The Russell H. Morgan Department of Radiology and Radiological Science, School of Medicine, The Johns Hopkins University, Baltimore, MD 21205, USA.
The James Buchanan Brady Urological Institute, Department of Urology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
Tomography. 2021 Mar 2;7(1):80-94. doi: 10.3390/tomography7010008.
Upper urinary tract obstructions (UTOs) are blockages that inhibit the flow of urine through its normal course, leading to impaired kidney function. Imaging plays a significant role in the initial diagnosis of UTO, with anatomic imaging (primarily ultrasound (US) and non-contrast computed tomography (CT)) serving as screening tools for the detection of the dilation of the urinary collecting systems (i.e., hydronephrosis). Whether hydronephrosis represents UTO or a non-obstructive process is determined by functional imaging (typically nuclear medicine renal scintigraphy). If these exams reveal evidence of UTO but no discernable source, multiphase contrast enhanced CT urography and/or dynamic contrast enhanced MR urography (DCE-MRU) may be performed to delineate a cause. These are often performed in conjunction with direct ureteroscopic evaluation. While contrast-enhanced CT currently predominates, it can induce renal injury due to contrast induced nephropathy (CIN), subject patients to ionizing radiation and is limited in quantifying renal function (traditionally assessed by renal scintigraphy) and establishing the extent to which hydronephrosis is due to functional obstruction. Traditional MRI is similarly limited in its ability to quantify function. DCE-MRU presents concerns regarding nephrogenic systemic fibrosis (NSF), although decreased with newer gadolinium-based contrast agents, and regarding cumulative gadolinium deposition in the basal ganglia. DCE-MR CEST urography is a promising alternative, employing new MRI contrast agents and imaging schemes and allowing for concurrent assessment of renal anatomy and functional parameters. In this review we highlight clinical challenges in the diagnosis and management of UTO, identify key advances in imaging agents and techniques for DCE-MR CEST urography and provide perspective on how this technique may evolve in clinical importance.
上尿路梗阻(UTOs)是指阻止尿液正常流动的阻塞物,导致肾功能受损。影像学在 UTO 的初步诊断中起着重要作用,解剖影像学(主要是超声(US)和非对比计算机断层扫描(CT))作为检测尿收集系统扩张(即肾积水)的筛查工具。肾积水是否代表 UTO 还是非阻塞性过程,取决于功能影像学(通常是核医学肾闪烁扫描)。如果这些检查显示存在 UTO 的证据,但没有发现明显的原因,则可能进行多期增强 CT 尿路造影和/或动态对比增强磁共振尿路造影(DCE-MRU)以确定原因。这些通常与直接输尿管镜检查评估一起进行。虽然目前增强 CT 占主导地位,但它会因造影剂肾病(CIN)而导致肾损伤,使患者暴露在电离辐射下,并且在定量肾功能(传统上通过肾闪烁扫描评估)和确定肾积水的功能阻塞程度方面受到限制。传统 MRI 在定量功能方面也存在类似的局限性。DCE-MRU 存在与造影剂相关的肾源性系统性纤维化(NSF)有关的问题,尽管使用新型钆基造影剂有所减少,但存在与基底神经节中钆沉积累积有关的问题。DCE-MR CEST 尿路造影是一种有前途的替代方法,它采用了新的 MRI 造影剂和成像方案,同时评估肾脏解剖结构和功能参数。在这篇综述中,我们强调了 UTO 的诊断和管理中的临床挑战,确定了 DCE-MR CEST 尿路造影中成像剂和技术的关键进展,并就该技术在临床重要性方面的发展提供了观点。
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