Number, Location, Size of Lesions on MRI Can Predict Progression to MS, Study Shows

The number, location, and size of lesions can help predict the risk of progression from clinically isolated syndrome (CIS) to multiple sclerosis (MS) within one year, a new study shows.

The study, “MRI in predicting conversion to multiple sclerosis within 1 year,” was published in the journal Brain and Behavior.

Most patients diagnosed with MS initially present with CIS. In 50-70% of patients, magnetic resonance imaging (MRI) is taken at the time of CIS diagnosis, and it usually reveals multiple white matter brain lesions that suggest the presence of demyelination (or myelin loss, the process that underlies the pathology of MS).

Studies have shown that in about 30% of patients with an abnormal MRI scan, a second clinical attack, or a change in MRI occurs within one year, confirming the diagnosis of MS. But long-term studies have shown that up to 20% of patients do not have another clinical attack for at least 20 years.

This wide clinical spectrum puts physicians and patients in a situation of uncertainty at the time of disease presentation, as guidelines suggest that early treatment is the key to slowing the progression of MS.

So, researchers set out to identify the MRI characteristics of patients at first presentation that would predict either a second clinical episode or conversion to MS within the first year.

For this purpose, researchers assessed the medical records of 46 individuals who presented with an episode of CIS, and who were followed both clinically and through imaging for a year.

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A neuroradiologist, who did not have access to the clinical data, reviewed the MRI images from CIS patients and recorded the number, location, and the largest diameter of the lesions.

One year after the first MRI, 25 patients (54%) progressed to MS.

The cerebral cortex, the largest part of the human brain, is composed of four major lobes – temporal, occipital, parietal, and frontal – and each has its own individual roles.

The corpus callosum is the region of the brain that connects the two hemispheres. It is responsible for integrating motor, sensory, and cognitive signals between the two hemispheres of the cerebral cortex.

When looking at the location of lesions, CIS patients with lesions that were either in the temporal lobe, occipital lobe or perpendicular to the corpus callosum were more likely to have recurrence of a clinical episode.

Researchers also identified a specific combination of location, number, and size of lesions that would significantly increase chances of progressing to MS. According to the team, patients with a combination of more than 13 lesions, with a maximal lesion diameter greater than 0.75 cm, and lesions perpendicular to the corpus callosum, had a 19 times greater chance of progressing to MS during the following year.

“Assessment of the number of lesions, lesion location, and maximal lesion size can predict the risk to develop another clinical episode or a new lesion/new enhancement in MRI during the year after CIS,” the researchers concluded.

“For patients with a higher risk of recurrence, we recommend closer follow‐up,” they added.