Comparison of conventional diffusion-weighted imaging and intravoxel incoherent motion in differentiating between chromophobe renal cell carcinoma and renal oncocytoma: a preliminary study

Objective: Quantitative comparison of the diagnostic efficacy of conventional diffusion-weighted imaging (DWI) and intravoxel incoherent motion (IVIM) in differentiating between chromophobe renal cell carcinoma (ChRCC) from renal oncocytoma (RO). Methods: A total of 48 patients with renal tumours who had undergone DWI and IVIM were divided into two groups-ChRCC (n = 28) and RO (n = 20) groups, and the apparent diffusion coefficient (ADC), true diffusivity (D), pseudo-diffusion coefficient (D*), perfusion fraction (f) and their diagnostic efficacy were compared between the two groups. Results: The D* values were higher in the ChRCCs group compared to the RO groups (0.019 +/- 0.003 mm(2)/s vs 0.008 +/- 0.002 mm(2)/s, P < .05). Moreover, the ADC, D and f values were higher in ROs compared to ChRCCs (0.61 +/- 0.08 x 10(-3) mm(2)/s vs 0.51 +/- 0.06 x 10(-3) mm(2)/s, 1.02 +/- 0.15 x 10(-3) mm(2)/s vs 0.86 +/- 0.07 x 10(-3) mm(2)/s, 0.41 +/- 0.05 vs 0.28 +/- 0.02, P < .05). The areas of the ADC, D, D* and f values under the ROC curves in differentiating ChRCCs from ROs were 0.713, 0.839, 0.856 and 0.906, respectively. The cut-off values of ADC, D, D* and f were 0.54, 0.91, 0.013 and 0.31, respectively. The AUC, sensitivity, specificity and accuracy of the f values were 0.906, 89.3%, 80.0% and 89.6%, respectively. For pairwise comparisons of ROC curves and diagnostic efficacy, IVIM parameters, that is, D, D* and f offered better diagnostic accuracy than ADC in differentiating ChRCCs from ROs (P = .013, .016, and .008) with f having the highest diagnostic accuracy. Conclusion: IVIM parameters presented better performance than ADC in differentiating ChRCCs from ROs.