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Abstract R enal masses are being discovered more frequently in the last decades due to advances in cross sectional imaging. CT and MR are used for better detection, characterization and staging of these masses. Accurate characterization of renal masses is essential to ensure appropriate case management and to assist in staging and prognosis and to differentiate surgical lesions from nonsurgical lesions. Diffusion-weighted Imaging (DWI) is a new imaging technique that derives image contrast from the differences in water molecule diffusion within tissues. Cellular tissues as tumors that exhibit the greatest degree of restricted diffusion are seen as areas of retained (bright) signal on high b-value images and show low signal intensity on the corresponding ADC map with low ADC value. DW MRI does not rely on intravenous contrast, so patients with renal failure who are at risk for nephrogenic systemic fibrosis or nephrotoxicity may particularly benefit from this technique in the evaluation for renal and upper urinary tract cancer in a noninvasive manner. Summary & Conclusion Recent studies indicate that benign and cystic renal masses had significantly higher ADC value compared with malignant and solid renal masses respectively. Unfortunately, in some cases there was overlapping between the ADC values of benign and malignant masses. So, the use of ADC values alone may lead to inaccurate assessment of renal masses. In conclusion, the combination of conventional MRI and ADC value in the diagnosis of renal masses can increase the diagnostic accuracy and considered of most value in cases where IV contrast agents are contraindicated. We recommend that DWI with low and high b value (b 0-800) and quantitative ADC measurements to be added to the routine Renal MR imaging protocol for better differentiation between benign and malignant renal masses. Further research is still needed to validate the potential diagnostic role of this imaging technique in assessment of renal masses in clinical practice. |