CHICAGO, Sept. 24 (Xinhua) -- Analyzing overlooked data from an MRI scan by a new technique developed by U.S. researchers surprisingly reveals how many and which brain cells are present, and shows where cells have been lost through injury or disease.

The researchers at Washington University School of Medicine in St. Louis analyzed the background data on an MRI scan and found a signal, which they called R2t*, that remained largely unchanged when people performed tasks but varied across parts of the brain.

They compared the R2t* signal with data from the Allen Human Brain Atlas, which maps genes active in various areas of the brain, and found three sets of gene networks that tracked with the R2t* signal.

These groups of genes, as it turned out, reflected the different kinds and numbers of brain cells, and the extent of connections between them.

In other words, this quick new MRI scan gave the researchers all they needed to know to determine how densely packed and interconnected the neurons are in any part of the brain.

The information could also help the researcher understand how a person's brain develops and changes from infancy to old age, and how human build memories and learn. It could also give clues to brain illness or injury.

"We did some studies on traumatic brain injury where we found some areas of the brain are already losing neurons even though the standard scans show nothing," said Dmitriy Yablonskiy, professor of radiology at the university's Mallinckrodt Institute of Radiology.

The researchers also applied their technique to the hippocampus, the memory center of the brain, in people with Alzheimer's disease. They found that not only was the hippocampus smaller than in healthy people, but the remaining part was not healthy: it had lost cells and begun to decay.

"There are MRI scans now that can detect brain atrophy even before people show symptoms of Alzheimer's disease," Yablonskiy said. "Our technique can show the brain degrading even before it begins to atrophy."

The researchers are now working on applying their technique to brain diseases and disorders including Alzheimer's, schizophrenia, multiple sclerosis and autism, as well as to understanding how a healthy brain develops and grows.

This eventually may lead to new ways to diagnose Alzheimer's disease, multiple sclerosis, traumatic brain injury, autism and other brain conditions through a simple brain scan.

The findings were published online the week of Sept. 24 in Proceedings of the National Academy of Sciences.