Quantitative Diffusion Tensor Imaging (DTI) Analysis Reveals Different Infiltrative Patterns of Oligodendrogliomas and Astrocytomas in Peri-Tumour White Matter

Abstract

INTRODUCTION: Gliomas are highly infiltrative primary brain tumours. Glioma infiltration is difficult to identify clinically using conventional diagnostic imaging. We used diffusion tensor imaging (DTI) to identify glioma infiltration in peritumour white matter (WM) and characterized differences between histological subtypes. METHODS: We recruited 8 patients with a histological diagnosis of grade II or III glioma and 10 healthy controls. We compared fractional anisotropy (FA) maps of each patient against the control group using SPM8 (Matlab 2014a) to identify regions of glioma infiltration. The FA and mean diffusivity (MD) of formerly WM matter tumour regions, infiltrated WM and normal appearing WM were compared with a 2-sample t-test and characterized with respect to normal control data. RESULTS: Our results have identified radiological evidence of infiltration in the peri-tumour WM of glioma patients. The infiltrated region of oligodendrogliomas extended further than that of astrocytomas. Oligodendrogliomas preferentially infiltrated larger WM tracts, whereas astrocytomas infiltrated more peripheral WM. In all grades, the 3 regions had significantly different diffusion parameters and there were significant differences between oligodendrogliomas and astrocytomas. CONCLUSION: We identified previously unrecognized study wide significant changes in the peri-tumour WM of gliomas. Despite the known propensity of these tumours to infiltrate WM we found no significant DTI changes distant to the tumour. Our DTI results suggest oligodendrogliomas and astrocytomas demonstrate different infiltrative patterns, which highlights the need for astrocytomas and oligodendrogliomas to be studied separately.