My desktop is connected to our office network. If I use the Tor browser, can our IT trace that I'm the one using Tor in the office? Could the websites I visited using Tor browser also traced back?
This interactive diagram offers a good explanation of who can can know what.
Your IT is able to see that you are using Tor. In general Tor doesn't hide this fact. There is one famous example of a Tor user who was identified because he was the only one using it.
One possible way to work around this is to use Tor's bridges. They try to hide the fact that you are using Tor.
In general it is not possible that your network administrator can find out what pages you visit using Tor Browser. However if the department is able to remotely logon to your computer or to manipulate files they might be able to see everything you're doing with your whole system.