Why has a lesion grown from 0.5 cm to 1.9 cm?

Here is My Question:
Why has a previous lesion from a year ago grown from 0.5 cm to 1.9 cm? I have no symptoms, and am not on a DMD.

Answer:

Lesions can appear larger on repeat MR imaging for several reasons:

1. Technical reasons: for instance, a higher resolution scan (3 tesla instead of 1.5 tesla) can identify a greater extent of a lesion and make it appear larger on repeat imaging. Usually the changes in lesion size in this situation are less than 25 %. Your lesion is 280 % larger, so this seems like an unlikely explanation unless different parts of the lesion were measured at each time point. Essentially this would mean they were comparing apples to oranges. Remember MS lesions tend to have odd shapes with varying diameters in different directions of measurement.
2. Greater edema surrounding an acutely enlarged lesion. These enlarged lesions usually shrink with resolution of the edema (basically excess water in the tissue) but may always remain larger than the initial lesion.
   
3. The MS lesion can enlarge along its leading edge because of continued progression. These enlarged lesions are less likely to shrink unless also associated with edema
   
4. Another process is taking place: for instance, what was thought to be an MS lesion was really another chronic condition. This is more likely if the enlarging lesion is the only lesion in the brain or if it has atypical features or if the individual is at risk for other conditions like PML.

Hope this helps answer your question.

Revere (Rip) Kinkel MD
Professor of Clinical Neurosciences
Director of the Multiple Sclerosis Program
Clinical Neurosciences Director
University of California San Diego