Dti In Development And Aging

Development and senescence of neural systems is associated with profound alterations in connective anatomy and tissue architecture. Classical neuroimaging has allowed the in vivo examination of these dynamic changes, and prior studies utilizing quantitative methods have revealed many basic principles of cerebral organization across the lifespan. Recent developments in diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI) have provided a significant advance in the parameters available for the in vivo examination of tissue changes across the lifespan. The microstructural measurements provided by diffusion imaging are particularly helpful in charting the change in myeloarchitecture and connectivity that occurs during brain development, as well as mapping the decline or alterations in brain networks that result from aging and disease. Diffusion methods may allow the measurement of tissue parameters that precede functional or macroscopic structural alterations, or even differentiate among the various histological processes that have been documented to occur across the lifespan. Knowledge of normal variations in diffusion parameters across the lifespan is necessary to develop the sensitivity to detect early changes in tissue architecture which result from disease. Here we review the current literature examining the use of diffusion metrics to gain neurobiological insight into the developing and aging brain, as well as work exploring the clinical utility of diffusion imaging towards understanding patterns of abnormal development and age-associated neurodegenerative disease. We additionally review related concepts, including discussion of the common metrics obtained from diffusion imaging and how lifespan changes in diffusion metrics relate to classically utilized macrostructural volumetric measures. With the great promise of diffusion imaging, it will be critical to advance procedures for data acquisition and analysis that provide the most accurate and sensitive measures of anatomy and microstructure possible. In this regard, we review some of the current limitations and challenges in the application of diffusion imaging to address clinical questions, and discuss the great potential for future applications once these challenges are addressed.