Can someone have a stroke and not know it? would it show up on imaging?

Mini stroke?: There are small vascular incidents that may, indeed, go w/out notice and depending on the locus and size it may also not show on any imaging. But as these events usually are not singular, eventually they'll be noticed both in experience and imagry. Consider a Health Psychologist to support you thru medical issues and teach mgmt/communication skills. Best!

Can occur: Usually present in a very confined small area, so called lacunar event. Present in older adults who have widespread microvascular angiopathy associated with causes for "hardening of arteries".

Lacunar strokes: are often "silent". only to be discovered on CT or MRI scanning later. These tend to be about the size of a piece of un-popped pop corn. Weather or not one becomes aware of their occurrence depends on the location within the brain.