lytic lesion

Basics for the Wards: Reading a Chest X Ray

Chest X-rays (aka CXR) are one of the most basic imaging studies done in medicine. Almost every hospitalized patient has one and you will see hundreds of them by the time you finish med school.

But it was be super easy to get distracted by the huge glaring pathology (like a giant mass) that you miss other pathology (like a broken clavicle). So, like with reading EKGs, it’s best to have an algorithm you run through for every CXR so you don’t miss anything.

Disclaimer: Again, this is just a general introduction with some basics to help you start out on wards. There is a lot more to interpreting chest x-rays that what I mention, that is why radiologists are awesome.

First: What is the view- is it AP (front to back) or PA (back to front)? Lateral CXRs are obvious.



If the patient is able to stand, a PA view is generally preferred. AP is generally when patients are confined to the bed- also you usually cannot diagnose cardiomegaly from an AP view because the heart is almost always bigger in this view. How do you tell the difference between them? Look at the scapula- in a PA view the scapula are usually clear of the lungs, whereas in an AP view the two generally overlap. Sometimes the clavicle positioning can be a good clue too- see the differences between the two?


Second- what is the quality, because that can have a major effect on your interpretation. A good mnemonic is RIP.

- Rotation - Measure the distance of each clavicle from the spinous processes at that level, if they are equidistant then the patient is not rotated.

- Inspiration - If you can count nine posterior ribs within the lung fields before you reach the diaphragm, then there was enough inspiratory effort. Poor inspiratory effort will look like the patient has an airspace disease.
Note: Posterior ribs = more apparent, look more horizontal. Anterior ribs = less visible, 45ish degree angle towards feet

- Penetration - With flawless penetration, you should be able to see the thoracic spine through the heart.

Underpenetration= Left hemidiaphragm and left lung base will not be visible, and pulmonary markings will appear more prominent than they actually are. Ahhhh!!!!

Overpenetration= what is even happening here

OK, now you’re ready to see what is going on with the patient. I suggest the systematic approach, which has the handy mnemonic ABCDE= airway, bones, cardiac, diaphragm, everything else (lungs). I’m not going to go into all the pathology associated with everything, because that would take forever.

- Airway: Is the trachea patent and midline? Can you see the mainstem bronchi and the carina? If there is an endotracheal tube in place, make sure that it is 3-4 cm above the carina. Also check to make sure the mediastinum is not deviated or abnormally wide.

- Bones: Is anything broken or dislocated? Any lytic lesions? 

- Cardiac: How clear is the cardiac silhouette? Is the heart enlarged? What about all the vessels- the aorta, SVC, IVC, etc. 

- Diaphragm: Is the right side higher than the left but not like wayyyy too much? Are the costophrenic angles clear (if not, could be an effusion!)? 

- Everything else: NOW you can look at the lungs. Is there an infiltrate or a mass? What about pneumothorax? Also check for you friendly neighborhood gastric air bubble, it’s supposed to be below the diaphragm. 

Easy enough, right? Good luck! 

Chest X-Rays (CXR) Interpretation

DRSABCD is a familiar acronym for those who have undertaken First Aid/Basic Life Support courses. Now DRSABCDE can used as a simple, yet comprehensive, approach to CXR interpretation.

Normal CXR 

D – Details: 

  • Patient name, age / DOB, sex
  • Type of film – PA or AP, erect or supine, correct L/R marker, inspiratory/expiratory series
  • Date and time of study

R – RIPE (assessing the image quality)

  • Rotation – medial clavicle ends equidistant from spinous process
  • Inspiration – 5-6 anterior ribs in MCL or 8-10 posterior ribs above diaphragm, poor inspiration?, hyperexpanded?
  • Picture – straight vs oblique, entire lung fields, scapulae outside lung fields, angulation (ie ’tilt’ in vertical plane)
  • Exposure (Penetration) – IV disc spaces, spinous processes to ~T4, L) hemidiaphragm visible through cardiac shadow.

S – Soft tissues and bones (it is common to leave it until the end)

  • Ribs, sternum, spine, clavicles – symmetry, fractures, dislocations, lytic lesions, density
  • Soft tissues – looking for symmetry, swelling, loss of tissue planes, subcutaneous air, masses
  • Breast shadows
  • Calcification – great vessels, carotids

A – Airway & mediastinum

  • Trachea – central or slightly to right lung as crosses aortic arch
  • Paratracheal/mediastinal masses or adenopathy
  • Carina & RMB/LMB
  • Mediastinal width <8cm on PA film
  • Aortic knob
  • Hilum – T6-7 IV disc level, left hilum is usually higher (2cm) and squarer than the V-shaped right hilum.
  • Check vessels, calcification.

