Fig. 6

Discordance between PET, perfusion and diffusion in a case of recurrence: 31-year-old male operated for right frontal ODG 14 months back; last radiation dose 10 months ago. PET images fused with axial T1 MPRAGE (A, B) show an area of uptake in the right superior frontal gyrus (white arrow in A, B). The uptake (block white arrow) is seen along the margins of the resection cavity (small white arrow) on the coronal fused PET-MR image (C). rCBV map (D) generated using the leakage correction algorithm shows no unequivocal elevation of perfusion in the area. There is no diffusion restriction on the ADC map (E). Few foci of enhancement (block white arrow) are seen along the margins of the resection cavity (small white arrow) on post-contrast coronal T1 MPRAGE (F). In view of PET uptake, recurrence was suspected and chemotherapy administered. Follow-up PET image after chemotherapy fused with coronal T1 MPRAGE (G) shows reduction in the degree of uptake (block white arrow) along the resection cavity margin when compared with prechemo coronal PET image in C. Reduction in the degree of enhancement is also seen on the follow-up post-contrast coronal T1 MPRAGE (white arrow in H) compared to that in F