Introduction to Radiographic Interpretation Special Emphasis on CXRs

2. Introduction to Radiographic InterpretationSpecial Emphasis on CXRs

3. Differential Absorption of X-rays • Dependent upon • Physical density • Atomic number • Thickness • Determine the gray scale of the radiograph • Absorb few x-rays = film black many x-rays = film white

4. Five Radiographic Opacities Air Fat Soft tissue Bone Metal least opaque to most opaque most lucent to least lucent Black to White

5. Radiographic Opacities & Contrasts Air Air Fat Mineral oil Water Water Bone Tums Metal ???

6. Five Radiographic Opacities

7. Five Radiographic Opacities

8. Standard Radiographic Positions

9. Standard Radiographic Positions

10. Standard Radiographic DirectionsAs seen when viewing Dorsal Proximal Cranial Cranial Rostral Dorsal Right Caudal Palmar Plantar Left Ventral Distal Caudal

11. Radiograph: two-dimensional image of a three-dimensional object So . . . What is it? Lateral view Cranial-caudal view

12. Radiograph: two-dimensional image of a three-dimensional object So . . . What is it? Dorsoventral view

13. Interpretation Challenges • Magnification • Distortion • Image of a familiar object is unfamiliar • Loss of depth perception • Summation • Silhouette effect

14. Interpretation Challenges:Magnification • Enlargement of the radiographic image of an object relative to its actual size • Increased film-subject distance

15. Interpretation Challenges:Magnification

16. Interpretation Challenges:Magnification

17. Interpretation Challenges:Distortion • Distortion:Misrepresentation of the true shape of an object

18. Interpretation Challenges:Unfamiliar image of a familiar object

19. Interpretation Challenges:Depthperception

20. Interpretation Challenges:Summation • Superimposition of structures in different planes • Resultant image = summation of opacities

21. Interpretation Challenges:Summation

22. Interpretation Challenges:Silhouette Effect • Two structures of the same radiopacity in contact – their margins cannot be identified

23. Interpretation Challenges:Silhouette Effect

24. Interpretation Challenges:Silhouette Effect

25. CXR InterpretationHave a system!! • Method 1: “Outside-to-inside” • Soft tissues • Bony framework • Lungs & hila • Diaphragm & pleura • Mediastinum & heart • Method 2: “Are There Many Lung Lesions?” • Abdomen & diaphragm • Thorax • Mediastinum & heart • Lung (single) • Lungs (both)

26. CXR InterpretationHave a system!! T • Method 1: “Outside-to-inside” • Soft tissues • Bony framework • Lungs & hila • Diaphragm & pleura • Mediastinum & heart • Method 2: “Are There Many Lung Lesions?” • Abdomen & diaphragm • Thorax • Mediastinum & heart • Lung (single) • Lungs (both) L L M A

29. CXR InterpretationBeware the poor-quality film!! • Poor inspiration • High diaphragms, crowded lung markings • “Penetration”: • Disappearing thoracic vertebral details through the heart. • Rotation: • Note equal distances from the vertebral spines to the medial ends of the clavicles.

30. CXR InterpretationBeware the poor-quality film: Inspiration

31. CXR InterpretationNormal structures visible • Tracheal air column. • Carina. • First rib. • Peripheral lung fields have no markings except: • The minor fissure. • Top of the R diaphragm is usually between the anterior 6th & 7th ribs, and overlying the posterior 10th & 11th ribs. • Left diaphragm is lower (in 90-95%) by roughly half an interspace. • Inferior margins of the posterior ribs. • Anterior mediastinal line. • Superior vena cava. • Azygous vein. • Right descending pulmonary artery. • Pulmonary arteries and veins. • Right atrium. • Inferior vena cava. • Aortic arch. • Left pulmonary artery. • Border of the left ventricle. • Descending aorta. • Fat density lines in the intermuscular fascial layers

32. CXR InterpretationNormal structures visible • Costophrenic angle • Diaphragm • Heart • Aortic arch • Trachea • Hilum • Main carina • Stomach bubble • Ascending aorta

33. CXR InterpretationNormal structures visible • Costophrenic angle • Diaphragm • Heart • Aortic arch • Trachea • Hilum • Main carina • Stomach bubble • Ascending aorta

34. CXR InterpretationNormal structures visible • Tracheal air column. • Carina. • First rib. • Peripheral lung fields have no markings except: • The minor fissure. • Top of the R diaphragm is usually between the anterior 6th & 7th ribs, and overlying the posterior 10th & 11th ribs. • Left diaphragm is lower (in 90-95%) by roughly half an interspace. • Inferior margins of the posterior ribs. • Anterior mediastinal line. • Superior vena cava. • Azygous vein. • Right descending pulmonary artery. • Pulmonary arteries and veins. • Right atrium. • Inferior vena cava. • Aortic arch. • Left pulmonary artery. • Border of the left ventricle. • Descending aorta. • Fat density lines in the intermuscular fascial layers

35. CXR InterpretationPA vs. AP views

36. CXR InterpretationPA & Lateral views

37. CXR InterpretationHyperexpansion = “Air Trapping”

38. CXR Interpretation“Big Lungs” & “Little Lungs”

39. CXR InterpretationInterstitial Infiltrates • Generalized interstitial thickening = linear (“reticular”). • Discrete interstitial thickening = nodules. • Interstitial & alveolar filling = silhouette.

40. CXR InterpretationInterstitial Infiltrates

42. CXR InterpretationInterstitial Infiltrates

44. CXR InterpretationAlveolar Infiltrates Alveolar-filling, or “airspace” disease: “Pointillist” patterns. Air bronchograms.

45. CXR InterpretationAlveolar Infiltrates