Download Chest X Rays

Chest X Rays: Interpretation
DRSABCDE
D – Details (patient name, DOB, date, film type, orientation, supine/erect)
R – RIPE image (rotation, inspiration, picture, exposure (penetration))
S – soft tissue
A – airways (trachea, bronchi)
B – bones
C – cardiac (size, position, shape, borders)
D – diaphragm
E – equipment (ETT, ECG, oxygen, NG tube, PICC line, chest tube, pacemaker etc)
F – lung fields, pleura
G – gastric (bubbles, air under diaphragm)
H – hila and hardware
Quality assessment
- rotation: medial ends of the clavicles should be an equal distance from the spinous
processes of thoracic vertebrae
o If R clavicle closer  rotated to left, and vice versa
- inspiration: 5-7 ribs should be visible anteriorly (curly red ribs) or 9-10 posteriorly
(straight ribs that meet the spine)
o incomplete x-rays can lead to perceived cardiomegaly and exaggeration of
lung markings
- position: entire thoracic cage and lung fields should be visible
- exposure: vertebrae should be just visible behind the heart. under-exposed = too
white, over-exposed = too black
Normals
- L hilum higher than R (difference should be <2.5cm)
- R hemidiaphragm higher than L (because of liver, should be <3cm)
- Trachea central or slightly deviated to the right
o deviated by collapse (towards the lesion), tension (away from the lesion) or patient rotation
- Cardiothoracic ratio: maximal horizontal heart diameter/maximal horizontal chest diameter, should be <50%
- 3 lumps of left border of mediastinum (supinf): aortic knuckle, pulmonary outflow track, left ventricle
- Pulmonary vasculature less prominent higher up due to gravity
- Heart: 1/3 of diameter to the right of the thoracic vertebrae spinous processes, 2/3 to the left
- R heart border = right atrium; L heart border = left ventricle
- Lung fissures should not be visible – if so, it’s pathological
PA projection
-
conventional/standard
not always possible due to patient being too
unwell to stand
patient places arms around detector plate or
with hands on hips – ensures scapulae do not
overlap the lungs
AP projection
-
heart size exaggerated due to the heart being further from the detector
can be taken by mobile X-ray
scapulae are not retracted laterally
Consolidation - any pathologic process that fills the alveoli
with fluid, pus, blood, cells (including tumour cells) or other
substances resulting in lobar, diffuse or multifocal illdefined opacities.
Interstitial - involvement of the supporting tissue of the
lung parenchyma resulting in fine or coarse reticular (net
like) opacities or small nodules.
Nodule or mass - any space occupying lesion either
solitary or multiple.
Atelectasis - collapse of a part of the lung due to a
decrease in the amount of air in the alveoli resulting in
volume loss and resulting increased density.
Tracheal displacement
- Volume loss  pulls trachea to the same side as the pathology
o Causes: obstruction (mass in bronchus), compression (effusion/pneumothorax), contraction (previous
inflammation)
 Direct signs: displaced septa, increased radiodensity in affected lobe, crowding of vascular and
bronchial markings
- increased pressure/volume  pushes trachea to the contralateral side
- Causes: pneumothorax, pneumonectomy, atelectasis, pleural effusion, pleural fibrosis, space occupying lesions,
lymphomas
Hilar abnormalities
- bilateral hilar enlargement
o sarcoidosis, lymphoma, metastatic malignancy, infection (TB, IMN, Brucellosis, taxoplasmosis), SLE, RA
- uni/bilateral hilar enlargement
o lymphadenopathy
o hilar malignancy (e.g. small cell carcinoma)
o vascular disease (e.g. pulmonary hypertension or proximal pulmonary artery aneurysm)
- abnormal hilar position
o loss of volume in hemithorax  pulling of hilum
o increase in volume/pressure in hemithorax  pushing of hilum
Lung abnormalities
Consolidation
- alveoli filled with material:
o pus – pneumonia
o blood – haemorhhage, DIC
o water – pulmonary oedema, renal/liver failure, ARDS, near drowning
 ARDS = non cardiogenic pulmonary oedema – onset within 1 week. CXR: bilateral opacification
o cells – lymphoma, bronchioalveolar carcinoma
o protein – alveolar proteinosis, ARDS, fat emboli
- produces silhouette sign = loss of border between thoracic structures
