Magnetic resonance imaging of pineal region tumours.

Objectives: Pineal lesions can present as a heterogeneous collection of benign and malignant disease conditions. Pineal lesions include germ cell tumours, neoplasms arising from the pineal parenchyma, as well as other pineal region masses.

Methods: A variety of cases of pineal lesions are presented. The important clinical features and typical imaging findings of each pineal lesion are described with emphasis on their morphological appearance and signal intensity characteristics on magnetic resonance imaging (MRI).

Conclusion: Knowledge of the imaging characteristics and clinical features of varying pineal lesions can assist in narrowing the differential diagnosis for more accurate and rational therapeutic planning.

Teaching Points: • Pineal parenchymal tumours show an "explosion" of normal pineal calcifications towards the periphery. • Pineoblastomas often have restricted diffusion, with apparent diffusion coefficient (ADC) values lower than germinomas. • Pineal teratomas and pineal lipomas display fat signal characteristics and fat saturation on MRI. • Pineal lesions in patients with known malignancy should raise suspicion of metastatic involvement. • Pineal cysts and arachnoid cysts show MRI signal characteristics similar to cerebrospinal fluid (CSF).