Somatostatin Receptor SPECT/CT using (99m)Tc Labeled HYNIC-TOC Aids in Diagnosis of Primary Optic Nerve Sheath Meningioma

Primary optic nerve sheath meningiomas (ONSM) are rare, benign and slow growing tumor involving the intra-orbital/intra-canalicular segment of the optic nerve. Untreated, they can potentially lead to visual deterioration. Magnetic resonance (MR) is the gold standard imaging modality for diagnosing the entity. Often, a clinical dilemma exists to narrow the differential diagnosis of an enhancing intra-orbital mass on MR. Molecular imaging provides a high degree of precision in diagnosing meningioma in view of relatively high levels of somatostatin receptor expression by these tumors. The following case demonstrates the potential clinical utility of somatostatin receptor SPECT using (99m)Tc- labeled HYNIC-TOC in clinical diagnosis of ONSM.