Conventional and Advanced MRI Techniques in the Evaluation of Primary CNS Lymphoma.

Primary central nervous system lymphoma (PCNSL) is a rare form of extranodal non-Hodgkin's lymphoma that accounts for 1%-5% of all central nervous system tumors. Contrast-enhanced MR is the imaging technique of choice. PCNLs have a predilection for the periventricular and superficial regions, often abutting the ventricular or meningeal surfaces. Although PCNLs may have characteristic imaging features on conventional MRI, none of these will unequivocally differentiate PCNSLs from other brain lesions. Diffusion restriction, relative hypoperfusion, increased choline/creatinine, decrease of N-acetyl aspartate (NAA) peak as well as the presence of lactate and lipid peaks are consistent advanced imaging findings in CNS lymphoma that may help in the differentiation of Primary central nervous system lymphomas (PCNSLs) from other malignancies. Furthermore, advanced imaging techniques will presumably play an important role in the planning of new targeted therapies, for prognostication, and for the monitoring of treatment response in the future.