Investigation of renal lesions by diffusion-weighted magnetic resonance imaging applying intravoxel incoherent motion-derived parameters—Initial experience

PurposeUsefulness of biexponentially fitted signal attenuation at different b-values for differentiating the histological characteristics of renal tumors.Materials and methodsA total of 26 patients with 28 renal masses (histologically proven: 20 clear cell renal cell carcinomas [ccRCC], three transitional cell carcinomas, two oncocytomas, and one papillary RCC) and 30 volunteers with healthy kidneys were examined at 1.5 Tesla using an echo-planar DWI sequence. Using the IVIM model, we calculated the perfusion fraction f and the diffusion coefficient D. Furthermore, the ADC was obtained. These tumor parameters were compared to healthy renal tissue nonparametrically, and a receiver operating characteristic (ROC) analysis was performed.ResultsHealthy renal parenchyma showed higher ADC and D values (p < 0.001) than ccRCC (ADC 1.95 ± 0.10 [SD] μm2/ms, f 18.32 ± 2.52%, and D 1.88 ± 0.11 μm2/ms versus ADC 1.45 ± 0.38 μm2/ms, f 18.59 ± 6.16%, and D 1.34 ± 0.38 μm2/ms). When detecting malignancies the area under the curve for D was higher than for ADC. The f values for ccRCC were higher (p < 0.001) than for non-ccRCC (ADC 1.52 ± 0.47 μm2/ms, f 8.44 ± 1.24%, and D 1.30 ± 0.18 μm2/ms). Both f and D correlated with ccRCC grading.ConclusionIVIM imaging is able to provide reliable diffusion values in the human kidney and may enhance the accuracy of tumor diagnosis. The D value was the best parameter to distinguish renal tumors from healthy renal tissue. The f value is promising for determining the histological subgroups.