VI-RADS score: Prospective Validation and its Implication in the Management of Bladder Cancer in COVID-19 Pandemic

 

Summary

Vesical Imaging Reporting and Data System ( VI-RADS) is a five-point (VI-RADS 1 to 5) score, based on mpMRI (Multiparametric Magnetic Resonance Imaging), derived using T2- weighted imaging, diffusion-weighted imaging, and dynamic contrast enhancement, which suggests the risks of muscle invasion. It has been endorsed as a reporting system for bladder cancer (BCa) by the Japanese Society of Abdominal Radiology, European Association of Urology (EAU), and European Society of Urological imaging.¹ 

The recently published article by Del Giudice et al. ^.2  in the Europian urology prospectively validates the accuracy of VI-RADS to differentiate non-muscle invasive bladder cancer (NMIBC) to muscle invasion (MIBC)[Primary aim] and also explore the possible role in the selection of patients who are candidate for Re-TURBT (Repeat Transurethral Resection of Bladder Tumor) in high-risk NMIBC (HR-NMIBC)[Secondry aim].

Between December 2017 to May 2019, all patients of suspected Bca were offered mpMRI before TURBT unless contraindication. All the patients who underwent mpMRI with adequate bladder distension, signed consent, and the biopsy of the first TURBT showed urothelial carcinoma type, accounted for the primary endpoint analysis(n-231), and patients with high-grade histology (Ta orT1) of NMIBC included for secondary endpoints (n-114) analysis. All the patients underwent the same mpMRI protocol at 3 Tesla scanner (Discovery 750; GE, Italy), before the first TURBT. Imaging was reviewed by two urogenital radiologists without knowing the patient history and assigned a VI-RADS score (1–5) to each lesion (up to 3 per patient), and for each patient, only the one with the highest VI-RADS score was considered as a final score and a score of ≥3 was defined as MIBC. The Intrareader agreement was near perfect for both readers (Ƙ > 0.92).

All the Patients underwent TURBT within 6 weeks of mpMRI scan, and Re-TURBT was done in selected high-risk NMIBC patients within 2-6 weeks of first surgery by the same two experienced surgeons by the conventional bipolar white light system. Patients with T1 histology and Ta high-grade histology missing muscularis propria, underwent Re-TURBT as per protocol.

Out of 231 patients, 72 (31.17%) patients had VI-RADS score ≥3. Histopathology of first TURBT specimen revealed MIBC in 42 (18.2%), low risk –NMIBC (LR-NMIBC) in 58(25.1%), and carcinoma in situ (CIS) in 17 (7.3%). The performance of mpMRI to discriminate NMIBC from MIBC tumors provided sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 91.9% (95% confidence interval [CI]: 82.2–97.3) and 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.

 After the exclusion of MIBC, LR-NMIBC, and CIS, a total of 114 HR-NMIBC underwent Re-TURBT in which 23 (20.17%) patients had VI-RADS score ≥3. On Re-TURBT biopsy, 58 (50.9%) patients had no evidence of tumor, 36 (31.6%) were diagnosed with persistent HR-NMIBCs, and 20 (17.5%) were upstaged to MIBC. So in HR-NMIBC group, out of 23 patients who had VIRADS score ≥ 3 before TURBT, 20 came out as MIBC in Re-TURBT. The sensitivity, specificity, PPV and NPV of mpMRI before  TURBT was 85% (95% CI: 62.1–96.8) and 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 diagnosed with MIBC at Re-TURBT..

The authors conclude that the VI-RADS score is accurate for discriminating between NMIBC and MIBC and within HR-NMIBC cases, VI-RADS could, in the future, improve the selection of patients who are candidates for Re-TURBT.

Comments

The Receiver operating characteristic (ROC) curve analysis of this study showed the high accuracy of VI-RAD score (≥3) to detect adverse pathology (MIBC) at Re-TURBT (AUC was 0.93 (95% CI: 0.87– 0.97). In HR-NMIBC, 91(79.82%) Patients had VI-RADS score ≤2 and out of them only 3.29% (3) had upstaging (Score>2) of disease after Re-TURBT. This means a high proportion (96.70%) of patients can be managed on TURBT only and Re-TURBT can be safely omitted and further intravesical BCG can be started early.

Although clear guidelines and recommendations are there for the management of different stages of Bca patients in COVID-19 pandemic, VI-RADS score may be best utilized in this situation i.e patients with HR-NMIBC and VI-RADS score of ≤2 can be directly started on intravesical BCG and further operation room (OR) visit can be avoided, to minimize exposure to the patient and health personnel. An alternative risk risk-adapted approach based on VI-RADS score to the management of Bca, proposed by Panebianco V et al. is quite justifiable in this pandemic situation.³  Another advantage of mpMRI based VI-RADS scoring is, escape from radiation exposure and iodinated contrast.

A recently published meta-analysis of six studies (1770 patients) showed a high diagnostic performance of VI-RADS score to detect MIBC and the pooled sensitivity and specificity were 0.83 %(95% CI 0.70–0.90) and 0.90% (95% CI 0.83–0.95)  respectively.⁴ In a retrospective validation study of 340 patients by Wang et al. the authors demonstrated high diagnostic performance (AUC of 0.94) and with comparable sensitivity (87.1%) and specificity(96.5%) for detection of MIBC of VI-RADS score  >2.⁵

To date, most of the study on VI-RADS score focussed on the detection of MIBC and retrospective in nature, but the index study is a prospective study and validate the VI-RADS in HR-NMIBC also. The limitation of VI-RADS scoring is, it cannot detect CIS so the VI-RADS score cannot be adopted and validated in this high-risk group of patients.

To conclude, the VI-RADS score has high sensitivity and specificity to detect MIBC at primary TURBT and Re-TURBT, and a potential to select patients in which Re-TURBT can be omitted, but before that, a well-designed, large, multicentre randomized control trial focussed on HR-NMIBC is required to compare oncological outcomes.

                     Figure: Single papillary tumor on the posterior wall of the urinary bladder 

 

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). European urology. 2018 Sep 1;74(3):294-306.
2. 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. European Urology. 2020 Jan 1;77(1):101-9.
3. Panebianco V, Del Giudice F, Leonardo C, et al. VI-RADS Scoring Criteria for Alternative Risk-adapted Strategies in the Management of Bladder Cancer During the COVID-19 Pandemic. European Urology. 2020 Apr 27.
4. Woo S, Panebianco V, Narumi Y, Del Giudice F, et al. Diagnostic performance of Vesical Imaging Reporting and Data System for the prediction of muscle-invasive bladder cancer: a systematic review and meta-analysis. European Urology Oncology. 2020 Mar 19.
5. Wang H, Luo C, Zhang F, Guan J, et al. Multiparametric MRI for bladder cancer: validation of VI-RADS for the detection of detrusor muscle invasion. Radiology. 2019 Jun;291(3):668-74.