MEP to Navisworks for clash detection

[revit7777]

Hi, I was wondering how to open up/convert... or whatever needs to be done... so that I can open up my revit model in navisworks to use the clash detection tool? I have used the interference check in revit, but it tells me everything is good, then the architect runs it through navisworks and there are problems all over the place. I was hoping to save myself the time and run it through navisworks myself before hand. I am using Revit MEP 2009 on this project. Thanks for any help! I have navisworks Freedom and navisworks Manage, but there doesn't seem to be an option to import revit files, and there doesn't seem to be a way to export from Revit either.