Abstract：
Bladder cancer (BC), predominantly comprising urothelial carcinomas (UCs), ranks as the tenth most common cancer worldwide. UCs with variant histology (variant UC), including squamous differentiation, glandular differentiation, plasmacytoid variant, micropapillary variant, sarcomatoid variant, and nested variant, accounting for 5-10% of cases, exhibit more aggressive and advanced tumor characteristics compared to pure UC. The Vesical Imaging-Reporting and Data System (VI-RADS), established in 2018, provides guidelines for the preoperative evaluation of muscle-invasive bladder cancer (MIBC) using multiparametric magnetic resonance imaging (mpMRI). This technique integrates T2-weighted imaging (T2WI), dynamic contrast-enhanced (DCE)-MRI, and diffusion-weighted imaging (DWI) to distinguish MIBC from non-muscle-invasive bladder cancer (NMIBC). VI-RADS has demonstrated high diagnostic performance in differentiating these two categories for pure UC. However, its accuracy in detecting muscle invasion in variant UCs is currently under investigation. These variant UCs are associated with a higher likelihood of disease recurrence and require precise preoperative assessment and immediate surgical intervention. This review highlights the potential value of mpMRI for different variant UCs and explores the clinical implications and prospects of VI-RADS in managing these patients, emphasizing the need for careful interpretation of mpMRI examinations including DCE-MRI, particularly given the heterogeneity and aggressive nature of variant UCs. Additionally, the review addresses the fundamental MRI reading procedures, discusses potential causes of diagnostic errors, and considers future directions in the use of artificial intelligence and radiomics to further optimize the bladder MRI protocol.
摘要：
膀胱癌（BC），主要包括尿路上皮癌（UC），排在全球第十位最常见的癌症。具有变异组织学的UC（变异UC），包括鳞状分化，腺体分化,浆细胞样变体，微乳头状变异体，肉瘤样变异体，和嵌套变体，占病例的5-10%，与纯UC相比，表现出更具侵袭性和晚期的肿瘤特征。Vesical影像报告和数据系统（VI-RADS），建立于2018年,为使用多参数磁共振成像(mpMRI)进行肌层浸润性膀胱癌(MIBC)的术前评估提供了指南.该技术集成了T2加权成像（T2WI），动态对比增强(DCE)-MRI,和弥散加权成像（DWI）以区分MIBC和非肌肉浸润性膀胱癌（NMIBC）。VI-RADS在区分纯UC的这两个类别方面表现出很高的诊断性能。然而,目前正在研究其检测变体UC中肌肉入侵的准确性。这些变异的UC与更高的疾病复发可能性相关，需要精确的术前评估和立即的手术干预。这篇综述强调了mpMRI对不同变异UCs的潜在价值，并探讨了VI-RADS在管理这些患者中的临床意义和前景。强调需要仔细解释包括DCE-MRI在内的MPMRI检查，特别是考虑到变异UCs的异质性和攻击性。此外,这篇综述讨论了基本的MRI阅读程序，讨论诊断错误的潜在原因，并考虑了未来使用人工智能和影像组学的方向，以进一步优化膀胱MRI协议。
