SOMATOSTATIN RECEPTOR SCINTIGRAPHY IN BRAIN-TUMORS AND PITUITARY-TUMORS - 1ST EXPERIENCES

Somatostatin receptors have been demonstrated on various tumors of neu roendocrine and other origin. They have been detected in vitro by bioc hemical techniques as well as by autoradiography The development of lo ng-acting somatostatin analogs and the recent availability of radiolab eled octreotide have made the in vivo detection of somatostatin recept ors possible. This preliminary study embraced 45 patients with meningi omas, brain tumors or pituitary tumors, which were imaged by planar an d tomographic scintigraphy after intravenous injection of Indium-111-l abeled octreotide. In all of the meningiomas studied (unifocal and mul tifocal tumors in various locations), a high density of somatostatin r eceptors was detected by scintigraphy. Pituitary tumors were slightly positive in 50% of cases only, independent of the endocrine activity. Gliomas with an intact blood-brain barrier showed no enhanced tracer u ptake in vivo, while gliomas with disturbed blood-brain barrier had a high activity uptake. We conclude that in vivo somatostatin receptor s cintigraphy, although not tumor-specific, may aid in the preoperative diagnosis and staging of intracranial tumors, especially skull base tu mors.