Imaging of primary central nervous system lymphoma.

Primary central nervous system lymphoma (PCNSL) comprises 5% of all primary brain tumours. PCNSL demonstrates a variety of well-documented imaging findings, which can vary depending on immune status and histological type. Imaging features of PCNSL may overlap with other tumours and infection making definitive diagnosis challenging. In addition, several rare variants of PCNSL have been described, each with their own imaging characteristics. Advanced imaging techniques including 2-[(18)F]-fluoro-2-deoxy-d-glucose ((18)FDG) and (11)C positron-emission tomography (PET), (201)Tl single-photon emission computed tomography (SPECT), (1)H-magnetic resonance spectroscopy (MRS), and MR perfusion, have been used to aid differentiation of PCNSL from other tumours. Ultimately, no imaging method can definitively diagnose PCNSL, and histology is required.