Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA.
Abdom Radiol (NY). 2018 Oct;43(10):2604-2614. doi: 10.1007/s00261-018-1585-1.
Ultrasound is routinely used as the first imaging exam for evaluation of renal transplants and can identify most major surgical complications and evaluate vascularity with color Doppler. Ultrasound is limited, however, in the detection of parenchymal disease processes and Doppler evaluation is also prone to technical errors. Multiple new ultrasound applications have been developed and are under ongoing investigation which could add additional diagnostic capability to the routine ultrasound exam with minimal additional time, cost, and patient risk. Contrast-enhanced ultrasound (CEUS) can be used off-label in the transplant kidney, and can assist in detection of infection, trauma, and vascular complications. CEUS also can demonstrate perfusion of the transplant assessed quantitatively with generation of time-intensity curves. Future directions of CEUS include monitoring treatment response and microbubble targeted medication delivery. Elastography is an ultrasound application that can detect changes in tissue elasticity, which is useful to diagnose diffuse parenchymal disease, such as fibrosis, otherwise unrecognizable with ultrasound. Elastography has been successfully applied in other organs including the liver, thyroid, and breast; however, it is still under development for use in the transplant kidney. Unique properties of the transplant kidney including its heterogeneity, anatomic location, and other technical factors present challenges in the development of reference standard measurements. Lastly, B-flow imaging is a flow application derived from B-mode. This application can show the true lumen size of a vessel which is useful to depict vascular anatomy and bypasses some of the pitfalls of color Doppler such as demonstration of slow flow.
超声检查通常作为评估肾移植的首选影像学检查，可以识别大多数主要的手术并发症，并使用彩色多普勒评估血管。然而，超声在检测实质疾病方面存在局限性，多普勒评估也容易出现技术错误。已经开发出多种新的超声应用，并正在进行进一步研究，这可能会为常规超声检查增加额外的诊断能力，而不会增加额外的时间、成本和患者风险。对比增强超声（CEUS）可在移植肾中进行非适应证使用，并有助于检测感染、创伤和血管并发症。CEUS 还可以定量评估移植肾的灌注情况，并生成时间-强度曲线。CEUS 的未来发展方向包括监测治疗反应和微泡靶向药物输送。超声弹性成像是一种可以检测组织弹性变化的超声应用，对于诊断弥漫性实质疾病（如纤维化）很有用，而这些疾病在超声检查中无法识别。弹性成象已经成功地应用于其他器官，包括肝脏、甲状腺和乳房；然而，它在移植肾中的应用仍在开发中。移植肾的独特性质，包括其异质性、解剖位置和其他技术因素，给参考标准测量的发展带来了挑战。最后，B 型血流成像（B-flow imaging）是一种源自 B 型模式的血流应用。该应用程序可以显示血管的真实管腔大小，这对于描绘血管解剖结构很有用，可以避免彩色多普勒的一些陷阱，如显示缓慢的血流。
