To find all streams within file.txt:
Get-Item .\file.txt -Stream *
PSPath : Microsoft.PowerShell.Core\FileSystem::C:\file.txt::$DATA
PSParentPath : Microsoft.PowerShell.Core\FileSystem::C:\
PSChildName : file.txt::$DATA
PSDrive : C
PSProvider : Microsoft.PowerShell.Core\FileSystem
PSIsContainer : False
FileName : C:\file.txt