VI-RADS score system - A primer for urologists

Urologic Imaging of the Bladder: Cancers and Mimics

Bladder cancer (BC) represents a significant global health challenge with notable incidence and mortality rates. Despite treatment advancements, its management remains complex, requiring a multidisciplinary approach. Imaging techniques play a pivotal role in diagnosis, staging, and treatment planning by aiding lesion localization, differentiation, and assessment of tumor extent. Primary modalities like computed tomography and MRI offer detailed anatomic insights. Imaging provides valuable insights into tumor biology, vascular patterns, and molecular profiles, enabling personalized medicine strategies to optimize therapeutic efficacy and minimize adverse effects, crucial for improving BC management and prognosis.

Prospective Assessment of VI-RADS with Muscle Invasion in Urinary Bladder Cancer and Its Implication on Re-Resection/Restaging TURBT Patients

BACKGROUND

Bladder cancer (BCa) diagnosis relies on distinguishing muscle-invasive bladder cancer (MIBC) from non-muscle-invasive bladder cancer (NMIBC) forms. Transurethral resection of the bladder tumor (TURBT) is a standard procedure for initial staging and treatment. The Vesical Imaging-Reporting and Data System (VI-RADS) enhances diagnostic accuracy for muscle invasiveness through advanced imaging techniques, potentially reducing reliance on repeat TURBT and improving patient management.

OBJECTIVE

We aimed to evaluate the role of VI-RADS in predicting muscle invasiveness in BCa and its potential to predict adverse pathology in high-risk NMIBC to avoid unnecessary repeat TURBT procedures.

METHODS

In this prospective study, we included 62 patients over the age of 18 years who underwent TURBT. In a secondary phase, patients selected for restaging TURBT (re-TURBT) were included, but those with T2 tumors or low-risk NMIBC were excluded. Multiparametric magnetic resonance imaging (MRI) examinations were scored by a radiologist using the VI-RADS 5 method, while a pathologist analyzed TURBT and re-TURBT samples for accurate staging. Statistical analysis evaluated the role of VI-RADS in BCa staging.

RESULTS

The VI-RADS score was the only predictive factor for muscle invasion in multivariate analysis. Setting the VI-RADS score at >3 resulted in the highest sensitivity, specificity, and diagnostic accuracy, with values of 67.0%, 89.0%, and 78%, respectively. The receiver operating characteristic area under the curve score for VI-RADS for muscle invasion was 85% for stage Ta, 61% for stage T1, and 88% for stage T2, which shows the utility of VI-RADS in the predictiveness of MIBC/NMIBC.

CONCLUSION

VI-RADS is effective in stratifying BCa patients by predicting muscle invasiveness and identifying NMIBC cases that may not need repeat TURBT.

Diagnostic accuracy and inter-reader agreement of the nacVI-RADS for bladder cancer treated with neoadjuvant chemotherapy: a prospective validation study

OBJECTIVE

The primary aim was to determine the performance of neoadjuvant chemotherapy VI-RADS (nacVI-RADS) in predicting response to systemic therapy in patients with MIBC and to evaluate its inter-reader agreement.

MATERIALS AND METHODS

Prospective study, including patients with non-metastatic muscle-invasive bladder cancer (MIBC) who underwent neoadjuvant chemotherapy before radical cystectomy (RC). Patients underwent pre- and post-treatment MRI. Radiological response was evaluated by two experienced radiologists using nacVI-RADS scoring system. Reference standard was defined using histopathological findings. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and accuracy were calculated to assess nacVI-RADS performance for each reader. Inter-reader agreement was determined with Cohen's k statistics.

RESULTS

Fifty-five patients with non-metastatic MIBC, 46 males (84%) and 9 females (16%) with a median age of 69 (interquartile range (IQR) 66-72 years) were enrolled. Diagnostic performance of nacVI-RADS in detecting complete response to neoadjuvant chemotherapy showed a sensitivity of 76.5-85.3% and specificity of 76.2-81%. The area under the curve was 0.93 (95% CI: 0.86-0.99) for detecting any residual tissue, for the more experienced reader. Inter-reader agreement was optimal with a K of 0.85. In the multivariable logistic regression model, the variables showing independent correlation with response prediction to neoadjuvant therapy were nacVI-RADS score (p = 0.01 for the more experienced reader) and tumor regression grade (TRG; p < 0.001).

