Will taking a ct scan help determine if pe that was diagnosed in april 2012 has disappeared?

It certainly should.: Just to make sure the study should be done with vascular contrast media.

CT and PE: A high resolution chest ct scan can be used to follow up a former pe, especially if you've been on a blood thinner like warfarin (coumadin) or lovenox (enoxaparin).

Not a great idea: If you had a pe in april but no longer have any symptoms, there is no need for a ct scan. Your body has a natural way of handling and dissolving clots. The point of hospital treatment is just to avoid short-term (first 7 days) recurrence or progression. Unnecessary ct scans should be avoided because of false positives (which trigger unnecessary tests) and because of high-dose ratiation -> cancer.