How MRI's Show MS Lesions

[Quixotic1]

MY QUICK AND DIRTY EXPLANATION OF HOW MRI'S SHOW LESIONS IN MS

I am going to overexplain the MRI with contrast / without contrast thing again, so that you and your husband can have it as clear as possible in your minds.

MS does it's damage by causing the nerves in localized areas in the brain and spinal cord to lose their protective sheaths, called myelin.  At first, when the myelin is being attacked, the body brings a higher blood supply to the area to fight the attack and the area becomes inflamed.  These areas, now become lesions.  At this point they are called "active lesions."   At first the nerves haven't changed much and they appear (and have the same density) as the healthy areas around them.  At this point after some time, probably months, the body CAN repair the damage and remyelinate the nerve.  This repaired nerve still won't be as good as new, but the lesion "looks" like normal brain.  Sometimes later an old scarred lesion will "reactivate" and the adjacent areas will inflame and have increased blood flow.

If the attack on the myelin sheath is too strong for the immune system to repair, more and more myelin disappears and the area of nerves eventually dies.  Then it contracts and scars.  The blood flow is decreased to that area and the area becomes "less dense" then the surrounding normal nerve tissue.  After a longer time - probably years - the scar can reabsorb and the area becomes "empty."  It's called a black hole.

When you image these lesions with an MRI you can see different things, depending on the technique,the age (stage) of the lesion, the power of the MRI, and whether contrast is used.

The first image is done without contrast.  This technique will show old lesions that are big enough to be seen by the power of that MRI machine.  WE KNOW that many lesions in MS are too small to be seen.  If the newer, more powerful MRI with a 3 Tesla magnet is used many more lesions will be seen (by at least 25%) than on the older 1.5 Tesla machines.  The classic old, mature MS lesion is a little bit oval, will have well-defined borders and will be in the white matter.  Characteristic places are subcortical, peri-ventricular and in the corpus callosum.  The classic MS lesion will also have it's long axis perpendicular to the ventricles of the brain.  Also, important and very symptomatic lesions are found in the brainstem, the cervical and the thoracic spine.  The spinal cord ends at the bottom of the thoracic spine, so there is no such thing as a lumbar spinal cord lesion in the normal spine.

These scarred lesions will show up as light, bright areas.  These are the classic, MS lesions or "plaques."

Now the very old, scarred ones that have been reabsorbed will show up as a black (empty) space or black hole.  If there are many of these empty areas the brain will contract around them eventually and show up as a loss of brain volume.  This is also know as brain atrophy.  This is particularly seen in the progressive types of MS.

However, a newly active MS lesion may not show up on a regular MRI because the area of nerves, though inflamed, is still pretty much intact and has normal brain density.  On the MRI it will look like normal brain.  Without contrast it won't show up and will be missed.

When the next phase of MRI is done the contrast is in the blood vessels.  So the large blood vessels show up, too.   Anywhere the tiny blood blood vessels are more dilated than usual, as in inlfammation, the areas will "highlight"  or "enhance."  They show up as even brighter.  So new lesions will show up as enhancing, or active.  Also, older lesions, that have undergone new attack right around them will show an enhancing rim or ring.  When you compare the regular MRI to the Contrast MRI you can see this reactivated, old lesion.

That's how some reports can call active lesions or some report no newly enhancing lesions.  Also since some new ones heal they can be compared to old films and show they disappeared.  In addition, between different sets of MRI done after a time has passed, the radiologist can see an increase in old and in new activity.

Please ask question where I haven't been clear.

Quix

[6-paq]

Thanks so much Quix!!  Great info!  Very concise and informative! :)

A question for you ~ what is the difference between T1, T2 and FLAIR?  My neuro said the FLAIR images were best to look at when we were viewing my films.

Have a great evening!  Pat :)

[oncetri]

Thank you for the info, it's amazing.

I just had one more question.  I have small white circular dots all over my MRI films/pictures, not sure what to call them.  Do you know what those could be?  I know I'm going to the doctor soon, and will find out, but it kind of bugs me to see on the film.  And I"m just curious by nature.

[jenn38018]

Could you please take a look at my posting about my test results when you get a chance please?  I'm not wanting you to interpret anything, just want your opinion on my neurologist.  I hope you are doing well, and look forward to hearing from you.

Jenn

[sllowe]

Thank you so much for the above MRI/Lesion explanation - it's so thorough, helpful and written in a way that can be understood and retained.

[uk2]

Very interesting info where do you find the time to do all this research your amazing!!

Iv got my scan on the 14th of August and i am so worried they will miss something im already getting worked up that this will not show something and im on a long journey to find out whats wrong!!

Iv cut and pasted the info as off to spend some time with my husbands parnets as finding it hard to look after kids as feeling rough so will read it in more detail when i get back.

[ALS like mom?]

I'm wondering if you could comment on my situation.

I went to the ER because I was very dizzy.  I have high blood pressure and suspected it was up (I had not been taking my meds for a long time - bad, I know).  Blood pressure was up - 184/126.  They did a CT to see if I had a stroke.  No stroke, but the CT showed "brain atrophy."  My primary physician ordered an MRI.

My MRI report says, "In the periventricular deep white matter are multiple abnormal bright T2 and FLAIR weighted foci, which do not appear to contrast enhance.  Their location and appearance is suspicious for demylenating disorder, such as multiple sclerosis.  The rest of the brain appeared unremarkable. There are no contrast enhancing lesions.  Posterior fossa appeared unremarkable.  Brain stem appeared normal.  Seventh adn eighth cranial nerves appeared unremarkable.  The parasellar region appeared normal."

I have an appointment to see a neurologist on 8/20.  In the meantime, I can't help but wonder if there's any chance what they're seeing could be indicative of ALS, since my mother died from ALS.  I guess what confuses me about what the MRI report says is where it says "there are no contrast enhancing lesions."  I thought with MS they were supposed to see lesions on the MRI - or is the report saying there are lesions, but they do not contrast enhance?

Anyway, any thoughts you have are appreciated, and you are doing such a wonderful thing here - definitely using your education for good.  Many thanks.