CONCLUSION

NacVI-RADS scoring system offers a reliable and reproducible approach, employing a well-structured and easily interpretable method, to assess the response to systemic therapy in patients with MIBC.

KEY POINTS

Question There is a lack of a standardized approach to distinguish between responders and non-responders to neoadjuvant chemotherapy for muscle-invasive bladder cancer. Findings The neoadjuvant chemotherapy VI-RADS (nacVI-RADS) score diagnostic performance for detecting complete response to neoadjuvant chemotherapy showed 85.3% sensitivity, 81% specificity, and an AUC of 0.93. Clinical relevance NacVI-RADS score represents a valid predictor of response to neoadjuvant systemic therapy, impacting therapeutic decision-making and improving overall patients' management.

Retrospective analysis of partial cystectomy in patients with muscle-invasive urothelial carcinoma: A German single-center experience

OBJECTIVES

Partial cystectomy (PC) has been proposed as a less invasive alternative to radical cystectomy (RC) for the treatment of localized muscle-invasive bladder cancer (MIBC). The aim of this study was to evaluate the outcome of PC in a contemporary patient cohort to identify potential risk factors for this procedure.

METHODS

Data from 58 MIBC patients who underwent PC were retrospectively analyzed. Demographics, tumor characteristics, clinical outcomes, and pathology results were collected. Statistical analysis was performed using Cox regression and Kaplan-Meier method to determine survival rates and risk factors.

RESULTS

The cohort consisted of 58 patients with MIBC with a median age of 71 years. The 5-year overall survival (OS), cancer specific survival (CSS) and recurrence-free survival (RFS) rates were 55%, 67% and 51%, respectively. Clinical suspicion for lymph node metastases (HR 3.82, CI 1.09-13.39, P = 0.036), advanced T-stages (HR 3.80, CI 1.38-10.49, P = 0.010), a higher grading (HR 6.57, CI 0.76-49.19, P = 0.010), positive resection margins (HR 1.81, CI 1.10-2.96, P = 0.012), lymphovascular invasion (HR 5.14, CI 1.77-14.88, P = 0.003), vascular invasion (HR 6.62, CI 2.16-20.27, P = 0. 001), and longer time from initial diagnosis to surgery (HR 1.003, CI 1.001-1.01, days, P = 0.010) were associated with decreased OS. Complications within the first 30 and 90 postoperative days were observed in 31% and 36% of patients, respectively. 4% experienced a Clavien-Dino grade III/IV complication. One patient developed acute respiratory distress syndrome and died 46 days after surgery.

CONCLUSION

Partial cystectomy appears to be a safe bladder-sparing approach for highly selected MIBC patients with favorable oncologic outcomes and acceptable complication rates. Patient selection and assessment of tumor characteristics are essential for successful outcomes. Prospective randomized controlled trials are needed.

Novel Methods to Assess Tumor Burden and Minimal Residual Disease in Genitourinary Cancers

BACKGROUND AND OBJECTIVE

Advances in molecular diagnostics have ushered in a new era for patients with prostate, renal, and urothelial cancers, with novel radiographic and molecular modalities for the assessment of disease burden and minimal residual disease (MRD). Conventional imaging has a limited threshold for disease detection and is often unable to discern clinically occult disease with varying risks of false-negative or false-positive findings depending on the disease state and type of imaging.

METHODS

We provide an overview of emerging radiographic and molecular tools in development within the genitourinary (GU) disease space. A literature review of contemporary basic, translational, and clinical research studies was performed, covering the timeframe of 1980-2024 through the MEDLINE (via PubMed) and Scopus databases. We highlight select examples of emerging technologies and biomarker-informed clinical trials, which aim to quantify disease at lower thresholds and have the potential for integrating MRD in clinical practice for GU patients.

