Reading the scan is only half the equation
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Imagine you're on a radiology sub-internship, reviewing an abdominal ultrasound for a non-pregnant, 13-year-old female patient with right-lower quadrant pain. While discussing the case with your attending, you realize the images are inconclusive, and the appendix can't be visualized well enough to call a definitive diagnosis.
The natural follow-up question arises: "Given the ultrasound is non-diagnostic, what's the next best step?"
You pause.
A CT scan seems like the obvious answer, but you're not sure whether it’s the recommended next step. Perhaps MRI should be considered first, due to the patient’s age?
Then it hits you: You know how to interpret the study, but you don't know how to proceed if the study fails to answer the pertinent clinical question.
Mastering radiology involves a steep learning curve. One of the most effective ways to learn is by reviewing a large volume of cases. Normal studies establish a baseline, allowing you to recognize abnormal findings over time.
As medical students, however, we can become so focused on interpreting images that we overlook an equally important question: Why was this study ordered in the first place?
Developing the habit of asking "why" is valuable regardless of your future specialty. The process is similar to deciding which laboratory tests to order for a patient who presents to the emergency department with chest pain.
This is why the ACR Appropriateness Criteria® are so essential. These free, evidence-based guidelines help clinicians select the most appropriate imaging study or treatment for specific clinical scenarios. You can filter by scenario, topic and procedure, and the guidelines contain diagnostic imaging and interventional radiology documents for thousands of clinical scenarios while also providing clinical variants and patient-friendly summaries.
For example, in a patient presenting with acute kidney injury, the initial imaging recommendation is a renal and retroperitoneal ultrasound. In addition to identifying studies that are the "usually appropriate," the Appropriateness Criteria identify options that are "usually not appropriate", such as CT of the abdomen with IV contrast or a DMSA renal scan, for that same scenario.
Choosing the correct imaging modality, however, is only half the equation.
Although the Appropriateness Criteria may guide you to select a CT of the abdomen with IV contrast, they don’t tell you whether contrast administration is safe for a specific patient.
That's where the ACR Manual on Contrast Media becomes essential. This companion resource addresses topics such as renal function thresholds, premedication protocols for patients with prior allergic-like reactions as well as pediatric dosing and safety considerations.
Learning to consult both the Appropriateness Criteria and the Manual on Contrast Media early in training helps establish habits that will become second nature throughout your career.
Selecting the right study accelerates diagnosis, and selecting the right contrast plan allows clinicians to focus on patient care. Neither task is prominently displayed on the patient medical record, but patients will benefit from both. This collaborative approach is one reason referring physicians and radiologists rely on each other, and it's a practice worth building now.
The question is: How can we use these tools as medical students? There's no single answer, because the approach depends on your level of training.
As a preclinical student, you can incorporate these resources into problem-based or case-based learning discussions. As a clinical student, you can use them during pre-rounding to better understand and explain why a particular study was appropriate. During an away rotation or sub-internship, these resources can help you strengthen clinical reasoning and decision-making skills.
You can also build a radiology interest group session around an Appropriateness Criteria topic, walking through the clinical reasoning process step-by-step. Similarly, discussing ACR Contrast Reaction Cards for adults and pediatric patients can provide valuable in-person or virtual educational activities.
Returning to the ultrasound case, the Appropriateness Criteria would have provided a clear answer:
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