Gray-Scale, Color Doppler, Spectral Doppler, and Contrast-Enhanced Renal Artery Ultrasound: Imaging Techniques and Features

Abstract

Renal artery stenosis (RAS) is increasingly being detected in elderly patients as life expectancy increases. RAS induces hypertension or reduces renal function. Computed tomography or magnetic resonance angiography are objective in detecting RAS but may cause iodine-induced nephrotoxicity or nephrogenic systemic fibrosis in patients with RAS. Ultrasound (US) is, by contrast, a noninvasive and real-time imaging modality useful in patients with reduced renal function. Renal US is not as sensitive for detecting RAS because this technique indirectly assesses the renal artery by analyzing intrarenal hemodynamic changes. Although, ideally, US would be used to directly evaluate the renal artery, its current utility for RAS detection remains unclear. The purpose of this review is to introduce how to assess renal artery with US, to describe imaging features of renal artery US, to compare renal artery US and renal US, and to show how to perform work-up in patients in whom RAS is suspected.

2023 ESH Guidelines for the management of arterial hypertension The Task Force for the management of arterial hypertension of the European Society of Hypertension

“…Hemodynamic changes in the renal artery and the kidney can be evaluated with color and spectral Doppler ultrasound. Contrast-enhanced ultrasound may directly show a diameter change in the renal artery with intravascular contrast material that is not harmful even to patients with poor renal function [198].…”

Magnetic Resonance Imaging in Atherosclerotic Renal Artery Stenosis: The Update and Future Directions from Interventional Perspective

“…Preoperative assessment of the degree of RAS is essential for determining the treatment options [ 17 ]. CTA is currently the screening tool for preoperative angiography of the kidney with high sensitivity [ 19 ]; however, CTA carries a risk of radiation exposure, requires exogenous contrast agents that are potentially nephrotoxic, and cannot be performed in patients allergic to iodine contrast agents [ 20 ].…”

“…Imaging techniques, such as magnetic resonance angiography (MRA), computed tomography angiography (CTA), or Doppler ultrasound, are crucial in the diagnosis of RAS [ 16 ]. Magnetic resonance imaging (MRI) stands out as being noninvasive, radiation-free, and multiparameter, with the potential for future functional applications [ 17 ]. Traditionally, contrast-enhanced MRI can improve image contrast, but its application has been constrained in patients with RAS due to the risk of renal fibrosis caused by contrast agents [ 18 ].…”