PCNSL imaging pattern on MRI. Characteristic PCNSL imaging features on MRI. (A) T1 sequence with gadolinium contrast (T1c) demonstrates homogenously enhancing lesions affecting the deep white matter. (B) Fluid-attenuated inversion recovery (FLAIR) sequence demonstrates moderate edema surrounding the lesion. (C) Diffusion-weighted imaging sequence (DWI) demonstrates restricted diffusion within the lesions.