Bladder Cancer:Detection,Image Quality And T Stage Compared Among IShim,RESOLVE And Ss-EPI Diffusion-weighted MR Imaging With High B Value At 3.0T MRI

Purpose:To compare the detection of bladder neoplasms and image quality among the diffusion-weighted imaging(DWI)acquired by the prototype ss-EPI sequence for integrated slice-specific dynamic shimming(iShim),readout segmentation of long variable echo trains(RESOLVE)and conventional single-shot echo-planar-imaging(ss-EPI)sequences and to prospectively compare the ability of three abovementioned DWI to be used to determine the T stage of bladder cancer.Methods:63 patients with 77 bladder lesions were enrolled.The MR protocol included T1WI,T2WI and three types of DWI.The sensitivity,specificity,PPV,NPV,and accuracy of each DWI for detection of bladder tumor were computed.The subjective scores of imaging quality,diagnostic confidence and detection of tumors of stage T2 or greater were recorded.The contrast-to-noise ratio(CNR),signal intensity ratios and ADC values were measured.The univariate analysis of variance technique,the Friedman test,and Bland-Altman plots were used in the statistical analysis.Observer performance of tumor T stage was tested using receiver operating characteristic(ROC)curve analysis.Results:The sensitivity,NPV and accuracy of iShim(92.75%;61.54%;93.51%)for detection of bladder tumor were superior to those of RESOLVE(84.06%;42.11%;85.71%)and ss-EPI(86.96%;47.06%;88.31%).All qualitative scores of i Shim were higher than RESOLVE(all p<0.05)and ss-EPI(all p<0.05).The CNR,signal intensity ratios between bladder lesion and urine,lesion and submucosal stalk(or nearby normal bladder wall),and between distal normal bladder wall and urine of i Shim(39.84±12.11,2.40±0.60,1.98±0.43,1.28±0.16)were higher than RESOLVE(16.97±7.08,1.62±0.41,1.52±0.42,1.15±0.29,all p<0.05)and ss-EPI(27.89±9.65,1.66±0.46,1.57±0.50,0.99±0.22,all p<0.05).No significant difference of ADC values were found for iShim and RESOLVE(p=0.46),iShim and ss-EPI(p=0.97),RESOLVE and ss-EPI(p=0.48).The A_z value for the detection of tumors of stage T2 or greater was slightly higher with the iShim DWI sequence(0.89)than with the RESOLVE(0.87,p=0.72)or ss-EPI(0.85,p=0.38)sequence.Conclusion:The iShim DWI has relatively better detection of bladder tumor,image quality and T stage without significant ADC value difference.