• Marco Rovaris, Giuseppe Iannucci, Mara Cercignani, Maria Pia Sormani, Nicola De Stefano, Simonetta Gerevini, Giancarlo Comi, and Massimo Filippi.
• Neuroimaging Research Unit, Department of Neuroscience, Scientific Institute and University Ospedale San Raffaele, Via Olgettina 60, 20132 Milan, Italy.
• Radiology. 2003 Jun 1;227(3):731-8.

PurposeTo investigate the influence of aging on conventional magnetic resonance (MR) imaging-, magnetization transfer MR imaging-, and diffusion-tensor MR imaging-derived measurements.Materials And MethodsDual-echo T1-weighted magnetization transfer and diffusion-tensor MR images of the brain were obtained in 89 healthy subjects. Normalized brain parenchymal volume (NBV) was measured by using a fully automated technique. Magnetization transfer ratio (MTR), apparent diffusion coefficient (ADC), and fractional anisotropy (FA) histograms were created for the whole brain (MTR values) or for a large representative portion of it (ADC and FA values). Bivariate correlations were assessed by using the Spearman rank correlation coefficient. A stepwise selection procedure was used to identify the combination of variables that were most influenced by subject age in a multivariate regression model.ResultsSignificant correlations were found between subject age and the following variables: number of hyperintense areas in the brain at T2-weighted MR imaging (r = 0.63, P <.001), NBV (r = -0.79, P <.001), mean ADC (r = 0.34, P =.001), ADC peak height (r = -0.34, P =.001), and FA peak height (r = -0.57, P <.001). NBV correlated significantly with number of hyperintense areas (P <.001), MTR peak height (P <.001), mean ADC (P =.001), ADC peak height (P =.001), and FA peak height (P <.001). The final multivariable regression model included NBV and number of hyperintense areas at T2-weighted MR imaging as independent predictors of subject age.ConclusionIn addition to the extent of T2-weighted MR imaging hyperintense areas and the measurement of NBV, diffusion-tensor MR imaging provides additional in vivo information about microstructural age-related brain tissue changes.

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