Peak width of skeletonized mean diffusivity (PSMD) as marker of widespread white matter tissue damage in multiple sclerosis

C. Vinciguerra, A. Giorgio, J. Zhang, I. Di Donato, M.L. Stromillo, R. Tappa Brocci, A. Federico, M.T. Dotti, N. De Stefano
2019 Multiple Sclerosis and Related Disorders  
37 Parameters of water diffusion in white matter derived from diffusion-weighted imaging (DWI), 38 such as fractional anisotropy (FA), mean, axial, and radial diffusivity (MD, AD and RD), and 39 more recently, peak width of skeletonized mean diffusivity (PSMD), have been proposed as 40 potential markers of normal and pathological brain ageing. However, their relative evolution 41 over the entire adult lifespan in healthy individuals remains partly unknown during early and 42 late adulthood, and
more » ... particularly for the PSMD index. Here, we gathered and meta-analyzed 43 cross-sectional diffusion tensor imaging (DTI) data from 10 population-based cohort studies 44 in order to establish the time course of white matter water diffusion phenotypes from post-45 adolescence to late adulthood. DTI data were obtained from a total of 20,005 individuals aged 46 18.1 to 92.6 years and analyzed with the same pipeline for computing DTI metrics. For each 47 individual MD, AD, RD, and FA mean values were computed over their FA volume skeleton, 48 PSMD being calculated as the 90% peak width of the MD values distribution across the FA 49 author/funder. All rights reserved. No reuse allowed without permission. : bioRxiv preprint PSMD changes across adult life 3 skeleton. Mean values of each DTI metric were found to strongly vary across cohorts, most 50 likely due to major differences in DWI acquisition protocols as well as pre-processing and DTI 51 model fitting. However, age effects on each DTI metric were found to be highly consistent 52 across cohorts. RD, MD and AD variations with age exhibited the same U-shape pattern, first 53 slowly decreasing during post-adolescence until the age of 30, 40 and 50, respectively, then 54 progressively increasing until late life. FA showed a reverse profile, initially increasing then 55 continuously decreasing, slowly until the 70's, then sharply declining thereafter. By contrast, 56 PSMD constantly increased, first slowly until the 60's, then more sharply. These results 57 demonstrate that, in the general population, age affects PSMD in a manner different from that 58 of other DTI metrics. The constant increase in PSMD throughout the entire adult life, including 59 during post-adolescence, indicates that PSMD could be an early marker of the ageing 60 process. 61 Introduction 62 Parameters of water diffusion in white matter derived from diffusion-weighted imaging (DWI), 63 such as fractional anisotropy (FA), mean, axial, and radial diffusivity (MD, AD and RD) are 64 well-established markers of normal brain More recently, peak width of skeletonized mean diffusivity (PSMD, (20)), a new phenotype of 68 white matter microstructure that can be derived from DWI, has been proposed as an imaging 69 biomarker of small vessel disease (SVD, (20)(21)) and a correlate of cognitive impairment, 70 particularly processing speed (20)(22)(21). So far, our knowledge of the PSMD distribution in 71 healthy individuals has been limited to these three previously mentioned studies that all 72 included people aged over 50 years. In addition, none of these studies addressed the issue 73 of changes in PSMD across lifespan, which is critical for establishing whether PSMD could 74 be used as an imaging marker of brain aging as well as an early predictor of age-related 75 disorders or to serve as a tool to monitor outcomes in clinical trials. Here, we gathered and 76 meta-analyzed cross-sectional diffusion tensor imaging (DTI) data from 10 population-based 77 cohort studies in order to establish the time course, from post-adolescence to late adulthood, 78 of the PSMD distribution and compare it with that of more commonly used white matter water 79 diffusion phenotypes in white matter. 80 author/funder. All rights reserved. No reuse allowed without permission.
doi:10.1016/j.msard.2018.11.011 fatcat:7dnedeu5xnezvc2byiipp3jiem