VI-RADS Calculator for Bladder MRI

The Vesical Imaging Reporting and Data System, or VI-RADS, is a five-category multiparametric MRI framework developed to standardize assessment and reporting of the likelihood of detrusor muscle invasion in bladder cancer. The original framework was published in 2018. Conventional VI-RADS evaluates T2-weighted imaging, diffusion-weighted imaging with apparent diffusion coefficient maps, and dynamic contrast-enhanced MRI.^[1][5]

VI-RADS is an imaging likelihood system rather than a pathologic staging system. The final category communicates the imaging likelihood of muscle invasion. Histopathologic diagnosis, pathologic staging, and the broader clinical assessment remain separate.^[1]

How VI-RADS Uses T2W, DWI/ADC, and DCE MRI

Each lesion is evaluated using three sequence-specific categories:

• The structural category, or SC, is based on T2-weighted imaging and evaluates tumor morphology and integrity of the muscularis propria.
• The diffusion-weighted category, or DW, uses DWI and the corresponding ADC map to assess restricted diffusion and extension relative to the muscular layer.
• The contrast-enhanced category, or CE, uses DCE MRI to assess early enhancement at the tumor-muscularis interface and extension into or beyond the muscularis propria.

The three sequence categories are not simply independent votes. T2W imaging provides the structural first-pass assessment. The original VI-RADS final-scoring framework identifies DWI as the first dominant functional sequence for estimating muscle invasion, with DCE second, particularly when DWI is suboptimal.^[1]

A 2024 pictorial review further describes the DW category as determining the final category when sequence categories are discordant and DWI is evaluable, with DCE used when DWI image quality cannot be evaluated.^[3] A 2025 Radiology practical review similarly emphasizes the dominant role of the functional sequences for higher-risk categories and the use of DCE when DWI is impaired by artifact.^[4]

The 2026 ACR VI-RADS Steering Committee paper summarizes the five overall categories and representative SC, DW, and CE combinations in its Table 1 and notes that the algorithmic approach for establishing the final score has been provided in prior VI-RADS literature.^[5]

How This Calculator Resolves Discordant Categories

This calculator first applies the explicit numeric sequence combinations summarized in the 2026 ACR Steering Committee Table 1.^[5] Some of those published combinations assign an overall category that differs from the DW category alone. In those cases, the explicit published combination takes precedence.

For a complete numeric SC, DW, and CE combination that is not represented in the Table 1 summary, the calculator applies the published dominant-sequence hierarchy: the DW category determines the final category when DWI/ADC is evaluable. If DWI/ADC is non-diagnostic, the CE category is used instead.^[1][3][4] If DCE is non-diagnostic but DWI/ADC remains evaluable, the DW category remains the dominant functional category.

If both DWI/ADC and DCE are non-diagnostic, this calculator does not force a numeric VI-RADS category. This is a conservative image-quality safeguard. The VI-RADS Quality Score classifies an examination as inadequate when at least two MRI sequences are inadequate and recommends repeat scanning when the examination is non-diagnostic.^[5][6] The calculator does not itself calculate the full VI-RADS Quality Score.

Overall VI-RADS Categories

The current ACR Steering Committee summary retains these five overall categories.^[5] A VI-RADS category is an imaging likelihood assessment and should not be interpreted as direct assignment of a pathologic T stage.

Appropriate Clinical Setting

The original VI-RADS framework applies to untreated patients and to patients who have undergone only diagnostic transurethral resection of bladder tumor, or TURBT, before repeat TURBT.^[1]

MRI is preferably performed before intervention. Prior TURBT, bladder biopsy, and intravesical treatment can cause edema and inflammatory change that may mimic or exaggerate local tumor extension. The original publication recommends performing MRI before these procedures when possible, or at least 2 weeks afterward.^[1]

Intravesical air introduced by cystoscopy or an indwelling catheter can produce susceptibility artifact on DWI. The original publication recommends an interval of 2 to 3 days between cystoscopy or Foley catheter removal and MRI when the patient condition permits.^[1]

Conventional VI-RADS is primarily a pretreatment framework. Assessment after systemic therapy is a separate clinical problem. A treatment-response framework called neoadjuvant chemotherapy VI-RADS, or nacVI-RADS, was introduced for assessment after neoadjuvant therapy and remains an evolving area of investigation.^[5][9]

Bladder Diverticula

Tumors arising in a bladder diverticulum are a special anatomic situation because diverticula lack the normal muscularis propria layer. Published VI-RADS reviews note that standard VI-RADS categories are not defined for intradiverticular bladder cancer.^[3] Current ACR Steering Committee work also identifies diverticula as an important staging pitfall for which modified or supplementary approaches require further study.^[5]

For that reason, this calculator does not apply the conventional muscularis-based VI-RADS algorithm to a tumor arising within a bladder diverticulum.

MRI Technique and Image Quality

T2W imaging, DWI/ADC, and DCE MRI are the key components of conventional VI-RADS multiparametric MRI.^[1][5]

Adequate bladder distention is important for assessment of the bladder wall. An underfilled bladder can appear thick and irregular and may contribute to misdiagnosis or overstaging. Excessive distention may cause discomfort and motion artifact.^[1]

DWI is especially vulnerable to susceptibility and motion artifacts. Because DWI is an important dominant sequence in final VI-RADS assessment, its diagnostic quality should be considered before its category is used to determine the final score.^[1][3][4]

DCE remains part of the current conventional multiparametric MRI standard and provides an important functional alternative when DWI is suboptimal. Biparametric MRI without DCE is under active investigation, but the 2026 ACR Steering Committee continues to describe contrast-enhanced multiparametric MRI as the current standard while broader evidence for omitting DCE develops.^[5]

Diagnostic Performance

Diagnostic performance varies with the selected VI-RADS threshold, MRI technique, population, reference standard, and reader experience.

An updated meta-analysis of 31 studies including 3,798 patients reported pooled sensitivity of 89% (95% CI, 86%-91%) and specificity of 89% (95% CI, 85%-91%) for detection of muscle-invasive bladder cancer using a VI-RADS threshold of 3 or greater.^[5][7]

A separate 2022 meta-analysis included 20 studies and 2,477 patients. At a threshold of VI-RADS 3 or greater, pooled sensitivity was 87% (95% CI, 82%-91%) and specificity was 86% (95% CI, 80%-90%). At a threshold of VI-RADS 4 or greater, sensitivity decreased to 78% (95% CI, 74%-81%) while specificity increased to 94% (95% CI, 91%-96%).^[8]

These pooled values describe study populations and threshold performance. They are not measures of the accuracy of an individual examination or of this calculator.

Practical Interpretation

VI-RADS 1 and 2 indicate low imaging likelihood of detrusor muscle invasion. VI-RADS 3 is equivocal. VI-RADS 4 and 5 indicate progressively greater suspicion for muscle invasion, with VI-RADS 5 including very high likelihood of invasion beyond the bladder wall.^[1][5]

The VI-RADS score should be integrated with cystoscopic findings, TURBT or other histopathologic information, patient factors, and additional staging studies as clinically appropriate. The calculator structures application of the imaging framework but does not replace image interpretation or multidisciplinary clinical judgment.

Frequently Asked Questions (FAQs)