Bright spots & black holes: 1 of 2
what doctors learn from advanced MRI
What doctors are learning is not comfortable news. I am presenting technical details to understanding MS.
The bottom line is brief:
uncontrolled MS damages to the central nervous system
--the brain and spinal cord—
and for many people the damage will, in time, be permanent.
The fatty material that protects nerve fibers (myelin)is destroyed and replaced by scarring; and some gray matter (nerve cells as well as the nerve-cell fibers, or axons).
Black holes and overall shrinkage of the brain, called atrophy, may occur. The sooner disease-modifying therapy is begun, the more effectively this damage can be delayed or prevented.
In other words, new findings confirm the wisdom of discussing this with your personal physician and or your neuologist.
Fifty years ago, MRI was called NMR. The letters stood for "nuclear magnetic resonance" and it was used in laboratory research. Then, late in the 1970s, as computer technology improved, NMR was enlarged, modified, and renamed. The developers were skittish about trying to persuade people to use a medical imaging device with the word "nuclear" in it. The name "magnetic resonance imaging" was adopted.
The basic technology didn't change. The MRI uses radio waves and magnetism. There has never been radiation or nuclear energy involved in MRI.
How the MRI works
- a strong magnetic field makes the hydrogen protons in water molecules line up
- radio waves knock the protons out of line.
- when the radio waves are stopped, the protons relax back into line, releasing "resonance" signals, which are transmitted to a computer.
- computer programs convert these data into a picture--of water. (The water in living human tissues.)
Where fat isn't, water is
Because the myelin layer that protects nerve-cell fibers is fatty, it repels water. Thus, MS damage reveals itself on MRI because areas that are stripped of fatty myelin hold more water. MS lesions, or damaged areas, show up as bright spots.
Early in the 1980s, the first serial MRI scans of people with MS changed physicians' fundamental understanding of this disease forever. Those pioneering MRI studies revealed that MS is a constantly active on-going disease from the very beginning.
Even when a person with MS is in remission and feels well, events are taking place in the brain or spinal cord. Some MS doctors call these events "explosions in the brain." MRI studies demonstrate that they happen five to ten times more frequently than visible MS relapses or attacks.
reliable measurement
Today, MRI is an essential measure of MS activity. Researchers can count the number and measure the size of lesions, and that gives them an objective measure of multiple sclerosis activity. In a slow-moving, notoriously variable illness like MS, researchers had been hard-pressed to find a benchmark for evaluating the effect of treatments. MRI data are simple:
Ø smaller and fewer lesions = good;
Ø more and larger lesions = bad.
The big glitch is the lack of clear correlation between the MRI picture of MS and the clinical picture of MS--which is how a person feels or acts in daily life. But as MRI technology has marched forward, it has become more and more clear why fewer and smaller lesions = good. Over a longer term, the total extent of damage seen on MRI is definitely related to a person's disability. Indeed, some of the cognitive problems people have--with memory, word-finding, or problem-solving--have now been linked to the location of lesions as well as to their number and size.