Differentiation between Optic Nerve Glioma and Meningioma Using 68GA-DOTOTATE PET/CT: Two Case Reports

Contrast-enhancing lesions with mass effect from or nearby optic nerve/chiasm include optic nerve sheath meningioma (ONSM), metastasis, lymphoma, and optic gliomas. Biopsy is necessary for a definitive diagnosis, at this location they prove problematic given the high risk of causing iatrogenic visual loss. We present two cases using Gallium-68-labeled dodecane tetraacetic acid-tyrosine-3-ocreotate (68Ga-labeled DOTATATE) positron emission tomography (PET)/CT to aid in the assistance for noninvasive diagnosis of an orbital space-occupying lesion.

Patient 1 A 54-year-old female was referred for an optic nerve process. She had gradual visual blurriness, no pain or discomfort, no diplopia in her right eye for 5 months. History of atypical lobular hyperplasia, and patient was on tamoxifen. Ophthalmology reported pallor of the optic nerve. Neurological and visual exam nonfocal. Two months after beginning of symptoms, MRI ([Fig. 1A]) with enhancement of the right optic nerve without additional intracranial findings. Patient underwent a course of IV methylprednisolone followed by a prednisone taper without change, ruling out optic neuritis. Glioma and meningioma high in the differential. The patient was presented with the options of obtaining a biopsy, which could potentially place the optic nerve at risk. Literature evidence of 90% of meningiomas express sandostatin receptors, we recommended a DOTATATE PET scan which has a high sensitivity at identifying sandostatin receptors. [Fig. 1B, C] shows focal thickening of the right optic nerve with associated mild focal radiotracer uptake favoring meningioma. Surgical resection was offered as an option to the patient discussing high risk of loss of vision given involvement withing the nerve sheath. Patient preferred external beam radiation therapy using IMRT scheduled for 25 to 27 treatments. Patient underwent radiation therapy without complications and 9 months after treatment patient has remained clinically and radiographically stable [Fig. 2].

Patient 2 A 57-year-old female was referred for intracranial mass lesion and presented with right sided blurry vision and loss of color vision over 1 year. Imaging demonstrated intracranial lesion that was centered around the suprasellar space and appeared to be bilobed. Differential included optic glioma versus suprasellar meningioma. Risk of surgical biopsy was discussed with patient again regarding goals. DOTATATE scan was recommended to help differentiate the etiology of the lesion between cystic glioma or a suprasellar meningioma. The optic chiasm lesion demonstrated only minimal DOTATATE avidity which suggested the lesion was not a meningioma and supported the diagnosis of cystic glioma. Surgery was deemed to be the best option and agreed with patient. One month ago, the patient underwent endoscopic endonasal approach for resection of the mass, final pathology was pilocytic astrocytoma. She was discharged next day with worsening of right eye blurriness but otherwise doing well. Further treatment with intensity-modulated radiation therapy (IMRT) will be discussed in further visits.

In our experience, DOTOTATE PET/CT can be a very useful noninvasive diagnostic adjuvant in the setting of optic nerve tumors.

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Publication History

Article published online:
12 February 2021