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/mm². 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 × 10⁻³ mm²/s) was significantly different (P = 0.001) from that of benign tumors (1.87 ± 0.50 × 10⁻³ mm²/s). Selection of 1.84 × 10⁻³ mm²/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 × 10⁻³ mm²/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 × 10⁻³ mm²/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.