Medical Ultrasound Physics and Technology Group, School of Physics & FOCAS, Technical University Dublin - Kevin Street Campus, Dublin 6, Ireland; Department of Radiology, Mayo Clinic, Rochester, 55901 MN, USA.
Medical Physics, Blackrock Clinic, Dublin, Ireland.
Ultrasonics. 2019 Jul;96:48-54. doi: 10.1016/j.ultras.2019.04.003. Epub 2019 Apr 11.
The objective of the study was to investigate whether clinically used ultrasonic contrast agents improved the accuracy of spectral Doppler ultrasound in the detection of low grade (<50%) renal artery stenosis. Low grade stenoses in the renal artery are notoriously difficult to reliably detect using Doppler ultrasound due to difficulties such as overlying fat and bowel gas.
A range of anatomically-realistic renal artery phantoms with varying low degrees of stenosis (0, 30 and 50%) were constructed and peak velocity data was measured from within the pre-stenotic and mid-stenotic regions in each phantom, for both unenhanced and contrast-enhanced spectral Doppler data acquisitions. The effect of a 20 mm overlying fat layer on the ultrasound beam distortion and phase aberration, and hence on the measured peak velocity data, was also investigated.
The overlying fat layer produced a statistically significant underestimation (p < 0.01) in both the peak velocity and peak velocity ratio [Stenotic Region(Vmax)/Pre-stenotic Region(Vmax)] for the 0% and 30% stenosis models, but not the 50% model. A statistically significant increase (p < 0.01) in the peak velocity was found in the contrast-enhanced Doppler spectra; however, no significant difference was found between the unenhanced and contrast enhanced peak velocity ratio data, which suggests that the ratio metric has better diagnostic accuracy. The peak velocity ratios determined for each of the contrast-enhanced phantoms correctly predicted if the phantom had a stenosis and furthermore correctly classified the degree of stenosis.
Contrast-enhanced Doppler ultrasound could significantly assist in the early detection of renal artery disease.
本研究旨在探讨临床上使用的超声对比剂是否能提高频谱多普勒超声检测低级别（<50%）肾动脉狭窄的准确性。由于存在脂肪和肠气等因素，低级别肾动脉狭窄很难通过多普勒超声可靠地检测到。
构建了一系列具有不同低级别狭窄程度（0、30 和 50%）的解剖逼真的肾动脉模型，并在每个模型的狭窄前和狭窄中部测量了未增强和增强的频谱多普勒数据采集的峰值速度数据。还研究了 20mm 脂肪层对上超声束变形和相位差的影响，以及对测量的峰值速度数据的影响。
脂肪层对 0%和 30%狭窄模型的峰值速度和峰值速度比[狭窄区（Vmax）/狭窄前区（Vmax）]均产生了统计学上的显著低估（p<0.01），但对 50%狭窄模型没有影响。在增强的多普勒谱中发现峰值速度有统计学显著增加（p<0.01）；然而，未增强和增强的峰值速度比数据之间没有显著差异，这表明比值指标具有更好的诊断准确性。每个增强后的模型确定的峰值速度比值正确预测了模型是否存在狭窄，并进一步正确分类了狭窄程度。
增强的多普勒超声可以显著辅助早期检测肾动脉疾病。
