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Multiparametric Magnetic Resonance Imaging for Bladder Cancer: Development of VI-RADS (Vesical Imaging-Reporting And Data System)

  • Valeria Panebianco,
  • Yoshifumi Narumi,
  • Ersan Altun,
  • Bernard H. Bochner,
  • Jason A. Efstathiou,
  • Shaista Hafeez,
  • Robert Huddart,
  • Steve Kennish,
  • Seth Lerner,
  • Rodolfo Montironi,
  • Valdair F. Muglia,
  • Georg Salomon,
  • Stephen Thomas,
  • Hebert Alberto Vargas,
  • J. Alfred Witjes,
  • Mitsuru Takeuchi,
  • Jelle Barentsz,
  • James W.F. Catto

Publication: European Urology, Volume 74, Issue 3, September 2018, Pages 294-306

DOI: https://doi.org/10.1016/j.eururo.2018.04.029

Context

Management of bladder cancer (BC) is primarily driven by stage, grade, and biological potential. Knowledge of each is derived using clinical, histopathological, and radiological investigations. This multimodal approach reduces the risk of error from one particular test, but may present a staging dilemma when results conflict. Multiparametric magnetic resonance imaging (mpMRI) may improve patient care through imaging of the bladder with better resolution of the tissue planes than computed tomography and without radiation exposure.

Objective
To define a standardized approach to imaging and reporting mpMRI for BC, by developing a VI-RADS score.

Evidence acquisition
We created VI-RADS (Vesical Imaging-Reporting And Data System) through consensus using existing literature.

Evidence synthesis
We describe standard imaging protocols and reporting criteria (including size, location, multiplicity, and morphology) for bladder mpMRI. We propose a five-point VI-RADS score, derived using T2-weighted MRI, diffusion-weighted imaging, and dynamic contrast enhancement, which suggests the risks of muscle invasion. We include sample images used to understand VI-RADS.

Conclusions
We hope that VI-RADS will standardize reporting, facilitate comparisons between patients, and in future years, will be tested and refined if necessary. While we do not advocate mpMRI for all patients with BC, this imaging may compliment pathology or reduce radiation-based imaging. Bladder mpMRI may be most useful in patients with non–muscle-invasive cancers, in expediting radical treatment or for determining response to bladder-sparing approaches.

Patient summary
Magnetic resonance imaging (MRI) scans for bladder cancer are becoming more common and may provide accurate information that helps improve patient care. Here, we describe a standardized reporting criterion for bladder MRI. This should improve communication between doctors and allow better comparisons between patients.

Commented by Dr. Francesco Soria

In bladder cancer (BCa), local clinical staging is mainly provided by transurethral resection of the bladder (TURBT). TURBT is a fundamental step for the diagnosis and treatment of BCa, aiming to completely remove the tumor and to provide, besides T stage and tumor grading, additional information such as the presence of carcinoma in situ (CIS), lymphovascular invasion (LVI) and histological variants, all essential for the decision-making process. TURBT is not devoid of limitations, especially in the determination of T stage and in the discrimination between non-muscle invasive (NMIBC) and muscle-invasive bladder cancer (MIBC). Upstaging from T1 high-grade tumors to muscle-invasive disease is found in up to 30% at second-look resection (re-TURBT) while historical series reported that up to 40% of pT1 high-grade tumors treated with early radical cystectomy were upstaged at final pathology.

Unfortunately, conventional imaging does not add to the discrimination between NMIBC and MIBC. Actually, computed tomography (CT) is unable to differentiate between stages from Ta to T3a and magnetic resonance (MRI) showed acceptable sensitivity (68-97%) but unsatisfactory specificity (55-91%) when evaluating the involvement of the muscularis propria. Recently, following the success obtained in prostate cancer, multiparametric MRI (mpMRI) has been tested with promising results in BCa. In this study, Panebianco and colleagues tried to define a standardized approach to imaging and reporting mpMRI for BCa by developing a VI-RADS (vesical imaging-reporting and data system) score. The five-points VI-RADS score is generated combining the individual T2-weighted, diffusion-weighted and dynamic contrast-enhanced image categories, suggesting the risk of muscle invasion.

The potential clinical impact of mpMRI and VI-RADS scoring system is unquestionable, especially in the case of T1 tumors. Actually, mpMRI may potentially help in the selection of patients for re-TURBT, helping to avoid an unnecessary procedure in those with a completely resected tumor, detrusor muscle present in the specimen and no signs of muscle invasion at mpMRI and, on the contrary, suggesting a deeper resection in those at high-risk of muscle-invasive disease. Moreover, another useful application could be the evaluation of treatment response, such as response to neoadjuvant chemotherapy before radical treatment (surgery or trimodal therapy). Based on these assumptions, it is clear that mpMRI may represent a game-changer for the local staging of BCa. Clinical validation of these criteria is mandatory and strongly awaited.