Exploring the Possibility of Estimating Degree of Glioma Tumors by Measuring Apparent Diffusion Coefficient

Introduction: Most common glioma tumors are tumors of the central nervous system (CNS) which are the cause of about 40 to 50 percent of brain tumors. This type of cancer includes 2 to 3 percent of cancers in the world. Conventional MRI is powerless in the detection and differentiation of benign and malignant tumors. In this case, diffusion weighted imaging (DWI) can create contrast between normal and abnormal tissues and in terms of the emissions, benign and malignant tumors being detected. The apparent diffusion coefficient (ADC) only depends on the extent (mass), temperature and viscosity of the tissue molecules. In this study, we measured apparent diffusion coefficient of the tumors and quantified the ammount of the ADC values and recognized benign or malignant tumors without biopsy. Materials and Methods: We used diffusion weighted images and pathologic findings of 56 patients with glioma tumors, 28 patients with benign and 28 cases with malignant tumors. DicomWorks software was used to calculate apparent diffusion coefficient of tumor and also by use of ROC curve, we introduced an optimized cut off for this type of tumor. Results: In this study we have measured the amount of ADC of four regions. Diagnostic threshold for ADC of tumor center (ADC1) was found to be equal to 1.12 × 10-3 mm2/s, for which the sensitivity and specificity were equal to 1 and 0.96, respectively. The resulting diagnostic threshold for tumor edema areas (ADC2), is 1.15 × 10-3 mm²/s. The diagnostic thresholds of sensitivity and specificity are equal to 0.75 and 0.64, respectively. The diagnostic threshold for ADC3 (Areas between the Tumor and Normal Tissue) values was also gained. Numerical threshold was equal to 0.84 × 10-3 mm²/s; both sensitivity and specificity are equal to 0.5. Conclusion: According to the different characteristics of the release of water molecules in different tissues, DWI and ADC values can help to diagnose and determine the severity of the tumor. By determining cut off for apparent diffusion coefficient of the tumor prior to surgery, we can diognose that is benign tumor or malignant one; so that tumors with ADC values of higher than 1.12*10-3 mm2/s are benign and tumors with ADC values lower than this ammount are malignant.