Biparametric Versus Multiparametric MRI for VI-RADS Assessment: Reproducibility Relative to Routine mpMRI Reporting...

Area of Science:

• Urologic Radiology
• Oncologic Imaging
• Diagnostic Accuracy

Background:

• Assessing the feasibility of contrast-free multiparametric MRI for VI-RADS scoring.
• Evaluating the impact of radiologist expertise on VI-RADS assessment without contrast agents.

Purpose of the Study:

• To determine if biparametric MRI (T2-weighted and diffusion-weighted imaging) can reproduce contrast-enhanced VI-RADS scores.
• To investigate the influence of reader experience on the reliability of contrast-free VI-RADS scoring.

Main Methods:

• Retrospective analysis of 65 patients with bladder multiparametric MRI.
• Two blinded radiologists (expert and non-expert) assigned VI-RADS scores using only biparametric MRI.
• Reproducibility assessed against original contrast-enhanced VI-RADS scores; accuracy against histopathology.

Main Results:

• Higher agreement with reference standard for expert (73.9%) vs. non-expert (56.5%).
• Area under the curve for detecting muscle invasion (VI-RADS ≥ 4) was 0.87 (expert) and 0.81 (non-expert).
• Sensitivity was high (88.6%) for both readers, but specificity was lower for the non-expert (73.5%). Discrepancies increased in post-resection cases.

Conclusions:

• Contrast-free biparametric MRI may approximate VI-RADS scoring in simple, treatment-naïve cases.
• Performance is reader-dependent and less reliable for equivocal, higher-risk, or post-resection cases.
• Contrast-enhanced multiparametric MRI remains the gold standard for accurate bladder cancer staging.