Evaluation of Diagnostic Value of Apparent Diffusion Coefficient in Differentiation of Glioblastoma and Metastasis in Peritumoral Edema

Abstract

peritumoral area of glioblastoma multiforme (GBM) is infiltrated with malignant cells along with vasogenic edema; however, in a brain metastasis (BM), the peritumoral areas contain predominantly vasogenic edema. The purpose of this study was to determine whether the mean apparent diffusion coefficient (ADC) and absolute standard deviation (SD) derived from ADC measurements can be used to differentiate GBM from BM based on cellularity levels, in the enhancing tumor and in the peritumoral region. Materials and Methods: MR imagings of 34 patients with histologically verified brain tumors (19 cases of GBM and 15 cases of BM) were evaluated retrospectively. ADC and SD values were measured in the enhancing tumor, peritumoral region, and contralateral healthy white matter. Then to determine whether there was a statistical difference between BM and GBM, we analysed patient age and sex, mean ADC value and ratio, and mean SD value and ratio of the two groups. Results: Neither mean ADC values and ratios nor SD values and ratios were significantly different between GBM and BM. According to ROC curve analysis, using the model combining all 13 variables, a threshold of 0.48 generated the best combination of sensitivity (84%) and specificity (67%) (AIC=61.70 and AUC=0.81) for distinguishing between GBM and BM. The absolute SD and SD ratios were significantly higher in the peritumoral edema compared to the tumor region in each case (both p-values less than 0.001)