Today we're looking at basic CXR interpretation, a topic that I have seen come up at all stages of undergraduate assessment. Basic radiological anatomy is essential for 1st and 2nd years students and by the end of medical school all students should have developed a system to look at chest xrays. In this blog post I will quickly refresh anatomy and walk you through a common system used to interpret a chest xray. To finish there is a quiz with 15 of my favourite patients i've seen (progressive difficulty!)
I'm sure everyone knows basic chest anatomy. Ive seen the corresponding picture appear in junior year OSCEs with students having to label the diagram.
Film Description
In an OSCE setting examiners will be expecting you to comment on the details of the film itself. You have to state the following:
1) Patient Name 2) Area of Xray 3) Orientation of the film AP/lateral/PA (it should state on the Xray)
Next is the quality of the image looking at the following:
1) Rotation - Each head of the clavicle should be equidistant from the spinous process.
2) Penetration - The intervertebral discs should be visible behind the heart.
3) Inspiration - 9 posterior ribs should be seen before the diaphram
A great summary of these with questions can be found HERE
Image interpretation
Some people use the ABCDE approach but I find it awkward and unnatural in order. I would advocate a visual approach, starting at the top and moving down through the middle and then back up through the lungs:- Trachea - Is it central? It should overlie the vertebrae
- Mediastinum - Is it enlarged? If >3cm it is
- Heart - Is there cardiomegaly? It should be less than half of the thorax ?Can I see the heart borders?
- Diaphram - Are they elevated? Any gas below them?
- Costophrenic angles - Are they visable? Obscuration may suggest a small pleural effusion
- Lung Fields - Any abnormalities, opacification, lung markings
- Bones - Any rib fractures? How do the shoulders look?
- Special Areas - Apices and behind the heart
Simple! Follow those steps and you'll have no problem at examination. Now put them to the test with the below quiz and practice going through the quality of the film spheel! The link to the answers is below, but try to come to a definite answer and description for each xray before you look!
ANSWERS
ANSWERS