o loss of R heart border  R middle lobe pathology (e.g. consolidation)
o loss of L heart border  lingular pathology (e.g. consolidation)
o loss of aortic knuckle  left upper lobe/middle mediastinum pathology
- consolidated lung becomes dense and white – if the larger airways are spared, they are relatively blacker (lower
density) = air bronchogram
- ARDS - bilateral, predominately peripheral, asymmetric consolidations with air bronchograms
Hyperlucency
- due to alveolar distension (air retention) and/or reduced arterial flow
- causes: pneumothorax, obstructive emphysema, PE
Lung masses
Solitary pulmonary nodule
- malignancy – primary lung cancer, metastasis
- benign – granuloma (80%), hamartoma (10%), pulmonary infarct (late stage: wedge shape pleural based
opacification), AV malformation
Cavitary lung lesions
- abscess (typically thick walls and may have air/fluid levels)
- TB (usually upper lobe)
- carcinoma
- Wegener’s granulomatosis (smaller lesions, can be multiple)
- metastatic cancer (typically thin walled, may have a variable appearance)
- septic emboli (smaller lesions)
Pleural disease
Pneumothorax = air/gas in pleural space
- a pneumothorax may be identified by a discrete shadowed line beyond which no lung markings are present
o most commonly occur in the lung apices, which are the least dependent part of the lung
o expiratory projections make a pneumothorax more obvious (expiration  reduced lung volume 
increased density of parenchyma  makes the distinction clearer)
- tension pneumothorax = the accumulation of air under pressure in the pleural space
o develops when injured tissue creates a one-way valve for air to enter, but not leave, the pleural space.
o ipsilateral lung collapse with widened intercostal spaces and contralateral tracheal/mediastinal deviation
o With a left pneumothorax, the left hemidiaphram may be depressed, but the liver prevents this from
developing on the right side.
Hydropneumothorax
- air and fluid within pleural space
- oesophageal rupture, trauma, infection with gas forming organism, bronchopleural fistula, iatrogenic after surgery
- horizontal air fluid level that extends across the whole length of the hemithorax
Pleural effusion = collection of fluid in pleural space
- settles with gravity
- causes blunting of the costophrenic angles and hemidiaphragm if the patient is erect
- meniscus sign = concavity of fluid surface
Pleural thickening
- unilateral – malignant mesothelioma (can be either plaque or nodular; caused by asbestos exposure), empyema,
trauma, post-op scarring, metastatic disease
o Malignant mesothelioma = primary pleural neoplasm
 well circumscribed, homogeneous soft tissue mass closely related to pleura
 shadowing over whole lung due to circumferential pleural thickening

Lesions may be found anywhere along the lung periphery (shown), pulmonary fissures,
mediastinum, or diaphragm.
 Large lesions may be confused for lobar consolidation
- bilateral – metastases, trauma, asbestosis
Pleural plaques
- calcified plaques due to asbestos exposure with peripheral pleural thickening
- bilateral well defined irregular shadows as dense as bone
Diaphragmatic abnormalities
Loss of diaphragmatic outline
- fluid, consolidation or collapse of adjacent lung (i.e. R/L lower lobe)
Pneumoperitoneum
- = free gas under diaphragm = rupture of abdominal hollow viscus (e.g. bowel perforation)
- crescents of relatively low density (black) under diaphragm
Raised hemidiaphragm
- causes: lung volume loss, damage to the phrenic nerve, diaphragmatic hernia, trauma
Hyperexpansion – COPD
- >7 ribs visible, bilateral flattening of hemidiaphragms, narrowing of heart (decreased cardiothoracic ratio),
prominent lower zone markings, blunting of costophrenic angles
- Emphysema
o hyperinflation + bullae present
Heart contour abnormalities
Increased cardiothoracic ratio (cardiomegaly)
- ventricular dilatation (usually left)
- atrial enlargement
o LA enlargement  splaying of the carina to >90 degrees (the carina lies directly above the left atrium)
- cardiac failure
o look for other signs of heart failure
 ABCDE of cardiac failure:
 A – alveolar batwinging (pulmonary oedema)
 B – Kerley B lines (pulmonary oedema)
 C – cardiomegaly
 D – distribution of vasculature increased in upper lobes
