How to rename multiple registry entries at once.

Hi all, 

I just started trying to learn powershell and I thought I'll create a script to clean up office. 

For folders I managed to write the code:

Get-ChildItem -Path "C:\MSOCache\All Users" *0FF1CE*| Rename-Item -NewName {$_.Name + ".OLD"} -Force -ErrorAction 'silentlycontinue

However, this does not work with Registry where I need to search with wildcard? Correct me if I'm wrong.

$Path="HKLM:\SOFTWARE\Microsoft"
Get-Item -Path $Path\Windows\CurrentVersion\Uninstall\*TEST* | Rename-Item -NewName TEST.OLD -Force

Get-Item -Path $Path\Windows\CurrentVersion\Uninstall\*TEST*


    Hive: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall


SKC  VC Name                           Property                                                                                                                                        
---  -- ----                           --------                                                                                                                                        
  0   0 xxxTESTzzz                     {}                                                                                                                                              
  0   0 zzzTESTzzz                     {}            

So the Reg  keys are being found. If I run the code as above, it only changes one of the two.

I also tried exactly as per Office folder. 

$Path="HKLM:\SOFTWARE\Microsoft"
Get-Item -Path $Path\Windows\CurrentVersion\Uninstall\*TEST* | Rename-Item -NewName {$_.Name + ".OLD"} -Force

It just says that the key at the specified path does not exist. I assume that when I run the ps it searches for *TEST* folder and not for keys containing TEST in name. 

What I want to achieve is exactly as per MSOCache, renaming xxxTESTxxx to xxxTESTxxx.OLD and zzzTESTzzz to zzzTESTzzz.OLD

Greatly appreciating your help, also if possible with explanation.

Thanks!