Multiparametric MRI of the bladder: inter-observer agreement and accuracy with the Vesical Imaging-Reporting and Data System (VI-RADS) at a single reference center

Role of Additional MRI-Based Morphologic Measurements on the Performance of VI-RADS for Muscle-Invasive Bladder Cancer

BACKGROUND

Vesical Imaging-Reporting and Data System (VI-RADS) is a pathway for the standardized imaging and reporting of bladder cancer staging using multiparametric (mp) MRI.

PURPOSE

To investigate additional role of morphological (MOR) measurements to VI-RADS for the detection of muscle-invasive bladder cancer (MIBC) with mpMRI.

STUDY TYPE

Retrospective.

POPULATION

A total of 198 patients (72 MIBC and 126 NMIBC) underwent bladder mpMRI was included.

FIELD STRENGTH/SEQUENCE

3.0 T/T2-weighted imaging with fast-spin-echo sequence, spin-echo-planar diffusion-weighted imaging and dynamic contrast-enhanced imaging with fast 3D gradient-echo sequence.

ASSESSMENT

VI-RADS score and MOR measurement including tumor location, number, stalk, cauliflower-like surface, type of tumor growth, tumor-muscle contact margin (TCM), tumor-longitudinal length (TLL), and tumor cellularity index (TCI) were analyzed by three uroradiologists (3-year, 8-year, and 15-year experience of bladder MRI, respectively) who were blinded to histopathology.

STATISTICAL TESTS

Significant MOR measurements associated with MIBC were tested by univariable and multivariable logistic regression (LR) analysis with odds ratio (OR). Area under receiver operating characteristic curve (AUC) with DeLong's test and decision curve analysis (DCA) were used to compared the performance of unadjusted vs. adjusted VI-RADS. A P-value <0.05 was considered statistically significant.

RESULTS

TCM (OR 9.98; 95% confidence interval [CI] 4.77-20.8), TCI (OR 5.72; 95% CI 2.37-13.8), and TLL (OR 3.35; 95% CI 1.40-8.03) were independently associated with MIBC at multivariable LR analysis. VI-RADS adjusted by three MORs achieved significantly higher AUC (reader 1 0.908 vs. 0.798; reader 2 0.906 vs. 0.855; reader 3 0.907 vs. 0.831) and better clinical benefits than unadjusted VI-RADS at DCA. Specially in VI-RADS-defined equivocal lesions, MOR-based adjustment resulted in 55.5% (25/45), 70.4% (38/54), and 46.4% (26/56) improvement in accuracy for discriminating MIBC in three readers, respectively.

DATA CONCLUSION

MOR measurements improved the performance of VI-RADS in detecting MIBC with mpMRI, especially for equivocal lesions.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Development of deep learning model for diagnosing muscle-invasive bladder cancer on MRI with vision transformer

Rationale and objectives

To develop and validate a deep learning (DL) model to automatically diagnose muscle-invasive bladder cancer (MIBC) on MRI with Vision Transformer (ViT).

Materials and methods

This multicenter retrospective study included patients with BC who reported to two institutions between January 2016 and June 2020 (training dataset) and a third institution between May 2017 and May 2022 (test dataset). The diagnostic model for MIBC and the segmentation model for BC on MRI were developed using the training dataset with 5-fold cross-validation. ViT- and convolutional neural network (CNN)-based diagnostic models were developed and compared for diagnostic performance using the area under the curve (AUC). The performance of the diagnostic model with manual and auto-generated regions of interest (ROImanual and ROIauto, respectively) was validated on the test dataset and compared to that of radiologists (three senior and three junior radiologists) using Vesical Imaging Reporting and Data System scoring.

Results

The training and test datasets included 170 and 53 patients, respectively. Mean AUC of the top 10 ViT-based models with 5-fold cross-validation outperformed those of the CNN-based models (0.831 ± 0.003 vs. 0.713 ± 0.007-0.812 ± 0.006, p < .001). The diagnostic model with ROImanual achieved AUC of 0.872 (95 % CI: 0.777, 0.968), which was comparable to that of junior radiologists (AUC = 0.862, 0.873, and 0.930). Semi-automated diagnosis with the diagnostic model with ROIauto achieved AUC of 0.815 (95 % CI: 0.696, 0.935).

Conclusion

The DL model effectively diagnosed MIBC. The ViT-based model outperformed CNN-based models, highlighting its utility in medical image analysis.

Development and Validation of an MRI-Based Nomogram for Preoperative Detection of Muscle Invasion in VI-RADS 3

BACKGROUND

The relationship between tumor and muscle layer in the vesical imaging-reporting and data system (VI-RADS) 3 is ambiguous, and there is a lack of preoperative and non-invasive procedures to detect muscle invasion in VI-RADS 3.

PURPOSE

To develop a nomogram based on MRI features for detecting muscle invasion in VI-RADS 3.

STUDY TYPE

Retrospective.

POPULATION

235 cases (Age: 67.5 ± 11.5 years) with 11.9% females were randomly divided into a training cohort (n = 164) and a validation cohort (n = 71).

FIELD STRENGTH/SEQUENCE

3T, T2-weighted imaging (turbo spin-echo), diffusion-weighted imaging (breathing-free spin echo), and dynamic contrast-enhanced imaging (gradient echo).

ASSESSMENT

3 features were selected from the training cohort, including tumor contact length greater than maximum tumor diameter (TCL > Dmax), flat tumor morphology, and lower standard deviation of apparent diffusion coefficient (ADCSD). Three readers assessed VI-RADS scores and the tumor morphology.

STATISTICAL TESTS

Interobserver agreement was assessed by Kappa analysis. Features for final analysis were selected by logistic regression. The performance of the nomogram was evaluated by the receiver operating characteristic curve, decision curve analysis, and calibration curve.

RESULTS

TCL > Dmax, flat morphology, and lower ADCSD were the independent risk factors for muscle invasive in VI-RADS 3. The AUCs, accuracy, sensitivity, and specificity of the nomogram 1 composed of three features for detecting muscle invasion were 0.852 (95% CI: 0.793-0.912), 0.756, 0.917, and 0.663 in the training cohort, and 0.885 (95% CI: 0.801-0.969), 0.817, 0.900, and 0.784 in the validation cohort. The nomogram 2 without ADCSD has nearly the same performance as the nomogram 1.

DATA CONCLUSION

Nomogram can be an efficient tool for preoperative detection of muscle invasion in VI-RADS 3.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Detecting Muscle Invasion of Bladder Cancer: An Application of Diffusion Kurtosis Imaging Ratio and Vesical Imaging-Reporting and Data System

BACKGROUND

Independent factors are needed to supplement vesical imaging-reporting and data system (VI-RADS) to improve its ability to identify muscle invasive bladder cancer (MIBC).

PURPOSE

To assess the correlation between MIBC and diffusion kurtosis imaging (DKI) ratio, VI-RADS, and other factors (such as tumor location).

STUDY TYPE

Retrospective.

POPULATION

Sixty-eight patients (50 males and 18 females; age: 70.1 ± 9.5 years) with bladder urothelial carcinoma.

FIELD STRENGTH/SEQUENCE

1.5 T, conventional diffusion-weighted imaging (DWI), and DKI (single shot echo-planar sequence).

ASSESSMENT

Three radiologists independently measured the diffusion parameters of each bladder cancer (BCa) and obturator internus, including the mean apparent diffusion coefficient (ADCmean), mean kurtosis (MK), and mean diffusion (MD). And the ratio of diffusion parameters between BCa and obturator internus was calculated (diffusion parameter ratio = bladder cancer:obturator internus). Based on the VI-RADS, the target lesions were independently scored. Furthermore, the actual tumor-wall contact length (ACTCL) and absolute tumor-wall contact length (ABTCL) were measured.

STATISTICAL TESTS

Multicollinearity among independent variables was evaluated using the variance inflation factor (VIF). Multivariable logistic regression analysis was used to determine the independent risk factors of MIBC. The receiver operating characteristic curve was used to evaluate the efficacy of each variable in detecting MIBC. The DeLong test was used to compare the area under the curve (AUC). A P < 0.05 was considered statistically significant.

RESULTS

MKratio (median: 0.62) and VI-RADS were independent risk factors for MIBC. AUCs for MKratio, VI-RADS, and MKratio combined with VI-RADS in assessing MIBC were 0.895, 0.871, and 0.973, respectively. MKratio combined with VI-RADS was more effective in diagnosing MIBC than VI-RADS alone.

DATA CONCLUSIONS

MKratio has potential to assist the assessment of MIBC. MKratio can be used as a supplement to VI-RADS for detecting MIBC.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY: Stage 2.

Evaluation of magnetic resonance imaging for bladder cancer detection following transurethral resection of bladder tumour (TURBT)

PURPOSE

To evaluate the performance of MRI for detection of bladder cancer following transurethral resection of bladder tumour (TURBT).

METHODS

This single-centre retrospective study included forty-one consecutive patients with bladder cancer who underwent bladder MRI after TURBT. Two uroradiologists retrospectively assessed the presence of tumour using bladder MRI with and without DWI (diffusion weighted imaging) using a five-point Likert scale. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated and inter-reader agreement was assessed. Histopathology was used as the reference standard.

RESULTS

24 out of 41 patients (58.5%) had no residual tumour or Tis (carcinoma in situ) after TURBT. Sensitivity, specificity, PPV and NPV for detection of tumour using T1WI (T1-weighted imaging) and T2WI (T2-weighted imaging) was 50.0%, 54.6%, 21.1%, and 81.8%, respectively and for T1WI, T2WI and DWI combined was 100%, 76.5%, 50.0% and 100%, respectively. Overestimation of tumour was more common than underestimation. MRI showed high accuracy for patients in whom there was no residual tumour (78.9%). Inter-reader agreement for tumour detection improved from fair (κ = 0.54) to moderate (κ = 0.70) when DWI was included.

CONCLUSION

Non-contrast MRI with DWI showed high sensitivity and relatively high specificity for detection of residual tumour after TURBT. Inter-reader agreement improved from fair to moderate with the addition of DWI. MRI can be useful after TURBT in order to guide further management.

Deep Learning Algorithms for Bladder Cancer Segmentation on Multi-Parametric MRI

BACKGROUND

Bladder cancer (BC) segmentation on MRI images is the first step to determining the presence of muscular invasion. This study aimed to assess the tumor segmentation performance of three deep learning (DL) models on multi-parametric MRI (mp-MRI) images.

