Abstract:Objective: To analyse MRI findings of primary central nervous system lymphoma(PCNSL) in immunocompetent patients. Materials and Methods: MRI findings in 21 patients with pathologically proved PCNSL were analyzed retrospectively, 14 male and 7 female, mean age, 49.6 years old. Results: Thirty lesions were identified in 21 patients. The MRI findings of PCNSL were as follows: ①hypo- or iso-intense on T1WI and iso- or slightly hyper-intense on T2WI, solitary or multiple well-defined lesions; ②slight or moderate peritumoral edema, and characteristic flame-like edema; ③enhancement is intense and homogeneous, the presence of “incision sign” and “angular sign” are more specific. Conclusion: Conventional MRI plays an important role in the diagnosis of PCNSL.