Many students, including myself, struggled during second and third year with a lot of the diagnostic images given on the USMLE exams – namely, pathology and radiology. There are what seems like an infinite number of diagnoses to know and be able to identify, and imaging and path for pretty much every one of them. I’ll speak more to radiology here – as it is more commonly seen on the USMLE exams and in clinical practice by other physicians not specializing in that particular field.
I’ll start by saying that 80-90% of the questions with these pictures can be answered without looking at the picture at all. The majority of them have enough content in the question stem to really lead you to one particular diagnosis (likely with a characteristic imaging finding), and the image is really there as a confirmatory test more than anything.
I try to recommend to my students to ignore the picture for the first portion of the question, and act as though you don’t have that piece of data at all. Try to get the answer from the question stem itself, and see if you can identify what finding is classically seen on x-ray or CT scan. Try to find that in the image. Otherwise, there are only a handful of images that are really pathognomonic which can be tested on the exam. CXRs are usually trying to demonstrate pneumothorax, pulmonary edema, nodules, pneumonia, effusion, or hilar lymphadenopathy. Abdominal XRs are typically showing free air, obstruction, toxic megacolon, or in kids, an infection such as NEC. CT Scans can be a bit more challenging, with the inclusion of liver, pancreas, and kidney pathology most commonly. Focus on these common diagnoses that could be tested.
As always for imaging, though, the more normal you see, the more you will be able to identify abnormal. So make sure you take the time to study every scan and see what you can learn!