| Part Ⅰ:Preliminary Discussion of Diagnostic Value of Ultra-high b-value Diffusion-weighted Imaging in Prostate CancerObjective:To explore the value of ultra-high b-value DWI in diagnosis of prostate cancer.Methods:According to inclusion and exclusion criteria,73 consecutive examinees were prospective screened. Written informed consent was obtained from all patients. T2WI, Conventional DWI with b-value of 1000 s/mm2 and ultra-high b-value DWI with 2000 s/mm2 and 3000 s/mm2 were performed in each examinee.12-core ultrasound guided prostate systematic biopsy interval less than 3 weeks after MRI examination. Images were interpreted and were corresponding to histological results conducted by ultrasound guided prostate systematic biopsy. Reference biopsy as the gold standard, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for each image. Sensitivity and specificity differences between ultra-high b-value DWI and conventional DWI were analyzed using the McNemar test. The areas under the curves (AUCs) between ultra-high b-value DWI and other modalities were compared by using the Z test. Corroboration of observations made by the two readers, was achieved with the kappa coefficient.Results:54 cases of prostate cancer, benign prostatic hyperplasia in 17 cases,2 cases of normal in 73 examinees.141 lesions were identified as prostate cancer including 99 in peripheral zone and 42 in transition zone. MRI analysis of lesions in peripheral zone,65.7%(65/99),61.6%(61/99)76.8%(76/99)and 84.8%(84/99)were diagnosed accurately with the T2WI, conventional DWI and ultra-high b-value DW-MRI(b=2 000、3000 s/mm2) respectively; 69%(29/42),52.4%(22/42),69%(29/42) and 88.1%(37/42) were diagnosed accurately in transition zone. The sensitivity and specificity for ultra-high b-value DWI was 92.5% and 68.8% with a b-value of 3000 s/mm2, was 88.1% and 53.1% for 2000 s/mm2 in peripheral zone;was 88.0% and 88.2% with a b-value of 3000 s/mm2, was 80.0% and 52.9% for 2000 s/mm2 in transition zone. The values of sensitivity were significantly higher than conventional DWI with a b-value of 1000 s/mm2 (p<0.05) both in peripheral zone and transition zone. The detection of lesions was comparable with ultra-high b-value DWI at 2000 s/mm2 and 3000 s/mm2 (P>0.05) in peripheral zone, whereas the values of specificity were significantly higher than other b values in transition zone. PPV and NPV between 3000 s/mm2 and the other three modalities were significantly higher both in peripheral zone (0.861,0.815) and in transition zone (0.917,0.833). In peripheral zone, the AUCs were 0.591、0.553、0.698 and 0.806 in T2WI、conventional DWI and ultra-high b-value DWI at 2000 s/mm2 and 3000 s/mm2 respectively, for the diagnosis of transition zone cancer were 0.693、0.506、0.665'0.881 respectively. ROC analysis showed greater AUCs for the ultra-high b-value.Conclusion:The ultra-high b-value DWI is an accurate and reliable MRI modality in the diagnosis of prostate cancer. The b-value of 3000 s/mm2 DWI is more valuable in transition zone prostate cancer diagnosis.Part Ⅱ:Apparent Diffusion Coefficient of Diagnostic Value of Ultra-high b-value Diffusion-weighted Imaging in Prostate CancerObjective:To explore the apparent diffusion coefficient value of ultra-high b-value DWI and the diagnostic cutoff point in prostate cancer.Methods:According to inclusion and exclusion criteria,78 consecutive examinees were prospective screened. Written informed consent was obtained from all patients. T2WI, Conventional DWI with b-value of 1000 s/mm2 and ultra-high b-value DWI with 2000 s/mm2 and 3000 s/mm2 were performed in each examinee.12-core ultrasound guided prostate systematic biopsy interval less than 3 weeks after MRI examination. The suspicious prostate lesions were selected on DWI images in maximum level, and the same region of interest (ROI) corresponding ADC values were measured in different b value DWI images. Reference biopsy as the gold standard, the ADCs of each b value DWI image was analyzed by nonparametric Friedman test. According to different b values ROC curves, determining the ADC diagnostic cutoff point value of prostate cancer. Consistency between conventional DWI and ultra-high b-value DWI were analyzed using were analyzed using Bland-Altman method.Corroboration of observations made by the two readers was achieved with the intra-class correlation coefficients (ICC).Results:57 cases of prostate cancer, benign prostatic hyperplasia in 19 cases,2 cases of normal in 78 examinees.154 lesions were identified as prostate cancer including 103 in peripheral zone and 51 in transition zone. Two radiologists’measurement ADC values in conventional DWI and ultra-high b-value DWI with 2000 s/mm2 and 3000 s/mm2 of the ICC were greater than 0.90, showed excellent agreement in peripheral zone and transition zone. The consistency of ADC values measured by conventional DWI and ultra-high b-value DWI with 2000 s/mm2 were 97.1% in peripheral zone and 94.1% in transition zone respectively; and were 95.1% in peripheral zone and 96.1% in transition zone between conventional DWI and ultra-high b-value DWI with 3000 