CXR Flashcards
Which projection of CXR produces the best images of the thorax? What is the problem with this?
PA
Require patient to be able to stand/sit up straight
Why are AP CXRs less favourable for assessing the thorax?
magnification of heart size
position of scapulae
When might you perform an AP CXR?
In haemodynamically unstable pt
If a CXR isn’t marked with AP or PA, how can you tell which projection it is?
Scapulae are pulled almost out of lung fields in PA. Scapulae projected further in to the lungs
What are the key things that must be included in a CXR to make sure you have imaged full thorax?
both lung apices
Lateral sides of ribcage
both costophrenic angles
How do you assess the technical quality of a CXR?
RIP: rotation, inspiration and penetration
Rotation: heads of clavicles should be equidistant from the spinous processes of the vertebral bodies. If not = rotated
Inspiration: count down to lowest rib crossing through diaphragm - should show 6 anterior ribs or 10 posterior ribs.
Penetration: should be able to see vertebral bodies behind the heart
Under-penetrated = cannot see behind heart
Over-penetrated = see the vertebral bodies v. clearly
Why might an CXR be under-inspired?
Timing of X-ray (all X-rays taken at deep inspiration)
Pt. unable to take and hold a deep breath (due to pain, SOB or confusion)
What problems are there with interpreting an under-inspired CXR?
Crowding of lung markings at bases
Incorrectly giving impression of consolidation or other pathology
False impression of cardiomegaly
Why might a CXR be over-inflated?
airway obstruction eg. COPD
What might you see on a CXR that indicate hyperinflation?
More than desired no of ribs (6 anterior, 10 posterior)
FLATTENED DIAPHRAGM
What should you say about any obvious abnormalities you’ve spotted on a CXR?
Describe them:
Lung
Lobe/zone
Size
Shape (focal/diffuse, round/spiculated, well/poorly demarcated)
Density (compared to other surrounding tissue eg. more or less dense aka. increased opacity or increased lucency/reduced density)
Texture (uniform ot heterogenous)
Other features eg. bronchogram, fluid levels, volume change, boney abnormalities, surgical clips
After RIP and obvious abnormalities, what should you next do when interpreting a CXR?
Systematic review of the X-ray
ABCDD (airways, breathing, circulation, diaphragm and delicates)
Assess from zoomed-out image first, THEN close up
What are you looking for when assessing the ‘airways’ of a CXR?
trachea central? If not: rotation or pathology.
If a trachea is deviated due to pathology is it being:
pulled to one side due to volume loss? eg. lobar/lung collapse
pushed to one side due to increased volume? eg. large pleural effusion or mediastinal mass
What are you looking for when assessing the ‘breathing’ of a CXR?
Start in apices
Move down to costophrenic angles
Compare both of differences
L hilum should never be lower than R If this is the case, look for volume loss (pushing R hilum up or L hilum down)
Both hila should have same density, no lumps or convex margins
Look around edges of lungs, looking for pneumothoraces
What are you looking for when assessing the ‘circulation’ of a CXR?
Heart size (cardiothoracic ratio >0.5/cardiac diameter > 50% of thoracic diameter = cardiomegaly) Best to assess this is PA projection
Cardiac and mediastinal borders clearly visible
Mediastinum and heart should be positioned over thoracic vertebra (not the case: assess volume changes in lungs which might cause this)
Size of mediastinum (widening may be due to: AP projection, vascular structures (unfolding of thoracic aorta aortic dissection), masses, haemorrhage (eg. ruptured aorta)
R paratracheal stripe should be <5mm (shows tissue between medial wall of R lung and R wall of trachea)
aortopulmonary window (shows lack of tissue between aortic arch and L pulmonary artery). Lack of window: consider lymph node enlargement
Assess presence of gas in mediastinum (pneumomediastinum) - linear lucencies over mediastinum. May be associated with surgical emphysema
Whether cardiac shadow is of uniform density (if not, invert colours, could indicate retrocardiac pathology)
What are you looking for when assessing the ‘diaphragm’ in a CXR?
both hemidiaphragms should be visible and upwardly convex
flattening = lung hyper expansion eg. COPD, tnesion pneumothorax
R hemidiaphragm normally slightly higher than L due to liver. If not = ?pathological cause
Look behind diaphragm to assess base of lungs (invert image colour)
Look for free air under diaphragm
COSTOPHRENIC ANGLES reduced: pleural fluid likely
What are you looking for when assessing the ‘delicates’ of a CXR?