KEY FINDINGS AND LIMITATIONS

The development of novel radiotracers, such as prostate-specific membrane antigen or carbonic anhydrase IX, is being evaluated in both clinical practice and trial setting, aiming to change the management of these tumors. Molecular tools including circulating tumor cells and byproducts such as plasma and urine cell-free circulating tumor DNA provide the opportunity for MRD detection. MRD capture on single-cell or cellular byproducts can serve as a conduit for genomic and transcriptomic analyses, providing insight into the molecular underpinnings and clonal evolution of disease.

CONCLUSIONS AND CLINICAL IMPLICATIONS

While the full potential for MRD applications has yet to be realized, we are witnessing the emergence of novel techniques aimed at MRD detection and the rapid development of elegantly designed studies implementing iterative detection of MRD as means to provide biological rationale and tailor therapeutic options in GU tumors.

Practical Guide to VI-RADS: MRI Protocols, Lesion Characterization, and Pitfalls

Urothelial carcinoma is the most common type of bladder cancer (BC), accounting for approximately 90% of all cases. Evaluating the depth of tumor invasion in the bladder wall (tumor staging) is essential for determining the treatment and prognosis in patients with BC. Neoadjuvant therapy followed by radical cystectomy is the most common treatment of localized muscle-invasive BC (MIBC). Therefore, it is vital to differentiate non-MIBC from MIBC. Transurethral resection of bladder tumor (TURBT) is the reference standard to determine the extent of tumor invasion into the bladder wall through tissue sampling. However, this diagnostic and therapeutic method may not adequately sample the muscularis propria, leading to a higher risk of residual disease, early recurrence, and tumor understaging in approximately 50% of patients during the initial TURBT. Multiparametric MRI can overcome some of the limitations of TURBT when evaluating BC, particularly regarding tumor staging. In this context, the Vesical Imaging Reporting and Data System (VI-RADS) classification was developed to establish standards for bladder multiparametric MRI and interpretation. It uses a 5-point scale to assess the likelihood of detrusor muscle invasion. T2-weighted MR images are particularly useful as an initial guide, especially for categories 1-3, while the presence of muscular invasion is determined with diffusion-weighted and dynamic contrast-enhanced sequences. Diffusion-weighted imaging takes precedence as the dominant method when optimal image quality is achieved. The presence of a stalk or a thickened inner layer and no evidence of interruption of the signal intensity of the muscular layer are central for predicting a low likelihood of muscle invasion. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material. See the invited commentary by Hoegger in this issue.

Progress of Multiparameter Magnetic Resonance Imaging in Bladder Cancer: A Comprehensive Literature Review

Magnetic resonance imaging (MRI) has been proven to be an indispensable imaging method in bladder cancer, and it can accurately identify muscular invasion of bladder cancer. Multiparameter MRI is a promising tool widely used for preoperative staging evaluation of bladder cancer. Vesical Imaging-Reporting and Data System (VI-RADS) scoring has proven to be a reliable tool for local staging of bladder cancer with high accuracy in preoperative staging, but VI-RADS still faces challenges and needs further improvement. Artificial intelligence (AI) holds great promise in improving the accuracy of diagnosis and predicting the prognosis of bladder cancer. Automated machine learning techniques based on radiomics features derived from MRI have been utilized in bladder cancer diagnosis and have demonstrated promising potential for practical implementation. Future work should focus on conducting more prospective, multicenter studies to validate the additional value of quantitative studies and optimize prediction models by combining other biomarkers, such as urine and serum biomarkers. This review assesses the value of multiparameter MRI in the accurate evaluation of muscular invasion of bladder cancer, as well as the current status and progress of its application in the evaluation of efficacy and prognosis.

Magnetic resonance radiographic features which might lead to misdiagnosis of muscle-invasive bladder cancer based on vesical imaging reporting and data system: the application experience of a single center

Background

The Vesical Imaging Reporting and Data System (VI-RADS) has been widely used for diagnosing muscle-invasive bladder cancer (MIBC), yet instances of misdiagnosis persist. However, limited research discusses the factors affecting its accuracy. This study aimed to evaluate the diagnostic efficacy of the VI-RADS in our center and to preliminarily identify possible magnetic resonance imaging (MRI) characteristics of misdiagnosis.

