Validation of VI-RADS for the Detection of Detrusor Muscle Invasion

Bladder cancer (BC) is one of the most common and expensive human malignancies to manage. Most BCs are urothelial cell carcinomas (UCCs), and histologically stratified into cancers with low and high grade. The latter are subdivided into those with and without muscle invasion.(1) Non-muscle-invasive BCs (NMIBCs) are often low grade and have an indolent natural history. Muscle-invasive BCs (MIBCs) are aggressive tumors with an ominous prognosis. (2) Non-muscle invasive bladder cancer is treated with transurethral resection of bladder tumor with or without adjuvant intravesical chemotherapy or photodynamic therapy, whereas muscle-invasive bladder cancer is treated with radical cystectomy, radiation therapy, chemotherapy, or a combination(3).

Bladder cancer staging is accomplished by the combination of clinical (examination), pathologic (transurethral resection of bladder tumor specimens), and radiologic means. The quality of the transurethral resection of bladder tumors often varies among surgeons, and it may miss muscle infiltration in up to 25% of invasive cancers. (4) Radiological examination looks for second urinary tract malignancies (5% of BCs may have an upper tract UCC) or other pathologies. Most guidelines suggest cross-sectional imaging for MIBCs and high-grade NMI cancers, due to the risks of invasion and regional or distant metastases, and upper urinary tract involvement. (5) MRI is currently the best imaging technique for bladder cancer local regional staging because of its superior soft tissue contrast, lack of ionizing radiation, in addition, it clearly differentiates the layer of bladder wall and enables accurate assessment of tumor depth invasion in bladder wall and extra-vesical extension. (6) During the past few years, important improvements in MRI technology have been achieved and led to the introduction of Multiparametric MRI (mp MRI) which combines functional sequences as diffusion weighted imaging (DWI) and dynamic contrast enhanced MRI (DCE-MR) with anatomic T1 and T2 weighted images (T1 and T2WI), that improves the accuracy of tumor detection and staging, helps to monitor post-therapy response and identify local disease recurrence. (7) Recently also standardized approach for imaging and reporting mp-MRI for bladder cancer was created by developing VI-RADS score (Vesical Imaging Reporting and Data System). This aims to standardize bladder mpMRI for clinical and research applications to create a systematic approach for reporting bladder mp-MRI and defining the risk of muscle invasion (NMIBC versus MIBC). (8) The Final VI-RADS score is generated using all categories and suggests the probability of muscle invasion ,It's graded from VIRADS 1 (muscle invasion is highly unlikely) to VI-RADS 5 (ivasion of muscle and beyond the bladder is very likely) (9) In our study we aim to evaluate role of Multiparametric MRI in differentiation between invasive and non-invasive bladder cancer and accuracy of vesical imaging reporting and data system (VI-RADS) score.

2- AIM:

To evaluate the accuracy of Multiparametric MRI in differentiation between invasive and non-invasive bladder cancer using vesical imaging reporting and data system (VI-RADS) score.