METHODS

We studied 53 patients with bladder cancer. Bladder tumors were segmented on each slice of T2-weighted (T2WI), diffusion-weighted imaging/apparent diffusion coefficient (DWI/ADC), and T1-weighted contrast-enhanced (T1WI) images acquired at a 3Tesla MRI scanner. We trained Unet, MAnet, and PSPnet using three loss functions: cross-entropy (CE), dice similarity coefficient loss (DSC), and focal loss (FL). We evaluated the model performances using DSC, Hausdorff distance (HD), and expected calibration error (ECE).

RESULTS

The MAnet algorithm with the CE+DSC loss function gave the highest DSC values on the ADC, T2WI, and T1WI images. PSPnet with CE+DSC obtained the smallest HDs on the ADC, T2WI, and T1WI images. The segmentation accuracy overall was better on the ADC and T1WI than on the T2WI. The ECEs were the smallest for PSPnet with FL on the ADC images, while they were the smallest for MAnet with CE+DSC on the T2WI and T1WI.

CONCLUSIONS

Compared to Unet, MAnet and PSPnet with a hybrid CE+DSC loss function displayed better performances in BC segmentation depending on the choice of the evaluation metric.

Vesical Imaging-Reporting and Data System (VI-RADS) as a grouping imaging biomarker combined with a decision-tree mode to preoperatively predict the pathological grade of bladder cancer

AIM

To investigate whether the Vesical Imaging-Reporting and Data System (VI-RADS) could be used to develop a new non-invasive preoperative grade-prediction system to partially predict high-grade bladder cancer (HG-BC).

MATERIALS AND METHODS

The present study enrolled 89 primary BC patients prospectively from March 2022 to June 2023. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic performance of VI-RADS for predicting HG-BC and muscle-invasive bladder cancer (MIBC) in the entire group. In the low VI-RADS (≤2) group, the decision tree-based method was used to obtain significant predictors and construct the decision-tree model (DT model). The performance of the DT model and low VI-RADS scores for predicting HG-BC was determined using ROC, calibration, and decision curve analyses.

RESULTS

At a cut-off of ≥3, the specificity and positive predictive value of VI-RADS for predicting HG-BC in the entire group was 100%, and the area under the ROC curve (AUC) was 0.697. Among 65 patients with low VI-RADS scores, the DT model showed an AUC of 0.884 in predicting HG-BC compared to 0.506 for low VI-RADS scores. Calibration and decision curve analyses showed that the DT model performed better than the low VI-RADS scores.

CONCLUSION

Most VI-RADS scores ≥3 correspond to HG-BCs. VI-RADS could be used as a grouping imaging biomarker for a pathological grade-prediction procedure, which in combination with the DT model for low VI-RADS (≤2) populations, would provide a potential preoperative non-invasive method of predicting HG-BC.

Performance of VI-RADS in predicting muscle-invasive bladder cancer after transurethral resection: a single center retrospective analysis

PURPOSE

To assess VIRADS performance and inter-reader agreement for detecting muscle-invasive bladder cancer (MIBC) following transurethral resection of bladder tumor (TURBT).

METHODS

An IRB-approved, HIPAA-compliant, retrospective study from 2016 to 2020 included patients with bladder urothelial carcinoma who underwent MRI after TURBT, and cystectomy within 3 months without post-MRI treatments. Three radiologists blinded to pathology results independently reviewed MR images and assigned a VI-RADS score. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of VI-RADS were assessed for diagnosing MIBC using VI-RADS scores ≥ 3 and ≥ 4. Inter-reader agreement was assessed using Gwet's agreement coefficient (AC) and percent agreement.

RESULTS

The cohort consisted of 70 patients (mean age, 68 years ± 11 [SD]; range 39-85; 58 men) and included 32/70 (46%) with MIBC at cystectomy. ROC analysis revealed an AUC ranging from 0.67 to 0.77 and no pairwise statistical difference between readers (p-values, 0.06, 0.08, 0.97). Percent sensitivity, specificity, PPV, NPV and accuracy for diagnosing MIBC for the three readers ranged from 81.3-93.8, 36.8-55.3, 55.6-60.5, 77.3-87.5, and 62.9-67.1 respectively for VI-RADS score ≥ 3, and 78.1-81.3, 47.4-68.4, 55.6-67.6, 72.0-78.8 and 61.4-72.9 respectively for VI-RADS score ≥ 4. Gwet's AC was 0.63 [95% confidence interval (CI): 0.49,0.78] for VI-RADS score ≥ 3 with 79% agreement [95% CI 72,87] and 0.54 [95%CI 0.38,0.70] for VI-RADS score ≥ 4 with 76% agreement [95% CI 69,84]. VIRADS performance was not statistically different among 31/70 (44%) patients who received treatments prior to MRI (p ≥ 0.16).

CONCLUSION

VI-RADS had moderate sensitivity and accuracy but low specificity for detection of MIBC following TURBT, with moderate inter-reader agreement.

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.

Amide Proton Transfer-Weighted MRI and Diffusion-Weighted Imaging in Bladder Cancer: A Complementary Tool to the VI-RADS

RATIONALE AND OBJECTIVES

To investigate the feasibility of amide proton transfer-weighted (APTw) and diffusion-weighted Magnetic Resonance Imaging (MRI) as a means by which to add value to the Vesical Imaging Reporting and Data System (VI-RADS) for discriminating muscle invasive bladder cancer (MIBC) from nonmuscle invasive bladder cancer (NMIBC).

MATERIALS AND METHODS

This prospective study enrolled participants with pathologically confirmed bladder cancer (BCa) who underwent preoperative multiparametric MRI, including APTw and diffusion-weighted MRI, from July 2020 to January 2023. The exclusion criteria were lesions smaller than 10 mm, missing smooth muscle layer in the operation specimen, neoadjuvant therapy before MRI, inadequate image quality, and malignancy other than urothelial neoplasm. Two radiologists independently assigned the VI-RADS score for each participant. Quantitative parameters derived from APTw and diffusion-weighted MRI were obtained by another two radiologists. Receiver operating characteristic (ROC) curve analysis with the area under the ROC curve (AUC) was performed to evaluate the diagnostic performances of quantitative parameters for discriminating BCa detrusor muscle invasion status.

RESULTS

A total of 106 participants were enrolled (mean age, 64 ± 12 years [SD]; 90 men): 32 with MIBC and 74 with NMIBC. Lower apparent diffusion coefficient (ADC) values (0.88 × 10-3 mm2/s ± 0.12 vs. 1.08 × 10-3 mm2/s ± 0.25; P < 0.001) and higher APTw values (6.89% [interquartile range {IQR}, 5.05%-12.17%] vs. 3.61% [IQR, 2.23%-6.83%]; P < 0.001) were observed in the MIBC group. Compared to VI-RADS alone, both APTw (P = 0.003) and ADC (P = 0.020) values could improve the diagnostic performance of VI-RADS in differentiating MIBC from NMIBC. The combination of the three yielded the highest diagnostic performance (AUC, 0.93; 95% CI:0.87,0.97) for evaluating muscle invasion status. The addition of the APTw values to the combination of VI-RADS and ADC values notably improved the diagnostic performance for differentiating NMIBC from MIBC (VI-RADS+ADC vs. VI-RADS+APTw+ADC, P = 0.046).

CONCLUSION

MRI parameters derived from APTw and diffusion-weighted MRI can be used to accurately assess muscle invasion status in BCa and provide additional value to VI-RADS.

Tumor contact length with bladder wall provides effective risk stratification for lesions with a VIRADS score of 2-3

OBJECTIVES

To evaluate the diagnostic performance of the tumor contact length (TCL) in the prediction of MIBC (muscle-invasive bladder cancer) in lesions corresponding to the vesical imaging-reporting and data system (VIRADS) score 2-3.

METHODS

This is a single institution, retrospective study targeting 191 consecutive patients assigned of VIRADS score 2-3, who had pre-transurethral resection MRI from July 2019 to September 2021. Logistic regression analyses were performed to determine meaningful predictors of MIBC for this score group, and a nomogram was plotted with those variables. The diagnostic performance of each predictor was compared at predefined thresholds (VIRADS score 3 and TCL 3 cm) using the generalized linear model and ROC analysis.

RESULTS

Both VIRADS score and TCL remained independent predictors of MIBC for this score group (odds ratio 7.3 for VIRADS score, and 1.3 for TCL, p < 0.01 for both). The contribution of TCL to the probability of MIBC in the nomogram was greater than that of the VIRADS score. VIRADS score had a sensitivity of 0.54 (14/26), specificity of 0.92 (203/221), and diagnostic accuracy of 0.88 (217/247), and TCL showed a sensitivity of 0.89 (23/26), specificity of 0.95 (209/221), and diagnostic accuracy of 0.94 (232/247). The difference in sensitivity (p = 0.03) and accuracy (p = 0.04) was statistically significant. The AUC was also significantly wider for TCL than for VIRADS (0.97 vs. 0.73, p < 0.01).

CONCLUSION

A simple index, TCL, may be helpful in further risk stratification for MIBC in patients with a score of VIRADS 2-3.

CLINICAL RELEVANCE STATEMENT

For bladder cancer patients with insufficient qualitative evidence of muscle layer invasion using VIRADS categorization, TCL, a simple quantitative indicator defined as the curvilinear contact length between the bladder wall and the tumor, may be helpful in risk stratification.

KEY POINTS

• Even when only lesions with score 2-3 were targeted, VIRADS was still a meaningful indicator of MIBC. • With a predefined threshold of 3 cm applied, TCL outperformed VIRADS in the score 2-3 group, in predicting MIBC. • A longer TCL for a lesion with a VIRADS score 2 may warrant an additional warning for MIBC, whereas a shorter TCL for a lesion with a score 3 may indicate a lower risk of MIBC.

Accuracy of Vesical Imaging-Reporting and Data System for muscle-invasive bladder cancer detection from multiparametric magnetic resonance imaging

PURPOSE

The Vesical Imaging-Reporting and Data System (VI-RADS) was used to distinguish the invasive nature of bladder masses before surgery. These imaging criteria can be used to carefully select patients who are candidates for repeat transurethral resection of bladder tumor (Re-TUR-BT). One-third of patients are understage at the time of Re-TUR-BT. This study aimed to evaluate the discrimination accuracy of VI-RADS between non-muscle-invasive bladder cancer and muscle-invasive bladder cancer.

