[IN-111]-DTPA-D-PHENYLALANINE-OCTREOTIDE SPECT FOR SCINTIGRAPHIC IMAGING OF AN ENHANCED SOMATOSTATIN RECEPTOR DENSITY IN ENDOCRINE OPHTHALMOPATHY

Recently, [In-111]-DTPA-D-phenylalanine-octreotide was introduced for clinical use. This radioligand binds specifically to somatostatin-rece ptors and is suitable for SPECT examinations. The aim of this study wa s to clarify whether an increased somatostatin receptor density can be imaged and quantified in patients with endocrine ophthalmopathy (e.o. ). 7 patients between 34 and 55 years with e. o. at stages III to VI a nd 4 controls between 38 and 63 years were examined. All patients and controls received approximately 200 MBq [In-111]DTPA-D-phenylalanine-o ctreotide by IV injection. A SPECT examination was performed 4 hours a fter injection and a normalised tracer uptake (A(n)) was calculated fo r both orbitae. In patients with e. o. the values of A(n) were signifi cantly higher compared with controls (P = 0.002). There was a correlat ion between A(n) and exoph thalmus stages according to Hertel with r = 0.844 (P = 0.001). These results indicate that [In-111]-DTPA-D-phenyl alanine-octreotide SPECT might be useful for the in vivo assessment of an increased somatostatin receptor density in e. o. These findings co uld have an impact on the treatment with somatostatin analogous in e. o.