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ESOU 2019

ESOU 2019: MRI for Bladder Cancer Staging

Prague, Czech Republic (UroToday.com) Dr. Valeria Panebianco from Italy presented her collaborative group’s development of the mpMRI VI-RADS for bladder cancer. This is a landmark initiative that was recently published in European Urology1. As Dr. Panebianco notes, there are clinical questions and imaging answers when it comes to staging bladder cancer and that a multimodal approach reduces the risk of error from one particular test, but may present a dilemma when results conflict. As clinicians that treat prostate cancer, we are all familiar with the PI-RADS system for mpMRI of the prostate, however, there are other disease sites that also use a ‘RADS’ format, including breast (BI-RADS) and liver (LI-RADS).

Certainly, the prognosis and management of bladder cancer mostly reflect tumor stage, and the most critical step in bladder cancer staging is to differentiate muscle-invasive bladder cancer (MIBC) from non-muscle invasive bladder cancer (NMIBC). Clinical staging, based on cystoscopy and TURBT, is associated with 23-50% diagnostic inaccuracy. According to Dr. Panebianco, mpMRI offers an opportunity to reduce staging errors by better anatomical visualization, with the added value of DWI and DCE.

The rationale and aim of the VI-RADS scoring system were to define a standardized approach to imaging and reporting mpMRI for bladder cancer, defining the risk of muscle invasion. Furthermore, VI-RADS was created through a consensus using existing literature. The scoring is applicable to untreated patients and to treated patients having only received a diagnostic TURBT, but prior to re-TURBT. mpMRI is best performed before or at least 2 weeks after TURBT, bladder biopsy or intravesical treatment. Administration of an intramuscular antispasmodic agent is recommended, in addition to adequate bladder distention. MRI does not necessarily have the ability to visualize all of the histological bladder wall layers, however, it is able to assess size, location, multiplicity, and morphology. A 5-point VI-RADS score is generated using the individual T2W, DWI, and DCE MRI categories and suggests the probability of muscle invasion. The dominant sequences for risk estimates are DWI (first) and DCE (second, especially if DWI is sub-optimal). The T2 sequence (structural category) is helpful as a first pass guide.

The VI-RADS 1.0 scoring is as follows:

  • VI-RADS 1: SC CE and DW category 1 (muscle invasion is highly unlikely)
  • VI-RADS 2: SC, CE, and DW category 2; both CE and DW category 2 with SC category 3 (muscle invasion is unlikely to be present)
  • VI-RADS 3: SC, CE, and DW category 3; SC category 3, CE or DW category 3, and the remaining sequence category 2 (the presence of muscle invasion is equivocal)
  • VI-RADS 4: At least SC and/or DW and CE category 4; the remaining category 3 or 4 SC category 3 plus DW and/or CE category 4; SC category 5 plus DW and/or CE category 4 (muscle invasion is likely)
  • VI-RADS 5: at least SC plus DW and/or CE category 5; the remaining category 4 or 5 (invasion of muscle and beyond the bladder is very likely)
The score is firstly based on structural category (T2W) for the morphology (high spatial resolution), and the presence of definitive muscular invasion is decided by DWI and DCE. If there is any discordance between T2W and DCE sequences (a deviation of two categories between T2W and DCE MRI). DWI improves the accuracy when the image quality of DWI sequence is optimal.

VI-RADS may have several potential roles:

  • Can be helpful in planning a re-TURBT
  • The scoring should be used to establish the risk of residual cancer after TURBT
  • Surveillance of NMIBC
Dr. Panebianco summarized her talk with the following points:
1. VI-RADS hopefully creates a foundation for mpMRI in bladder cancer staging in untreated patients
2. VI-RADS can be a user-friendly method to simplify reporting and communication
3. VI-RADS will be tested, validated and refined where necessary
4. The next step is to create a foundation for mpMRI in bladder cancer staging in treated patients (ie. after pembrolizumab in the NMIBC state)


Presented by: Valeria Panebianco, Department of Radiological, Oncological and Pathological Sciences, Sapienza University of Rome

Written by: Zachary Klaassen, MD, MSc – Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, Twitter: @zklaassen_md, at the 16th Meeting of the European Section of Oncological Urology, #ESOU19, January 18-20, 2019 Prague, Czech Republic

References:
1. Panebianco V, Narumi Y, Altun E, et al. Multiparametric Magnetic Resonance Imaging for Bladder Cancer: Development of VI-RADS (Vesical Imaging-Reporting and Data System). Eur Urol 2018 Sep;74(3):294-306.