I think there are several great teaching points with this case:

1. When I first read this case, the specific abnormality was not immediately apparent to me when I scrolled through the axial images, but I sensed that something was not right. I think that feeling that "something is abnormal here, but I am not sure exactly what" should always be listened to. Over time, radiologists develop a bit of a "sixth sense", and when you think there is something wrong but you're not sure what, keep looking until you find it!

2. There are all of the classic signs of IVC/deep vein thrombosis on this examination, but the provided history was misleading. I was told the patient had abdominal pain, and the ordering provider had no idea that the patient even had an IVC filter! The findings are: vein expansion, absent opacification, perivenous edema/congestion, lower extremity edema, epidural venous plexus engorgement. 

3. The epidural venous plexus engorgement is pretty impressive on sagittal view, and confirms the diagnosis and the presence of collateral flow. That was a new finding from the prior study. 

4. Finally, remember DVT is a great mimic for lower abdominal pain, often with the ordering provider asking you to look for appendicitis or diverticulitis. Always run the vasculature, and use secondary signs (such as stranding, haziness, fluid, etc) to help guide your search!