MATERIALS AND METHODS

Patients with a bladder mass identified by cystoscopy who were assigned for TUR-BT were offered multiparametric magnetic resonance imaging (mpMRI) for VI-RADS. TUR-BT reports were compared with preoperative VI-RADS scores to evaluate the accuracy of discrimination of the muscle-invasive nature of the bladder mass.

RESULTS

A total of 58 bladder tumor lesions were included, 13 with muscle-invasive bladder cancer and 45 with non-muscle-invasive bladder cancer. Sensitivity and specificity were 92.3% and 86.7%, respectively, when a VI-RADS cutoff of 4 or more was used to define muscle-invasive bladder cancer. Positive predictive value and negative predictive value were 66.7% and 97.5%, with an accuracy of 87.9%. The area under the receiver operating characteristic curve was 0.932 (95% confidence interval, 0.874-0.989), and the empirical optimal cutpoint from the Youden method was 3.

CONCLUSIONS

VI-RADS is an accurate tool for correctly differentiating muscle-invasive bladder cancer from non-muscle-invasive bladder cancer. We found a cutpoint of VI-RADS 1-3 vs. 4-5 to have the highest specificity and accuracy for the discrimination of non-muscle-invasive from muscle-invasive bladder cancer.

Novel utility of Vesical Imaging-Reporting and Data System in multimodal treatment for muscle-invasive bladder cancer

OBJECTIVES

To examine the clinical significance of the Vesical Imaging-Reporting and Data System (VI-RADS) in predicting outcome of multimodal treatment (MMT) in muscle-invasive bladder cancer (MIBC) patients.

METHODS

We reviewed 78 pathologically proven MIBC patients who underwent MMT including transurethral resection and chemoradiotherapy, followed by partial or radical cystectomy. Treatment response was assessed through histologic evaluation of cystectomy specimens. Two radiologists categorized the index lesions of pretherapeutic MRI according to the 5-point VI-RADS score. The associations of VI-RADS score with the therapeutic effect of MMT were analyzed. The diagnostic performance of VI-RADS scores with a cut-off VI-RADS scores  ≤ 2 or ≤ 3 for predicting pathologic complete response to MMT (MMT-CR) was evaluated.

RESULTS

MMT-CR was achieved in 2 (100%) of VI-RADS score 1 (n = 2), 16 (84%) of score 2 (n = 19), 12 (86%) of score 3 (n = 14), 7 (64%) of score 4 (n = 11), and 14 (44%) of score 5 (n = 32). VI-RADS score was inversely associated with the incidence of MMT-CR (p = 0.00049). The cut-off VI-RADS score  ≤ 2 and  ≤ 3 could predict the favorable therapeutic outcome of MMT with high specificity (0.89 with 95% confidence interval [CI]: 0.71-0.98 and 0.82 with 95% CI: 0.62-0.94, respectively) and high positive predictive value (0.86 with 95% CI: 0.64-0.97 and 0.86 with 95% CI: 0.70-0.95, respectively).

CONCLUSION

VI-RADS score may serve as an imaging marker in MIBC patients for predicting the therapeutic outcome of MMT.

CLINICAL RELEVANCE STATEMENT

Muscle-invasive bladder cancer patients with a lower Vesical Imaging-Reporting and Data System score can be a good candidate for bladder-sparing treatment incorporating multimodal treatment.

KEY POINTS

• Vesical Imaging-Reporting and Data System (VI-RADS) score was potentially valuable for classifying pathologic tumor response in patients with muscle-invasive bladder cancer. • The likelihood of achieving complete response of multimodal treatment (MMT) decreased with increasing VI-RADS score. • VI-RADS score could serve as an imaging marker that optimizes patient selection for MMT.

Predicting muscle invasion in bladder cancer by deep learning analysis of MRI: comparison with vesical imaging-reporting and data system

OBJECTIVES

To compare the diagnostic performance of a novel deep learning (DL) method based on T2-weighted imaging with the vesical imaging-reporting and data system (VI-RADS) in predicting muscle invasion in bladder cancer (MIBC).

METHODS

A total of 215 tumours (129 for training and 31 for internal validation, centre 1; 55 for external validation, centre 2) were included. MIBC was confirmed by pathological examination. VI-RADS scores were provided by two groups of radiologists (readers 1 and readers 2) independently. A deep convolutional neural network was constructed in the training set, and validation was conducted on the internal and external validation sets. ROC analysis was performed to evaluate the performance for MIBC diagnosis.

RESULTS

The AUCs of the DL model, readers 1, and readers 2 were as follows: in the internal validation set, 0.963, 0.843, and 0.852, respectively; in the external validation set, 0.861, 0.808, and 0.876, respectively. The accuracy of the DL model in the tumours scored VI-RADS 2 or 3 was higher than that of radiologists in the external validation set: for readers 1, 0.886 vs. 0.600, p = 0.006; for readers 2, 0.879 vs. 0.636, p = 0.021. The average processing time (38 s and 43 s in two validation sets) of the DL method was much shorter than the readers, with a reduction of over 100 s in both validation sets.

CONCLUSIONS

Compared to radiologists using VI-RADS, the DL method had a better diagnostic performance, shorter processing time, and robust generalisability, indicating good potential for diagnosing MIBC.

KEY POINTS

• The DL model shows robust performance for MIBC diagnosis in both internal and external validation. • The diagnostic performance of the DL model in the tumours scored VI-RADS 2 or 3 is better than that obtained by radiologists using VI-RADS. • The DL method shows potential in the preoperative assessment of MIBC.

Fully automated bladder tumor segmentation from T2 MRI images using 3D U-Net algorithm

Introduction

Bladder magnetic resonance imaging (MRI) has been recently integrated in the diagnosis pathway of bladder cancer. However, automatic recognition of suspicious lesions is still challenging. Thus, development of a solution for proper delimitation of the tumor and its separation from the healthy tissue is of primordial importance. As a solution to this unmet medical need, we aimed to develop an artificial intelligence-based decision support system, which automatically segments the bladder wall and the tumor as well as any suspect area from the 3D MRI images.

Materials

We retrospectively assessed all patients diagnosed with bladder cancer, who underwent MRI at our department (n=33). All examinations were performed using a 1.5 Tesla MRI scanner. All images were reviewed by two radiologists, who performed manual segmentation of the bladder wall and all lesions. First, the performance of our fully automated end-to-end segmentation model based on a 3D U-Net architecture (by considering various depths of 4, 5 or 6 blocks) trained in two data augmentation scenarios (on 5 and 10 augmentation datasets per original data, respectively) was tested. Second, two learning setups were analyzed by training the segmentation algorithm with 7 and 14 MRI original volumes, respectively.

Results

We obtained a Dice-based performance over 0.878 for automatic segmentation of bladder wall and tumors, as compared to manual segmentation. A larger training dataset using 10 augmentations for 7 patients could further improve the results of the U-Net-5 model (0.902 Dice coefficient at image level). This model performed best in terms of automated segmentation of bladder, as compared to U-Net-4 and U-Net-6. However, in this case increased time for learning was needed as compared to U-Net-4. We observed that an extended dataset for training led to significantly improved segmentation of the bladder wall, but not of the tumor.

Conclusion

We developed an intelligent system for bladder tumors automated diagnostic, that uses a deep learning model to segment both the bladder wall and the tumor. As a conclusion, low complexity networks, with less than five-layers U-Net architecture are feasible and show good performance for automatic 3D MRI image segmentation in patients with bladder tumors.

Is high accuracy of Vesical Imaging-Reporting and Data System (VI-RADS) sufficient for its implementation in the urological practice?

AIMS

Currently, the only method used to differentiate between MIBC and NMIBC is transurethral resection of the bladder tumour (TURBT). Magnetic resonance and Vesical Imaging-Reporting and Data System (VI-RADS) would allow for discrimination between NMIBC and MIBC. We evaluate the sensitivity and specificity of VI-RADS in the diagnosis of muscle-invasive bladder cancer and discuss its value in everyday urological practice.

METHODS

64 patients with bladder cancer (BC) were enrolled into this prospective study. Multiparametric magnetic resonance imaging (mpMRI) was performed before transurethral resection of the bladder tumour (TURBT) and evaluated using the VI-RADS score. Score were compared to histopathology results. We evaluated the sensitivity, specificity, positive and negative predictive value of this system using both cut-off VI-RADS ≥ 3 and ≥ 4.

RESULTS

Sensitivity of 92.3% (95%CI: 64.0; 99.8), specificity of 81.4% (95%CI: 69.1; 90.3), positive predictive value of 52.2% (95%CI: 30.6; 73.2) and negative predictive value of 98.0% (95%CI: 89.1; 99.9) was determined using cut off VI-RADS ≥ 3, while sensitivity of 76.9% (95%CI: 46.2; 95.0), specificity of 91.5% (95%CI: 81.3; 97.2), positive predictive value of 66.7% (95%CI: 38.4; 88.2), and negative predictive value of 94.7% (95%CI: 85.4; 98.9) was determined using cut-off VI-RADS ≥ 4. Based on our results, we consider the optimal cut-off point to be VI-RADS ≥ 3 with the overall prediction accuracy of 83.3% (95%CI: 72.7; 91.1).

CONCLUSIONS

We acknowledge that mpMRI provides valuable information with regard to BC staging, however, despite its high overall accuracy, we do not consider the VI-RADS could replace TURBT in discrimination between non-muscle invasive and MIBC.

To determine correlation between VIRADS scoring and pathological staging in bladder cancer: A prospective study and review of literature

The development of standardized reporting systems is of paramount importance in medical-imaging. Based on the "RADS" methodology, PIRADS and BI-RADS have been successfully used. The management of bladder cancer (BC) depends on the stage at the time of identification. Accurate assessment of the muscle-invasive stage can alter therapies that are radically different. MRI can accurately diagnose this in a standardized manner (Vesical Imaging-Reporting and Data System: VIRADS) and spare additional procedures. The aim of the study is to determine diagnostic accuracy of VIRADS scoring in evaluation of muscle invasiveness in patients with BC. This study was conducted in a single center over a period of 2 years from April 2020. A total of 76 patients with bladder SOL/diagnosed BC were included. Final VIRADS scoring was calculated and compared with histopathological report.76 patients were evaluated which included 64 males and 12 females. Most of the cases came under the VIRADS-II category (23, 30.26%) followed by VIRADS-V (17, 22.36%). VIRADS-I was reported in 14 cases (18.42%). A total of 8 cases (10.52 %) were reported as VIRADS III and 14 cases (18.42%) as VIRADS IV. VIRADS-III was taken as cut off and found to have a sensitivity of 94.44%, a specificity of 87.50%, a positive predictive value of 87.17% and a negative predictive value of 94.59%. Though number of cases are still less to accurately predict test characteristics of VIRADS, our results are consistent with previously done retrospective studies and VIRADS has got good correlation with pathological staging.

