EAU 2018: mpMRI in Bladder Cancer: Development of VI-RADS ver 1.0

Copenhagen, Denmark (UroToday.com) Dr. Valeria Panebianco from Italy presented their collaborative group’s development of the mpMRI VI-RADS 1.0 for bladder cancer. 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 reflects 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 additional value of DWI and DCE.

The rationale and aim of VI-RADS 1.0 was to define a standardized approach to imaging and reporting mpMRI for bladder cancer, defining the risk of muscle invasion. Furthermore, VI-RADS 1.0 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.

Dr. Panebianco summarized her talk with the following points: (i) VI-RADS 1.0 can be a “user friendly” method to simplify reporting and communication, (ii) VI-RADS 1.0 will be tested, validated, and refined where necessary, and (iii) the next step will be to create a foundation for mpMRI in bladder cancer staging in treated patients.

Presented by: Valeria Panebianco, Sapienza University of Rome, Rome, Italy

Written by: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre, twitter: @zklaassen_md at the 2018 European Association of Urology Meeting EAU18, 16-20 March, 2018 Copenhagen, Denmark

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