 E – pleural effusion
- left ventricular aneurysm
o uncommon complication of MI
o bulging left heart border with a circular rim of calcification
- pericardial effusion
- pneumopericardium
o caused by ruptured alveoli (in pneumothorax), tracheobronchial rupture, oesophageal rupture, blunt chest
trauma
 continuous diaphragm sign – diaphragm continuous crossing spine
Pulmonary oedema
- Pulmonary oedema: 3 stages
o 1 – pulmonary venous congestion (= upper lobe diversion)
 normally: veins higher more wispy, those lower thicker (due to gravity)
 pulmonary venous congestion: “juicy, fat” veins in upper zones
o 2 – interstitial oedema
 transudate from pulmonary veins seeps into interstitial spaces
 Kerley B lines
o 3 – alveolar oedema
 looks like airspace disease – fluffy white opacification with loss of hemidiaphragms and heart
borders in pattern of ‘bat wings’
 looks the same as pneumonia superimposed on interstitial oedema
 airspace disease will disappear quickly with diuretic therapy
- Kerley B lines (fluid leaking into interlobular septae) = short 1-2cm white horizontal lines near costophrenic
angles, running perpendicular to the pleura
- bilateral increased lung markings classically perihilar and shaped like bats wings
- Kerley A lines - longer (at least 2cm and up to 6cm) unbranching lines coursing diagonally from the hila out to the
periphery of the lungs. Caused by distension of anastomotic channels between peripheral and central lymphatics
of the lungs. Kerley A lines are less commonly seen than Kerley B lines. Kerley A lines are never seen without
Kerley B or C lines also present.
- Kerley C lines - the least commonly seen of the Kerley lines. They are short, fine lines throughout the lungs, with
a reticular appearance. They may represent thickening of anastomotic lymphatics or superimposition of many
Kerley B lines.
Mediastinal abnormalities
Widened mediastinum
- AP CXR view
- unfolded aortic arch (not pathological)
- thoracic aortic aneurysm
- mediastinal lymphadenopathy
- mediastinal mass – 4 T’s – teratoma, teratodermoid cyst, thymoma, thyroid mass + paravertebral mass,
lymphoma
- retrosternal thyroid
- oesophageal dilatation
- ruptured aorta
- mediastinal emphysema (secondary to penetrating wound +/- lacerated lung, perforated oesophagus/trachea,
asthma or whooping cough (pneumomediastinum)
o pneumomediastinum = free air in mediastinum - most commonly occurs following trauma or iatrogenic
injury to the esophagus or adjacent alveoli
o On chest radiography free air may outline anatomic structures.
o Common findings are a thin line of radiolucency that outlines the cardiac silhouette (white arrow),
vertically oriented streaks of air in the mediastinum, a double bronchial wall sign, or lucency around the
right pulmonary artery, the "ring around the artery" sign.
o most easily detected retrosternally on lateral chest radiographs
- pericardial effusion
o accumulation of fluid within the pericardial space.
o enlarged cardiac silhouette – globular, water droplet shaped with loss of LA – LV notch
o If fluid accumulates rapidly, minimal cardiomegaly may be present.
o Other potential findings include pleural effusion and rarely pericardial calcifications.
o Pericardial effusion in an Asian patient - always think of TB.
o Other causes are uremia and metastatic carcinoma
Bone abnormalities
- Typical findings of acute osteomyelitis on plain radiographs
o soft tissue swelling, periosteal reaction, cortical irregularity, and demineralization.
- In chronic osteomyelitis, there is thick, irregular, sclerotic bone with radiolucencies and an elevated periosteum.
- Primary and metastatic cancer to the bones may be evident on chest radiographs.
- Boney lesions may be sclerotic or lytic and can give clues as to the etiology.
- Common malignancies giving rise to sclerotic metastasis:
o prostate cancer, breast cancer and lymphoma
- Common malignancies giving rise to lytic metastasis:
o renal cell cancer, multiple myeloma and thyroid cancer.
Soft tissue abnormalities
- surgical/subcutaneous emphysema (gas/air trapped in layer under skin)
o causes: trauma, pneumothorax, pneumopericardium, pneumomediastinum, iatrogenic, infection (skin
necrotising infections such as gangrene)