The Additional Value of Tri-parametric MRI in Identifying Muscle-invasive Status in Bladder Cancer

RATIONALE AND OBJECTIVES

Identification of muscle-invasive status (MIS) of bladder cancer (BCa) is critical for treatment decisions. The Vesical Imaging-Reporting and Data System (VI-RADS) has been widely used in preoperatively predicting MIS using tri-parametric MR imaging including T2-weighted (T2W), diffusion-weighted (DW), and dynamic contrast-enhanced (DCE) sequences. While the diagnostic values of radiomics features from bi-parametric MRI such as T2W + DW to identification of MIS have been reported, whether the tri-parametric MRI could provide additional diagnostic value to the radiomics prediction task, and how to integrate DCE features into the radiomics model, which is the objectives of this study, remain unknown.

MATERIALS AND METHODS

Patients with postoperatively confirmed BCa lesions (150 in non-muscle-invasive BCa and 56 in muscle-invasive BCa groups) were retrospectively included. Their T2W, DW with apparent diffusion coefficient (ADC) maps, and DCE sequences were acquired using a 3.0T MR system. Regions of interest were manually depicted and VI-RADS scores were assessed by three radiologists. Three predictive models were developed by the radiomics features extracted from sequence combinations of T2W + DW (Model one), T2W + DCE (Model two), and T2W + DW + DCE (Model three), respectively, using the least absolute shrinkage and selection operator. The performance of each model was quantitatively assessed on both the training (n = 165) and testing (n = 41) cohorts. Then a 10 times five-fold cross validation was conducted to assess the overall performance.

RESULTS

Three models achieved area under the curve of 0.888, 0.869, and 0.901 in the cross validation, respectively. The tri-parametric model performed significantly superior than the two bi-parametric models and VI-RADS. The analysis of feature coefficients derived from least absolute shrinkage and selection operator algorithm showed features from the tri-parametric MRI are effective in MIS discrimination.

CONCLUSION

The tri-parametric MRI provides additional value to the radiomics-based identification of MIS.

Seeing is Believing: State of the Art Imaging of Bladder Cancer

Imaging plays an important role in bladder cancer (BCa) diagnostic work-up. Ultrasound achieves an intermediate sensitivity in detecting urinary tract alterations and is considered a suboptimal imaging technique in diagnosis of BCa. CT urography accurately detects BCa in patients presenting with hematuria Multiparametric MRI achieves a very high rate of BCa detection and helps with accurate staging of patients; however, this modality is still not widely supported by international guidelines. The main applications of MRI are local tumor staging and differentiation between non-muscle-invasive BCa and muscle-invasive BCa. These applications led to development of Vesical Imaging-Reporting and Data System (VI-RADS) scoring system. The VI-RADS scoring system was developed in the setting of post-resection of primary bladder tumor and instillation of intravesical Bacillus Calmette-Guerin therapy; however validation of this system in the post-treatment setting showed promising results. The high risk of BCa recurrence leads to its application in the assessment of response to therapy and for disease surveillance after treatment. MRI is rapidly becoming a leading imaging modality in BCa diagnostic workup, assessment of response to therapies and for longitudinal surveillance, and plays an important role in BCa surgical and radiation therapy treatment planning.

Adjuvant Systemic Therapy for High-risk Muscle-invasive Bladder Cancer After Radical Cystectomy: Current Options and Future Opportunities

We describe the case of a 71-yr-old woman with locally advanced muscle-invasive bladder cancer and stage III chronic kidney disease due to an obstructed nonfunctional left kidney. She was started on neoadjuvant immunotherapy, but had to stop treatment because of acute worsening of renal function. Radical cystectomy was then performed uneventfully, revealing pT3aN1 urothelial carcinoma of the bladder. Adjuvant chemotherapy in high-risk locally advanced bladder cancer after radical cystectomy currently poses several challenges, especially for cisplatin-ineligible candidates. Recent data on adjuvant immunotherapy trials suggest a disease-free survival advantage for this subgroup of patients. The current and future role of immuno-oncology agents in this setting is discussed. PATIENT SUMMARY: Patients with advanced bladder cancer might benefit from further chemotherapy or immunotherapy following bladder removal, but it is still unclear which patients benefit the most from this strategy. Measurement of biomarkers and scans to show urinary function will probably help in optimising patient selection for this treatment in the near future.

Inter-reader reliability of the vesical imaging-reporting and data system (VI-RADS) for muscle-invasive bladder cancer: a systematic review and meta-analysis

To evaluate the diagnostic agreement between readers in VI-RADS interpretation to detect muscle-invasive bladder cancer (MIBC) preoperatively, we conducted a systematic review and meta-analysis of the available data. Scopus, PubMed, Web of Science, and Embase databases were systematically searched up to November 13, 2021. Case reports, review articles, editorials, and studies with insufficient data were eliminated. The Quality Appraisal of the Diagnostic Reliability Checklist was used to assess the risk of bias. The degree of agreement was determined by Cohen's kappa coefficient (κ) for comparison of data. The heterogeneity of these studies was explored using subgroup analysis and meta-regression analysis. The level of confidence was set at 0.05. All analyses were conducted in STATA 16.0. Overall, 19 eligible studies, consisting of 2439 participants, were included in this meta-analysis. The inter-reader agreement for VI-RADS in MIBC detection ranged from κ of 0.45 to 0.96 among included studies. The pooled inter-reader reliability was calculated as 0.76 [95% CI 0.73-0.80; I² = 92.13%, Q(50) = 635.08, p < 0.01]. Sources of heterogeneity included magnetic strength, T2WI slice thickness, number of readers, sample size, study design, number of centers, year of publication, proportion of male patients, and mean age. There is substantial reliability in VI-RADS interpretation for MIBC among radiologists with various levels of expertise. The high degree of inter-reader agreement for MIBC detection supports the implementation of VI-RADS in routine clinical practice for the staging paradigm of bladder cancer.

Comparison between biparametric and multiparametric MRI in predicting muscle invasion by bladder cancer based on the VI-RADS

This study aimed to compare the diagnostic validity of biparametric magnetic resonance imaging (bpMRI) with that of multiparametric MRI (mpMRI) based on the Vesicle Imaging-Reporting and Data System (VI-RADS) in predicting muscle invasion by bladder cancer (BCa). We retrospectively examined 357 patients with an initial diagnosis of BCa who underwent preoperative MRI; 257 and 100 patients underwent mpMRI and bpMRI, respectively. Two urogenital radiologists evaluated all bpMRI and mpMRI scans using VI-RADS, and the diagnostic validity of VI-RADS for predicting muscle invasion by BCa was analyzed based on histopathology of the first and/or second transurethral resection of bladder tumors and radical cystectomy. Receiver operating characteristic (ROC) curves were plotted with the calculation of area under the curves (AUCs), and the level of significance was P < 0.05. Both groups showed optimal performance with a VI-RADS score ≥ 3. BpMRI showed comparable diagnostic performance to mpMRI (reader 1: AUC, 0.903 [0.827-0.954] vs. 0.935 [0.884-0.968], p = 0.510; and reader 2: AUC, 0.901 [0.814-0.945] vs. 0.915 [0.874-0.946]; p = 0.655). The inter-reader agreement between both readers was excellent (Cohen's kappa value = 0.942 and 0.905 for bpMRI and mpMRI, respectively). This comparative study suggests that bpMRI has comparable diagnostic performance to mpMRI and may be an alternative option to predict muscle invasion by BCa.

A novel pathway to detect muscle-invasive bladder cancer based on integrated clinical features and VI-RADS score on MRI: results of a prospective multicenter study

PURPOSE

To determine the clinical, pathological, and radiological features, including the Vesical Imaging-Reporting and Data System (VI-RADS) score, independently correlating with muscle-invasive bladder cancer (BCa), in a multicentric national setting.

METHOD AND MATERIALS

Patients with BCa suspicion were offered magnetic resonance imaging (MRI) before trans-urethral resection of bladder tumor (TURBT). According to VI-RADS, a cutoff of ≥ 3 or ≥ 4 was assumed to define muscle-invasive bladder cancer (MIBC). Trans-urethral resection of the tumor (TURBT) and/or cystectomy reports were compared with preoperative VI-RADS scores to assess accuracy of MRI for discriminating between non-muscle-invasive versus MIBC. Performance was assessed by ROC curve analysis. Two univariable and multivariable logistic regression models were implemented including clinical, pathological, radiological data, and VI-RADS categories to determine the variables with an independent effect on MIBC.

RESULTS

A final cohort of 139 patients was enrolled (median age 70 [IQR: 64, 76.5]). MRI showed sensitivity, specificity, PPV, NPV, and accuracy for MIBC diagnosis ranging from 83-93%, 80-92%, 67-81%, 93-96%, and 84-89% for the more experienced readers. The area under the curve (AUC) was 0.95 (0.91-0.99). In the multivariable logistic regression model, the VI-RADS score, using both a cutoff of 3 and 4 (P < .0001), hematuria (P = .007), tumor size (P = .013), and concomitant hydronephrosis (P = .027) were the variables correlating with a bladder cancer staged as ≥ T2. The inter-reader agreement was substantial (k = 0.814).

CONCLUSIONS

VI-RADS assessment scoring proved to be an independent predictor of muscle-invasiveness, which might implicate a shift toward a more aggressive selection approach of patients' at high risk of MIBC, according to a novel proposed predictive pathway.

VI-RADS score system - A primer for urologists

Bladder cancer (BCa) is one of the most common cancers worldwide and is also considered to be one of the most relapsing and aggressive neoplasms. About 30% of patients will present with muscle invasive disease, which is associated with a higher risk for metastatic disease. The aim of this article is to review the state of art imaging in Radiology, while providing a complete guide to urologists, with case examples, for the rationale of the development of the Vesical Imaging Reporting and Data System (VI-RADS), a scoring system emphasizing a standardized approach to multiparametric Magnetic Resonance Imaging (mpMRI) acquisition, interpretation, and reporting for BCa. Also, we examine relevant external validation studies and the consolidated literature of mpMRI for bladder cancer. In addition, this article discusses some of the potential clinical implications of this scoring system for disease management and follow-up.

