3 Tips to Formulate an Accurate and Valuable Differential Diagnosis

Aristotle on skepticism

At the core of diagnostic radiology is the differential diagnosis. This is the set of various diagnoses that may explain certain findings on a particular radiology exam, whether it is a mass seen on ultrasound, an opacity on a chest radiograph, or abnormal signal characteristics on an MRI. I recently came across the quote above from Aristotle, and it inspired this post on formulating an accurate differential diagnosis. Below are three quick tips I’ve put together to help.

1. Knowledge – it has been said the eye will only see what the mind is prepared to comprehend. I can think of no other area in medicine where this applies more than in radiology. Having a strong knowledge base will assist the radiologist in identifying the findings and more importantly, giving the impression of what those findings mean.

2. Skepticism – the above quote from Aristotle illustrates this point beautifully. From day one in medical training we learn to be skeptics. A naive physician is one who thinks there could only be one possible explanation for a patient’s presentation of findings on a radiology exam. Always question yourself on whether you may be missing something in your differential diagnosis.

3. Brevity – part of being good radiologists is being able to provide a valuable service to the ordering clinician. If we can’t do that we will quickly be replaced. When giving a differential diagnosis, being succinct cannot be overemphasized. Within reason there are usually only a few entities that can cause a finding on a radiology exam. Be sure to give your differential in order of likelihood, and limit it to the most likely entities. Giving a laundry list differential diagnosis to the clinician is not helpful, and will only foster more questions and provide less clarity.

-J. L. Koning, M.D.