Clinical relevance of somatostatin receptor scintigraphy in patients with skull base tumours.

The differential diagnosis of tumours in the skull base is often difficult. With the experience that various intracranial tumours differ in their expression of somatostatin binding sites (SBS) somatostatin receptor scintigraphy (SRS) with the somatostatin analogue octreotide can give additional information of the tumour entity. Seventy patients with various tumours of the skull base were examined with 111Indium-labelled DTPA-octreotide injected i.v.. Planar and tomographic images were obtained with a gamma camera 4-6 and 24 hours after injection. All of the meningiomas (unifocal and multifocal tumours in various locations) showed a high density of SBS whereas in none of the examined neurinomas SR were found. Pituitary adenomas revealed in only 50% SR in different concentrations and independent of the endocrine activity. SRS can help in the differential diagnosis between meningiomas and other tumours, postoperative scar or radionecrosis at the skull base. A dural infiltration with meningioma tissue ("meningeal sign") may be discriminated from a reactive hypervascularisation in lesions with a diameter > 0.5 cm. We conclude that SRS can offer additional diagnostic aspects in the pre- and postoperative management of patients with skull base tumours.