Learn how to identify a classic MRI finding in Multiple Sclerosis – and, what does the TV show Dawson’s Creek have to do with it?

Multiple sclerosis is the most common condition in neuroimmunology. The body’s immune system attacks the myelin sheath of axons in the central nervous system, for reasons that remain unclear.

Although MS lesions (called plaques) representing episodes of demyelination, can affect any part of the central nervous system, there are several locations in the brain that are most commonly affected.

Look at the brain MRI below, and see if you can answer a few questions. 1) What MRI sequence is it? 2) Where are the abnormalities? 3) Do you know what this classic finding is called?

A “classic” brain MRI in Multiple Sclerosis.

Ok, you’ve had a chance to look at the brain MRI above. The MRI sequence is a T2W FLAIR image – white matter appears grey, grey matter appears white, CSF is dark and pathologic lesions may appear bright white. See the annotated MRI below for more details or refer to our article on MRI sequences for an explanation.

Second, the lesions are in the corpus callosum, and are highlighted in the image below with orange arrows. These, vertically aligned white matter lesions are a common imaging finding in multiple sclerosis. In fact, radiologists will often protocol an MRI to include the sagittal T2W FLAIR specifically to look for this. The lesions often follow the path of a small vertically oriented vein within the brain.

Lastly, these lesions are known as Dawson’s Fingers. Look at the annotated brain MRI below for an explanation of lesions.

T2W FLAIR. Sagittal image. The orange arrows show Dawson’s Fingers. The blue arrow shows the white cortex, the green * shows the grey colored white matter.

It’s important to remember that Dawson’s Fingers aren’t seen in every case of MS, and having imaging findings that look like Dawson’s Fingers aren’t enough to make a diagnosis of multiple sclerosis on their own. But, it is a highly characteristic findings and a memorable eponym, and in case you’re wondering, not named after James Van Der Beek.

The finger like projections are caused by inflammation of the white matter along medullary veins.