The thing about brain aneurysms is that your doctor has to suspect you already have one, in order to bother scheduling a CT or MRI scan to look for it. Without any advance notice like that, it's like the sudden catastrophic failure of a dam wall once it does happen.
The real irony here is that he probably could've built his own scanner, given enough advance notice. RIP to an absolute genius; the world is a poorer place without him.