Methods

From January 2018 to February 2023, a consecutive series of 211 participants pathologically diagnosed with bladder cancer (BC) who underwent an MRI exam were retrospectively enrolled. MRI was interpreted by 2 radiologists with different levels of experience, the diagnostic performance was validated using the receiver operating characteristic (ROC) curve, and VI-RADS ≥4 was considered to indicate MIBC-positive status. The clinical and radiographic characteristics of the true-positive (TP), true-negative (TN), false-positive (FP), and false-negative (FN) groups were analyzed using Kruskal-Wallis test or Fisher exact test.

Results

With VI-RADS ≥4 as the cutoff value, the area under the ROC curves (AUCs) were 0.951 (0.912-0.976) and 0.847 (0.791-0.893) for the more-experienced reader and less-experienced reader, respectively, with good interobserver agreement (κ=0.74105). The median tumor size in the TP (more experienced: 57 cases; less experienced: 44 cases) and FP (more experienced: 8 cases; less experienced: 9 cases) groups was larger than that in the TN (more experienced: 141 cases; less experienced: 139 cases) group for the more-experienced reader (TP: 28 mm; FP: 31 mm; TN: 19 mm; P<0.001 and P=0.031, respectively) and the less-experienced reader (TP: 31 mm; FP: 28 mm; TN: 19 mm; P<0.001 and P=0.042, respectively). The tumor base in the TP and FP groups was larger than that in the TN group for the more-experienced reader (TP: 37 mm; FP: 48 mm; TN: 15 mm; both P<0.001) and for the less-experienced reader (FP: 42 mm; FP: 36 mm; TN: 15 mm; P<0.001 and P=0.022, respectively). The median tumor base in the TP group was larger than that in the FN group for the less-experienced reader (TP: 42 mm; FN: 17 mm; P=0.004).

Conclusions

We observed good to excellent AUCs with good interobserver agreement among radiologists with different levels of expertise using VI-RADS. Large tumor size and wide tumor base affected the accuracy of VI-RADS in MIBC diagnosis.

Diagnostic performance of multiparametric MRI based Vesical Imaging-Reporting and Data System (VI-RADS) scoring in discriminating between non-muscle invasive and muscle invasive bladder cancer

Purpose

The purpose of the present study was to assess the diagnostic accuracy of the Vesical Imaging-Reporting and Data System (VI-RADS) scoring system in predicting muscle infiltration of bladder cancer (BC) on a pre-operative multiparametric magnetic resonance imaging (mpMRI).

Methods

The prospective study enrolled patients with bladder lesions detected on a preliminary ultrasonography or cystoscopy. The patients underwent mpMRI on a 3T MRI scanner followed by surgery within 2 weeks. The tumours were assigned a VI-RADS score by 2 experienced abdominal radiologists. The VI-RADS score was compared with postoperative histopathological findings to confirm detrusor muscle infiltration. The diagnostic performance of VI-RADS for predicting muscle invasion was assessed by calculating sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy.

Results

A total of 60 patients were included in the study with a male: female ratio of 4.4 : 1. Transurethral resection of bladder tumour (TURBT) was performed in 47 (78.4%) and radical cystectomy in 13 (21.6%) patients. 19 (31.7%) had non-muscle invasive invasive BC (NMIBCa) and 41 (68.3%) had muscle invasive BC (MIBCa) on histopathology. There was a significant association between VI-RADS score and its components with muscle invasion (p < 0.05). A VI-RADS score of ≥ 3 had a sensitivity of 97.56% (95% CI: 0.87-0.99%), specificity of 73.68% (95% CI: 0.49-0.91), positive predictive value of 88.9% (95% CI: 0.79-0.94), negative predictive value of 93.33% (95% CI: 0.66-0.99), and diagnostic accuracy of 90% (95% CI: 0.80-0.96) for prediction of muscle invasion.

Conclusion

VI-RADS scoring system pre-operatively predicts the likelihood of muscle invasion in BC with a satisfactory diagnostic performance, and it should be incorporated in the diagnostic work-up of BC patients.