In vivo quantification of white matter microstructure for use in aging: a focus on two emerging techniques.
Human brain imaging has seen many advances in the quantification of white matter in vivo. For example, these advances have revealed the association between white matter damage and vascular disease as well as their impact on risk for and development of dementia and depression in an aging population. Current neuroimaging methods to quantify white matter damage provide a foundation for understanding such age-related neuropathology; however, these methods are not as adept at determining the underlying microstructural abnormalities signaling at risk tissue or driving white matter damage in the aging brain. This review will begin with a brief overview of the use of diffusion tensor imaging (DTI) in understanding white matter alterations in aging before focusing in more detail on select advances in both diffusion-based methods and multi-component relaxometry techniques for imaging white matter microstructural integrity within myelin sheaths and the axons they encase. Although DTI greatly extended the field of white matter interrogation, these more recent technological advances will add clarity to the underlying microstructural mechanisms that contribute to white matter damage. More specifically, the methods highlighted in this review may prove more sensitive (and specific) for determining the contribution of myelin versus axonal integrity to the aging of white matter in brain.
Department of Psychiatry, University of Illinois at Chicago, Chicago, IL; Graduate Program in Neuroscience, University of Illinois at Chicago, Chicago, IL. Electronic address: mlamar@psych.uic.edu.
Melissa
M
Lamar
Center for Magnetic Resonance Research and Departments of Radiology and Neurosurgery, University of Illinois at Chicago, Chicago, IL.
Xiaohong Joe
XJ
Zhou
Department of Psychiatry, University of Illinois at Chicago, Chicago, IL.
Rebecca A
RA
Charlton
School of Engineering, Brown University, Providence, RI.
Douglas
D
Dean
Scott & White Healthcare and Texas A&M Health Sciences, Temple, TX.
Deborah
D
Little
School of Engineering, Brown University, Providence, RI.
Sean C
SC
Deoni
D000375:Aging / Q000473:pathology*; D001369:Axons / Q000473:pathology; D056324:Diffusion Tensor Imaging / Q000379:methods; D006801:Humans; D009186:Myelin Sheath / Q000473:pathology; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D059906:Neuroimaging / Q000379:methods*
Multi-component relaxometry; aging; axons; diffusion tensor imaging; myelin