(UroToday.com) The joint session of the European Association of Urology and the Maghreb Union Countries included a bladder cancer session and presentation by Dr. Valeria Panebianco discussing the role of MRI in the management of muscle invasive bladder cancer. The diagnostic workup in patients with confirmed muscle invasive bladder cancer includes either CT urogram or MRI, with PET-CT increasingly being used for detection of lymph node metastasis in clinical practice, however, its exact role continues to be evaluated.
The rationale and aim of VI-RADS were to define a standardized approach to imaging and reporting mpMRI for bladder cancer, defining the risk of muscle invasion.1 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)
Dr. Panebianco notes that since their initial publication in 2018, there has been several studies that have provided (retrospective) validation of the scoring system, with a high inter-reader agreement:
Dr. Panebianco’s group recently published a study prospectively validating VI-RADS for discrimination between NMIBC and MIBC at TURBT, and evaluated the accuracy of VI-RADS for identifying high-risk NMIBC patients who could avoid re-TURBT and detecting those at higher risk for understaging after TURBT.4 There were 231 patients with bladder cancer suspicion that were offered mpMRI before TURBT, and according to VI-RADS, a cutoff of ≥3 to define MIBC was assumed. mpMRI showed sensitivity, specificity, PPV, and NPV for discriminating NMIBC from MIBC at initial TURBT of 91.9% (95% CI 82.2-97.3), 91.1% (95% CI 85.8-94.9), 77.5% (95% CI 65.8-86.7), and 97.1% (95% CI 93.3-99.1), respectively. Furthermore, the AUC was 0.94 (95% CI 0.91-0.97). Among HR-NMIBC patients (n=114), mpMRI before TURBT showed sensitivity, specificity, PPV, and NPV of 85% (95% CI 62.1-96.8), 93.6% (95% CI 86.6-97.6), 74.5% (95% CI 52.4-90.1), and 96.6% (95% CI 90.5-99.3) respectively, to identify patients with MIBC at re-TURBT (AUC 0.93, 95% CI 0.87-0.97).
As follows is Dr. Panebianco’s MRI pathway for patient stratification prior to definitive treatment:
Earlier this year, Node-RADS was published in order to standardize reporting of possible cancer involvement of regional and distant lymph nodes on CT and MRI [3]. Node-RADS aims to increase consensus among radiologists for primary staging and in response assessment settings. Furthermore, there is also a role for MRI/VI-RADS for assessing response to therapy, as there are no available tools to select patients who have a higher probability of benefitting from neoadjuvant chemotherapy:
Dr. Panebianco concluded her presentation with the following take-home messages:
- MRI/VI-RADS are already changing the hematuria workup and helping to delineate T1 from T2 tumors
- It is a very useful tool to differentiate confined versus extravesical disease (VI-RADS 4 versus 5)
- Additional tools are now available, such as the Node-RADS system
- MRI is also now being used for assessment of cancer response to neoadjuvant chemotherapy
Presented by: Valeria Panebianco, MD, Sapienza University/Policlinico Umberto I, Rome, Italy
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2021 European Association of Urology, EAU 2021- Virtual Meeting, July 8-12, 2021.
References:
- 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.
- Del Giudice F, Barchetti G, De Berardinis E, et al. Prospective assessment of Vesical Imaging Reporting and Data System (VI-RADS) and its Clinical Impact on the Management of High-risk non-muscle-invasive bladder cancer patients candidate for repeated transurethral resection. Eur Urol 2020 Jan;77(1):101-109.
- Elsholtz FHJ, Asbach P, Haas M, et al. Introducing the Node Reporting and Data System 1.0 (Node-RADS): A concept for standardized assessment of lymph nodes in cancer. Eur Radiol. 2021 Feb 14 [Epub ahead of print].