Differentiating non enhancing grade II gliomas from grade III gliomas using diffusion tensor imaging and dynamic susceptibility contrast MRI.

Abstract: Background Contrast enhancement in a brain tumour MRI is typically indicative of a high-grade glioma. However, a significant proportion of non-enhancing gliomas can either be grade II (GII) or grade III (GIII). Whilst gross total resection remains the primary goal, imaging biomarkers may guide management where surgery is not possible, especially for non-enhancing gliomas. The utility of diffusion tensor imaging (DTI) and dynamic susceptibility contrast (DSC) MRI was evaluated in differentiating non-enhancing gliomas. Methods Retrospective analysis was performed on MRI data from 72 non-enhancing gliomas, including GII (n = 49) and GIII (n=23) gliomas. DTI and DSC data were used to generate fractional anisotropy, mean diffusivity, axial diffusivity and radial diffusivity as well as cerebral blood volume, cerebral blood flow and mean transit time (MTT) maps. Univariate and multi-variate logistic regression along with area under the curves (AUC) analyses were used to measure the sensitivity and specificity of imaging parameters. A sub-analysis was performed to evaluate the utility of imaging parameters in differentiating between different histological groups. Results Logistic regression analysis indicated that tumour volume and relative MTT could differentiate between GII and GIII non-enhancing gliomas. At a cut-off value of 0.33, this combination provided an AUC of 0.71, 70.6% sensitivity and 64.3% specificity. The logistic regression analyses demonstrated much higher sensitivity and specificity in the differentiation of astrocytomas from oligodendrogliomas or identification of grades within these histological subtypes. Conclusion DTI and DSC imaging can aid in the differentiation of non-enhancing GII and GIII gliomas, and between histological subtypes.