Somatostatin receptor scintigraphy in brain tumors and pituitary tumors: first experiences

Somatostatin receptors have been demonstrated on various tumors of neuroendocrine and other origin. They have been detected in vitro by biochemical techniques as well as by autoradiography. The development of long-acting somatostatin analogs and the recent availability of radiolabeled octreotide have made the in vivo detection of somatostatin receptors possible. This preliminary study embraced 45 patients with meningiomas, brain tumors or pituitary tumors, which were imaged by planar and tomographic scintigraphy after intravenous injection of 111Indium-labeled octreotide. In all of the meningiomas studied (unifocal and multifocal tumors in various locations), a high density of somatostatin receptors 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 uptake in vivo, while gliomas with disturbed blood-brain barrier had a high activity uptake. We conclude that in vivo somatostatin receptor scintigraphy, although not tumor-specific, may aid in the preoperative diagnosis and staging of intracranial tumors, especially skull base tumors.