Diffusion Tensor Imaging and Its Application to Neuropsychiatric Disorders

Abstract

Magnetic resonance diffusion tensor imaging (DTI) is a new technique that can be used to visualize and measure the diffusion of water in brain tissue; it is particularly useful for evaluating white matter abnormalities. In this paper, we review research studies that have applied DTI for the purpose of understanding neuropsychiatric disorders. We begin with a discussion of the principles involved in DTI, followed by a historical overview of magnetic resonance diffusion-weighted imaging and DTI and a brief description of several different methods of image acquisition and quantitative analysis. We then review the application of this technique to clinical populations. We include all studies published in English from January 1996 through March 2002 on this topic, located by searching PubMed and Medline on the key words "diffusion tensor imaging" and "MRI." Finally, we consider potential future uses of DTI, including fiber tracking and surgical planning and follow-up.Diffusion tensor imaging (DTI) is an exciting recent technique in neuroimaging that affords a unique opportunity to quantify the diffusion of water in brain tissue. It is based upon the phenomenon of water diffusion known as Brownian motion, named after the English botanist Robert Brown, who in 1827 observed the constant movement of minute particles suspended within grains of pollen. * We now know that molecular motion is affected by the properties of the medium in which it occurs and that diffusion within biological tissues reflects both tissue structure and architecture at the microscopic level. Equal, or isotropic, diffusion occurs when a medium does not restrict molecular motion, as would be the case with cerebrospinal fluid. Skewed, or anisotropic, diffusion, seen in crystals and polymer films, is not equal in all directions. DTI measures diffusion properties and consequently allows spatial description of the medium under study.Taking advantage of the fact that diffusion is not uniform throughout the brain (differing, for example, between gray matter, white matter, and cerebrospinal fluid), researchers can employ DTI to evaluate tissue characteristics. The technique is particularly useful in the study of white Reprint requests: Martha E. Shenton, PhD, Department of Psychiatry-116A, VA Boston Healthcare System-Brockton Division, 940 Belmont St., Brockton, MA 02301 (martha_shenton@hms.harvard.edu). * It was long thought that Brown observed the movement of pollen grains suspended in water. Many now believe that he observed the movement of particles suspended within the grains of pollen. See, for example, BJ Ford, Brownian movement in Clarkia pollen: a reprise of the first observations. The Microscope 1992;40:235-41 (available on the World Wide Web at: http://www.sciences.demon.co.uk/wbbrowna.htm). NIH Public Access Author ManuscriptHarv Rev Psychiatry. Author manuscript; available in PMC 2010 April 13. Published in final edited form as:Harv Rev Psychiatry. 2002 ; 10(6): 324-336. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Man...

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