How accurate is an MRI when diagnosing MS? Do lesions show up right away or is it years before it shows as a demyelination disease?
Let answer each question separately:
1. How accurate is MRI in the diagnosis of MS?
MS remains a clinical diagnosis. MRIs are used to assist in the diagnosis. This means that there is NO MRI appearance that is capable of defining a definite diagnosis of MS in the absence of clinical symptoms and findings that support this diagnosis. Therefore, the accuracy of MRI in the diagnosis of MS is dependent upon two variables; the interpretation of the person reading the MRI scan and the interpretation of the individual obtaining the history and doing the examination. These two variables are primarily responsible for diagnostic error. Specifically, a person misinterprets the MRI findings or the clinically presentation or both as consistent with MS.
2. Do lesions show up right away?
The simple answer is yes. The problem is that the MRI may not be of good technical quality or the abnormality may involve a part of the brain that is not easy to visualize on standard MRI
3. Do Lesions show years before a diagnosis of demyelinating disease?
The answer is yes in many individuals. This is why an average person with MS will have up to 8 visible lesions on their MRI scan that are inactive at the time that they present with their first symptom of MS
Hope this helps.
Revere (Rip) Kinkel MD
Director of the Multiple Sclerosis Program
Professor of Clinical Neurosciences
University of California San Diego