O7.03IDH-1 MUTATED GLIOBLASTOMAS HAVE A LESS INVASIVE PHENOTYPE THAN IDH-1 WILD TYPE GLIOBLASTOMAS: A DIFFUSION TENSOR IMAGING STUDY

摘要

INTRODUCTION: IDH-1 mutated glioblastomas are associated with a better prognosis than glioblastomas with wild type IDH-1. Most explanations for this improved prognosis is due to these tumours responding better to therapy. Recent work has suggested they have a different behaviour. Diffusion tensor imaging (DTI) is able to explore the invasive behaviour of glioblastomas and can identify a number of invasive phenotypes. Approximately 20% have a minimally invasive pattern that have improved survival. This study aims to look at differences in invasive behaviour in pre-operative GBMs with IDH-1 mutation status. METHODS: Patients with resectable glioblastomas were imaged at 3T with a protocol including DTI. The DTI data was decomposed into isotropic (p) and anisotropic (q) components and these abnormalities were outlined. The difference between these regions have been shown previously to be the region of invasion and was classified according to previously published classification. The tumours were resected and the IDH-1 status assessed using immunohistochemistry for the R132 mutation. RESULTS: 68 patients were studied with 9 IDH-1 mutated GBMs, and 57 with wild type IDH-1. All of the IDH-1 tumours exhibited minimally invasive DTI patterns. Only 5 (8%) of the IDH-1 negative tumours were minimally invasive, 14 (24%) had a localised invasive pattern and the majority 41 (69%) had a diffuse pattern of invasion. In all of the IDH-1 group there was the tumour surrounded by intact white matter as confirmed by diffusion tissue signature measurements. CONCLUSION: We have shown that IDH-1 mutated GBM have a different invasive behaviour compared to the non-mutated GBMs. This difference is seen at first presentation and is not related to response to therapy. This lack of invasion can help explain the better prognosis of this GBM subtype.