American Board of Internal Medicine (ABIM) Certification Practice Exam

Which imaging technique is not typically used for diagnosing Lyme arthritis?

1. X-ray

2. Ultrasound

3. MRI

4. CT scan

The correct answer is: Ultrasound

Ultrasound is not typically used for diagnosing Lyme arthritis, which is primarily caused by the bacterium Borrelia burgdorferi transmitted through tick bites. Lyme arthritis is characterized by joint inflammation, and while ultrasound can visualize structures in the body, it does not provide specific information regarding the presence of Lyme disease. X-rays are often employed to assess changes in the bone and joint that could result from arthritis, including Lyme arthritis. They may reveal joint swelling or damage but do not show the infection itself. MRI is a more sensitive imaging technique that can visualize soft tissues and detect changes associated with Lyme arthritis, such as synovitis and effusion, thereby providing a clearer view of the condition. CT scans can also be used to assess more complex cases, but they are less common for routine diagnosis in this context. In summary, ultrasound is not the primary imaging modality for diagnosing Lyme arthritis, as it lacks the specificity and sensitivity required to confirm the diagnosis, while the other imaging techniques have established roles in the evaluation of joint conditions associated with Lyme disease.