B – Breathing

  • Lung fields
  • Pleura: reflections, thickenning
  • Vascularity – to ~2cm of pleural surface (~3cm in apices), vessels in bases > apices
  • Pneumothorax – don’t forget apices
  • Lung field outlines – abnormal opacity/lucency, atelectasis, collapse, consolidation, bullae
  • Horizontal fissure on Right Lung
  • Pulmonary infiltrates – interstitial vs alveolar pattern
  • Coin lesions
  • Cavitary lesions

C – Circulation

  • Heart position –⅔ to left, ⅓ to right
  • Heart size – measure cardiothoracic ratio on PA film (normal <0.5)
  • Heart borders – R) border is R) atrium, L) border is L) ventricle & atrium
  • Heart shape
  • Aortic stripe

D – Diaphragm

  • Hemidiaphragm levels – Right Lung higher than Left Lung (~2.5cm / 1 intercostal space)
  • Diaphragm shape/contour
  • Cardiophrenic and costophrenic angles – clear and sharp
  • Gastric bubble / colonic air
  • Subdiaphragmatic air (pneumoperitoneum)

E – Extras

  • CVP line, NG tube, PA catheters, ECG electrodes, etc

More medical content here!

Traps for New Vets: Part 4, neoplasia

Approximately a third of our senior pets with develop cancer at some point in their life. Facts are, if they live long enough then it will definitely happen. Our job is to identify it, and do something about. For some types of cancer a chance to cut is a chance to cure, but only if identified early enough. 

Sometimes you don’t get a chance to identify neoplasia early enough. If a pet owner decides that their pet is ‘healthy’ and elects not to come to the vet for regular checkups until that lump is the size of a watermelon, or until that mast cell tumor has been sitting there for months, then there’s not much you can do about that. But we all do our best with what we’ve got. Different neoplasias have different biological behaviors, and some are sneakier than others. 

  • Mast Cell Tumors cannot be overestimated. They are always considered bad news until proven otherwise. They can pop up anywhere you have immune surveillance, including the spleen. they can also look like just about anything. Subcutaneous Mast Cell Tumors can look and feel exactly like a benign lipoma. The only way to know is a Fine Needle Aspirate (FNA).
  • Speaking of lipomas, don’t tell a client they are absolutely nothing to worry about. There is a tiny chance that it might be a liposarcoma or infiltrative lipoma. That’s really hard to pick on FNA alone, so monitoring is always advised. 
  • The further away from the trunk of the body, the more likely that lump is going to be a nasty little bugger. A 2mm tumor on the toe concerns me much more than a 5cm tumor on the body. 
  • Again, toe tumors are nasty until proven otherwise, especially so if there is lytic lesions in the bones. 
  • Melanomas are not always dark. You can get amelanotic melanomas with no pigment at all. 
  • Haemangiosarcomas/Hemangiosarcomas are most commonly found in spleen and liver, but they can show up anywhere you find blood vessels (almost everywhere). Watch out for intramuscular haemangiosarcomas. They present a bit like a haematoma or a seroma, but they are not. If you try to ‘drain’ these, they will bleed for weeks. They may not stop. Cut the whole thing out and hope for the best.
  • White cats develop squamous cell carcinomas of the face. They can also appear normal on the outside but have horrific oral tumors inside the mouth. Look, and don’t assume it’s just a flesh wound. 
  • If the tumor is annoying the pet or causing pain, cut it out even if it’s benign. This is especially true for eyelid lumps rubbing on the eyeball.
  • In male entire dogs, remember to check those testicles and the anus. Perianal adenocarcinomas are easy to miss.
  • Lymphoma is the most common cancer across all species and age groups. It breaks the rules. It can show up in any age, even juveniles, and anywhere. If it’s anywhere, assume it’s everywhere.
  • Osteosarcomas can present initially as mild lameness that is easy to confuse for arthritis. You only know with an xray. Also, while we learn that they are more common away from the elbow and towards the knee, this is only true in large dogs. Dogs of any size can get them, and in smaller dogs they are more common in the spine and skull. 
  • Multiple myeloma can also look like arthritis if a lesion is near a joint. 
  • Mammary gland tumors are malignant until proven otherwise. If they are present, spey that thing if she isn’t already. Doing so can potentially triple their life expectancy. 

Always look. More things are missed by not looking than not knowing.

Other traps for few vets: