I realised there is an easier way to get the data

function get-SID {            
param (            
 [string]$computername = $env:COMPUTERNAME            
)            
            
Get-WmiObject -Class Win32_AccountSID -ComputerName $computername |            
foreach {            
             
 $exp = "[wmi]'" + $($_.Element) + "'"            
 Invoke-Expression -Command $exp |            
 select Domain, Name, SID, LocalAccount            
}            
}

Use the wmi type accelerator with the path from the Element and you can just select the data you want.  As a bonus you can discover if the account is local or not