Role of diffusion weighted MR imaging in characterization of focal kidney and upper urinary tract lesions

Previous studies suggested that the apparent diffusion coefficient (ADC) value could help in the differentiation and characterization of the benign and malignant renal masses.However, there is still wide overlap in the ADC values between the benign and malignant tumors. Objectives: To retrospectively assess the usefulness of the diffusion weighted imaging (DWI) for the characterization and differentiation between benign and malignant renal masses. Methods: A total of 87 renal and/or upper ureteric masses were included in our study. The signal intensity of the lesions was assessed on both the DWI and ADC map and the ADC value was calculated. t test, ANOVA test and Receiver operating characteristic (ROC) curve analysis were performed. Results: The ADC values of benign lesions were significantly higher than those of the malignant masses [3.2 versus 1.3 × 10−3 mm2/s], Median, P < 0.0001.The sensitivity and specificity of the DWI for the differentiation of benign and malignant masses were 98% and 73% using an ADC cutoffvalue of 2.2. Clear cell renal cell carcinoma demonstrates higher ADC value than non clear cell RCC. Conclusion: DWI-MRI has a role in differentiation of benign and malignant renal masses and the characterization of different malignant categories, subtypes and grades.