Reading Chest Radiographs

Basics

Anterior-Posterior vs. Posterior-Anterior

AP exaggerates cardiac size

PA requires pt to stand

Look at the whole radiograph

Learn a system - do it the same EVERY time

System

A-B-C-D-E-F

A - Airway/lung fields

B - Bones/soft tissueC - Cardiac/mediastinumD - DiaphragmE - Examine TechniqueF - Foreign bodies

Lung Parenchyma

Classify disease into 3 categories

Airspace: alveolar filling

fluffy, opacities, air-bronchograms

Interstitial: lines and small dots

reticulonodular, reticular, nodular

Nodule: single or multiple, vary in size, w/ or w/o cavitation/calcification, smooth or irregular

Consolidation

Filling or loss of air spaces

Pus - Pneumonia

Fluid - Pulmonary edemaBlood - infarct, hemorrhageForeign body - aspirationTumor - bronchoalveolar carcinomaVolume loss - atelectasis

RML atelectasis

Consolidation

Radiographic signs

Opacity, air bronchograms, silhouetting

Silhouette sign: intrathoracic lesion touching border of heart, aorta, diaphragm obliterating that border

Helps to identify location of consolidation

Left HeartSilhouette sign

Consolidation

Silhouette sign:

What structure is silhouetted on PA?R heart = RMLL heart = lingulaAorta, diaphragm = Lower lobe

Lateral view: which diaphragm is silhouetted?

Fissure sign: abrupt edge @ margin

Increased density of vert. just above diaphragm on lateral

Collapse

Atelectasis - volume loss

Extrinsic compression (effusion, tumor, etc)

Airway obstruction

Extraluminal - tumor, LADIntraluminal - tumor, foreign body

Lobar collapse: mediatstinal shift to affected side, displacement of hilum/fissures, fewer vessels on affected side

Interstitial Pattern

Acute process:

Pneumonia - viral, fungal, Tb, PCP

Edema - CHF, Renal failure w/ overload

Drug/Transfusion reaction

Chronic: many etiologies

Normal/low lung volumes

Interstitial Pattern

Upper lobe predominant

Tb, pneumoconioses, fibrosis from ankylosing spondylitis

Mid lung predominant

sarcoid, berylliosis, allergic alveolitis, eosinophilic granulomatosis

Lower lung predominant

IPF, lymphangitic tumor spread, CVD fibrosis, chronic edema, drug rxn

Interstitial Pattern

Large Lung volumes: indicates air trapping

Cystic fibrosis

Eosinophilic granulomatosis

Lymhangioleiomyomatosis

Tuberous sclerosis

Pulmonary Nodule(s)Solitary Nodule: many etiologies

Primary lung tumor, mets, granuloma, septic emboli, pulmonary AVM, hamartoma, Wegener’s vasculitis, bronchiectasis, fungal infection, etc

Important features

Change over time: growing is worrisomeCalcification: eccentric is worrisomeSize: > 3cm more worrisome

Pulmonary Nodule(s)

Multiple Nodules

Metastatic until proven otherwiseseptic/bland embolivasculitides, CVDpneumoconiosesEosinophilic granulomatosisFungi, viral, Tb PNAWegener’sLymphoma

Cardiac Anatomy

Frontal view

Right atrium

SVC

Aortic knob

Left atrial appendage

Left ventricle

Lateral view

Right atrium/Ventricle

Left ventricle

Left atrium

Aortic arch

Main Pulm. Artery

Descending Thoracic Aorta

Cardiac Anatomy

On frontal CXR - 45% or less than largest diameter from inner aspect of rib to rib laterally

Right heart border - mostly RA

Left Border - Aortic arch, MPA, LAA, LV

Right Atrium - Right border >4cm from center of spine

Right Ventricle - fills retrosternal space >1/3 distance between diaphragm & sternomanubrial joint

Left Atrium - subcarinal angle >90 degrees, posterior deviation of left main stem bronchus

Left Ventricle - LV reaches spine prior to diaphragm

Atrial/Ventricular Hypertropy

Pulmonary Vasculature

Many potential patterns to help narrow differential for cardiac disease

3 you need to know

Normal - lower lobe vessels larger due to gravity, taper smoothly to periphery, interlobar arterial size (11-16mm M, 9-14mm F)

Pulmonary Vasculature

Pulmonary venous hypertension: upper lobe vessels larger “cephalization” result of hypoxic vasoconstriction; dependent edema

LV failure (ASCHD, valvular), atrial myxoma, PVOD

Pulmonary arterial hypertension: “pruning” or rapid tapering of peripheral vessels from large central arteries

Chronic venous HTN, COPD, Chronic PE, vasculitides, Primary PHTN, L-to-R shunt

Kerley A line

Mediastinum

Several compartments

Anterior: ant. = sternum, post. = pericardium

Middle: ant. = pericardium, post. = trachea

Posterior: ant. = trachea, post. = ribs

Don’t miss a widened mediastinum = could be an aortic aneurysm

Mediastinum

Masses by compartment

Anterior: “4T’s”

Teratoma

ThymomaTerrible tumor (lymphoma, mets)Thyroid - goiter

Middle:Aortic aneurysm

MediastinumLymph nodes - Lymphoma/Mets

Pericardial/bronchogenic cystPosterior:

AneurysmLymph nodesNeurogenic tumors - ganglion tumorSpine - osteophyteEsophagus - paraesophageal herniaSubsternal Thyroid

Pleural Abnormalities

Effusions: fluid

300-500cc to blunt CP angle on frontal150cc posterior to blunt CP angle on lateral

Free flowing or not?: obtain bilateral decubital films

Subpulmonic: lateral peaking of diaphragm, loss lung parenchyma below diaphragm

Pleural Abnormalities

Pneumothorax: air in pleural space

Apical or “deep sulcus”

Tension: flattened ipsilateral lung on mediastinum

MassesAngle w/ chest wall is obtuseCenter of MassWell defined margin only on 1 side

Pleural Abnormalities

ThickeningFocal: unilateral

usually from infection/hemorrhagePlaque from asbestosis - near diaphragms

Diffuse: unilateralSmooth: Old Tb, empyem, hemothorax, mesothelioma, mets, lymphoma

Nodular: same except Tb