Ct scan dects brain aneurysms? Is it possible for a CT scan without contrast to reveal an unruptured brain aneurysm? Is the test meant to find that sort of thing?

NOT THE BEST WAY. Mri with contrast will pickup most large aneurysms over the blood vessels of the brain, and a cat angio or a magnetic resonance angio would be used to find smaller aneurysms. Standard cat not usually successful.
Unlikely. A ct scan of the head without contrast is meant to look for bleeding, not aneurysms. Unless and aneurysm is quite large and/or has a thrombus in it, it is unlikely to be seen on a non contrast ct scan. A cta or mra are good diagnostic tests for detecting brain aneurysms.
It . It is possible for a noncontrast ct to reveal an unruptured aneurysm, but generally this is a very poor test for aneurysm evaluation. A noncontrast head ct will usually only finding very large aneurysms and smaller aneurysms will almost always be overlooked. A mr angiogram may be performed to screen for aneurysm; this uses no intravenous contrast and is performed in a standard MRI machine. A ct angiogram can also screen for aneurysm; this uses intravenous iodinated contrast scan and is performed in a multidetector ct scanner. A conventional angiogram is the gold standard in evaluation for aneurysm; this is performed by placing a needle and catheter into an artery in the groin and then injecting iodinated contrast into the arteries of the neck while taking x-ray images of the head.