LDD presents on the MR as a nonenhancing unilateral lesion in the cerebellum with mass effect on surrounding structures. The lesion is hypointense on the T1 weighted images and hyperintense on the T2-weighted images with alternating parallel hyperintense and isointense stripes which are characteristic for the disease. These bands correspond to the inner molecular layer and the granular layer of the cerebellum. Tonsillar herniation and hydrocephalus are quite common and are caused by the mass effect of the lesion to the adjacent cerebellar parenchyma. On the DWI the high signal intensity is due to T2-shine-through effect. This is a 17 year old female. Also note tonsillar herniation and syrnix in the upper cervical spine.
Submitted by Dr Sangeeta Aneja, MD Head of Dept, LLRM Meerut.