Developmental venous anomaly (DVA) is a common benign brain vascular malformation, typically asymptomatic, with intervention required when complications arise. We present the case of a 63-year-old man with mild cognitive decline whose brain FDG PET showed decreased uptake not only at the site of DVA, but in the extended surrounding parenchyma where MRI showed no parenchymal abnormalities. DVAs arise from developmental irregularities in the embryonic venous system, but likely affecting a greater extent of the surrounding parenchymal functions. These findings highlight the clinical significance of DVAs and their effects on the parenchymal function seen on FDG PET albeit normal parenchyma on structural imaging.