Chest X-Ray Interpretation for the Internist

1. Chest X-Ray Interpretation for the Internist Theresa Cuoco, MD Medical University of South Carolina February 22, 2012

2. Disclaimer: I am NOT a radiologist!

3. Why do we need to know? • To direct care while awaiting an “official read” • Low level radiation for the patient • Easily available and noninvasive • Relatively inexpensive

4. Objectives • Basics of technique • Type of film and the “tions” • Identification of structures on a “normal” CXR • Alveolar vs interstitial, lobar anatomy, silhouette sign, air bronchograms, and patterns of lung disease • The mediastinum, pleura, and heart • Systematic approach to interpretation • Cases

5. Technique • PA and lateral • AP • Which is preferred and why? • Lateral film – left side of chest against x-ray cassette • Decubitus films

6. Which is which?

7. The “tions” • IdentificaTION • InspiraTION • PenetraTION • RotaTION

8. Inspiration vs Expiration Any indications for an expiratory film?

9. Penetration A B • Heavy light exposure causes the film to be black (A) • Little light exposure causes the film to be white (B)

10. Rotation

11. Normal Anatomy

12. The Normal Chest X-Ray

13. Alveolar vs Interstitial • Alveolar = air sacs • Radiolucent • Blood, mucous, tumor, or edema in alveoli obscure normal anatomy: “airless lung” • Interstitial = vessels, lymphatics, bronchi, and connective tissue • Radiodense • Interstitial disease: prominent lung markings with aerated lungs

14. Lobar Anatomy Posterior Anterior

15. Lobar Anatomy – Lateral Views Right Left

16. The Silhouette Sign • There are 4 basic radiographic densities • Gas, fat, soft tissue (water), and metal (bone) • Anatomic structures are recognized on x-ray by their density differences • Two substances of the same density in direct contact can’t be differentiated • Loss of the normal radiologic silhouette (contour) is called the “silhouette sign”

17. Localizing Lesions Where is the silhouette sign?

18. Localizing Lesions

19. Localizing Lesions A B

20. Localizing Lesions A B

21. Localizing Lesions • Obscured L heart border = lingula • Aortic knob obliterated = left upper lobe • Right lung base w heart border seen = right lower lobe • Right lung base w heart obscured = right middle lobe • Descending aorta obscured = left lower lobe • EXCEPTIONS: • Pseudosilhouette of diaphragm in underpenetrated film • Right heart border my overlap spine • Heart obscures anterior left diaphragm on lateral

22. The Air Bronchogram • When lung is consolidated and bronchi contain air, the dense lung delineates the air-filled bronchi • Visualization of air in the intrapulmonary bronchi is called the “air bronchogram sign” • Abnormal finding • Can be seen in: • PNA, edema, infarction • Chronic lung lesions

23. NO Air Bronchograms… • In pneumonia if bronchi are filled with secretions • If cancer obstructs a bronchus • Interstitial fibrosis • Asthma/emphysema (hyperinflation)

24. What do you see?

25. Lung and Lobar Collapse • When a whole lung collapses, the trachea deviates TOWARD the side of collapse (due to volume loss)

26. Fissures • Formed by 2 visceral pleural layers • Demarcate the boundaries of the lobes • Shift of fissures is best sign of lobar collapse

27. Which lobes have collapsed? Minor fissure is elevated – RUL partially collapsed Heart has moved to right and silhouette sign of right diaphragm – indicated RLL collapse

28. Hilar Displacement • The left hilum is normally slightly higher than the right • Hilar depression indicates collapse of lower lobe • Hilar elevation indicates collapse of upper lobe

29. Patterns of Lung Disease Pearls • Pulmonary markings are more visible in interstitial disease • Generalized interstitial markings = linear (reticular) • Discrete/focal thickening = nodular • Homogeneous or patchy consolidation = alveolar • Focal consolidation < 3cm = nodule • Focal consolidation > 3cm = mass • Heavy calcification generally = benign

30. What is the pattern? A: Focal/linear B: Diffuse/nodular C: Alveolar

31. The Mediastinum

32. The Mediastinum • I: Anterior Mediastinum • Heart • Retrosternal clear space • 5 T’s • II: Middle Mediastinum • Esophagus • Arch and descending aorta • Trachea • III: Posterior Mediastinum • Paravertebral area • Lymph nodes in all 3!

33. The Pleura • The posterior costophrenic angle is the deepest and only seen on the lateral film • The lateral film is more sensitive for detection of small pleural effusions • How much fluid can be seen on a radiograph? • Erect PA: 175 mL • Erect lateral: 75 mL • Decubitus: >5 mL • Supine: Several hundred mL

34. What do you see?

35. The Heart • The horizontal width of the heart should be less than ½ the widest internal diameter of the thorax

36. Left and Right Ventricular Enlargement • Left ventricular enlargement • Frontal: LHB moves laterally and cardiac apex inferolaterally • Lateral: LHB moves inferoposteriorly • Right ventricular enlargement • Frontal: RHB further right • Lateral: Contacts lower half of sternum (instead of lower 3rd)

37. Cephalization • Enlargement of the upper lobe vessels • “Vascular redistribution” • “Kerley B” lines: interstitial edema thickening the interlobular septa causing short lines perpendicular to the pleural surface

38. Systematic approach • ABCDE • Airway • Bones and breasts • Cardiac and costophrenic • Diaphragm • Edges and extrathoracic • Fields (lung fields and failure) • ATMLL (“Are There Many Lung Lesions?”) • Abdomen • Thorax – bones and soft tissues • Mediastinum • Lungs – unilateral and bilateral

39. Cases

40. Young man with cancer

41. Young man without symptoms

42. ICU patient with fever, WBC

43. Two older women with cough

44. Dyspnea with sudden CP & fever