Concussion-related brain changes are often subtle and primarily functional rather than structural, which makes them challenging to detect with standard MRI scans. A concussion is a mild traumatic brain injury that disrupts brain function, typically without causing obvious damage visible on conventional imaging. Therefore, routine MRI scans often appear normal even when a person experiences significant symptoms after a concussion.
However, advanced MRI techniques, especially diffusion MRI methods like diffusion tensor imaging (DTI), can reveal microstructural changes in the brain’s white matter that are associated with concussion. These techniques measure how water molecules move along nerve fibers, providing insight into the integrity of brain connections. For example, the corpus callosum, a major white matter tract connecting the two brain hemispheres, is particularly vulnerable to concussion-related injury. Studies using diffusion MRI in animal models have shown progressive changes in this region following a single concussion, indicating that even mild brain injuries can cause lasting alterations in brain microstructure over time.
In clinical practice, MRI is often used when symptoms persist or when initial CT scans (commonly used in acute trauma) do not fully explain neurological deficits. MRI is more sensitive than CT for detecting certain types of brain injury such as small hemorrhages, brainstem injuries, and diffuse axonal injury (DAI), which involves widespread damage to nerve fibers. While standard MRI may not show concussion itself, it can identify secondary injuries or complications that contribute to symptoms.
Emerging MRI technologies, including upright MRI, offer additional diagnostic value by allowing imaging in natural, weight-bearing positions, potentially revealing abnormalities missed in traditional supine scans. This can be particularly useful for patients with persistent symptoms like dizziness or vertigo after concussion.
Despite these advances, it is important to understand that a normal MRI does not rule out concussion or brain dysfunction. Concussions primarily affect brain function at a cellular and metabolic level, which current imaging cannot fully capture. This is why concussion diagnosis and management rely heavily on clinical evaluation, symptom assessment, and specialized testing rather than imaging alone.
In summary, while standard MRI often cannot directly visualize concussion-related brain changes, advanced MRI techniques such as diffusion imaging can detect subtle microstructural alterations in brain white matter. MRI plays a complementary role in concussion care, especially for identifying associated injuries or persistent neurological symptoms, but it is not a definitive tool for diagnosing concussion itself.
