In general, when an aneurysm is found and the size determined on
MRA, sometimes (depending on the quality of the
MRA and the appearance of the aneurysm on it) another confirmatory test such as a CT angiogram or cerebral angiogram may need to be done to confirm the presence of the aneurysm, confirm its size, and to exclude the presence of additional aneurysms too small to be seen on MRA.