The Diagnostic Value Of Multi Mathematical Models And Multi B-value Ranges Of MR Imaging In Prostate Cancer

Objective:To discuss the diagnostic performance of three kinds of mathematical models of multi b-value of diffusion-weighted magnetic resonance imaging in prostate cancer detection and the optimal b value range of each model variable.Materials and Methods:Diffusion-weighted magnetic resonance imaging using 16b-values(0,20,50,80,100,150,200,500,800,1000,1200,1400,1500,1600,1800,2000 s/mm~2)of 62 patients with histologically proven prostate cancer was analyzed.The mean signal intensities of the regions of interest(ROIs)placed in benign and cancerous tissues on DWI images were fitted using mono-exponential model,bi-exponential model,stretched-exponential model.The b-values were divided into three ranges:0-1000,0-1500 and 0-2000 s/mm~2,grouped as A,B,and C respectively.Apparent diffusion coefficient(ADC),pure diffusion coefficient(D),pseudo-diffusion coefficient(D*),perfusion fraction(f),distributed diffusion coefficient(DDC)and diffusion heterogeneity index(α)were estimated for each group.Normal distribution was assessed using the Kolmogorov-Smirnov test;if the data presented a normal distribution,an independent-samples t was performed to compare the differences in parameters between benign and cancerous tissues.For non-normally distributed variables,the Mann-Whitney U test was used.Receiver operating characteristic curve analysis(ROC)was performed,and the area under the curve(AUC)was calculated to evaluate and compare the diagnostic accuracy of the parameters.Results:(1)All parameters except D*and f of group B and C showed significant differences between cancerous and benign tissues.(2)The area under the curve value(AUC)of ADC was the highest in group C.The AUCs of D in group A and group C were similar and were significantly lower than that in group B.The AUCs of DDC in group A and group B were similar and were significantly lower than that in group C.(3)The parameters ADC,D and DDC provided higher AUCs in group A,and they were similar.The AUCs of ADC and D in group B were comparable and were significantly higher than DDC andα.The AUC of ADC was significantly higher than those of the other parameters in group C.Conclusion:Multi b-value diffusion weighted imaging can be used to identify benign and malignant prostate tissue safely and effectively.ADC derived from mono-exponential high b-value(2000 s/mm~2)provide the highest diagnostic performance in prostate cancer detection.There is no obvious advantage for bi-exponential model and stretched-exponential model compared to ADC.They can be used as a supplement.0-1500 s/mm~2 is the optimal b value range for D derived from bi-exponential model.0-2000 s/mm~2 is the optimal b value range for DDC andαderived from stretched-exponential mode.