Case 3

This is an MRI brain study showing a round lesion in the left temporal lobe adjacent to the temporal horn of the left lateral ventricle – it shows dark signal intensity on all sequences with a crescentic lateral component which exhibits high SI on both the fluid sensitive and T1 weighted series. The time of flight series shows flow into this lesion from the left supraclinoid internal carotid artery; this represents a saccular aneurysm. There is also high FLAIR and T1 signal in the adjacent temporal horn- this signal surrounding the aneurysm and in the lateral ventricle represents extracellular methaemoglobin from a late subacute haemorrhage. The susceptibility weighted series demonstrates blooming artifact around the aneurysm and in both lateral ventricles, indicating haemosiderin deposition caused by bleeding.  

Therefore, this is a saccular aneurysm which has bled in the last 1 – 4 weeks.

I would convey the findings to the referring physician in the first instance and recommend urgent referral to neurosurgery / neuro-interventional service for embolisation.