MRI diagnosis of rosette-forming glioneuronal tumor of the fourth ventricle

Objective: To summarize the MRI characteristics of rosette-forming glioneuronal tumor of the fourth ventricle (RGNT). Methods: The clinical, MRI and pathological data of 13 patients with RGNT were retrospectively analyzed. Results: The lesions were located in the fourth ventricle (7) with 1 also involving the culmen of cerebellum and fourth ventricle or in the cerebellar hemispheres and vermis (6). The tumors were mixed solid-cystic (6) or solid (4) masses with heterogeneous signal intensities in the solid part, 6 of which showed punctiform or patchy short T₁ and T₂ signals. The solid components of the tumors showed punctiform, patchy and botryoid enhancement. The 3 remaining cystic masses had heterogeneously enhanced partially thin or thick cystic walls. Of 7 patients with CT examinations, 4 showed hyperdense cystic wall or solid part corresponding to angiogenesis on pathology. Conclusion: RGNT should be considered in mixed solid-cystic or solid masses with heterogeneous signal intensities and contrast enhancement involving the cerebellum or forth ventricle. (authors)