Multiparametric MRI Evaluation of VI-RADS for Bladder Tumors Located at the Ureteral Orifice

Background The Vesical Imaging Reporting and Data System (VI-RADS) based on multiparametric MRI scans standardizes preoperative bladder cancer staging. However, limitations have been reported for VI-RADS, particularly for ureteral orifice tumors. Purpose To investigate the diagnostic performance and interobserver agreement of VI-RADS in evaluating muscle invasion for bladder tumors located at the ureteral orifice. Materials and Methods In this retrospective study, patients with histopathologically confirmed bladder cancer occurring at the ureteral orifice from January 2012 to November 2021 were analyzed. Two blinded radiologists independently scored multiparametric MRI scans according to VI-RADS. Interobserver agreement of the VI-RADS scores was evaluated with weighted κ analysis. Receiver operating characteristic curve analysis was used to evaluate the diagnostic performance of the VI-RADS scores in the prediction of muscle invasion. Results A total of 78 patients (mean age, 67 years ± 7 [SD]; age range, 46-90 years; 67 men) were included in the final analysis: 25 with non-muscle-invasive bladder cancer and 53 with muscle-invasive bladder cancer (MIBCa). At consensus reading, one (1%) case was scored as VI-RADS 1, 27 cases (35%) were scored as VI-RADS 2, six (8%) were scored as VI-RADS 3, 10 (13%) were scored as VI-RADS 4, and 34 (44%) were scored as VI-RADS 5. On comparison of the VI-RADS score with histopathologic findings, it was confirmed that the presence of muscle invasion was 0% (zero of one) for VI-RADS 1, 15% (four of 27) for VI-RADS 2, 83% (five of six) for VI-RADS 3, 100% (10 of 10) for VI-RADS 4, and 100% (34 of 34) for VI-RADS 5. The area under the receiver operating characteristic curve of VI-RADS in the detection of MIBCa was 0.96 (95% CI: 0.92, 1.00). Conclusion The Vesical Imaging Reporting and Data System could be used to accurately predict muscle invasion for bladder tumors occurring at the ureteral orifice. © RSNA, 2022 Online supplemental material is available for this article.

Head-to-Head Comparison between High-Resolution Microultrasound Imaging and Multiparametric MRI in Detecting and Local Staging of Bladder Cancer: The BUS-MISS Protocol

BACKGROUND

MRI has been proposed as a new staging tool for bladder cancer (BC), but use is limited by its high costs and low availability. 29-MHz high-resolution micro-ultrasound (mUS) technology has been suggested as an alternative to detect BC and distinguish between muscle-invasive and non-muscle invasive BC.

OBJECTIVE

The aim was to compare the diagnostic accuracy of mUS vs. magnetic resonance imaging (MRI) in differentiating NMIBC and MIBC at definitive pathological examination.

METHODS

This is a prospective study of patients with a primary diagnosis of BC with either positive urine cytology (UC) or negative UC and a tumor size > 25 mm from a tertiary care high volume center. mUS, with the ExactVu system with an EV29L 29 MHz side-fire transducer, and a 3-Tesla MRI were performed before transurethral resection of bladder tumor (TURBT) in every patient before undergoing TURBT. We compared the imaging results with pathological reports.

RESULTS

The analyzed population consisted of 58 individuals. The reported mUS and MRI sensitivity, specificity, positive, and negative predictive values were 85.0%, 76.3%, 65.4%, and 90.6%, versus 85.0%, 50.0%, 47.2%, and 86.4%, respectively. In accuracy analysis, the AUC for mUS and MRI were respectively 0.807 and 0.675.

CONCLUSIONS

In our population mUS seems to have a better performance in distinguishing NMIBC from MIBC. The main limitation of mUS is the probe shape that makes its use problematic in cases with a large prostate and inadequate rectal preparation. Further studies with a larger population are ongoing to compare and validate these techniques in this setting.

What is the impact of dynamic contrast-enhancement sequence in the Vesical Imaging, Reporting and Data System (VI-RADS)? A subgroup analysis

Background

A scoring system focusing on the risk of muscle layer invasion by Bladder cancer (BCa) has been released, Vesical Imaging - Radiological and Data System (VI-RADS), with a growing interest in evaluating its diagnostic accuracy.

Our goal was to assess the accuracy and reproducibility of the VI-RADS score for assessment of the vesical muscular layer with (multiparametric-mp) and without (biparametric-bp) a dynamic-contrast enhancement (DCE) sequence.

Methods

Retrospective study conducted from July 2018 to July 2020. All patients had suspicions of BCa and underwent Magnetic Resonance Imaging (MRI) before any intervention. MRI was interpreted by two radiologists with different levels of experience, and a VI-RADS score assigned in two different sessions (3 months apart) without and with DCE. After exclusions, 44 patients with 50 lesions were enrolled. The standard of reference was transurethral resection in 18 patients (40.9%) and cystectomy in 26 patients (59.1%).

Results

Twenty-five lesions (50%) were muscle-invasive. There was no significant difference between the two groups for gender and presence of a stalk, but mean age of NMIBCa group was significantly higher (p = 0.01). The sizes of lesions were significantly different between groups for both readers at 2.42+/− 1.58 vs. 5.70+/− 2.67 cm for reader 1 (p < 0.0001) and 2.37+/− 1.50 vs. 5.44 +/− 2.90 cm for reader 2 (p = 0.001). The area under the curve (AUC) for muscle invasion with mpVI-RADS, considering all lesions, was 0.885 +/− 0.04 (95% CI-0.79-0.98) for reader 1 and 0.924 +/− 0.04 (0.84–0.99) for reader 2, and for bpVI-RADS was 0.879+/− 0.05 and 0.916 +/− 0.04 (0.85–0.99), respectively, both differences not statistically significant (p = 0.24 and 0.07, respectively). When considering only small lesions (< 3.0 cm), the accuracy for mpVI-RADS was 0.795 +/− 0.11 (0.57–1.0) for reader1, and 0.80 +/− 0.11(0.57–1.0) for reader 2, a non-significant difference (p = 0.56) and for bpVI-RADS was 0.747 +/− 0.12 (0.50–0.99) for reader 1 and 0.80 +/− 0.11(0.57–1.0) for reader 2, a significant difference (p = 0.04). The intraclass correlation coefficient for the final score was 0.81 (0.60–1.0) for mpVI-RADS and 0.85 (0.63–1.0) for bpVI-RADS.

Conclusion

The VI-RADS system was accurate in demonstrating muscle-invasive BCa, for both experienced and less experienced reader, regardless of the use of a DCE sequence. However, when only small lesions were assessed the difference between the two readers was significant only for the biparametric analysis. The reproducibility was similar between multiparametric and biparametric approach.

Conspicuity and muscle-invasiveness assessment for bladder cancer using VI-RADS: a multi-reader, contrast-free MRI study to determine optimal b-values for diffusion-weighted imaging

OBJECTIVE

To (1) compare bladder cancer (BC) muscle invasiveness among three b-values using a contrast-free approach based on Vesical Imaging-Reporting and Data System (VI-RADS), to (2) determine if muscle-invasiveness assessment is affected by the reader experience, and to (3) compare BC conspicuity among three b-values, qualitatively and quantitatively.

METHODS

Thirty-eight patients who underwent a bladder MRI on a 3.0-T scanner were enrolled. The gold standard was histopathology report following transurethral resection of BC. Three sets of images, including T2w and different b-values for DWI, set 1 (b = 1000 s/mm2), set 2 (b = 1500 s/mm2), and set 3 (b = 2000 s/mm2), were reviewed by three differently experienced readers. Descriptive statistics and Intraclass Correlation Coefficient (ICC) were calculated. Comparisons among readers and DWI sets were performed with the Wilcoxon test. Receiver operating characteristic (ROC) analysis was performed. Areas under the curves (AUCs) and pairwise comparison were calculated.

RESULTS

AUCs of muscle-invasiveness assessment ranged from 0.896 to 0.984 (reader 1), 0.952-0.968 (reader 2), and 0.952-0.984 (reader 3) without significant differences among different sets and readers (p > 0.05). The mean conspicuity qualitative scores were higher in Set 1 (2.21-2.33), followed by Set 2 (2-2.16) and Set 3 (1.82-2.14). The quantitative conspicuity assessment showed that mean normalized intensity of tumor was significantly higher in Set 2 (4.217-4.737) than in Set 1 (3.923-4.492) and Set 3 (3.833-3.992) (p < 0.05).

CONCLUSION

Muscle invasiveness can be assessed with high accuracy using a contrast-free protocol with T2W and DWI, regardless of reader's experience. b = 1500 s/mm2 showed the best tumor delineation, while b = 1000 s/mm2 allowed for better tumor-wall interface assessment.

Biparametric magnetic resonance imaging assessment for detection of muscle-invasive bladder cancer: a systematic review and meta-analysis

OBJECTIVES

To investigate if removing DCE from the Vesical Imaging Reporting and Data System (VI-RADS) influences the diagnostic accuracy of muscle-invasive bladder cancer (MIBC). We also explored using different reference standards on the MRI diagnostic performance.

METHODS

We searched the Cochrane Library, Embase, and PubMed databases to June 26, 2021. Pooled biparametric MRI (bpMRI, T2WI+DWI) and multiparametric MRI (mpMRI, T2WI+DWI+DCE) sensitivities and specificities and the diagnostic performances of these methods for MIBC were compared using different reference standards.

RESULTS

Seventeen studies with 2344 patients were finally included, of which 7 studies, including 1041 patients, reported the diagnostic performance of bpMRI. VI-RADS showed sensitivities and specificities of 0.91 (95% CI 0.87-0.94) and 0.86 (95% CI 0.77-0.91) at cutoff scores of 3, and 0.85 (95% CI 0.77-0.90) and 0.93 (95% CI 0.89-0.96) at cutoff scores of 4. BpMRI showed sensitivities and specificities of 0.90 (95% CI 0.69-0.97) and 0.90 (95% CI 0.81-0.95), and 0.84 (95% CI 0.78-0.88) and 0.97 (95% CI 0.87-0.99), respectively, for cutoff scores of 3 and 4. The sensitivities of bpMRI vs mpMRI for MIBC were not significantly different, but bpMRI was more specific than mpMRI at cutoff scores of 3 (p = 0.02) and 4 (p = 0.02). The VI-RADS studies using primary transurethral resection of bladder tumors (TURBT) as the reference standard had significantly higher sensitivities (p < 0.001) than those using secondary TURBT or radical cystectomy as the reference.

