Body of sternum LA Confluence of pulmonary veins RV IVC LV Right hemidiaphragm Gastric air bubble Left hemidiaphragm

  30. Which valve has been replaced?

  31. Which valve has been replaced? Aortic valve Note the orientation of the valve perpendicular to the plane of the PA film.

  32. Which valve has been replaced?

  33. Which valve has been replaced? Pulmonic The pulmonary outflow tract is more superior and lateral than many people think.

  34. Last one, name the valves…

  35. Last one, name the valves… Aortic Aortic Tricuspid Mitral Tricuspid Mitral

  36. The Vascular Pedicle • Found in the superior mediastinum. • Right and left margins are normally formed by the superior vena cava and the descending portion of the aortic arch, respectively. • A widened vascular pedicle can have several etiologies including elevated intravascular volume, aortic trauma, or pericardial effusion.

  37. Aortic arch Vascular pedicle Superior vena cava

  38. Intravascular volume depletion Intravascular volume elevation vs.

  39. Intravascular volume depletion Intravascular volume elevation vs. Vascular pedicle Vascular pedicle Superior vena cava Aorta Superior vena cava Aorta Intravascular volume elevation resulting in an expanded SVC should not be mistaken for hematoma, which would have a less distinct border and more opacified appearance.

  40. Trauma patient with an aortic transection Note the vascular pedicle’s “fuzzy”, opacified right border.

  41. What is happening here?

  42. What is happening here? Looks pretty wide eh? Can you follow the heart borders?

  43. What is happening here? If you look closely you can make out the superior pericardial border The wide vascular pedicle here results from a pericardial effusion The pacemaker wires roughly outline the right atrium border The left heart border can be seen within the effusion effusion effusion Comparing this with older films can also help make the diagnosis.

  44. Pulmonary Airways & Vasculature • The lungs on the normal chest radiograph are made by pulmonary vessels, the bronchi are normally not seen. • This is because: • Pulmonary vessels are blood-filled with density similar to water. • Bronchi are filled with air and normally have thin walls that do not provide contrast to aerated lungs.

  45. Pulmonary Airways & Vasculature • When lung parenchyma fill with water or inflammatory material: • Water-density vessels become less distinct. • Air-filled bronchi can be seen as “air bronchograms”. • If airways are obstructed (e.g., tumor) they may fill with fluid and no “air bronchograms” will be appreciated.

  46. How do these two radiographs differ?

  47. How do these two radiographs differ? Abnormal indistinct vasculature Normal well-defined vessels

  48. In the normal chest radiograph only airways within the mediastinum are apparent. Trachea Trachea Left mainstem bronchus Right mainstem bronchus Left mainstem bronchus

  49. What is the source of this man’s chronic cough?

  50. What is the source of this man’s chronic cough? Unilateral lung opacification with ipsilateral tracheal shift from the pressure differential helps identify RUL collapse Obstruction RUL Horizontal fissure Tented right hemidiaphragm Inferior pulmonary ligament tethering the lobe and tenting the diaphragm Right upper lobe collapse secondary to obstruction of the bronchus by squamous cell carcinoma.

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