Somatostatin receptor imaging in non-functioning pituitary adenomas: value of an uptake index

Somatostatin receptor imaging (SRI) was performed in five patients with known non-functioning pituitary adenomas. To determine whether the pituitary uptake correlates with response to octreotide therapy, an uptake 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 tumour volume and visual function in response to octreotide therapy. The UI might be a good predictive parameter of octreotide therapy efficacy in non-functioning adenomas.