Role of diffusion-weighted magnetic resonance imaging in characterization of renal tumors.

Objective: To evaluate the role of diffusion-weighted magnetic resonance (MR) imaging in the characterization of renal tumors. Materials and Methods: Prospective study was conducted on 52 consecutive patients (24 males and 28 females) with renal tumor. They underwent diffusion-weighted echo planar MR imaging of the abdomen with b-factor of 0 and 800 seconds/mm(2). The apparent diffusion coefficient (ADC) value of the renal tumor was calculated and correlated with histopathological results. Results: The mean ADC value of malignant renal tumors (1.56 +/- 0.26 x 10(-3) mm(2)/s) was significantly different (P = 0.001) from that of benign tumors (1.87 +/- 0.50 x 10(-3) mm(2)/s). Selection of 1.84 x 10(-3) mm(2)/s as a cutoff point of ADC value to predict renal malignancy revealed accuracy of 89%, sensitivity of 89%, and specificity of 89%. The cutoff point of ADC value to differentiate renal cell carcinoma (RCC) from other malignancy (1.15 x 10(-3) mm(2)/s) revealed 72% accuracy, 95% sensitivity, 50% specificity. The cutoff point of ADC value used to differentiate clear and papillary RCC from other subtypes of RCC was 1.84 x 10(-3) mm(2)/s with an accuracy of 89%, sensitivity of 89%, and specificity of 89%. Conclusion: Apparent diffusion coefficient value can differentiate benign from malignant renal tumors and may be helpful for the differentiation of the histologic subtypes of RCC.