Chest X-ray
Systematic approach
Describing abnormalities
The art of radiology is not merely in spotting and describing abnormalities, it is also in knowing how to communicate the relevance of these abnormalities, and knowing what can be ignored.
At first, describing X-ray abnormalities can be difficult, and many medical students want rules of terminology. However, there really are no rules, as long as the terms used are not misleading.
The main difficulty comes in describing abnormalities of the lung parenchyma. What some may call 'shadowing,' others may call 'opacification,' 'whiteness,' or 'increased density.' In fact, all of these are acceptable terms.
Describing a chest X-ray abnormality can be likened to describing a skin rash in a dermatology patient, or a lump in a surgical patient. Attention should be given to factors such as location, size, shape and density of an abnormality. The process of description often helps with diagnosis - see the list of 'lesion describers.'
Key points
- 'Shadowing, opacification, density?' - Call it what you like!
- 'Lesion describers' may lead you towards a diagnosis
- Be descriptive rather than jumping to a diagnosis
'Lesion describers'
- Tissue involved - Lung, heart, aorta, bone etc
- Size - Large/Small/Varied
- Side - Right/Left - Unilateral/Bilateral
- Number - Single/Multiple
- Distribution - Focal/Widespread
- Position - Anterior/Posterior/Lung zone etc
- Shape - Round/Crescentic/etc
- Edge - Smooth/Irregular/Spiculated
- Pattern - Nodular/Reticular(net-like)
- Density - Air/Fat/Soft-tissue/Calcium/Metal
Hover over image to show findings
'Shadows, opacities, densities'
These opacities can be described as -
- Tissue involved - Lung
- Size - Small (<2cm)
- Side - Bilateral
- Number - Multiple
- Distribution - Widespread
- Position - Mainly middle to lower zones
- Shape - Round
- Edge - Irregular
- Pattern - Nodular
- Density - Soft-tissue
Diagnosis
Description helps with diagnosis. Once you have put all the above terms together, there can only be one diagnosis.
- Metastatic disease
Specific findings
There are also specific findings that may point you in the direction of a diagnosis. For example, blunting of the costophrenic angles may lead you to think there are pleural effusions. Evidence of consolidation such as air bronchogram, may make you think infection is the diagnosis. These phenomena often need little in the way of description.
If you see one of these 'tell-tale' signs, try not to jump in with a diagnosis. Taking a moment to systematically describe the abnormality may lead you to notice the blunt costophrenic angles are due to hyperexpansion, or that the lung consolidation has eroded a rib, making cancer more likely than infection.
Hover over image to show findings
'Tell-tale' pitfall
The costophrenic angles are blunt and you may assume there are pleural effusions.
However, a systematic assessment reveals that the diaphragm lies well below the 7th rib in the mid-clavicular line (white arrow). The diaphragm should not lie below the red line.
There are no pleural effusions.
Diagnosis
- Lung hyperexpansion due to emphysema