Edema along the optic tract: a useful MR finding for the diagnosis of craniopharyngiomas.

BACKGROUND AND PURPOSE The pattern of edema caused by craniopharyngiomas and other common suprasellar masses could be useful for determining the differential diagnosis of lesions in this region. The purpose of this study was to ascertain whether the pattern of edema spread on MR images can be used in the diagnosis of craniopharyngiomas. METHODS The preoperative MR images in eight consecutive patients with craniopharyngiomas, 15 patients with large pituitary adenomas compressing the optic chiasm, and six patients with tuberculum sellae meningiomas were evaluated. All the patients were treated surgically at our hospital and a pathologic diagnosis was obtained. We analyzed the spread of edema surrounding the tumor on the coronal dual-echo fast spin-echo images and compared this finding with tumor location and size as seen on contrast-enhanced T1-weighted images. RESULTS Not only peritumoral edema but also edema spreading along the optic tracts was observed in five patients with craniopharyngiomas, one of whom also had edema within one optic nerve. The location of edema in the visual pathway was not always associated with the degree of visual disturbance. None of the patients with large pituitary adenomas or with tuberculum sellae meningiomas had such edema along the visual pathway. CONCLUSION Edema caused by craniopharyngiomas tends to spread along the optic tracts. It is a useful MR finding for distinguishing craniopharyngiomas from other common parasellar tumors.