Basic Chest X-Ray Interpretation

Adam Guttentag, M.D.

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The Lateral Chest Film
Find abnormalities hidden on the frontal film
Confirm abnormalities suspected from frontal film
Don’t be afraid to look at it!

Looking at the lateral CXR

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Technical Factors
Positioning
straight vs oblique

Effect of obliquity on heart size

Technical Factors
Positioning
straight vs oblique
PA vs AP

Technical Factors
Positioning
straight vs oblique
PA vs AP
erect vs supine

Technical Factors
Positioning
straight vs oblique
PA vs AP
erect vs supine
lordotic vs kyphotic

Technical Factors
Positioning
straight vs oblique
PA vs AP
erect vs supine
lordotic vs kyphotic

Technical Factors
Depth of inspiration
Visualization of pathology depends on contrast provided by air in the lungs
Count ribs!

Short of breath

Technical Factors
Body habitus

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Recognizing air space disease
Alveolar spaces filled with…something.
Radiologist's report:
“consolidation”
“air space opacity”
“fluffy density”
“infiltrate”
Nonspecific:
Atelectasis, pneumonia, bleeding, edema, tumor

The Silhouette Sign
Indicates air space disease.
Obscuration of a normally seen border, e.g. diaphragm or heart.
Opacity with sharp edge along a fissure.

Localizing disease from the silhouette sign

Localizing disease from the silhouette sign

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Lobar Atelectasis
Best sign – shift of a fissure
Rapid development and clearance
Air bronchograms if non-obstructive
Secondary signs:
Mediastinal shift
Elevated diaphragm
Ribs closer together
Vague increased density

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Pneumonia
Signs:
Air bronchogram
Silhouette - “positive” or “negative”
Dense hilum
“Spine” sign
All are signs of any air space process
Dx of pneumonia depends on appropriate clinical scenario.

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Air bronchograms — CT

Right middle lobe

Right upper lobe

Right lower lobe

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Final Exam

21 y.o. with fever and cough

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Take home message #1
It’s a chest x-ray,
not a lung x-ray.

6 cm lung mass missed. How?

Take home message #2
Old films are your friend!

Elderly man with hypotension

Suddenly septic

Pneumatosis of small bowel

Take home message #3
The patient pays for
the whole film!

Review Questions

All are kinds of air space disease except:
Hemorrhage
Pneumonia
Tumor
Sarcoidosis
Atelectasis

The most specific sign of atelectasis is:
Obscuration of a diaphragm
Shift of a fissure
Air bronchograms
Density over the spine
Mediastinal shift

This can make the heart look larger than it is:
Lordotic positioning
AP positioning
Expiratory film
Supine positioning
All of the above

Additional Reading
Chest Roentgenology  Felson, B W.B. Saunders Co, Philadelphia 1973 Chapter 2: Localization of Intrathoracic Disease.  pp 22-70.
Pare JAP and Fraser RG Synopsis of Diseases of the Chest W.B. Saunders Co, Philadelphia 1983. Chapter 4: Roentgenologic Signs in the diagnosis of Chest Disease. pp164-187.

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