I am going to preface this article with a brief explanation of why I am sold on one Microsoft product – Microsoft Security Essentials(MSE) or Windows Defender. I say one because these products are essentially the same thing. I can tell you that I have used nearly every anti-virus product under the sun, but I always come back to MSE. Years ago, I deployed Microsoft Forefront Endpoint Protection for a client and was very pleased with the end result. If you have never heard of Microsoft Forefront Endpoint Protection, it is essentially the enterprise version of MSE. You may not have known that Microsoft is a player in the AV arena, but in my opinion their MSE product is as good as any other. The real take away here is that any AV program is only as good as the user who is using it. Meaning nothing is more important than an educated end user. With all that said, if you are running Windows 
8.x then you are most certainly aware that Windows Defender is the built in AV solution. That is great, however if you need to run an on demand scan, there are no options out-of-the-box. In the tutorial below we will modify the registry so the context menu will now contain “Scan with Windows Defender” as seen to the left. In order to add the context entry, we will need to make some modifications to the registry. Below is the registry file, simply copy the contents and paste into a document with a .reg file extension. Once the file is saved, you will need to double-click the file to import into your registry. Please note in the file below that the value of “MUIVerb” is what is actually shown in the context menu. Of course this can be modified to your liking.
Windows Registry Editor Version 5.00 ; Folder Scan [HKEY_CLASSES_ROOT\Folder\shell\WindowsDefender] "Icon"="%ProgramFiles%\\\\Windows Defender\\\\EppManifest.dll" "MUIVerb"="Scan with Windows Defender" [HKEY_CLASSES_ROOT\Folder\shell\WindowsDefender\Command] @="cmd.exe /s /c \"\"C:\\Program Files\\Windows Defender\\MpCmdRun.exe\" -scan -scantype 3 -SignatureUpdate -file \"%1 \"\" & pause" ; File Scan [HKEY_CLASSES_ROOT\*\shell\WindowsDefender] "Icon"="%ProgramFiles%\\\\Windows Defender\\\\EppManifest.dll" "MUIVerb"="Scan with Windows Defender" [HKEY_CLASSES_ROOT\*\shell\WindowsDefender\Command] @="cmd.exe /s /c \"\"C:\\Program Files\\Windows Defender\\MpCmdRun.exe\" -scan -scantype 3 -SignatureUpdate -file \"%1 \"\" & pause"
Once the file is imported, simply logoff and log back on and you will now have scan capability in your context menu.