Images of a 34-year-old woman (patient 11) with biopsy-proved PNET Images of a 34-year-old woman (patient 11) with biopsy-proved PNET.A, Contrast-enhanced axial view T1-weighted image (600/14/1) shows a peripherally enhancing mass in the genu of the corpus callosum. Images of a 34-year-old woman (patient 11) with biopsy-proved PNET.A, Contrast-enhanced axial view T1-weighted image (600/14/1) shows a peripherally enhancing mass in the genu of the corpus callosum. Approximately 50% of the lesion enhanced. Cystic/necrotic components can be seen in the lesion.B, Axial view T2-weighted image (3400/119/1) shows some areas of hypointensity within the mass, indicating the increased cellularity of these tumors, with a significant amount of peritumoral edema and mass effect. The signal intensity characteristics and involvement of the corpus callosum would raise the possibility of lymphoma as a differential diagnosis.C, Gradient-echo axial view perfusion MR image (1000/54) and rCBV color overlay map show increased perfusion with a high rCBV of 6.82 and vascular permeability (Ktrans) of 0.00034 s−1. Lymphoma would appear as reduced perfusion. Meng Law et al. AJNR Am J Neuroradiol 2004;25:997-1005 ©2004 by American Society of Neuroradiology