Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital and Women's College Hospital, University of Toronto, Toronto, Ontario, Canada.
Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Ontario, Canada.
J Magn Reson Imaging. 2021 Aug;54(2):341-356. doi: 10.1002/jmri.27364. Epub 2020 Oct 2.
Incidental cystic renal masses are common, usually benign, and almost always indolent. Since 1986, the Bosniak classification has been used to express the risk of malignancy in a cystic renal mass detected at imaging. Historically, magnetic resonance imaging (MRI) was not included in that classification. The proposed Bosniak v.2019 update has formally incorporated MRI, included definitions of imaging terms designed to improve interobserver agreement and specificity for malignancy, and incorporated a variety of masses that were incompletely defined or not included in the original classification. For example, at unenhanced MRI, homogeneous masses markedly hyperintense at T -weighted imaging (similar to cerebrospinal fluid) and homogeneous masses markedly hyperintense at fat suppressed T -weighted imaging (approximately ≥2.5 times more intense than adjacent renal parenchyma) are classified as Bosniak II and may be safely ignored, even when they have not been imaged with a complete renal mass MRI protocol. MRI has specific advantages and is recommended to evaluate masses that at computed tomography (CT) 1) have abundant thick or nodular calcifications; 2) are homogeneous, hyperattenuating, ≥3 cm, and nonenhancing; or 3) are heterogeneous and nonenhancing. Although MRI is generally excellent for characterizing cystic renal masses, there are unique weaknesses of MRI that bear consideration. These details and others related to MRI of cystic renal masses are described in this review, with an emphasis on Bosniak v.2019. A website (https://bosniak-calculator.herokuapp.com/) and mobile phone apps named "Bosniak Calculator" have been developed for ease of assignment of Bosniak classes. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 3.
偶然发现的囊性肾肿块很常见，通常为良性，且几乎总是惰性的。自 1986 年以来，Bosniak 分类法已被用于表达在影像学检查中发现的囊性肾肿块的恶性风险。从历史上看，磁共振成像（MRI）并不包括在该分类中。拟议的 Bosniak v.2019 更新正式纳入了 MRI，包括旨在提高观察者间一致性和恶性肿瘤特异性的影像学术语定义，并纳入了各种在原始分类中未完全定义或未包括的肿块。例如，在未增强的 MRI 上，T1 加权成像（类似于脑脊液）明显高信号的均匀性肿块和脂肪抑制 T1 加权成像（与相邻肾实质相比，大约高 2.5 倍以上）明显高信号的均匀性肿块被归类为 Bosniak II 级，可以安全忽略，即使它们没有使用完整的肾肿块 MRI 方案进行成像。MRI 具有特定的优势，推荐用于评估以下 CT 表现的肿块：1）有丰富的厚或结节状钙化；2）为均匀性、高衰减、≥3cm 且无强化；或 3）为异质性且无强化。尽管 MRI 通常非常适合于囊性肾肿块的特征描述，但 MRI 也有其独特的局限性，需要考虑。本文对囊性肾肿块的 MRI 进行了描述，重点介绍了 Bosniak v.2019。还开发了一个名为“Bosniak 计算器”的网站（https://bosniak-calculator.herokuapp.com/）和手机应用程序，用于方便 Bosniak 分级的分配。证据水平：5 技术功效分期：3。
