What Do These MRI Findings Indicate?

Question: My husband had an MRI 8.19.15 due to severe headache and hypertension. Results were unremarkable. 12 days later, he had a subaracnoid hemorrhage, was in ICU for 17 days and the had a lumbar drain that produced 300cc of mostly blood. angiogram revealed enlarged cerebral vascular system and aneurysms ranging from 7mm to 15mm. How could things be so different within such a short time? Never smoked. Non drinker. History on HBP since 20's. Sibling passed at 26 from aneurysm. He has recovered well. Uses a cane just for balance. Uses catheters now as he did lose ability to urinate on his own.
Part 1: There is a remote 5mm lacunar infarct centrally situated in the left mid pons.
No significant atrophy for age. Minor. No advanced or significant small vessel ischemic change. Minor.
No transcortical infarct. No hemorrhage. Patient indicates prior history of subarachnoid hemorrhage but no hemorrhage or chronic blood product obvious on the standard sequences.

No subacute infarct. Tiny focus of increased signal on the diffusion images in the posterior right centrum semiovale does not correlate with any of the minor small vessel type ischemic change.

Recommend magnetic residence angiogram

Unusual prominent caliber diffusely dilated central arterial vessels. There are large caliber vertebral arteries. Large caliber basilar. In particular the enlarged aneurysmal segment of the right intracavernous carotid. 12mm transverse. AP 15 mm with arterial enhancement projecting lateral to the right cavernous sinus or displacing it toward the right. Contiguously extends into the supraclinoid. It gives rise to a very large right posterior communicating. 1. remote 5 mm lacunar infarct centrally situated in the left pons
2. recommend magnetic resonance angiogram
-very unusual large claiber diffusely dilated central arterial structures. Greater involving the anterior circulation.
- The right intracavernous carotid is diffusely aneurysmal with a transverse diameter of 12mm. 15 mm AP with contiguous extension into the right
supraclinoid carotid
-diffuse aneurysmal dilation of the left supraclinoid carotid at its bifurcation into the A1 and M1 segments. Approximately 12mm AP 7xy 8mm AP and transverse
-Large caliber vertebrobasilar system

Diffuse aneurysmal dilation of the left supraclinoid internal carotid aneurysmal. This is seen at the junction of the supraclinoid with the A1 and M1 segments. Extends over a length of approximately 12 mm appeared AP and transverse diameters between 7 and 8 mm.

Basilar artery also large. Slightly lobulated midsection. No aneurysm obvious at the tip large caliber basilar arteries.