POMC and pituitary gland adenoma: The positive rate of 11C-Met PET–CT in ACTH-secreting pituitary adenoma is as high as 100% and a promising, noninvasive method that could even replace IPSS under specific circumstances. The sensitivity of 18F-FDG PET–CT is unsatisfactory. Functional pituitary adenoma in general: PET–CT may be useful to detect tumors in patients with equivocal MRI results. Met–PET can provide valuable diagnostic information when 18F-FDG–PET yields negative results (not vice versa).