Comparison of conventional DWI 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 tumors 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 ± 0.003mm2/s vs.0.008 ± 0.002 mm2/s, p < 0.05). Moreover, the ADC, D and f values were higher in ROs compared to ChRCCs (0.61 ± 0.08 × 10-3mm2/s vs. 0.51 ± 0.06 × 10-3mm2/s, 1.02 ± 0.15 × 10-3mm2/s vs. 0.86 ± 0.07 × 10-3mm2/s, 0.41 ± 0.05 vs. 0.28 ± 0.02, p < 0.05). 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, ie, D, D*and f offered better diagnostic accuracy than ADC in differentiating ChRCCs from ROs(p = 0.013, 0.016 and 0.008) with f having the highest diagnostic accuracy.

CONCLUSION: IVIM parameters presented better performance than ADC in differentiating ChRCCs from ROs.