Fig 4. FDG-PET versus Mn-MR imaging: single subject. Coronal sections through pituitary tumor of rat 2. Left column shows tumor 1 hour after intranasal administration of the calcium analog Mn2+. Right column shows an FDG-PET scan of tumor glucose metabolism. Single arrows (white on MR imaging, black on PET) indicate region of high glucose metabolism correlating with high calcium influx. Double arrows (white on MR imaging, black on PET) indicate low glucose metabolism and calcium influx in the area of necrosis.