Abstract. The present study aimed to explore the role of texture analysis with apparent diffusion coefficient (ADC) maps based on different regions of interest (ROI) in determining glioma grade. Thirty patients with glioma underwent diffusion-weighted imaging (DWI). ADC values were determined from the following three ROIs: i) whole tumor; ii) solid portion; and iii) peritumoral edema. Texture features were compared between high-grade gliomas (HGGs) and low-grade gliomas (LGGs) using the non-parametric Wilcoxon rank-sum test or the unpaired Student's t-test. Receiver operating characteristic (ROC) curves were constructed to determine the optimum threshold for inhomogeneity values in discrimination of HGGs from LGGs. With a spearman rank correlation model, the aforementioned ADC inhomogeneity values were correlated with the Ki-67 labeling index. With whole tumor ROI, inhomogeneity values proved to be significantly different between HGGs and LGGs (P<0.001). With solid portion ROI, inhomogeneity and median values showed significant difference between HGGs and LGGs (P=0.001 and P=0.043, respectively). With peritumoral edema ROI, entropy and edema volume demonstrated positive results (P=0.016, P<0.001). The whole tumor inhomogeneity parameter performed with better diagnostic accuracy (P=0.048) than selecting the solid portion ROI. The association between inhomogeneity and Ki-67 labeling index was significantly positive in whole tumor and solid portion ROI (R=0.628, P<0.001 and R=0.470, P=0.009). Texture analysis of DWI based on different ROI can provide various significant parameters to evaluate tumor heterogeneity, which were correlated with tumor grade. Particularly, the inhomogeneity value derived from whole tumor ROI provided high diagnostic value and predicting the status of tumor proliferation.
IntroductionGliomas are the most common type of primary brain tumor. The World Health Organization (WHO) classifies gliomas into grades I-IV, where I and II are low-grade gliomas (LGGs) and III and IV are high-grade gliomas (HGGs) (1). Determining the correct grade of the tumor is of great importance as it dictates the management and prognosis for the patient (2). HGGs are managed with radical resection and with adjuvant radiotherapy and/or chemotherapy, whereas LGGs are very slow growing and can undergo curative resection and have considerably better prognosis (3). The current gold standard for grading gliomas is histopathological assessment by stereotactic brain biopsy, which is an invasive procedure. Particularly with gliomas, the potential to increase clinical utility of imaging as a non-invasive technique to accurately ascertain tumor grade is gaining a lot of attention (4).Advanced MR imaging techniques such as diffusion-weighted imaging (DWI) and its estimated apparent diffusion coefficient (ADC) can probe the pathological changes in glioma providing abundant important information that is not apparent on conventional imaging (5-7). ADC, which reflects the volume of the extracellular water compartment, is sensitive ...