DATA CONCLUSION

BpMRI and conventional VI-RADS had similar diagnostic efficacies for MIBC. Since MRI overestimated MIBC diagnoses using primary TURBT as the reference standard, we recommend using secondary TURBT as the reference standard.

KEY POINTS

• Biparametric MRI without DCE had similar diagnostic efficacies for MIBC compared with conventional VI-RADS. • The sensitivity of VI-RADS was overestimated when referring to the primary TURBT results. • Biparametric MRI comprised of T2WI and DWI could be used for detecting MIBC in clinical practice.

Diagnostic accuracy of vesical imaging-reporting and data system (VI-RADS) for the detection of muscle-invasive bladder cancer: a meta-analysis

PURPOSE

Vesical Imaging-Reporting and Data System (VI-RADS) was proposed and considered as a standardized reporting criterion for bladder magnetic resonance imaging (MRI). VI-RADS could suggest the likelihood of muscle invasion based on the multiparametric MRI (mp-MRI) findings which contain five-point scores. The current study is designed to comprehensively and systematically evaluate the diagnostic performance of VI-RADS (score 3 and 4) for predicting muscle invasion.

METHODS

The Cochrane Library, Embase, and PubMed were searched comprehensively from inception to October 2021.

RESULTS

Finally, 19 studies incorporating 2900 patients were enrolled. The pooled sensitivity and specificity of VI-RADS 3 for predicting muscle invasion were 0.92 (95%CI 0.89-0.94) and 0.82 (95%CI 0.76-0.87), respectively. The pooled sensitivity and specificity of VI-RADS 4 were 0.78 (95%CI 0.72-0.83) and 0.96 (95%CI 0.93-0.97), respectively. And the area under the curve (AUCs) of VI-RADS 3 and 4 were all 0.94 (95%CI 0.92-0.96). No significant publication biases were not observed for VI-RADS 3 (P = 0.74) and 4 (P = 0.57).

CONCLUSION

The VI-RADS reveals a good diagnostic performance for predicting muscle invasive in bladder cancer, which also has good clinical utilities and applicability. And VI-RADS 3 and 4 as cutoff values provide similar overall diagnostic and could be selectively applied individually. Prospective studies with a large scale are further required to validate the accuracy of the VI-RADS score.

The accuracy of Vesical Imaging-Reporting and Data System (VI-RADS): an updated comprehensive multi-institutional, multi-readers systematic review and meta-analysis from diagnostic evidence into future clinical recommendations

Purpose

To determine through a comprehensive systematic review and meta-analysis the cumulative diagnostic performance of vesical imaging-reporting and data system (VIRADS) to predict preoperative muscle-invasiveness among different institutions, readers, and optimal scoring accuracy thresholds.

Methods

PubMed, Cochrane and Embase were searched from inception up to May 2021. Sensitivity (Sn), Specificity (Sp) were first estimated and subsequently pooled using hierarchical summary receiver operating characteristics (HSROC) modeling for both cut-off ≥ 3 and ≥ 4 to predict muscle-invasive bladder cancer (MIBC). Further sensitivity analysis, subgroup analysis and meta-regression were conducted to investigate contribution of moderators to heterogeneity.

Results

In total, n = 20 studies from 2019 to 2021 with n = 2477 patients by n = 53 genitourinary radiologists met the inclusion criteria. Pooled weighted Sn and Sp were 0.87 (95% CI 0.82–0.91) and 0.86 (95% CI 0.80–0.90) for cut-off ≥ 3 while 0.78 (95% CI 0.74–0.81) and 0.94 (95% CI 0.91–0.96) for cut-off ≥ 4. The area under the HSROC curve was 0.93 (95% CI 0.90–0.95) and 0.91 (95% CI 0.88–0.93) for cut-off ≥ 3 and ≥ 4, respectively. Meta-regression analyses showed no influence of clinical characteristics nor cumulative reader’s experience while study design and radiological characteristics were found to influence the estimated outcome.

Conclusion

We demonstrated excellent worldwide diagnostic performance of VI-RADS to determine pre-trans urethral resection of bladder tumor (TURBT) staging. Our findings corroborate wide reliability of VI-RADS accuracy also between different centers with varying experience underling the importance that standardization and reproducibility of VI-RADS may confer to multiparametric magnetic resonance imaging (mpMRI) for preoperative BCa discrimination.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-022-03969-6.

Accuracy of Inchworm Sign on Diffusion-Weighted MRI in Differentiating Muscle-Invasive Bladder Cancer

BACKGROUND

Inchworm sign is a finding on diffusion-weighted magnetic resonance imaging (DWI-MRI) and is used to better stratify T-staging in muscle invasive (MIBC) and non-muscle-invasive bladder cancer (NMIBC). An uninterrupted low submucosal signal on DWI, defined as inchworm sign (IS), indicates NMIBC.

OBJECTIVE

We aimed to define the diagnostic accuracy of IS in primary bladder cancer, as well as find agreement between the urologists and the radiologist.

METHODS

Between December 2018 and December 2020, we retrospectively analyzed 95 primary bladder cancer patients who had undergone multiparametric-MRI before transurethral resection. Patients with former bladder cancer history, tumors smaller than 10 mm, and MRI without proper protocol, as well as patients who did not attend follow-up, were excluded. In total, 71 patients' images were evaluated by a genitourinary specialist radiologist and two urologists. Sensitivity, specificity, positive and negative predictive values of IS and VI-RADS in differentiating MIBC and NMIBC, and interreader agreement between the radiologist and urologists were analyzed.

RESULTS

During follow-up, 38 patients (53.5%) were IS-positive, while 33 patients (46.5%) were negative. Among the 33 patients with negative IS, 14 patients (42.4%) had MIBC. Meanwhile, two out of the 38 IS-positive patients (5.3%) had MIBC (p = 0.00). Sensitivity, specificity, and positive and negative predictive values of IS in predicting MIBC were 87.5%, 63.6%, 41.2%and 94.6%, respectively. The interobserver agreement between the urologists and radiologist was almost perfect ( K  = 0.802 and K  = 0.745).

CONCLUSION

The absence of IS on DWI is useful in differentiating MIBC from NMIBC. It is a simple finding that can be interpreted by urologists.

Neoadjuvant Chemotherapy for Different Stages of Muscle-Invasive Bladder Cancer: A Systematic Review and Meta-analysis

The purpose of this meta-analysis is to determine the survival benefits and pathological outcomes of neoadjuvant chemotherapy (NAC) combined with radical cystectomy (RC) administered to patients with cT2 or cT3-4N0M0 muscle-invasive bladder cancer (MIBC). PubMed, Embase, and the Cochrane Library were searched for comparing the use of NAC in combination with RC and RC alone in patients with different MIBC stages. A fixed effects model was used to calculate hazard ratio (HR) and odds ratio (OR) with 95% confidence intervals (CIs), and the I² statistic was used to assess heterogeneity. Moreover, we determined possible sources of heterogeneity by subgroup and sensitivity analyses. Fifteen studies were finally selected. For cT2 bladder cancer, NAC combined with RC significantly increased the rates of pathological complete response (pCR) (OR = 4.84, 95% CI: 1.18–19.92, p = 0.029) but did not improve overall survival (OS) (HR = 0.86, 95% CI: 0.72–1.02, p = 0.078) across six studies. Regarding cT3-4 bladder cancer, NAC has a significantly improved effect on OS (HR = 0.69; 95% CI: 0.59–0.81, p < 0.001, across seven studies and 5726 patients) and pCR (pooled OR = 4.80; 95% CI: 2.06–11.23, p < 0.001, across two studies) than RC alone. Most studies were randomized prospective trials (level 1 evidence), and all the effects were irrespective of the type of study design and did not vary between subgroups of patients. In conclusion, NAC combined with RC is recommended for patients with T3-4aN0M0 but not for patients with T2N0M0.

Xpert Bladder Cancer Monitor May Avoid Cystoscopies in Patients Under "Active Surveillance" for Recurrent Bladder Cancer (BIAS Project): Longitudinal Cohort Study

Objectives

To test the hypothesis that patients under active surveillance (AS) for Non-muscle Invasive Bladder Cancer (NMIBC) who were negative on longitudinal re-testing by the Xpert^® Bladder Cancer Monitor (Xpert BC Monitor) assay may avoid unnecessary cystoscopies and urine cytology (UC).

Subjects/Patients (or Materials) and Methods

This is a prospective cohort study of patients enrolled in the AS protocol for recurrent NMIBC (Bladder Cancer Italian Active Surveillance, BIAS project), whose urine samples were analyzed by Xpert BC Monitor upon entry in the study (T0). Patients who had a negative Xpert test and did not fail AS, underwent additional Xpert tests after 4 (T1), 8 (T2), and 12 (T3) months. The clinical utility of Xpert was assessed by determining the number of cystoscopies and UC that could be avoided within 1 year.

Results

Overall, 139 patients were tested with Xpert at T0. Median follow-up was 23 (IQR 17–27) months. Sixty-eight (48.9%) patients failed AS, 65 (46.7%) are currently on AS, and 6 (4.3%) were lost at follow-up. At T0 57 (41.0%) patients had a negative test and 36 (63.2%) are still in AS. In patients with 2 consecutives negative Xpert tests, we could have avoided 73.9% of unnecessary cystoscopies, missing 26.4% failure, up to avoid all cystoscopies with 4 negative tests missing only 12% of failure. All the patients with negative Xpert had negative UC. Failure-free-survival at median follow-up (23 month) stratified for having 0, 1, or ≥2 negative tests was 67.0, 55.1. and 84.1, respectively.

Conclusion

Our findings suggest that Xpert BC Monitor assay, when it is longitudinally repeated, could significantly reduce the number of unnecessary cystoscopies and UC during their follow-up.

