Intravoxel incoherent motion (IVIM) diffusion imaging in prostate cancer - what does it add?

To compare 2 previously presented algorithms for extracting parameters from intravoxel incoherent motion (IVIM) studies and investigate them in the context of tissue differentiation. Magnetic resonance imaging (MRI) was performed in 23 patients without histologically proven prostate carcinoma (PCa) and 27 patients with histologically proven PCa. Two methods were used to determine IVIM parameters (f, D, D*). Receiver operating characteristic analysis was performed for IVIM parameters and apparent diffusion coefficient for discrimination of prostate tissue. The IVIM parameters showed no significant difference between patients without PCa and normal areas in patients with PCa (r = 0.46-0.99). Results for D were not significantly different for both methods (P = 0.22), whereas f from method 1 was significantly higher than the f from method 2 (P < 0.05). The diffusion parameters D (both methods) and apparent diffusion coefficient could discriminate between tumor and normal areas (receiver operating characteristic analysis, area under the curve, ≥0.90). Additionally, in subgroup analysis, only D was able to discriminate between low- and high-grade PCa. For tumor detection, IVIM diffusion does not yield a clear added value, but the perfusion-free diffusion constant D may hold potential for improved image-based tumor grading.