Chest X-Ray Interpretation for the

InternistTheresa Cuoco, MD

Medical University of South CarolinaFebruary 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 noninvasiveRelatively inexpensive

ObjectivesBasics of technique

Type of film and the “tions”Identification of structures on a “normal” CXRAlveolar vs interstitial, lobar anatomy, silhouette

sign, air bronchograms, and patterns of lung diseaseThe mediastinum, pleura, and heartSystematic approach to interpretationCases

TechniquePA and lateral AP Which is preferred and why?Lateral film – left side of chest against x-ray

cassetteDecubitus films

Which is which?

The “tions”IdentificaTIONInspiraTIONPenetraTIONRotaTION

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 InterstitialAlveolar = 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 SignThere are 4 basic radiographic densities

Gas, fat, soft tissue (water), and metal (bone)Anatomic structures are recognized on x-ray by

their density differencesTwo 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 LesionsObscured L heart border = lingulaAortic knob obliterated = left upper lobeRight lung base w heart border seen = right lower lobeRight lung base w heart obscured = right middle lobeDescending aorta obscured = left lower lobeEXCEPTIONS:

Pseudosilhouette of diaphragm in underpenetrated film Right heart border my overlap spine Heart obscures anterior left diaphragm on lateral

The Air BronchogramWhen lung is consolidated and bronchi contain air,

the dense lung delineates the air-filled bronchiVisualization of air in the intrapulmonary bronchi

is called the “air bronchogram sign”Abnormal findingCan be seen in:

PNA, edema, infarctionChronic lung lesions

NO Air Bronchograms…In pneumonia if bronchi are filled with secretionsIf cancer obstructs a bronchusInterstitial fibrosisAsthma/emphysema (hyperinflation)

What do you see?

Lung and Lobar CollapseWhen a whole lung collapses, the trachea

deviates TOWARD the side of collapse (due to volume loss)

Fissures Formed by 2 visceral pleural layersDemarcate the boundaries of the lobesShift 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 DisplacementThe left hilum is normally slightly higher than the

rightHilar depression indicates collapse of lower lobeHilar elevation indicates collapse of upper lobe

Patterns of Lung Disease PearlsPulmonary markings are more visible in interstitial

diseaseGeneralized interstitial markings = linear (reticular)Discrete/focal thickening = nodularHomogeneous or patchy consolidation = alveolarFocal consolidation < 3cm = noduleFocal consolidation > 3cm = massHeavy 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 PleuraThe posterior costophrenic angle is the deepest

and only seen on the lateral filmThe lateral film is more sensitive for detection of

small pleural effusionsHow 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 HeartThe 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