Vesical Imaging-Reporting and Data System (VI-RADS) for assessment of response to systemic therapy for bladder cancer: preliminary report

PURPOSE

The Vesical Imaging-Reporting and Data System (VI-RADS) criteria are expanding, providing fine differentiation of bladder wall layers involvement. We aimed to explore the feasibility of a novel categorical scoring, the Neoadjuvant chemotherapy VI-RADS (nacVI-RADS) for radiologic assessment of response (RaR), to define the spectrum of treatment response among patients with muscle invasive bladder cancer (MIBC).

METHODS

Ten consecutive patients diagnosed with non-metastatic MIBC were prospectively enrolled and addressed to NAC and underwent mpMRI before staging resection and after the chemotherapy cycles. The follow-up MRI assessment was performed using the nacVI-RADS algorithm for evaluation of response to therapy. NacVI-RADS categorically define complete RaR, based on prior VI-RADS score, presence of residual disease, tumor size, and infiltration of the muscularis propria.

RESULTS

NacVI-RADS categories were able to match all the final radical cystectomy pathology both for complete pT0 responders and for the patients defined as partial or minimal responders, who only showed some RaR inter-scoring class downstaging.

CONCLUSION

This report is the preliminary evidence of the feasibility of nacVI-RADS criteria. These findings might lead to possible paradigmatic shifts for cancer-specific survival risk assessment and to possibly drive the therapeutic decision through active surveillance programs, bladder-sparing modalities, or to the standard of care.

Comparison of the diagnostic accuracy and validity of biparametric MRI and multiparametric MRI-based VI-RADS scoring in bladder cancer; is contrast material really necessary in detecting muscle invasion?

PURPOSE

(1) To evaluate the accuracy and validity of the biparametric MRI (bp-MRI), including T2-weigthed image (WI) and DWI sequences, and the availability of an alternative to the multiparametric MRI (mp-MRI), for the muscle-invasiveness assessment of bladder cancer (BC). (2) To evaluate the diagnostic performance and agreement of readers with different experiences in the abdominal imaging of using both protocols.

METHODS

Preoperative bladder mp-MRI was performed on 128 patients with a initial diagnosis of BC. Two sets of images, set 1 (bp-MRI) and set 2 (mp-MRI), were independently evaluated by both readers. Descriptive statistics, including sensitivity, specificity, accuracy, and area under the curve (AUC), for VI-RADS scores were calculated using ≥ 4 as the cutoff for muscle invasion for each reader and image sets. Inter-reader agreement was evaluated using the Cohen's kappa coefficient.

RESULTS

The sensitivity ranged between 90.3-93.5% and 87.1-90.3%, specificity ranged between 96.6-99.1% and 91.6-96.6%, accuracy ranged between 96-97.3% and 91.3-94.6%, and AUC ranged between 0.947-0.951 and 0.919-0.921, for bp-MRI and mp-MRI, and reader 1 and reader 2, respectively. No significant differences were shown in diagnostic performance for either reader between both the protocols (p = 0.238 and 0.318). There was excellent agreement among the readers in the VI-RADS scores, using both protocols.

CONCLUSION

A bp-MRI protocol has a diagnostic accuracy comparable to an mp-MRI protocol for the detection of muscle-invasive BC using the VI-RADS criteria. Also, in both MRI protocols, the reader's experience does not appear to significantly affect diagnostic performance when using the VI-RADS criteria.

Accuracy and Challenges in the Vesical Imaging-Reporting and Data System for Staging Bladder Cancer

BACKGROUND

The Vesical Imaging-Reporting and Data System (VI-RADS) scoring system has been widely used to stage bladder cancer (BCa) since 2018.

PURPOSE

To describe the characteristics of cases with discordant T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) scores in patients with BCa and further verify the accuracy of the VI-RADS scoring system and the necessity of dynamic contrast-enhanced (DCE) sequence.

STUDY TYPE

Retrospective.

SUBJECTS

A total of 106 patients (include 16.5% female) with bladder cancer.

SEQUENCE

T2WI (fast spin echo), DWI (echo planer imaging), and DCE (gradient echo).

ASSESSMENT

Some cases are difficult to score according to the system, mainly when the T2WI (category 4) and DWI (category 2) sequence scores are discordant, termed the discordant group below. The complementary group will be termed concordant group. Each MRI sequence was reviewed respectively according to the 5-point VI-RADS scoring system by three observers. The diagnostic ability of sequences for evaluating muscle invasion by BCa was calculated using histopathology as the reference standards.

STATISTICAL TESTS

Receiver operating characteristic (ROC) curve, DeLong test, intraclass correlation coefficient. A P value of 0.05 or less was considered statistically significant.

RESULTS

Fourteen cases (13.2%) had discordant VI-RADS scoring system. In the discordant group, the area under the ROC curve (AUC) of DCE was 0.875, while the T2WI and DWI showed limited diagnostic performance (AUCs = 0.50). In the concordant group, there was no significant difference in diagnostic efficacy between the overall VI-RADS (AUC: 0.950) and the combination of T2WI and DWI (AUC: 0.946) (P = 0.56). Among all patients, the AUC of overall VIRADS was 0.939 with a 3 or greater cutoff value.

DATA CONCLUSION

The DCE was crucial in the discordant group for evaluating muscle-invasiveness, while DCE may not be necessary for the concordant group. The VI-RADS scoring system performed with overall good diagnostic performance in evaluating muscle-invasiveness in BCa patients.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY: Stage 3.

PIxel-Level Segmentation of Bladder Tumors on MR Images Using a Random Forest Classifier

Objectives: Regional bladder wall thickening on noninvasive magnetic resonance (MR) images is an important sign of developing urinary bladder cancer (BCa), and precise segmentation of the tumor mass is an essential step toward noninvasive identification of the pathological stage and grade, which is of critical importance for the clinical management of patients with BCa. Methods: In this paper, we proposed a new method based on the high-throughput pixel-level features and a random forest (RF) classifier for the BCa segmentation. First, regions of interest (ROIs) including tumor and wall ROIs were used in the training set for feature extraction and segmentation model development. Then, candidate regions containing both bladder tumor and its neighboring wall tissue in the testing set were segmented. Results: Experimental results were evaluated on a retrospective database containing 56 patients postoperatively confirmed with BCa from the affiliated hospital. The Dice similarity coefficient (DSC) and average symmetric surface distance (ASSD) of the tumor regions were adopted to quantitatively assess the overall performance of this approach. The results showed that the mean DSC was 0.906 (95% confidential interval [CI]: 0.852-0.959), and the mean ASSD was 1.190 mm (95% CI: 1.727-2.449), which were higher than those of the state-of-the-art methods for tumor region separation. Conclusion: The proposed Pixel-level BCa segmentation method can achieve good performance for the accurate segmentation of BCa lesion on MR images.

Clinical validity of non-contrast-enhanced VI-RADS: prospective study using 3-T MRI with high-gradient magnetic field

OBJECTIVES

To develop a modified Vesical Imaging Reporting and Data System (VI-RADS) without dynamic contrast-enhanced imaging (DCEI), termed "non-contrast-enhanced VI-RADS (NCE-VI-RADS)", and to assess the additive impact of denoising deep learning reconstruction (dDLR) on NCE-VI-RADS.

METHODS

From January 2019 through December 2020, 163 participants who underwent high-gradient 3-T MRI of the bladder were prospectively enrolled. In total, 108 participants with pathologically confirmed bladder cancer by transurethral resection were analyzed. Tumors were evaluated based on VI-RADS (scores 1-5) by two readers independently: an experienced radiologist (reader 1) and a senior radiology resident (reader 2). Conventional VI-RADS assessment included all three imaging types (T2-weighted imaging [T2WI], diffusion-weighted imaging [DWI], and dynamic contrast-enhanced imaging [DCEI]). Also evaluated were NCE-VI-RADS comprising only non-contrast-enhanced imaging types (T2WI and DWI), and "NCE-VI-RADS with dDLR" comprising T2WI processed with dDLR and DWI. All systems were assessed using receiver-operating characteristic curve analysis and simple and/or weighted κ statistics.

RESULTS

Muscle invasion was identified in 23/108 participants (21%). Area under the curve (AUC) values for diagnosing muscle invasion were as follows: conventional VI-RADS, 0.94 and 0.91; NCE-VI-RADS, 0.93 and 0.91; and "NCE-VI-RADS with dDLR", 0.96 and 0.93, for readers 1 and 2, respectively. Simple κ statistics indicated substantial agreement for NCE-VI-RADS and almost perfect agreement for conventional VI-RADS and "NCE-VI-RADS with dDLR" between the two readers.

CONCLUSION

NCE-VI-RADS achieved predictive accuracy for muscle invasion comparable to that of conventional VI-RADS. Additional use of dDLR improved the diagnostic accuracy of NCE-VI-RADS.

KEY POINTS

• Non-contrast-enhanced Vesical Imaging Reporting and Data System (NCE-VI-RADS) was developed to avoid risk related to gadolinium-based contrast agent administration. • NCE-VI-RADS had predictive accuracy for muscle invasion comparable to that of conventional VI-RADS. • The additional use of denoising deep learning reconstruction (dDLR) might further improve the diagnostic accuracy of NCE-VI-RADS.

Role of Vesical Imaging-Reporting and Data System in predicting muscle-invasive bladder cancer: A diagnostic meta-analysis

The objective of this study is to systematically evaluate the diagnostic performance of the Vesical Imaging-Reporting and Data System for predicting muscle-invasive bladder cancer. Embase, PubMed and Web of Science were systematically searched from 1 September 2018 to 30 July 2021 to include proper studies. We included studies that included data on Vesical Imaging-Reporting and Data System and their associated pathological findings, and we assessed their quality using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The pooled sensitivity and specificity were calculated and plotted using hierarchical summary receiver operating characterisijutic modeling. Meta-regression analysis was carried out to detect heterogeneity. A total of 20 studies with 2725 patients were included. When the cut-off point was 3, the pooled sensitivity and specificity were 0.92 (0.89-0.94) and 0.85 (0.78-0.90), respectively, and 0.82 (0.75-0.88) and 0.95 (0.91-0.97), respectively, when the cut-off point was 4. The area under the curve was 0.95 and 0.95, respectively. Heterogeneity was substantially considerable in sensitivity and specificity. All subgroup variables, including patient number, study design, magnetic resonance imaging field strength, number of radiologists, surgery pattern, diffusion-weighted imaging, and dynamic contrast-enhanced magnetic resonance imaging, contributed to sensitivity heterogeneity when the cut-off point was 3 and specificity heterogeneity when the cut-off point was 4. Multiple image acquisition plane of diffusion-weighted imaging achieved a higher sensitivity than single image acquisition plane of diffusion-weighted imaging in both the Vesical Imaging-Reporting and Data System 3 and 4 groups, and higher specificity in the Vesical Imaging-Reporting and Data System 4 group. Another significant source of heterogeneity was the cut-off point. The diagnostic performance of the Vesical Imaging-Reporting and Data System for predicting muscle-invasive bladder cancer was excellent in both cut-off points of the Vesical Imaging-Reporting and Data System 3 and 4. Multiple image acquisition planes of diffusion-weighted imaging should be given more attention in the Vesical Imaging-Reporting and Data System.

