Friday, August 13, 2010
Hiding in Plain Sight � American Scientist: "Diffusion MRI refers to a body of methods that map, noninvasively, the fiber architecture of a living organism’s brain. All these methods use the three-dimensional patterns of the random diffusion of water to trace microscopic tissue structure. The first, diffusion tensor imaging, looked promising but did not record crossing pathways. The brain has extensive systems of crossing fibers, which are essential for efficient circuits. To address this, we invented several more methods 10 years ago, including diffusion spectrum MRI (DSI). DSI acquires a detailed image of the three-dimensional pattern of water diffusion by measuring diffusion in dozens to hundreds of directions. This yields a six-dimensional image of the brain: three dimensions of anatomical location and an additional three dimensions for the distribution of water flux at each location. Just as they do in high-energy physics, extra dimensions can make a problem simpler. "