Study On Optimizing Magnetic Resonance Imaging Of Bladder Cancer Based On Ⅵ-RADS

Objective:1.To explore the best b-value DWI images for VI-RADS score for bladder cancer by using multi-b-value DWI images obtained from IVIM-DWI sequences to evaluate subjective image quality.2.To assess the diagnostic accuracy of staging and grading bladder tumor by using multi-parameter values obtained through IVIM-DWI examination,including D value(ADCslow),D*value(ADCfast),f value and standard ADC value(ADCst).3.To evaluate the diagnostic ability of dual-parameter magnetic resonance imaging(bpMRI)and multi-parameter magnetic resonance imaging(mpMRI)for staging bladder cancer based on the VI-RADS score.With the help of DWI quantitative parameter measurement,to evaluate whether it can improve diagnostic accuracy of VI-RADS scoring.To explore the value of "seeweed sign" and DCE-MRI time-signal intensity curve in improving the accuracy of VI-RADS staging of bladder cancer.4.To study the application value of mpMRI in the follow-up after treatment of bladder cancer.Methods:1.A total of 42 IVIM-DWI(b=800,1000s/mm2)images of bladder cancer were selected and scored using subjective image quality scoring method.2.The IVIM-DWI images of 76 cases of bladder cancer were retrospectively analyzed.The standard ADC value,D value,D*value,and f value of bladder cancer in the NMIBC and MIBC groups,high-grade and low-grade groups were quantitatively analyzed to evaluate value of various quantitative parameters in the staging of bladder cancer and classification of diagnostic performance.To study the diagnostic efficacy of the parameters of the junction wall between tumor and bladder in the staging of bladder cancer.3.Retrospective analysis of 119 cases of bladder cancer MRI,combined with VI-RADS score were performed to compare the diagnostic efficacy of bpMRI(T2WI+DWI)and mpMRI(T2WI+DWI+DCE)for bladder cancer.ADC value of ROI on DWI and ADC/gluteal muscle ratio(standard ADC value)were quantitatively measured to evaluate the value of mpMRI in distinguishing NMIBC and MIBC.Observe the time signal intensity curve of DCE-MRI.4.A total of 42 patients with postoperative bladder cancer recurrence and 23 patients with postoperative bladder wall localized thickening were collected to undergo bladder multi-parameter MRI examination.ADC value of ROI on DWI and standard ADC value were quantitatively measured to evaluate the value of mpMRI in distinguishing postoperative recurrence and response after treatment.Image analysis and parameter measurement of all imaging data were performed by two senior radiologists on the GE ADW4.6 post-processing workstation using blind method.The normal distribution data was analyzed using the t test,and the non-normal distribution data using the Mann-Whitney test.The Wilcoxon test was used for intra-group comparison.We plotted the receiver operating characteristic(ROC)curve and compared the area under the curve(AUC)and evaluated whether difference was statistically significant(P<0.05).Results:1.The subjective evaluation on image quality of 2 radiologists with different work experience had good consistency.When b=1000 s/mm2,the DWI image had better diagnosis accuracy of muscle-invasive bladder cancer and less distortion of bladder cancer characteristics comparing to the DWI image with b=800s/mm2.2.The difference of IVIM-DWI quantitative parameter,namely the standard ADC value,and D value showed in distinguishing NMIBC and MIBC,low-grade and high-grade bladder cancer(P<0.05)while there was no statistical significance in the difference of D*value and f value.The difference of the standard ADC value and D*value between the NMIBC and bladder wall on tumor borderline of MIBC was statistically significant.The difference of parameters in MIBC group between the bladder wall on tumor borderline and away from tumor showed statistical significance.The diagnostic efficacy of standardADC value in diagnosis of MIBC is the highest,with a cutoff value of 1.46 ×10-3mm2/s.3.The image evaluation of 2 radiologists shows both bpMRI and mpMRI had excellent consistency and diagnostic value of bladder cancer myometrial invasion.There was statistically significant difference in ADCtumor and ADCjunction between the NMIBC and MIBC group,but there was no statistically significant difference between the two groups in the time-signal intensity curve.Study showed that some low-grade urothelial carcinomas have a specific seeweed sign." 4.The difference in ADC and standard ADC values between the recurrence group and the wall-thickening group was statistically significant.The ROC curve analysis showed that the diagnostic thresholds for bladder cancer were respectively 1.42×10-3mm2/s and 0.95.In the wall-thickening group the diagnostic threshold for chronic inflammation is 1.64×10-3mm2/s.Conclusion:1.Subjective scoring and statistical analysis of DWI image quality by 2 radiologists shows that the best DWI b value for VI-RADS scoring of bladder cancer is 1000 s/mm2.2.IVIM-DWI multi-parameter quantification analysis is an effective method in staging and grading bladder cancer.The measurement of standard ADC value and D*value of NMIBC and MIBC tumor-bladder borderline is helpful in judging degree of bladder muscle invasion by bladder cancer.3.The bpMRI scanning protocol without contrast enhancement has the same diagnostic efficiency as the mpMRI scanning protocol in evaluating the bladder urothelial carcinoma muscle invasiveness.VI-RADS combined with DWI parameter measurement and "seeweed sign" can improve its staging ability for bladder cancer.4.Combining with DWI parameter measurement,mpMRI can identify bladder tumor recurrence and postoperative changes,which is expected to reduce the frequency of cystoscopy during long-term monitoring after TURBT or combination therapy.