Metric to quantify white matter damage on brain magnetic resonance images

Valdés Hernández, M. D. C. et al. (2017) Metric to quantify white matter damage on brain magnetic resonance images. Neuroradiology, 59(10), pp. 951-962. (doi: 10.1007/s00234-017-1892-1) (PMID:28815362) (PMCID:PMC5596039)

Abstract

Purpose: Quantitative assessment of white matter hyperintensities (WMH) on structural Magnetic Resonance Imaging (MRI) is challenging. It is important to harmonise results from different software tools considering not only the volume but also the signal intensity. Here we propose and evaluate a metric of white matter (WM) damage that addresses this need. Methods: We obtained WMH and normal-appearing white matter (NAWM) volumes from brain structural MRI from community dwelling older individuals and stroke patients enrolled in three different studies, using two automatic methods followed by manual editing by two to four observers blind to each other. We calculated the average intensity values on brain structural fluid-attenuation inversion recovery (FLAIR) MRI for the NAWM and WMH. The white matter damage metric is calculated as the proportion of WMH in brain tissue weighted by the relative image contrast of the WMH-to-NAWM. The new metric was evaluated using tissue microstructure parameters and visual ratings of small vessel disease burden and WMH: Fazekas score for WMH burden and Prins scale for WMH change. Results: The correlation between the WM damage metric and the visual rating scores (Spearman ρ > =0.74, p < 0.0001) was slightly stronger than between the latter and WMH volumes (Spearman ρ > =0.72, p < 0.0001). The repeatability of the WM damage metric was better than WM volume (average median difference between measurements 3.26% (IQR 2.76%) and 5.88% (IQR 5.32%) respectively). The follow-up WM damage was highly related to total Prins score even when adjusted for baseline WM damage (ANCOVA, p < 0.0001), which was not always the case for WMH volume, as total Prins was highly associated with the change in the intense WMH volume (p = 0.0079, increase of 4.42 ml per unit change in total Prins, 95%CI [1.17 7.67]), but not with the change in less-intense, subtle WMH, which determined the volumetric change. Conclusion: The new metric is practical and simple to calculate. It is robust to variations in image processing methods and scanning protocols, and sensitive to subtle and severe white matter damage.

• Item Type: Articles
• Additional Information: This study was funded by the Row Fogo Charitable Trust (Grant No. BRO-D.FID3668413). The Stroke sample data acquisition and processing was funded by The Wellcome Trust (Ref. No. 088134/Z/09/A). Funds from the European Union Horizon 2020 “SVDs@target” (Ref. PHC-03-15, Project no. 666881), the Innovate UK (Ref.46917–348,146) and Fondation Leducq (Ref no. 16 CVD 05) are also gratefully acknowledged. The Lothian Birth Cohorts (LBC) data collections were supported by Research Into Ageing and continues as part of The Disconnected Mind project, funded by Age UK, with additional funding from the UK Medical Research Council under grant numbers G0701120, G1001245 and MR/M013111/1. Magnetic resonance image acquisition and analyses were conducted at the Brain Research Imaging Centre, Neuroimaging Sciences, University of Edinburgh (www.bric.ed.ac.uk) which is part of the SINAPSE (Scottish Imaging Network—A Platform for Scientific Excellence) collaboration (www.sinapse.ac.uk) funded by the Scottish Funding Council and the Chief Scientist Office. Part of this study (LBC data) was undertaken within The University of Edinburgh Centre for Cognitive Ageing and Cognitive Epidemiology (www.ccace.ed.ac.uk), part of the cross council Lifelong Health and Wellbeing Initiative (MR/K026992/1) for which funding from the BBSRC and MRC are gratefully acknowledged.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Dickie, Dr David Alexander
• Authors: Valdés Hernández, M. D. C., Chappell, F. M., Muñoz Maniega, S., Dickie, D. A., Royle, N. A., Morris, Z., Anblagan, D., Sakka, E., Armitage, P. A., Bastin, M. E., Deary, I. J., and Wardlaw, J. M.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Neuroradiology
• Publisher: Springer
• ISSN: 0028-3940
• ISSN (Online): 1432-1920
• Copyright Holders: Copyright © 2017 The Authors
• First Published: First published in Neuroradiology 59(10):951-962
• Publisher Policy: Reproduced under a Creative Commons License