The Application Of Multiple-sequences MRI Imaging In Differentiating Tumor Stage And Grade Of Bladder Cancer

Part ? Non-muscle-invasive and Muscle-invasive Urinary Bladder Cancer: Image Quality and Clinical Value of Reduced Field-of-view versus Conventional Single-shot Echo-planar-imaging DWIPurpose:To compare the imaging quality, diagnostic accuracy, and apparent diffusion coefficient (ADC) values of reduced field-of-view diffusion-weighted imaging (rFOV DWI) and full field-of-view single-shot echo-planar-imaging DWI (fFOV DWI) in non-muscle-invasive and muscle-invasive bladder cancer.Materials and Methods:39 patients with a total of 60 bladder tumors underwent rFOV and fFOV DWI in this IRB approved study. Pathologic and histologic grades were determined for all tumors. Two observers rated DWI image quality using a 4-point scale. Two radiologists who were blinded to the pathology findings reviewed three image sets (T2-weighted alone, T2-weighted plus fFOV DWI and T2-weighted plus rFOV DWI), and assigned T stages and confidence levels for tumors of stage T2 or higher. The image quality scores for the two DWI sequences were assessed by the Wilcoxon signed rank test. Differences in the diagnostic accuracy, sensitivity, and specificity for each image set were evaluated using the McNemar test. Differences in the performance were analyzed by comparing the areas under the receiver operating characteristic curves (Az values). The Mann-Whitney U test was used to compare mean ADCs and the relationship between the tumor stage and histologic grade.Results:Image quality scores were statistically significantly higher for rFOV (mean 3.62) than for fFOV DWI (2.98, P<0.001). Pooled diagnostic accuracies were 57%,70%, and 78%for T2-weighted images alone, T2-weighted plus fFOV DWI and T2-weighted plus rFOV DWI, respectively. The overall accuracy, specificity, and Az for diagnosing T2 or higher stages were significantly improved by adding rFOV DWI (P<0.05). Mean ADC values of muscle-invasive and G3 grade bladder cancers were significantly lower than for non-muscle-invasive tumors and G1 grade regardless of both DWI sequences (P<0.01).Conclusions:rFOV DWI is superior to fFOV DWI with respect to image quality and diagnostic accuracy. ADC values may be useful in distinguishing non-muscle-invasive from muscle-invasive cancers and G1 from G3 grade lesions.Part ? Differentiating Histological Grade and Tumor Stage of Bladder Cancer by Using Monoexponential, Biexponential, and Stretched Exponential Diffusion-weighted MR ImagingPurpose:To quantitatively compare the potential of different diffusion parameters got from monoexponential, biexponential, and stretched exponential DWI models in the grading and staging of bladder cancers.Materials and Methods:37 patients with a total of 51 bladder tumors underwent conventional MRI and twelve b values DWI (0,50,80,100,150,200,300,500,800,1000, 1300 and 1700sec/mm2) in this IRB approved study. Pathologic and histologic grades were determined for all tumors. Two radiologists processed these DWI image data independently who were blinded to the histopathologic results and then got these values (ADC?D?D*? f?DDC and a). Interrater reliability between the two independent quantitative analyses was assessed by using the method of Bland and Altman. The Mann-Whitney U test was used to compare mean ADCs and the relationship between the tumor stage and histologic grade. Differences in the performance were analyzed by comparing the areas under the receiver operating characteristic curves (Az values).Results:The consistency of ADC, D, D*, f, DDC and a between the two observers was good. ADC, D and DDC were significantly higher in non-muscle-invasive bladder cancers than in muscle-invasive ones (P=0.002,0.003 and 0.007, respectively). However, D*, f and a did not show significantly different (P=0.533,0.402 and 0.876, respectively). ADC, D and DDC were significantly higher in low-grade bladder cancers than in high-grade ones (P=0.014,0.002 and 0.033, respectively). However, D*, f and a did not show significantly different (P=0.372,0.215 and 0.129, respectively). The Az values of ADC, D and DDC were compared with each other, but there were no statistical differences in tumor stage and histological grade (p>0.05).Conclusions:our study showed that ADC, D, and DDC values can distinguish tumor stage and histological grade of bladder cancers. Therefore, monoexponential, biexponential, and stretched exponential DWI models all can be effectively applied to differentiate between non-muscle invasive and muscle-invasive bladder cancers and between high-grade and low-grade bladder cancers.Part? The use of T2* weighted multi-echo GRE imaging as a novel method to identify the stage and grade of bladder cancer:A preliminary studyPurpose:The goal of the study was to assess the ability of T2*-weighted MRI sequence to identify the stage and grade of bladder cancerMaterials and Methods:This retrospective study was approved by the institutional review board. Patients gave their written informed consent for study enrollment.57 patients with a total of 90 bladder tumors underwent conventional MRI and T2*-weighted imaging in this study at a 3T MRI (GE Healthcare 750 Discovery, USA). Pathologic and histologic grades were determined for all tumors. The source images were transferred to GE ADW4.6 workstation for calculating the apparent transverse relaxation rates values (R2*=1/T2*) using the local software. The Mann-Whitney U test was used to compare mean R2* and the relationship between the tumor stage and histologic grade. Differences in the performance were analyzed by comparing the areas under the receiver operating characteristic curves (Az values).Results:The consistency of R2* between the two observers was good. R2* was significantly higher in high-grade bladder cancers than in low-grade ones (20.97±8.91H? 16.43±5.74 Hz respectively. P=0.002). R2* was also significantly higher in muscle-invasive bladder cancers than in non-muscle invasive ones (21.35±8.96Hz? 18.48±7.71Hz, respectively.p=0.046). The Az value for distinguishing high-grade bladder cancers from low-grade ones was 0.703; the Az value for distinguishing muscle-invasive bladder cancers from non-muscle invasive ones was 0.636.Conclusions:our study showed that R2* value can distinguish tumor stage and histological grade of bladder cancers. Therefore, T2*-weighted MRI may provide useful information for clinicians to the choice of the clinical treatment of bladder cancer.