[1] Leiden Univ, Dept Gen Internal Med, NL-2300 RA Leiden, Netherlands
[2] Leiden Univ, Dept Radiol, NL-2300 RA Leiden, Netherlands
[3] Leiden Univ, Dept Neurol, NL-2300 RA Leiden, Netherlands
[4] N Glasgow Univ NHS Trust, Robertson Ctr Biostat, Glasgow, Lanark, Scotland