[The optic pathways: a magnetic resonance study at 1.5 tesla. I. Anatomy]

The authors retrospectively examined one hundred and twenty-nine patients who had undergone MR examination of the sellar, parasellar and orbital regions, to evaluate MR capabilities in demonstrating the optic pathways and their relationship to the most important anatomical structures nearby. T1-weighted images allowed a very good evaluation not only of the optic pathways as a whole, but also of the intracanalicular and intracranial segments of the optic nerve; the optic tracts and geniculate bodies were also clearly demonstrated. Optic radiations were clearly visible on both T1- and T2-weighted images. The orbital portion of the optic nerve could be evaluated with T1-weighted images, which showed its external profile. However, only multi-echo T2-weighted images allowed the nerve to be differentiated from perineural spaces, filled with cerebrospinal fluid, thus giving a true cisternographic effect.