What features are helpful in confirming that this is fat?
Best clue is that it attenuates on fat saturated images. T2 weighted images also offer a clue... (see next question).
On the T2 weighted images, what artefact is visible?
Chemical shift artefact (see next section).
MRI of the brain demonstrates a rounded region of intense intrinsic high T1 signal located on the right, in the quadrigeminal plate cistern, abutting the inferior colliculus. On FLAIR and T2 weighted sequences it is also of high signal, with subtle chemical shift artefact seen on T2. On fat saturated sequences it fully attenuates.