Xiangde Min^{1}, Zhaoyan Feng^{1}, Liang Wang^{1}, and Zhongping Zhang^{2}

We performed multi-b value diffusion-weighted imaging (DWI) to compare four phenomenological models (mono-exponential, bi-exponential, stretched exponential, and diffusion kurtosis imaging) with in vivo prostate cancer DWI data. A secondary aim is to compare results for different b-value ranges. The result showed that ADC derived from conventional mono-exponential model high b value (about 3200s/mm2) is an optional parameter for peripheral zone prostate cancer detection.

The mean values and standard deviations of the diffusion parameters measured in groups A, B, C, and D are summarized in Table 1. All parameters except D* showed significant differences between cancerous tissues and benign PZs in each group.

The AUC, cutoff, sensitivity, and specificity of the parameters in distinguishing cancerous tissues from benign PZs are reported in Table 2. The ROC curves of each parameter calculated using different b-value ranges are shown in Fig 1. In group A, the AUC of Kapp had the largest AUC (0.940), but the AUCs of ADC and Kapp were not significantly different (p = 0.070). In groups B and C, the AUCs of ADC and Kapp were comparable and significantly higher than those of the other parameters. In group D, The AUCs of ADC were slightly higher than those of Kapp (0.957 vs 0.953, p = 0.002), and both were significantly higher than those of other parameters (p < 0.001 for all).

The parameters ADC, <D>, DDC and Kapp provided the highest AUCs among the four models. The AUCs of ADC in groups C and D were comparable (p = 0.980) and were significantly higher than that of groups A and B (p < 0.05 for all). The AUCs of Kapp calculated using groups B, C, D were significantly higher than in group A (p < 0.05 for all), however, no significant difference was observed among groups B, C, or D (p > 0.05 for all). The AUCs of <D> calculated in groups A, B, and C were significantly higher than in group D (p < 0.001 for all). The AUCs of DDC calculated using groups B and D were significantly higher than in group A (p = 0.016 and p = 0.014, respectively).

1. Roethke MC, Kuder TA, Kuru TH, et al. Evaluation of Diffusion Kurtosis Imaging Versus Standard Diffusion Imaging for Detection and Grading of Peripheral Zone Prostate Cancer. Invest Radiol 2015;50(8):483-489.

2. Bai Y, Lin Y, Tian J, et al. Grading of Gliomas by Using Monoexponential, Biexponential, and Stretched Exponential Diffusion-weighted MR Imaging and Diffusion Kurtosis MR Imaging. Radiology 2016;278(2):496-504.