Accumulation of 11C-methionine in the normal pituitary gland on 11C-methionine PET.

Background For pituitary tumors, positron emission tomography (PET) with 11C-methonine (MET) has been reported as feasible to facilitate diagnosis. MET is well-known to accumulate in the normal pituitary glands, but almost no studies have examined the degree of MET accumulation in the normal pituitary gland. Purpose To investigate accumulation of MET in normal pituitary gland on PET/CT. Material and Methods Among patients who underwent PET/CT using MET over the past 7 years, 77 patients who fulfilled our criteria for normal pituitary glands were retrospectively selected. Maximum standardized uptake value (SUVmax) for the pituitary gland was measured. Results SUVmax of MET in the pituitary gland was in the range of 0.9-6.6 (mean ± standard deviation = 2.60 ± 1.04). A negative correlation between SUVmax and patient age (y = -0.032 × + 4.29, n = 77, r = 0.55) was found by linear regression analysis. SUVmax of the pituitary gland did not differ significantly between women and men. Conclusion MET shows strong accumulation in normal pituitary gland. PET/CT would thus be feasible to differentiate between normal and abnormal pituitary glands.