?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aulast=Liu&rft.au=Liu%2C+Z&rft.aufirst=Z&rft.atitle=Magnetisation+transfer+ratio+measures+in+normal+appearing+white+matter+show+periventricular+gradient+abnormalities+in+multiple+sclerosis&rft.volume=138&rft.date=1+May+2015&rft.issue=5&rft.title=Brain&rft.pages=1239-1246&rft.issn=0006-8950&rft.genre=article