Which imaging modality is best to evaluate thymic pathology in suspected myasthenia gravis?

• A. Chest CT
• B. Brain MRI
• C. Abdominal ultrasound
• D. PET-CT

Answer: (A)

In myasthenia gravis, thymic pathology is common and imaging is aimed at assessing the thymus in the anterior mediastinum to look for hyperplasia or thymoma. Chest CT provides high-resolution, cross-sectional images of the mediastinal thymus, allowing precise visualization of thymic tissue, masses, contour changes, and invasion if present. It can distinguish thymic hyperplasia from a thymic tumor and shows details like calcifications and relationships to surrounding structures, which are critical for planning management such as thymectomy. Although MRI can be used and PET-CT adds metabolic information, CT is the most practical and sensitive initial test for evaluating thymic morphology. Brain MRI and abdominal ultrasound don’t evaluate the thymus, so they aren’t appropriate for this purpose.