Prostate cancer: correlation of intravoxel incoherent motion MR parameters with Gleason score

Purpose: To evaluate the potential of intravoxel incoherent motion (IVIM) imaging to predict histological prognostic parameters by investigating whether IVIM parameters correlate with Gleason score. Materials and methods: The institutional review board approved this retrospective study, and informed consent was waived. A total of 41 patients with histologically proven prostate cancer who underwent prostate MRI using a 3 T MRI machine were included. For eight diffusion-weighted imaging b-values (0, 10, 20, 50, 100, 200, 500, and 800 s/mm(2)), a spin-echo echo-planar imaging sequence was performed: D, f, D*, and ADC(fit) values were compared among three groups of patients with prostate cancer: Gleason score 6 (n = 9), 7 (n = 16), or 8 or higher (n=16). Receiver operating characteristic (ROC) curves were generated for D, f, D*, and ADC(fit) to assess the ability of each parameter to distinguish cancers with low Gleason scores from cancers with intermediate or high Gleason scores. Results: Pearson's coefficient analysis revealed significant negative correlations between Gleason score and ADC(fit) (r=-0.490, P=.001) and Gleason score and D values (r=-0.514, P=.001). Gleason score was poorly correlated with f (r=0.168, P=.292) and D* values (r=-0.108, P=.500). The ADC(fit) and D values of prostate cancers with Gleason scores 7 or >= 8 were significantly lower than values for prostate cancers with Gleason score 6 (P<.05). ROC curves were constructed to assess the ability of IVIM parameters to discriminate prostate cancers with Gleason score 6 from cancers with Gleason scores 7 or >= 8. Areas under the curve were 0.671 to 0.974. ADC(fit) and D yielded the highest Az value (0.960-0.956), whereas f yielded the lowest Az value (0.633). Conclusions: The pure molecular diffusion parameter, D, was the IVIM parameter that best discriminated prostate cancers with low Gleason scores from prostate cancers with intermediate or high Gleason scores. (C) 2016 Elsevier Inc. All rights reserved.