Chest X-Ray Tips

Chest X-Rays invariably show up in the exam, either in the VAQ or SCE sections.  At work in the ED, and in exams, non-radiologists descriptions of lung opacities invariably inlcude the words “fluffy”, “hazy”, “white-out”.  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 in these areas:
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

congestion1   congestion2
2) Get blocked: which shows up as pulmonary infarcts



2) Alveolar (airspace) Opacity:
Xray Appearance: soft, fluffy, ill-defined, 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)
Eg Pneumonia
2) Pulmonary Oedema – as the fluid leaks out the vessels into the surrounding tissue
Can be:
3) Blood:
Eg Goodpastures, CF
4) Neoplastic Cells
Ca lung (usually interstitial, but can fill airspaces)

alveolar1  alveolar2

3) Interstitial Opacity
Xray Appearance: Linear, streaky, Kerly A/B
Causes: There’s even fewer things that can infiltrate your interstitium!
1) Acute = Water (CCF)
2) Chronic =
a. Fibrosis (hence the term “interstitial lung disease”)
b. Sarcoid
c. Lymphangitis
d. Pneumonocoiosis

intersitial1  intersitial2

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