Principles of Chest X-Ray Interpretation

1. Principles ofChest X-Ray Interpretation Dr Rod Taylor Consultant Respiratory Physician

2. Different from us….

3. Only Two Choices Hmmn! There are far too many white bits! That’s funny - this one’s got too many black bits!

5. Chest X-ray P = important radiological principle

6. The Normal CXR Vertebral spines equidistant Horizontal fissure Left hilum Cardiophrenic angle Descending aorta Right diaphragm Costophrenic angle

7. It’s All Relative… 1 P Stupid humans…

8. Why Does It Show Up? Because there is something of a different radiological density next to it. Four main densities: P

9. Étienne de Silhouette The silhouette sign If a structure shows up, there must be adjacent to it something of a different radiological density. If a structure does not show up, there must be adjacent to it something of a similar radiological density. Controller-General of Finances during the Seven Years War (1754 – 63)

10. Silhouetted Hills This one doesn’t This hill shows up

11. Rotation PA

12. The Lobes Front Back

13. Lateral View (Right) Oblique fissure Upper Lobe Apical segment of lower lobe Middle Lobe Lower Lobe Horizontal fissure Heart Vertebral bodies appear to darken

14. Lateral View (Left) No fissure (normally) Upper Lobe Oblique fissure Lingula Lower Lobe Heart

15. Naming of Segments Apical Medial Anterior Posterior Lateral

16. Don’t Forget…. The bones Has this patient had a chest x-ray? Oh, good, then I can start! Gas under the diaphragm

17. It’s All Relative… 2 Too White? Too Black? Normal CXR P Look for collateral evidence

18. What Do You See? The most obvious abnormality is likely to be the primary event. Other, more subtle, changes are likely to be secondary to this. P

20. The Man in the Street Dryclough Lane Er, there’s a white bit on the right… at the top… um… which comes… ooh, about halfway down… with a sharp, um, line, at the bottom…

21. Right Upper Lobe Consolidation

22. The ‘Pair of Scissors Sign’ P If you could cut along a line seen on a CXR with a pair of scissors - think of a pleural boundary or fissure.

23. Interlobar Effusion

25. Right Upper Lobe Collapse Horizontal fissure is pulled up, producing a sharply-defined RUZ opacity. Trachea is pulled to the right. Right hilum is pulled upwards. Right hemidiaphragm may be pulled up.

26. Fissure extends medial to hilum Vertebrae get whiter Diaphragm indistinct Diaphragm disappears

27. Right Lower Lobe

28. Right Lower Lobe Collapse

29. Horizontal fissure Oblique fissure

32. Horizontal fissure

33. Middle Lobe Collapse

36. Right M & LL Collapse Oblique fissure Horizontal fissure

38. Displaced oblique fissure Overinflated lower lobe Tongue of collapsed upper lobe Elevated left diaphragm

39. Left Upper Lobe Collapse Overinflated left lower lobe

40. Collapse Consolidation

41. What is it?

43. “Radiological Homeostasis” If a structure is displaced on a CXR, then something else will happen to compensate for that displacement. Example: collapse of one lobe  overinflation of another P

44. If a Structure is Displaced P Pulled out of place Look for collateral evidence Pushed out of place

45. Left heart border indistinct

46. Oblique fissure Left heart border visible Diaphragm indistinct

47. Descending aorta indistinct Triangular opacity Diaphragm indistinct

48. Collapsed Left Lower Lobe Descending aorta Diaphragm visible

50. Left Lower Lobe Collapse