Bones: ribs
Rib spaces (should be roughly equal). Narrowing = volume loss of underlying lung
Rest of skeleton
Signs of surgical emphysema
previous surgery: surgical clips, mastectomy etc.
What forms the L heart border in a CXR?
LV
What forms the R heart border in a CXR?
RA
Where should an ET tube have its tip?
Proximal to the carina to ventilate both lungs
Only in one bronchi = collapse of non-ventilated lobe
What is the correct position of an NG tube in a CXR? What are common positioning errors?
well below L hemidiaphragm of stomach
misplacement in to lungs
tip being within distal oesophagus
Where is the common correct position of a central line? What are the complications associated with incorrect placement?
mid or lower SVC
pneumothorax
After you have completed a systematic review of a CXR, what should you do?
Review areas: Apices Hila Behind heart Costophrenic angles Under diaphragm
What is the general pattern with which you should interpret a CXR?
Pt details
Technical quality: RIP (rotation, inspiration, penetration)
Obvious abnormality (site, size, shape, density, texture)
Systematic review: ABCDD (airways, breathing, circulation, diaphragm, delicate bits)
Lines
Review
How might you summarise the findings of a CXR when presenting to a senior?
Summary of findings Differential list (given Hx etc.) Whether you would like to review previous images Further investigations Management plan
What might you expect to find on a CXR in a patient with pneumonia?
dense or patchy consolidation (usually unilateral)
bronchograms (air-containing bronchioles running through consolidated lung)
in lower zones, pneumonia may be difficult to distinguish from effusions - both should be in differentials (can also get parapneumonic effusion)
Silhouette sign (loss of silhouette of heart border or diaphragm)
Which lobes contact the heart and diaphragmatic borders?
Diaphragm: R and L lower lobes (R and L hemidiaphragm respectively)
R heart border: R middle lobe
L heart border: lingual (part of L upper lobe)
What might you expect to find on a CXR in a pt. with pleural effusions?
Blunting of costophrenic angles
Homogenous opacification
fluid level (meniscus)
What might you expect to find on a CXR in a pt. with pulmonary oedema?
ABCDEF (may not all be present)
A: alveolar and interstitial shadowing B: Kerley B lines C: cardiomegaly D: upper lobe venous blood Diversion (prominent upper lobe vasculature relative to lower zones) E: effusions F: fluid in horizontal fissure
What might you expect to find on a CXR in a pt. with pneumothorax?
air within pleural space
loss of lung marking in peripheral lung field
discrete lung edge
tension pneumothorax: tracheal, mediastinal deviation, flattened ipsilateral diaphragm (BUT SHOULDN’T BE HAVING AN XRAY)
What might you expect to find on a CXR in a pt. with lobar collapse?
loss of volume: raised hemidiaphragm, tracheal and mediastinal shift towards collapse side, displacement of hola, narrowing of space between ribs
What sign should you look out for in left upper lobe (LUL) collapse?
Veil sign - whole lung field looks like it’s covered by a veil
Luftsichel sign - radiolucency in LU zone around aortic arch
What sign should you look out for in left lower lobe (LLL) collapse?
Sail sign - sharp line like the edge of a sail AT SAME ANGLE AS HEART BORDER (double L heart border)
indistinct L hemidiaphragm border, preserved L heart border
What sign should you look out for in right upper lobe (RUL) collapse?
opacification in RU zone
raised horizontal fissure (usually has concave border)
abnormality well demarcated
Golden S’s sign ( right hilar mass)
What sign should you look out for in right middle lobe (RML) collapse?
depression of horizontal fissure
indistinct R heart border
What sign should you look out for in Right lower lobe (RLL) collapse?
Sail sign (similar to LLL collapse)
Indistinct R hemidiaphragm
Preserved R heart border
Which projection is usually used for abdominal X-rays?
AP (pt. will be supine in position)
What should be included in the X-ray for it to be considered complete?
hemidiaphragm down to symphysis pubis and herbal orifices
How should you systematically review a film of a small bowel?
large and small bowel
diameter of bowel
bowel wall thickness
