Differentiation between High Grade Glioma and Solitary Brain Metastasis Using Combined Diffusion-Weighted Imaging and Diffusion Tensor Imaging

Abstract

Background: High-grade gliomas (HGGs) and brain metastases (BMs) can display similar imaging characteristics on conventional MRI. In HGGs, the peritumoral edema is infiltrated by the malignant cells, which was not observed in BMs. Our study aims to determine whether the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values could differentiate HGGs from BMs. Results: Twenty patients with provisional MRI diagnosis of high grade gliomas WHO grade III & IV versus metastatic brain tumors, examination was done on 1.5 tesla scanner, patients were divided into two groups based on pathology results, the fraction anisotropy (FA) was measured in the enhancing tumor parts and immediate peri-tumoral edema. The minimum and mean ADC in the enhancing tumor (ADCmin, ADCmean) and the minimum ADC in the peritumoral region (ADCedema) were measured from ADC maps. Values of FA and ADC measured in the peri-tumoral edema were significantly high in the metastatic than primary high malignant glial tumors, yet no significant differences in the values of FA and ADC measured in the enhancing tumor parts of the two groups. According to ROC curve analysis, a cutoff value of 0.119 for the FA measured in the peri-tumoral edema with sensitivity (100%) and specificity (75%) and a cutoff value of 1.7 x 10-3 for the ADCedema with sensitivity (87.5%) and specificity (75%) generated the best combination of for distinguishing between HGGs and BMs. Conclusion: FA and ADC values were found to distinguish between HGGs and solitary BMs. The peritumoral FA and ADC values are better than the intratumoral FA and ADC values in predicting the tumor type.