From the case: Joubert syndrome
Joubert Syndrome: T1 AXIAL There is enlargement of the retrocerebellar subarachnoid spaces. Abnormal configuration of the fourth ventricle, which appears high in position. Small cerebellar vermis with central clefting noted. The superior cerebellar peduncles are thickened with midline splitting. The midbrain is narrowed as the midline is forming with the thickened cerebellar peduncles, a characteristic molar-tooth appearance.