对于评估变异组织学尿路上皮癌（VUC）的无造影对比剂双参数磁共振成像（bpMRI，结合T2加权成像[T2WI]和扩散加权成像[DWI]）的诊断性能尚不清楚。比较bpMRI和多参数磁共振成像（mpMRI，结合T2WI、DWI和动态增强磁共振成像）在评估VUC肌层浸润的诊断性能。这项多机构回顾性分析包括2010年至2019年间进行膀胱mpMRI术前经尿道膀胱肿瘤切除术的118名经病理证实的VUC患者。三名获得认证的放射科医师根据膀胱成像报告和数据系统（VI-RADS）分别评估两组图像，第1组（bpMRI）和第2组（mpMRI）。组织病理学结果被用作参考标准。采用受试者工作特征曲线分析、Z检验和Wald检验评估诊断能力。分析结果显示，在纳入分析的118名VUC患者中，66例（55.9%）和52例（44.1%）分别具有肌层浸润性膀胱癌（MIBC）和非MIBC（平均年龄为71 ± 10岁；男性88名）。对于MIBC的诊断，bpMRI的曲线下面积明显小于mpMRI（0.870-0.884 vs 0.902-0.923，p < 0.05）。以VI-RADS分数4作为截断点，bpMRI的敏感性显著低于mpMRI（65.2-66.7% vs 77.3-80.3%，p < 0.05）。对于所有观察者，bpMRI和mpMRI的特异性没有显著差异（88.5-90.4 vs 88.5-92.3，p > 0.05）。研究的一个局限是VUC罕见导致样本规模有限。对于VUC患者，应用VI-RADS时，bpMRI的诊断结果较mpMRI差，用于评估肌层浸润性。因此，建议采用基于mpMRI的方法评估VUC肌层浸润性。基于无造影对比剂的双参数磁共振成像（bpMRI）的膀胱成像报告和数据系统（VI-RADS）可准确诊断纯性尿路上皮癌，类似于基于传统多参数磁共振成像的VI-RADS。然而，当VI-RADS截断点为4时，bpMRI的VI-RADS可能会错误诊断具有变异组织学的尿路上皮癌的肌层浸润性，这是本研究的局限之一。版权所有 © 2023年欧洲泌尿学协会。由Elsevier B.V.出版。保留所有权利。

The diagnostic performance of contrast medium-free biparametric magnetic resonance imaging (bpMRI; combining T2-weighted imaging [T2WI] and diffusion-weighted imaging [DWI]) for evaluating variant-histology urothelial carcinoma (VUC) remains unknown.To compare the diagnostic performance of bpMRI and multiparametric MRI (mpMRI; combining T2WI, DWI, and dynamic contrast-enhanced MRI]) for assessing muscle invasion of VUC.This multi-institution retrospective analysis included 118 patients with pathologically verified VUC who underwent bladder mpMRI before transurethral bladder tumor resection between 2010 and 2019.Three board-certified radiologists separately evaluated two sets of images, set 1 (bpMRI) and set 2 (mpMRI), in accordance with the Vesical Imaging Reporting and Data System (VI-RADS). The histopathology results were utilized as a reference standard. Receiver operating characteristic curve analysis, Z test, and Wald test were used to assess diagnostic abilities.Sixty-six (55.9%) and 52 (44.1%) of the 118 patients with VUC included in the analysis (mean age, 71 ± 10 yr; 88 men) had muscle-invasive bladder cancer (MIBC) and non-MIBC, respectively. For the diagnosis of MIBC, the areas under the curve for bpMRI were significantly smaller than those for mpMRI (0.870-0.884 vs 0.902-0.923, p < 0.05). The sensitivity of bpMRI was significantly lower than that of mpMRI for all readers with a VI-RADS cutoff score of 4 (65.2-66.7% vs 77.3-80.3%, p < 0.05). The specificity of bpMRI and mpMRI did not differ significantly for all readers (88.5-90.4 vs 88.5-92.3, p > 0.05). A limitation of the study is the limited sample size because of the rarity of VUC.In patients with VUC, on applying VI-RADS, the diagnostic results of bpMRI were inferior to those of mpMRI for evaluating muscle invasion. Therefore, mpMRI-based methods are recommended for evaluating muscle invasiveness of VUC.Contrast medium-free biparametric magnetic resonance imaging (bpMRI)-based Vesical Imaging Reporting and Data System (VI-RADS) can accurately diagnose pure urothelial carcinomas, similar to conventional multiparametric magnetic resonance imaging-based VI-RADS. However, bpMRI-based VI-RADS may misdiagnose muscle invasiveness of urothelial carcinoma with variant histology, particularly when its cutoff score is 4.Copyright © 2023 European Association of Urology. Published by Elsevier B.V. All rights reserved.