BACKGROUND AND PURPOSE: We used quantitative diffusion MR imaging to investigate the microstructural changes that occur in white matter during normal aging in order to identify regional changes in anisotropy and to quantify global microstructural changes by use of whole-brain diffusion histograms. METHODS: Full diffusion tensor MR imaging was performed in 20 healthy volunteers, 20 to 91 years old. Thirteen subjects also underwent high-resolution T1-weighted imaging, so that diffusion images could be coregistered and standardized to normal coordinates for statistical probability mapping. Relative anisotropy (RA) was calculated, as was linear regression of RA with age for each pixel; pixels with a significant correlation coefficient were displayed. For histographic analysis, the average apparent diffusion coefficient (ADC) histograms were calculated on a pixel-by-pixel basis. Subjects were divided into two equal groups by the median age (55 years) of the population and plotted for statistical comparison. RESULTS: Regional analysis showed statistically significant decreases in RA with increasing age in the periventricular white matter, frontal white matter, and genu and splenium of the corpus callosum, despite the absence of signal abnormalities on visual inspection of conventional images. Significant increases in RA were found in the internal capsules bilaterally. ADC histograms showed higher mean ADC and reduced peak height and skew in the older age group on group comparisons. CONCLUSION: Quantitative diffusion histograms correlate with normal aging and may provide a global assessment of normal age-related changes and serve as a standard for comparison with neurodegenerative diseases.
BACKGROUND AND PURPOSE: We used quantitative diffusion MR imaging to investigate the microstructural changes that occur in white matter during normal aging in order to identify regional changes in anisotropy and to quantify global microstructural changes by use of whole-brain diffusion histograms. METHODS: Full diffusion tensor MR imaging was performed in 20 healthy volunteers, 20 to 91 years old. Thirteen subjects also underwent high-resolution T1-weighted imaging, so that diffusion images could be coregistered and standardized to normal coordinates for statistical probability mapping. Relative anisotropy (RA) was calculated, as was linear regression of RA with age for each pixel; pixels with a significant correlation coefficient were displayed. For histographic analysis, the average apparent diffusion coefficient (ADC) histograms were calculated on a pixel-by-pixel basis. Subjects were divided into two equal groups by the median age (55 years) of the population and plotted for statistical comparison. RESULTS: Regional analysis showed statistically significant decreases in RA with increasing age in the periventricular white matter, frontal white matter, and genu and splenium of the corpus callosum, despite the absence of signal abnormalities on visual inspection of conventional images. Significant increases in RA were found in the internal capsules bilaterally. ADC histograms showed higher mean ADC and reduced peak height and skew in the older age group on group comparisons. CONCLUSION: Quantitative diffusion histograms correlate with normal aging and may provide a global assessment of normal age-related changes and serve as a standard for comparison with neurodegenerative diseases.
Authors: E A Hazlett; M S Buchsbaum; R C Mohs; J Spiegel-Cohen; T C Wei; R Azueta; M M Haznedar; M B Singer; L Shihabuddin; C Luu-Hsia; P D Harvey Journal: Neurobiol Aging Date: 1998 Sep-Oct Impact factor: 4.673
Authors: M E Moseley; Y Cohen; J Kucharczyk; J Mintorovitch; H S Asgari; M F Wendland; J Tsuruda; D Norman Journal: Radiology Date: 1990-08 Impact factor: 11.105
Authors: Marek Kubicki; Carl-Fredrik Westin; Stephan E Maier; Hatsuho Mamata; Melissa Frumin; Hal Ersner-Hershfield; Ron Kikinis; Ferenc A Jolesz; Robert McCarley; Martha E Shenton Journal: Harv Rev Psychiatry Date: 2002 Nov-Dec Impact factor: 3.732