111In-octreotide scintigraphy in pituitary adenomas

This study reports on 111In-octreotide scintigraphy in 20 patients affected with pituitary adenomas, including tracer uptake ratios and in vitro immunohistochemical characterization of the matostatin receptor state. 111In-octreotide uptake was already observed at 4 hours in 7/8 GH-secreting adenomas, in 5/7 non-secreting adenomas and in 1/5 prolactinomas. Concordance between the scan and the histochemical results was observed in all cases. The uptake ratios evaluated at 24 hours ranged from 2.3 to 4.2. The following conclusions were drawn: 1) 111In-octreotide is a suitable tracer to evaluate the somatostatin receptor state of pituitary adenomas; 2) Semi-quantitative measures of tracer uptake can be easily obtained with static planar scanning, but more refined techniques are needed for receptor kinetics evaluation; 3) This nuclear technique is a promising non-invasive tool to identify patients with somatostatin receptor positive pituitary adenomas who might potentially benefit from pre- and/or post-surgery cold octreotide medical treatment.