Somatostatin Receptor Scintigraphy for Optic Nerve Sheath Meninglomas

Objective: To investigate the value of somatostatin receptor scintigraphy (SSRS) in the diagnosis of optic nerve sheath meningiomas (ONSMs). Design: Prospective, comparative case series. Participants: SSRS was used to investigate 68 orbits in 61 patients diagnosed with an orbital tumor. Methods: Patients were injected intravenously with 200 MBq of indium-111 (In-111)-octreotide. SSRS with single photon emission computed tomography (SPECT) was performed 24 hours after injection. Main Outcome Measures: The In-111-octreotide uptake in orbital lesions was determined by semiquantitative uptake-ratio analysis (lesion/brain) on attenuation-corrected transverse SPECT slices. Results: All orbital meningiomas, including 14 ONSMs and 12 spheno-orbital meningiomas, showed high median In-111-octreotide uptake ratios of 7.2 (range, 4.6-15.4) and 16.3 (range, 4.6-15.4), respectively. In 7 patients with a diagnosis of ONSM, the SSRS uptake ratio was significantly decreased 2.7 (1-6.8) after treatment with 54 Gy of radiotherapy. Median uptake ratios of other tumors were vascular anomalies/vascular tumors, 1.2 (range, 0.5-3.3); non-Hodgkin lymphomas, 2.9 (range, 0.9-4.2); optic nerve gliomas, 1.5 (range, 0.2-3.3); and idiopathic orbital inflammation, 1.6 (range, 1.4-1.9). By using a threshold uptake ratio of 5.9, the sensitivity of SSRS with In-111-octreotide for ONSM was 100%, with a specificity of 97.2%. Conclusions: SSRS is a useful additional tool in diagnosing ONSM and has 100% sensitivity and 97% specificity at a threshold uptake ratio of 5.9. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2009;116:1581-1586 (C) 2009 by the American Academy of Ophthalmology.