MRI Findings of Rathke Cleft Cyst

ABSTRACT

PURPOSE: To describe the characteristic MRI findings of the Rathke cleft cyst. MATERIALS AND METHODS: During a seven-year period, we retrospectively evaluated the MRI findings of 24 pathologically-proven Rathke cleft cysts. The patients included ten men and 14 women, And their mean age was 37. MRI findings were analyzed in terms of location, shape, size, signal intensity, homogeneity of cyst content, pattern of contrast enhancement, displacement of the pituitary stalk, and mass effect of the cyst on adjacent structures. RESULTS: The location of 14 cases (58%) was sellar or suprasellar; nine (37%) were intrasellar. The mean size of the cysts was 16 x 12mm, as seen on sagittal or coronal images. The characteristic shape of the cyst was a sagging water bag in 13 cases (54%) and upward tenting in eleven (46%). The signal intensity of the cyst varied ; on T1-and T2WI, eleven cases (46%) showed high signal intensity relative to brain parenchyma ; five (21%) showed iso signal intensity on T1WI and high signal intensity on T2WI. While 18 (75%) showed inhomogeneous signal intensity on T1- and T2WI;13 (54%) showed a smudge pattern within the cysts, and six (25%) showed homogeneous signal intensity on T1 and T2WI. On Gd-DTPA enhanced images, thin-rim enhancement surrounding the cyst was seen in 20 cases (83%). While no enhancement was seen within the cyst. Seventeen cases (71%) showed anterior displacement of the pituitary stalk; two showed posterior displacement and five were indeterminate. Mass effect included compression of the optic chiasm (11cases) and bony erosion or tilting of the sellar floor (8 cases). CONCLUSION: MRI findings of midline intrasellar cyst with a sagging water bag appearance, high signal intensity on T1- and T2WI, inhomogeneity of cyst content, and peripheral rim enhancement surrounding the cyst are common, and are characteristic of the Rathke cleft cyst.