Should one perform a subsequent screening CTA or MRA head for mycotic aneurysm after cardio-embolic strokes in a setting of endocarditis with initial unremarkable CTA or MRA head/neck?  

If the initial CTA is unremarkable and there is no intracranial hemorrhage, I do not routinely obtain follow-up imaging. In my practice, CTA is preferred over MRA due to the lower sensitivity of non-contrast/TOF imaging in detecting small mycotic aneurysms. As mentioned above, CTA may also mis...

I would definitely do a CTA, though small mycotic aneurysms or embolic occlusions might be missed, and if there is high suspicion, a cerebral arteriogram might be necessary.