Chest X-Ray Interpretation for the

InternistTheresa Cuoco, MD

Medical University of South Carolina

February 22, 2012

Disclaimer: I am NOT a radiologist!

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

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

Technique

PA and lateral

AP

Which is preferred and why?

Lateral film – left side of chest against x-ray cassette

Decubitus films

Which is which?

The “tions”

IdentificaTION

InspiraTION

PenetraTION

RotaTION

Inspiration vs Expiration

Any indications for an expiratory film?

Penetration

Heavy light exposure causes the film to be black (A)Little light exposure causes the film to be white (B)

A

B

Rotation

Normal Anatomy

The Normal Chest X-Ray

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

Lobar Anatomy

Anterior Posterior

Lobar Anatomy – Lateral Views

Right Left

The Silhouette Sign

There are 4 basic radiographic densitiesGas, 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”

Localizing Lesions

Where is the silhouette sign?

Localizing Lesions

Localizing Lesions

A B

Localizing Lesions

A B

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

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, infarctionChronic lung lesions

NO Air Bronchograms…

In pneumonia if bronchi are filled with secretions

If cancer obstructs a bronchus

Interstitial fibrosis

Asthma/emphysema (hyperinflation)

What do you see?

Lung and Lobar Collapse

When a whole lung collapses, the trachea deviates TOWARD the side of collapse (due to volume loss)

Fissures Formed by 2 visceral pleural layers

Demarcate the boundaries of the lobes

Shift of fissures is best sign of lobar collapse

Which lobes have collapsed?

Minor fissure is elevated – RUL partially collapsedHeart has moved to right and silhouette sign of right diaphragm – indicated RLL collapse

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

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

What is the pattern?

A: Focal/linear B: Diffuse/nodular C: Alveolar

The Mediastinum

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!

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 mLErect lateral: 75 mL Decubitus: >5 mLSupine: Several hundred mL

What do you see?

The Heart

The horizontal width of the heart should be less than ½ the widest internal diameter of the thorax

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)

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

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

Cases

Young man with cancer

Young man without symptoms

ICU patient with fever, WBC

Two older women with cough

Dyspnea with sudden CP & fever