Radiological Evaluation of Infratentorial Gangliogliomas in Various Anatomic Locations of the Cerebellum and Brainstem.

PURPOSE: To review the imaging features of infratentorial gangliogliomas (GGs) and compare between Infratentorial GGs located within the cerebellum and brainstem.

METHODS: The cases of 24 patients with histologically-confirmed infratentorial GGs were reviewed retrospectively. These subjects' cases were divided into a cerebellar group (n = 8) and a brainstem group (n = 16) based upon the anatomic location of the tumor. Imaging features (including tumor volume, margins, cystic/solid ratio, enhancement, peritumoral edema, and ipsilateral cerebellar atrophy) were compared between these two groups.

RESULTS: On magnetic resonance imaging, infratentorial GGs showed isointensity or hypointensity on T1WI and heterogeneous hyperintensity on T2WI, with ipsilateral cerebellar atrophy observed in seven cases. Computed tomography images available in the cerebellar group showed heterogeneous isodensity with calcifications. Cerebellar GGs (median = 67.25 cm(3), inter-quartile range = 27.78-83.27 cm(3)) were larger in volume than brainstem GGs (median = 16.89 cm(3), interquartile range = 6.08-27.26 cm(3)) (p = 0.002). Cystic-solid mass (5 of 8) and solid mass (11 of 16) were more commonly represented in the cerebellar and brainstem group, respectively (p = 0.033). Cerebellar GGs showed varying degrees of enhancement, while most of brainstem GGs showed moderate-to-marked enhancement (p = 0.012). Dorsal-predominant enhancement (n = 3) and posterior-marginal enhancement (n = 5) were observed in the brainstem group. The degrees of peritumoral edema and rate of ipsilateral cerebellar atrophy were not significantly different between the two study groups.

CONCLUSION: Ipsilateral cerebellar atrophy can be found in infratentorial GGs involving the middle and inferior cerebellar peduncles. GGs should therefore be considered in the differential diagnoses when a solid-cystic mass with calcification is encountered in the cerebellum. Brainstem GGs tend to be smaller, solid masses with moderate-to-marked enhancement. Dorsal-predominant and posterior-marginal enhancement may be the specific imaging findings for brainstem GGs.