Diagnostic accuracy of vesical imaging-reporting and data system (VI-RADS) in suspected muscle invasive bladder cancer: A systematic review and diagnostic meta-analysis

OBJECTIVE

To investigate the accuracy of Vesical Imaging-Reporting and Data System (VI-RADS) in detection of muscle-invasive bladder cancer (MIBC) we performed a systematic review and meta-analysis of the available literature.

MATERIALS AND METHODS

Scopus, Web of Science, PubMed, and EMBASE were searched up to 8 March 2021 for the studies evaluating the diagnostic performance of VI-RADS for the detection of MIBC. Inclusion criteria were patients with bladder cancer; index test of VI-RADS based on multiparametric MRI; reference test of histopathological findings from TURBT, re-TURBT, or cystectomy and study design of cohort. Case reports, review articles, and editorials were eliminated, as well as studies with insufficient knowledge to acquire TP, FP, FN, and TN values of VI-RADS. The MIDAS module of STATA was for statistical analysis. The heterogeneity was explored using subgroup analysis and meta-regression analysis.

RESULTS

Overall, 22 eligible studies, consisting of 2,576 participants and 5,414 MRI reports, were included in this meta-analysis. The area under curve (AUC) of VI-RADS at cut-point values of 3 and 4 were 0.93 (95%CI: 0.91, 0.95), 0.93 (95%CI: 0.90, 0.95), respectively. Based on Youden's J statistic, the optimal VI-RADS cutoff value for predicting MIBC was determined as 3 which granted a pooled sensitivity of 89% (95%CI: 87%, 91%; I²=48%) and a specificity of 84% (95%CI: 80%, 87%; I²=90%). Based on meta-regression, the sources of inter-study heterogeneity for VI-RADS ≥ 3 were the sample size > 70, study design, single-center vs multi-center, patient population characteristics (i.e., gender, age), reference standard, histology, magnetic strength, T2WI slice thickness, and the number of radiologists reporting the MRI results (P value ≤ 0.01).

CONCLUSION

The VI-RADS demonstrates consistently high diagnostic accuracy to predict MIBC. This scoring system could be applied in standard staging MRI reports of bladder cancer and can be incorporated into future MIBC work up guidelines.

Diagnostic benefit of multiparametric MRI over contrast-enhanced CT in patients with bladder cancer: A single-center 1-year experience

PURPOSE

To assess the clinical applicability of local tumor staging in urinary bladder cancer (BC) with preoperative multiparametric MRI (mpMRI) using the five-point Vesical Imaging-Reporting and Data System (VI-RADS) scoring system and to compare it to dual-phase contrast-enhanced computed tomography (CECT).

METHODS

33 patients with primary untreated bladder cancer underwent CECT followed by preoperative multiparametric 3.0 T MRI between July 2019 and August 2020 and were enrolled in this retrospective study. Two radiologists initially performed staging on the CECT image data sets and - blinded to CT results - on subsequent mpMRI. BCs were staged according to the VI-RADS scoring system. Postoperative pathology was correlated to the VI-RADS score and the CECT results. The performance of VI-RADS in determining detrusor muscle invasion was analyzed using a receiver operating characteristic curve. Based on the histopathology, sensitivity, specificity and accuracy for muscle invasiveness between both image modalities were compared using the Chi square test.

RESULTS

A total of 33 patients (29 male, median age 70 years, IQR: 59-81 years) were included. 10 tumors were categorized as non-muscle invasive (30%) and 23 as muscle invasive BC (70%) in final histology. Tumor stages were correctly assigned as being either muscle invasive or non-muscle invasive on both CECT and mpMRI with regard to both early and late stages of BC (Ta-Tis and T3a-T4b). T-stages bordering the histopathologic limits of muscle invasiveness (T1-T2a-b) resulted in overestimation of muscle invasion in 43% of cases (VI-RADS 3-4) for the mpMRI image data sets and in an underestimation of muscle invasion in up to 55.5% of cases analysing the CECT data. Sensitivity and specificity for the determination of muscle invasion in CECT and mpMRI were 80%/80% and 74%/61% for Radiologist#1 and 70%/90% and 83%/70% for Radiologist#2, respectively.

CONCLUSIONS

There are advantages and disadvantages of both CECT and mpMRI when used in the clinical assessment of BC muscular tumor invasion. In borderline cases, only the combination of cross-sectional imaging and histopathological staging may help in making the optimal treatment decisions.

The efficacy and reliability of VI-RADS in determining candidates for repeated transurethral resection in patients with high-risk non-muscle invasive bladder cancer

OBJECTIVE

Our study aims to evaluate the efficiency and reliability of Vesical Imaging Reporting Data System (VI-RADS) in prospectively identifying the patients to undergo RE-TURBT in the management of patients with high-risk non-muscle invasive Bladder Cancer(HR-NMIBC).The secondary objective was to evaluate the performance of the VI-RADS scoring system in differentiating between muscle-invasive bladder cancer (MIBC) and non-muscle invasive bladder cancer(NMIBC) prospectively.

METHODS

The study included 330 patients who underwent transurethral resection of bladder tumour(TURBT) for Bladder Cancer (BC) in our clinic. All patients underwent multiparametric-magnetic resonance imaging (Mp-MRI) before the operation and VI-RADS scoring was administered. The cut-off value of VI-RADS was accepted as three and above. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for the differentiation between NMIBC and MIBC distinction in all patients. Receiver operating characteristic (ROC) analysis was performed to evaluate the performance of the VI-RADS scoring system. In the second phase of the study, patients with MIBC and low-risk NMIBC (LR-NMBIC) were excluded and 158 patients with HR-NMIBC were included, and their sensitivity, specificity, PPV and NPV values were measured. ROC analysis was performed.

RESULTS

In all patients, sensitivity, specificity, PPV and NPV values of the VI-RADS scoring in the differentiation of MIBC and NMIBC were 91.3, 91.8, 81.7 and 96.3 respectively. The AUC value was 0.934 (95%CI: 0.903-0.964). Sensitivity, specificity, PPV and NPV values were found to be 87, 91.8, 74.1, 95.2 in the evaluation specifically made for patients with HR-NMIBC. The AUC value was 0.900 (95% CI:0.843-0.957). Inter-reader agreement was excellent (Ƙ = 0.90, 95% CI:0.71-0.95).

CONCLUSIONS

The VI-RADS scoring system is an effective and reliable method in determining the patients who will undergo RE-TURBT and in differentiating MIBC and NMIBC.

Study Progress of Noninvasive Imaging and Radiomics for Decoding the Phenotypes and Recurrence Risk of Bladder Cancer

Urinary bladder cancer (BCa) is a highly prevalent disease among aged males. Precise diagnosis of tumor phenotypes and recurrence risk is of vital importance in the clinical management of BCa. Although imaging modalities such as CT and multiparametric MRI have played an essential role in the noninvasive diagnosis and prognosis of BCa, radiomics has also shown great potential in the precise diagnosis of BCa and preoperative prediction of the recurrence risk. Radiomics-empowered image interpretation can amplify the differences in tumor heterogeneity between different phenotypes, i.e., high-grade vs. low-grade, early-stage vs. advanced-stage, and nonmuscle-invasive vs. muscle-invasive. With a multimodal radiomics strategy, the recurrence risk of BCa can be preoperatively predicted, providing critical information for the clinical decision making. We thus reviewed the rapid progress in the field of medical imaging empowered by the radiomics for decoding the phenotype and recurrence risk of BCa during the past 20 years, summarizing the entire pipeline of the radiomics strategy for the definition of BCa phenotype and recurrence risk including region of interest definition, radiomics feature extraction, tumor phenotype prediction and recurrence risk stratification. We particularly focus on current pitfalls, challenges and opportunities to promote massive clinical applications of radiomics pipeline in the near future.

Preliminary Exploration of the Application of Vesical Imaging-Reporting and Data System (VI-RADS) in Post-treatment Patients With Bladder Cancer: A Prospective Single-Center Study

BACKGROUND

Vesical Imaging-Reporting and Data System (VI-RADS) has been shown to be effective in diagnosing muscle invasion of bladder cancer (BC) in primary patients.

PURPOSE

To evaluate the diagnostic efficacy of VI-RADS in a BC target population which included post-treatment patients, and to determine the repeatability.

STUDY TYPE

Prospective.

POPULATION

Seventy-three patients (42 with primary BC, 31 with post-treatment BC).

FIELD STRENGTH/SEQUENCE

3.0 T MRI with propeller fast spin-echo T₂ WI, echo planer imaging diffusion-weighted imaging (DWI), and dynamic contrast-enhanced imaging (DCEI).

ASSESSMENT

VI-RADS scores were independently assessed by five radiologists with different levels of experience. The diagnostic efficiency in each group (primary and post-treatment) and of each radiologist was assessed.

STATISTICAL TESTS

Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), and area under the curve (AUC) in receiver operating characteristic curve analysis were calculated to evaluate VI-RADS diagnostic performance. Interobserver agreement was assessed using weighted Kappa statistics. A P value <0.05 was considered statistically significant.

RESULTS

At the corresponding cut-off, AUC values of three groups range from 0.936 to 0.947 and AUC values of five observers range from 0.901 to 0.963. There was no significant difference between the AUCs in the primary and post-treatment groups (P = 0.870). The cut-off of the whole group and the post-treatment group was ≥4, and the cut-off of the primary group was ≥3. The Kappa values of interobserver agreements range from 0.709 to 0.923.

CONCLUSIONS

After expanding the target population to include post-treatment patients, VI-RADS still has good diagnostic efficacy and repeatability. VI-RADS could potentially be a preoperative staging tool for post-treatment patients.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 2.