It is clinically essential, but sometimes challenging, to distinguish pituitary tissue from pituitary adenomas (PAs). It is helpful to avoid damage of pituitary tissue during management

Researchers evaluated the ability of 13N-ammonia positron emission tomography (PET)/computed tomography (CT) to locate and distinguish pituitary tissue from PAs.

Forty-eight patients (four with prolactinoma, 10 with Cushing's disease, 12 with acromegaly, and 22 with nonfunctional PAs) prospectively underwent magnetic resonance imaging (MRI), 13N-ammonia PET/CT, 18F-FDG PET/CT, prior to surgery.

Pituitary position could be determined in 31 (64.5%) patients by 13N-ammonia PET/CT, and by MRI in 26 (54.2%) patients. It was detected by 13N-ammonia PET/CT and MRI in eight of eight patients (100%) with pituitary microadenoma, tumor maximum diameter (TMD) <1cm, and in nine of 10 patients (90%) with PAs with TMD ≥1cm, but <2cm.

Results

In 16 patients with PAs with TMD ≥2cm, but <3cm, pituitary tissue position was detected by 13N-ammonia PET/CT in nine (56%), and by MRI in 8 (50.0%) patients by MRI.

In 14 patients with PAs with TMD ≥3cm, pituitary tissue position was detected by 13N-ammonia PET/CT in five (35.7%) patient, and by MRI in 1 (7.1%). In seven patients, the pituitary tissue could be detected by 13N-ammonia PET, but not by MRI, and in two patients by MRI, but not by 13N-ammonia PET.

CONCLUSION: 13N-ammonia PET/CT imaging is a sensitive means for locating and distinguishing pituitary tissue from PAs, particularly those with TMD <2cm. It is potentially valuable in the detection of pituitary tissue in patients with PAs.

13N-ammonia PET/CT imaging is a sensitive means for locating and distinguishing pituitary tissue from PAs, particularly those with TMD <2cm. It is potentially valuable in the detection of pituitary tissue in patients with PAs.