Let’s get through a couple more cases of fundamental pathology on chest X-ray. We touched on pneumonia last time utilizing opacities to help localize lobar anatomy on chest X-ray. Pneumonia can appear different on chest X-ray depending on the pathogen. Bacterial pneumonia often cause the consolidative opacities we discussed in the last article. A viral pneumonia may cause increased perihilar markings and bronchial wall thickening. It is wise to remember multiorganism pneumonia caused by aspiration/stuff going down the wrong pipe!
Remember how the lungs are NOT symmetric. It should come as no surprise then that the airways are not symmetric either. Check it out:
You see how the right mainstem bronchus has a more obtuse angle with the trachea relative to the left mainstem bronchus with the more acute angle. Obviously, if your poured water into the top of the tube more would go into the right than the left. Voila! Aspiration pneumonia favors the right lower lobe!
This absolutely corresponds to the airways picture showing how an aspiration can have a relative straight shot into the right lower lobe. However,one tenet of pneumonia for radiologists is to suggest a follow up chest X-ray to resolution. Following antibiotic treatment and clinical improvement the opacity should resolve. Of course, there is a caveat! Chest X-ray often lags clinical findings, so a patient may be fairly sick and the chest X-ray only shows a small opacity that gets bigger over subsequent days. Conversely, the patient may be showing signs of clinical improvement, but an opacity persists on the chest X-ray. Now if the opacity fails to resolve despite several rounds of antibiotics, then a chest CT scan with IV contrast should be considered. For those that noticed the port catheter, you know where I’m going with this:
This patient in the above chest X-ray has a lung tumor and NOT an aspiration pneumonia. A pneumonia may take up to 8 weeks to resolve on chest X-ray, but most do so in 4-6 weeks.
Well I think we will keep this short and do one more article in our chest X-ray series for now, then I will be ready to move onto another topic. Fluoroscopy was promised, so we will touch on some of the standard outpatient procedures. If you haven’t seen my video in the About Me section, I hope you will spend the less then four minutes to learn about what it means to be a radiologist.