111Indium (DTPA-octreotide) scintigraphy in patients with cerebral gliomas

Somatostatin receptors (SR) have been identified in vitro in normal brain tissue, in neuro-endocrine tumours and in cerebral gliomas WHO grade 1 or 2 by autoradiography or using somatostatin-gold conjugates. In vivo, SR detection has become possible by scintigraphy applying the somatostatin analogue octreotide, radio-labelled with 111Indium. It was supposed that expression of SR in cerebral gliomas corresponds to low grade tumour malignancy and that, in vivo, somatostatin receptor scintigraphy (SRS) could refine and improve the WHO grading system for cerebral gliomas. Nineteen patients with cerebral gliomas (grade 2: n = 8, grade 3: n = 3, grade 4: n = 8) were examined with 111In (DTPA-octreotide) to evaluate, whether SRS could improve the pre-operative estimation of tumour biology and the postoperative management. The results of SRS were related with the histological findings and with the in vitro demonstration of somatostatin-binding sites on cultured tumour cells incubated with a somatostatin-gold conjugate. In vivo, none of the patients with glioma grade 2 showed enhanced tracer uptake in the SRS, whereas in vitro SR were detected in cultured tumour tissue in 5 out of 5 cases. Every patient with glioma grade 3 or 4 demonstrated a high focal uptake of 111In (DTPA-octreotide), as shown by SRS. Three patients with glioma grade 4, additionally examined with 99mTc-DTPA, showed an increased tracer uptake within the tumour area when compared with results of SRS.(ABSTRACT TRUNCATED AT 250 WORDS)