Backroud Gallium 68-tetraazacyclododecane-tetraacetic acid-octreotate (Ga-68‑DOTATATE) is a selective somatostatin analogue ligand, which shows increased affinity for somatostatin receptor subtype (SSTR) 2 and has been used routinely for imaging neuroendocrine tumors with PET/CT. We investigated the utility of Ga-68‑DOTATATE positron emission tomography/computed tomography (PET/CT) in patients with suspected pituitary pathology. We reviewed imaging for twenty consecutive patients (8 men, 12 women, mean age of 48.2, range: 14-78) with suspected pituitary pathology who were referred for Ga-68-DOTATATE PET-CT.
Results Nine patients presented with recurrent Cushing's syndrome following surgical resection of pituitary adenomas due to recurrent Cushing's disease (seven patients) and ectopic ACTH secreting tumor (2 patients). All seven patients with recurrent Cushing's disease showed positive pituitary Ga-68-DOTATATE uptake while both cases of ectopic hormonal secretion had absent pituitary uptake. In 1 of these 2 patients Ga-68-DOTATATE was able to localize the source of ectopic ACTH tumor.
Six patients presented de novo with Cushing's due to ectopic ACTH secretion; Ga-68‑DOTATATE PET/CT was able to localize ectopic tumors in six of eight patients (3 lungs, 2 pancreases, 1 mid-gut)
There was high uptake Ga-68-DOTATATE in 3 cases of recurrent central hyperthyroidism (SUVmax 6.6-14.3) and 2 cases of prolactinoma (SUVmax 5.5 and 11.3).
Conclusion Absent Ga-68-DOTATATE activity in the pituitary fossa is useful in excluding pituitary disease in recurrent Cushing’s. Recurrent pituitary thyrotropinomas and prolactinomas showed moderate to high pituitary activity. In addition, in Cushing’s syndrome Ga-68-DOTATATE is useful for detection of ectopic sources of ACTH production, especially where anatomic imaging is negative.