Around 1996/97 I heard two very similar rumors, from two people who did not know each other. Both rumors had it that the NT source at that time was at least in some part the source of "Micah", the OS that Dave Cutler and crew had been working on for the Prism architecture. The NT source still had DEC copyrights and mentions of Micah in it. That's why DEC had such a weird deal with Microsoft, and why there was an Alpha AXP port of NT long after all other architectures went by the wayside.
As far as credibility of this rumor, if you have a copy of "Inside the Windows NT file system" (https://www.amazon.com/Inside-Windows-NT-File-System/dp/1556...) by Helen Custer, you'll see a more than passing resemblance of NTFS to ODS-2, the on-disk layout of VMS filesystem. G. Pascal Zachary has a big chapter on the development of NTFS, if I recall "Showstopper!" correctly, but he doesn't mention this... coincidence at all, giving full credit for NTFS to a couple of guys on the NT team.
As far as credibility of this rumor, if you have a copy of "Inside the Windows NT file system" (https://www.amazon.com/Inside-Windows-NT-File-System/dp/1556...) by Helen Custer, you'll see a more than passing resemblance of NTFS to ODS-2, the on-disk layout of VMS filesystem. G. Pascal Zachary has a big chapter on the development of NTFS, if I recall "Showstopper!" correctly, but he doesn't mention this... coincidence at all, giving full credit for NTFS to a couple of guys on the NT team.