Chest X-Ray Interpretation for the

InternistTheresa Cuoco, MD

August 2, 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

Initial basics and type of filmIdentification of structures on a “normal” CXRAlveolar vs interstitial, lobar anatomy, silhouette

sign, air bronchograms, and patterns of lung disease

The mediastinum, pleura, and heart

The Basics (“the TIONS”)IdentificaTIONInspiraTIONPenetraTIONRotaTION

Inspiration vs. Expiration

Indications for an expiratory film?-To detect pneumothorax or look for air trapping (would remain inflated and black instead of white)

Penetration

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

A

B

Rotation

TechniquePA and lateral AP Which is preferred and why?

Less magnification, sharper imagesBetter inspiratory effort, pleural fluid and air easier

to see

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

Decubitus films

Which is which?

More magnification, dull images, poor inspiratory effort

Crisp CPA

Normal Anatomy

A. CPAB. Left diaphragmC. HeartD. Aortic knobE. Trachea

F. HilumG. CarinaH. Stomach bubbleJ. Ascending aorta

The Normal Chest X-Ray

A. Gas in splenic flexure B. CPA C. Heart D. Descending aorta E. Trachea F. Carina G. Hilum H. Aortic knob J. Ascending aorta K. Right diaphragmThe left hilum is slightly higher than the right – this is normal

Alveolar vs. InterstitialAlveolar = air sacs

Radiolucent Can contain blood,

mucous, tumor, or edema (“airless lung”)

Interstitial = vessels, lymphatics, bronchi, and connective tissue Radiodense Interstitial disease:

prominent lung markings with aerated lungs

Lobar Anatomy

Anterior Posterior

The fissure has to be parallel to the x ray beam for it to be seen on the film.The oblique (major) fissures are not visible on the normal frontal projection

Right: Upper, middle, lowerLeft:Upper and lower

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?• Obscured right heart border• Right middle lobe infiltrate

Localizing Lesions

You can still see right heart border

Localizing Lesions

A: lost heart border = lingular B: lost hemidiaphragm = LLL

Localizing Lesions

A: loss of right hilum; ascending aorta B: lost aortic knob

Localizing Lesions: ReviewAscending aorta, upper R heart border = RULR heart border = RMLR anterior hemidiaphragm = RLLAortic knob = LULL heart border = lingulaL anterior hemidiaphragm or descending aorta =

LLL

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)

Left lung consolidated and collapsed

Fissures Formed by 2 visceral pleural layersDemarcate the boundaries of the lobesShift of fissures is best sign of lobar collapse

Minor fissure shifts up: RUL collapseMinor fissure shifts down: RML collapseMajor fissures shift down: LL 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

The Mediastinum

A. Ascending aorta B. Aortic knob C. Descending aorta D. R heart border E. SVC F. R tracheal wall G. L heartX. retrosternal clear space

Outside mediastinum:L. L pulmonary artery R. R pulmonary artery

The Mediastinum I: Anterior Mediastinum

Heart Retrosternal clear space 4 T’s

II: Middle Mediastinum Esophagus Arch and descending aorta Trachea

III: Posterior Mediastinum Paravertebral area; most

masses neurogenic

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?

Pneumothorax

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 awayClinical signs: rapid onset respiratory failure, decreased breath sounds, deviated trachea, JVD

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

AirwayBones and breastsCardiac and costophrenicDiaphragmEdges and extrathoracicFields (lung fields and failure)

Cases

Young man with cancer

Osteosarcoma w Pulmonary Met

Metal nipple markers have been placed1. pulmonary nodule below right nipple marker where ribs cross2. Right shoulder amputated: pulmonary met from osteosarcoma

Young man without symptoms

Anterior Mediastinal Mass

Strange cardiomediastinal shape on left - causes silhouette of left atrium ,pulmonary artery, and aortic archLateral shows density in retrosternal clear space

Dyspnea with sudden CP & fever

Heart Failure and Perf Ulcer

Cephalization, enlarged heart, free air