SOMATOSTATIN RECEPTOR IMAGING IN NONFUNCTIONING PITUITARY-ADENOMAS - VALUE OF AN UPTAKE INDEX

Somatostatin receptor imaging (SRI) was performed in five patients wit h known non-functioning pituitary adenomas. To determine whether the p ituitary uptake correlates with response to octreotide therapy, an upt ake index (UI) was calculated. Pituitary adenomas were detected in all five patients. The UI was, respectively, 15.1, 3.7, 2.2, 2.2 and 2.2 (the UI calculated in 12 normal subjects was between 1 and 1.9). Only the patient with the highest UI (15.1) had a dramatic improvement in t umour volume and visual function in response to octreotide therapy. Th e UI might be a good predictive parameter of octreotide therapy effica cy in non-functioning adenomas.