Chest X-Rays invariably show up in the exam, either in the VAQ or SCE sections. At work in the ED, and in exams, I frequently hear descriptions of lung opacities on chest X-rays that invariably include the words “fluffy”, “hazy”, “patchy” and other hopelessly non-radiological, non-medical words. Have you ever read a radiology report that says “the lungs are a bit fluffy at the bases”? I haven’t. So why do we use these words? The main reason is that we’re lazy and haven’t bothered to learn my simple technique for describing lung opacities.
As with any X-Ray description in an exam, using the correct terminology will not only make you sound more professional, but it will give you a more succinct differential diagnosis. This article will also help you in your day-to-day work, not only by helping you make more accurate chest X-Ray diagnoses, but also by improving the standard of your documentation and referrals. (Click on the images to enlarge them).
There are only 3 things in your lungs, so opacities in the lung fields on Chest X-Rays can only be one of these 3 things
1) Blood Vessels (which run through the intersitium)
2) Interstitium (the actual solid lung tissue)
3) Airspaces (the majority of which are alveoli)
Blood Vessel Opacity:
Not much can happen to these, they can either:
1) Distend: which shows as pulmonary venous congestion
2) Get blocked: which shows up as pulmonary infarcts
2) Alveolar (airspace) Opacity:
Xray Appearance: diffuse opacity with ill-defined edges, (like cotton wool)
Causes: There’s only a few things that can fill your alveoli up and make them radio-opaque:
1) Inflammatory Exudate (pus)
2) Pulmonary Oedema – as the fluid leaks out the vessels into the surrounding tissue
Eg Goodpastures, CF
4) Neoplastic Cells
Ca lung (usually interstitial, but can fill airspaces)
3) Interstitial Opacity
Xray Appearance: Linear, streaky, Kerly A/B
Causes: There’s even fewer things that can infiltrate your interstitium!
Eg: Pulmonary oedema
a. Fibrosis (hence the term “interstitial lung disease”)
So there you have it, the simple, easy to remember way to describe chest X-rays that will not only make your diagnoses more accurate, but make you sound like you know what you’re talking about, at work and in the exam.