Can diffusion-weighted MRI predict the histological grade of urinary bladder carcinoma?

Aim
The aim of this study was to prospectively evaluate the ability of diffusion-weighted (DW) MRI in determining the T-stage of bladder cancer and to measure the correlation between the apparent diffusion coefficient and the histologic grade.
Patients and methods
Totally, 50 patients with suspected bladder cancer underwent MRI. These patients presented with gross (macroscopic) hematuria or had urinary bladder mass detected on ultrasound and/or computed tomography examinations. Human ethics committee approval for this study was obtained from the institutional review board of the hospital where these cases were treated. Two of 50 patients were excluded from the study because of technical difficulties or failure of data acquisition. All 48 patients underwent transurethral cystoscopic biopsy after imaging. Their MRI were read by two different radiologists who were blinded to the results of each other to minimize the bias.
Results
As regards the detection of urinary bladder carcinoma, DW-MRI showed an overall sensitivity of 100%, specificity of 75%, positive predictive value of 98%, negative predictive value of 100%, and accuracy of 98%. The sensitivity, specificity, and accuracy for differentiating superficial from invasive tumors using T2 images alone and combined use of T2 and diffusion-weighted images (DWIs) were 97, 64, and 88% and 100, 86, and 96%, respectively. The sensitivity, specificity, and accuracy for differentiating superficial from invasive tumors using postcontrast MRI alone and combined use of postcontrast MRI and DW images were 96, 71, and 91% and 100, 100, and 100%, respectively. In addition, we concluded that there is an inverse relationship between the mean apparent diffusion coefficient values and the histological grade of the tumor.
Conclusion
DW-MRI is a safe and confident method in the detection and local staging of urinary bladder carcinoma. In addition, DWIs may predict the histological grade of the tumor. Hence, DWI may be added to routine imaging protocols of urinary bladder tumors.