NEW YORK (Reuters Health) - Someday, a yearly brain scan might be as routine for some people as a blood pressure check.

An Ivy League research group is working on a computerized method for interpreting brain MRI scans, which will look for changes in the shape and size of certain brain regions. The researchers hope the technique will make it simpler and cheaper for physicians to make an early diagnosis of neurodegenerative conditions such as Alzheimer's disease, Huntington's disease and schizophrenia.

MRI produces a very detailed picture of structures inside the body. Even a highly trained specialist can require a week to analyze an MRI for brain changes that indicate Alzheimer's or similar diseases, and to distinguish them from the changes that accompany normal aging.

To speed things up, a team led by Dr. Anders Dale, a radiologist at Harvard Medical School in Massachusetts, is creating computerized ``atlases'' that show the position, shape and size of brain structures in healthy and diseased brains. With a single computer workstation, these atlases can be compared with a brain MRI in about 30 minutes. Each of 37 different brain regions is labeled and evaluated to determine whether it is normal.

As a first step, the researchers have shown that their system is able to distinguish people with Alzheimer's disease from healthy people. In 17 patients known to have Alzheimer's, three regions of the brain were smaller than in 25 healthy people, reflecting the degeneration that is characteristic of the disease.

These regions were the hippocampus, which is involved in learning and memory; the amygdala, which is involved in expression of emotions; and the thalamus, which receives almost all of the body's sensory information.

In addition, the lateral ventricle, one of the interconnecting cavities in the brain, was larger in Alzheimer's patients than in healthy people. All of these differences have been reported before, but ``no prior study has measured all of these structures in the same participants,'' the researchers explain in the January 31st issue of the journal Neuron.

They also studied 92 people who were suspected of having Alzheimer's at the time their scans were made. The automated system correctly distinguished between the 21 people who went on to be formally diagnosed with Alzheimer's over the next 3 years and the 71 people who did not develop Alzheimer's. The brain regions that differed in size between these two groups were the hippocampus, the amygdala and several ventricles.

Much more research is needed, Dale's group cautions, before the automated system for interpreting brain scans can be used to determine whether someone has a brain disease, or what stage of the disease the person is in.

For one thing, the scientists point out, there are probably many differences between individuals in terms of brain anatomy and how diseases affect the brain. Also, their study of Alzheimer's patients involved only one scan per person. Long-term studies are needed to track degenerative changes in each individual.

Still, the researchers are hopeful that ultimately, their new system ``may provide a more accurate and sensitive tool for early diagnosis of brain disorders.''

SOURCE: Neuron 2002;33:341-355.

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