Application of diffusion tensor imaging in infiltration zone investigation of high-grade gliomas

Abstract

Objective To explore the invasion characteristics of high-grade gliomas and to quantitatively investigate their infiltration zone using diffusion tensor imaging (DTI). Methods Ten patients of frontal high-grade gliomas (WHO Ⅲ-Ⅳ) were retrospectively reviewed who were admitted to Neurosurgery Department of Beijing Tiantan Hospital, Capital Medical University, China National Clinical Research Center for Neurological Diseases from October 2014 to October 2016. All patients underwent the examination of preoperative MRI and DTI. Three regions of interest (ROI), which were placed at the enhanced central region of the tumor, 1cm and 2cm from the tumor edge, were determined on T1-weighted imaging with contrast medium. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of those ROIs were measured prior to surgery. Before the incision of dura matter, specimens of those ROIs were obtained under the guidance of navigation. Postoperative examinations of specimens including histological, tumor cell density, MMP-9 and Ki-67 were carried out. Differences in tumor cell density, MMP-9 and Ki-67 values among 3 ROIs were analyzed. Correlations among the ADC, FA values and the tumor cell density were also evaluated. Results As the distance from the tumor entity increased, tumor cell density, expression levels of MMP-9 and Ki-67 significantly decreased compared with those in tumor entity (all P<0.05). To analyze the relationship of tumor cell density to ADC and FA values, the canonical discriminant formula was as follows: D=0.201 ADC+ 1.094 FA, which could be used to determine the tumor cell density with an accuracy rate of 66.7%. Conclusions As the distance from tumor entity increased, tumor cell density, invasion and proliferation decrease significantly compared with the tumor entity. There seems to be a quantitative relationship between DTI parameters and tumor cell density of high-grade gliomas, which could contribute to the formulation of surgical plan. Key words: Glioma; Neoplasm invasiveness; Diffusion tensor imaging