s/mm2. They have shown good agreement. The ADC values for conventional DWI and ultra-high b-value DWI with 2000 s/mm2 and 3000 s/mm2 were 1.097 X 10-3mm2/s (1.040-1.153),0.809×10-3mm2/s (0.766-0.851) and 0.622×10-3mm2/s (0.591-0.652) in peripheral zone; were 1.085 X 10-3mm2/s (1.022-1.147),0.815 ×10-3mm2/s (0.770-0.861)'0.651×10-3mm2/s (0.617-0.685)in transition zone. ADC values of prostate lesions were statistically significant in different b value images (P<0.05). The AUCs with ultrahigh b value DWI (2000 s/mm2 and 3000 s/mm)of the ADC values were 0.824 and 0.852 in peripheral zone, and with ultrahigh b value DWI (3000 s/mm2) of the ADC values was 0.905 in transition zone. The values of were significantly higher than conventional DWI with a b-value of 1000 s/mm2 (p<0.05). The AUCs was comparable with ultra-high b-value DWI at 2000 s/mm2 and conventional DWI (P>0.05) in transition zone., In peripheral zone, the ADC diagnostic cutoff point value of prostate cancer were 0.75×10-3mm2/s and 0.685×l0-3mm2/s in ultra-high b-value DWI with 2000 s/mm2 and 3000 s/mm2 respectively. For the diagnosis of transition zone cancer were 0.8×10-3mm2/s and 0.634×10-3mm2/s respectively.Conclusion:The ADC value of ultra-high b-value DWI showed better consistency and higher diagnostic efficacy in the diagnosis of prostate cancer. The b-value of 3000 s/mm2 DWI is more valuable in transition zone prostate cancer diagnosis.Part III:The Preliminary Study of Using Ultra-high b-value Diffusion-weighted Imaging to Predict the Gleason Score of Prostate CancerObjective:To explore the apparent diffusion coefficient value of ultra-high b-value DWI and the diagnostic cutoff point in the Gleason grading of prostate cancer.Methods:According to inclusion and exclusion criteria,78 consecutive examinees were prospective screened.Written informed consent was obtained from all patients. T2WI, Conventional DWI with b-value of 1000 s/mm2 and ultra-high b-value DWI with 2000 s/mm2 and 3000 s/mm2 were performed in each examinee.12-core ultrasound guided prostate systematic biopsy interval less than 3 weeks after MRI examination. Gleason score using 5 scoring 10 points methods. The suspicious prostate lesions were selected on DWI images in maximum level, and the same region of interest (ROI) corresponding ADC values were measured in different b value DWI images. Reference biopsy as the gold standard, ultra-high b-value DWI (b=2000 s/ mm2 and b=3000 s/mm2) ADC values cancer and non-cancer areas were compared using independent samples t-test. ADC value of ultra-high b-value DWI (b=2000 s/ mm2 and b=3000 s/mm2) in the cancer and Gleason score using Spearman correlation analysis. According to the results of Gleason score,the lesions were divided into low-risk group, intermediate-risk group and high-risk group. ADC between groups was compared by using one-way analysis of variance (ANOVA). The Gleason score≥7 group and Gleason score<7 group was compared by using independent samples t-test. The areas under the curves (AUCs) were compared by using the Z test. Draw the corresponding receiver operating characteristic (ROC) curves and figure out the cut-off ADCs.Results:57 cases of prostate cancer, benign prostatic hyperplasia in 19 cases,2 cases of normal in 78 examinees.154 lesions were identified as prostate cancer including 103 in peripheral zone and 51 in transition zone. Ultra-high b-value DWI (b=2000 s/ mm2 and b=3000 s/mm2) ADC values of prostate cancer and non-cancerous were 0.740×10-3mm2/s (95%CI:0.706-0.774),0.949×10-3mm2/s(95%CI:0.900 0.998)and 0.581 X 10-3mm2/s(95%CI:0.556-0.607),0.748 X 10-3mm2/s(95%CI: 0.698-0.798) respectively. ADC values of prostate cancer and non-cancerous were statistically significant in different b value images (P<0.05).Ultra-high b-value DWI (b=2000 s/mm2 and b=3000 s/mm2) ADC value of prostate cancer with Gleason scores were negatively correlated. The coefficient of determination R2=0.161 and R2 =0.240 respectively. ADC values of Ultra-high b-value DWI (b=2000 s/mm2 and b =3000 s/mm) in low-risk group, intermediate-risk group and high-risk group were (0.926 ± 0.125)×10-3mm2/s,(0.682 ± 0.140)×10-3mm2/s,(0.675+0.147)× 10-3mm2/s and(0.726 ± 0.097)×10-3mm2/s,(0.544 ± 0.104)×10-3mm2/s,(0.509+ 0.092)×10-3mm2/s. ADC values of between low-risk group and intermediate-risk and high-risk group were statistically significant in different b value images (P< 0.05). The ADC values was comparable with intermediate-risk group and high-risk group (P>0.05).The AUCs with ultrahigh b value DWI (2000 s/mm2 and 3000 s/mm2)of the ADC values were 0.893 and 0.908 respectively, the ADC diagnostic cutoff point value of poorly differentiated carcinoma and well-differentiated carcinoma is 0.799×10-3 mm2/s and 0.615×10-3 mm2/s respectively.Conclusion:The ADC value of ultra-high b-value DWI can improve the accuracy in the diagnosis of prostate cancer. ADC can be used as a quantitative measure of effective index to judge the degree of prostate cancer differentiation. It can be of great value to predict Gleason score and clinical prognosis. |
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