INTRODUCTION: Optic pathway gliomas pose a major management difficulty in NF1 and sporadic patients. Diagnosis and follow up are heavily based on multiple MR imaging. Currently, assessment of tumor volume and response to treatment is based on single slice linear measurements. Volumetric measurements, although considered the “gold standard” are rarely used in daily practice. The exact effect of chemotherapy on the gross total volume and internal composition of these tumors is therefore unknown.
METHODS: We retrospectively reviewed MRI scans of 9 patients with anterior optic pathway gliomas that were treated between 2006-2011. Of our group, 5 patients have NF1. Average follow up time was 2.7 years (1-4 years). All patients received at least one line of chemotherapy. A total of 45 MR imaging studies were measured. Tumor measurements were done using our own novel algorithm. The gross total volume of the tumor was measured, as well as sub-segmentation including the solid enhancing, solid non-enhancing and cystic components. Pre and Post treatment volumes were carefully calculated.
RESULTS: The gross total volume increased in an average of 27% during the follow up period. When excluding the cystic component, 14% enlargement was noted. Interestingly, the volume of the solid, non-enhancing component increased by an average of 40% while solid enhancing component decreased by an average of 15% following treatment.
CONCLUSION: Over the follow up period, oncological treatment did not seem to have significant effect on gross total tumor volume in this selected group. Chemotherapy seems to have no effect on the solid non-enhancing component while slightly reducing the solid enhancing part of the tumor. Internal segmentation may aid in the evaluation of treatment-effects in OPG patients receiving chemotherapy
