FIGURE 2. A 52-y-old man with CNS lymphoma (patient 11). (A) T₁-weighted MR image with gadolinium-diethylenetriaminepentaacetic acid shows heterogeneously enhancing mass in right parieto-occipital area. Mass is difficult to distinguish from high-grade glioma on MR image only. (B) ¹²³I-IMP SPECT images show normal and increased accumulation (arrowheads) corresponding to tumor on early (left) and delayed (right) images, respectively.