Ga-68-DOTA-TATE PET/CT for Discrimination of Tumors of the Optic Pathway

Purpose: Symptomatic tumors of the optic nerve pathway may endanger vision. They are difficult to classify by imaging alone and biopsy may damage visual function. Tumor pathology influences treatment decision and a diagnostic tool with a high sensitivity and specificity would therefore be invaluable. We hypothesized that Ga-68-DOTA-TATE PET/CT may help in discriminating optic nerve tumors as uptake of somatostatin is elevated in meningiomas.

Material and Methods: Ga-68-DOTA-TATE PET/CT was used to examine 13 patients with ambiguous, symptomatic lesions of the optic pathway for treatment planning. The presence or absence of meningioma was validated by histopathology or supplementary diagnostic work-up.

Results: Ga-68-DOTA-TATE PET/CT identified 10 meningiomas (en plaque?=?1, optic nerve sheath?=?4, sphenoidal?=?5) correctly via increased SSTR (somatostatin receptor) expression (mean SUV_max (maximum standardized uptake value)?=?14.3?±?15.4). 3 tumors did not show elevated Ga-68-DOTA-TATE uptake (SUV_max?=?2.1?±?1.0). Subsumizing all clinical-radiological follow-up tools available, these lesions were classified as an intracerebral metastasis of an advanced gastric carcinoma, histologically proven inflammatory collagenous connective tissue and presumed leukemic infiltration of a newly diagnosed chronic lymphocytic leukemia. In this case series, Ga-68-DOTA-TATE PET/CT demonstrated both a sensitivity and specificity of 100%. Yet, the golden standard of histopathology was only available in a subset of patients included.

Conclusion: Ga-68-DOTA-TATE PET/CT proved to be a valuable diagnostic tool for the correct classification of equivocal, symptomatic tumors of the anterior optic pathway requiring therapy. PET/CT results influenced therapy decision essentially in all cases.