The following bit of PowerShell code will search the registry for a string. Update $Filter with the string you are searching for and the registry path with the path you are searching. I used this code to determine whether or not SCCM installed an application on my workstation.
$Filter = "SIT00001" dir "HKLM:\SOFTWARE\Wow6432Node\Microsoft\SMS\Mobile Client\Software Distribution\" -rec -ea SilentlyContinue | ForEach-Object { if ($_.PsPath.ToLower().Contains($Filter.ToLower())) { Write-Host "True" } }