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
We need to have a basic knowledge of CXR interpretation

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
Mediastinum will cover anterior middle and posterior structures
Lungs: will cover lobar anatomy, silhouette sign, air bronchograms and patterns of lung disease
Also spend some time discussing the pleura
Airways, bones and breasts, cardiac and costophrenic diaphragm, edges and extrathoracic, fields lung fields and failure

5. Technique PA and lateral AP Which is preferred and why?
Lateral film – left side of chest against x-ray cassette
Decubitus films
PA and lateral – x-ray tube is 6 feet from film or detector
1. Less magnification 2. sharper images 3. better inspiratory effort and view of lungs 4. pleural fluid and air easier to see on erect film

6. Which is which?

7. The “tions” IdentificaTION InspiraTION PenetraTION RotaTION
Identification: make sure its your patient on particular day; male vs female; foreign objects
Inspiration: well inspired film you should be able to count 8 ribs…otherwise crowded lung markins, high diaphragms etc EXP film – to detect focal air trapping, may accentuate a PTX
Penetration- if not properly penetrated, xray can exaggerate or obliterate important findings…. You should be able to see thoracic vertebrae behind heart
Rotation: equal distance from vertebral spines to medical ends of clavicles.

8. Inspiration vs Expiration
Indications for expiratory film – to look for air trapping – In a film that would normally get whiter with expiration, the area would remain inflated and black; also to detect a pneumothorax
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
A costophrenic angle B left diaphragm C heart D aortic knob E trachea F hilum G carina H stomach bubble J ascending aorta

12. The Normal Chest X-Ray
A gas in splenic flexure B costophrenic angle C heart D descending aorta E trachea F carina G hilum H aortic knob J ascending aorta K right diaphragm
The left hilum is slightly higher than the right – this is normal

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
Interstitium is essentially branching pulmonary arteries

14. Lobar Anatomy Anterior Posterior
The fissure has to be parallel to the x ray beam for it to be visible on the film – therefore the oblique (major) fissures are not visible on the normal frontal projection

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?
RML Pneumonia with obscured right heart border
Where is the silhouette sign?

18. Localizing Lesions
Right lower lobe infiltrate

19. Localizing Lesions
A Left lingular infiltrate B left lower lobe infiltrate A B

20. Localizing Lesions
A. Right upper lobe infiltrate B left upper lobe patchy infiltrate 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
If the heart is positioned slightly to the left, the right heart border may overlap the spine

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?
Left lung consolidated and collapsed – trachea shifted toward that side; heart shifted left

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
Can review in detail each of these diagrams 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
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
C= alveolar filling disease
A: Focal/linear
B: Diffuse/nodular
C: Alveolar

31. The Mediastinum
A = ascending aorta B aortic knob C descending aorta D right heart border E superior vena cava F right tracheal wall G left heart
A ascending aorta B aortic knob C descending aorta D right heart G left heart {L left pulmonary artery and R right pulmonary artery – outside the mediastinum}
X= retrosternal clear space

32. The Mediastinum I: Anterior Mediastinum II: Middle 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!
Anterior mediastinal compartment – heart and retrosternal clear space – teratoma, thymoma, thyroid, terrible lymphoma, and thoracic aorta
Middle mediastinum – esophagus, lymph nodes, arch and descending aorta, trachea
Posterior mediastinum is the paravertebral area

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
Anterior, posterior and lateral costophrenic angles
Erect PA = 175 mL Lateral = 75 ml decubitus = >5 mL Supine = several hundred mL

34. What do you see?
Air enters pleural space with each breath but cant escape, increasing intrapleural pressure – increased pressure depresses the diaphragm, collapses the lung, and shifts the mediastinum away
Clinical signs: rapid onset respiratory failure, decreased breath sounds, deviated trachea, JVD

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 ATMLL (“Are There Many Lung Lesions?”)
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
Airways, bones and breasts, cardiac and costophrenic diaphragm, edges and extrathoracic, fields lung fields and failure

39. Cases

40. Young man with cancer Metal nipple markers have been placed
Is the lung abnormal: pulmonary nodule below right nipple marker where ribs cross
Right shoulder amputated: pulmonary met from osteosarcoma

41. Young man without symptoms
Strange cardiomediastinal shape on left - causes silhouette of left atrium ,pulmonary artery, and aortic arch
Lateral shows density in retrosternal clear space

42. ICU patient with fever, WBC
Bilateral dense consolidation with air bronchograms, silhouette signs of diaphragms, blunt right costophrenic angle
Dx: Pneumonia
2ndradiograph – several hours later – developed tension PTX with air in pleural space, low right diaphragm, heart shifted to the left.

43. Two older women with cough
Both have alveolar consolidation RUL
What forms the sharp lower edges of their lesions? The minor fissure
Patient A has right pleural effusion and hilar mass and NO air bronchograms due to central obstruction
A= cancer B = PNA

44. Dyspnea with sudden CP & fever
Cardiac silhouette is enlarged; Pulmonary vessels are enlarged with cephalization and mildly indistinct
DX – mild left ventricular failure
Dx: free air under diaphragms (from perf ulcer) explains sudden chest pain and fever