Preliminary study of histogram analysis of mono-exponential and intravoxel incoherent motion models in epithelial ovarian cancer

Objective: To evaluate the diagnostic performance of the histogram analysis of mono-exponential and intravoxel incoherent motion(IVIM) models to the dualistic model of epithelial ovarian cancer (E0C). Methods: Forty female patients with histopathologically proven epithelial ovarian cancer underwent preoperative MR examination. Scanning sequences included conventional imaging, diffusion-weighted magnetic resonance imaging with 11b values (0, 30, 50, 100, 150, 200, 400, 600, 800, 1000, 1500 s/mm²) and dynamic contrast enhanced MRI (DCE-MRI). Based on the dualistic model of E0C, all patients were divided into two groups: type I (low grade, n = 16) and type n (high grade, n = 24). ADC, D, D and f maps and their corresponding histograms were generated by post-processing software. Based on an entire-tumour measurement, the following histogram parameters were recorded, respectively: (a) Mean; (b) the 10th percentile (10th); (c) the mean of the top 10 percent (Mean_L); (d) the 90th percentile (90th); (e) the mean of the bottom 10 percent (Mean_R). Two types were compared using independent sample t test or Mann-Whitney U test. And areas under ROC curve between two groups were assessed. Results: For ADC , D, and f, all indices (Mean, 10th, Mean_L, 90th, Mean_R) of the histogram were significantly lower in type II than in type I (P < 0.05). All of parameters of D^* had no significant different(P > 0.05). D demonstrated a comparable accuracy with ADC in differentiating the grade of EOC (area under curve: Mean, 0.898 vs. 0.893; 10th, 0.880 vs. 0.846; Mean_L, 0.878 vs. 0.858; 90th, 0.895 vs. 0.839; Mean_R, 0.872 vs. 0.814), and both ADC and D have better performance than f. Conclusion: It is feasible to stratify the grade of EOC by mono-exponential and IVIM models with histogram metrics, diagnostic efficiency of ADC and D values are higher. (authors)