摘要
目的探讨使用四维磁共振血流加速度成像技术在不同空间分辨率下重建压力梯度的可靠性和准确性。方法构建一种血管狭窄的流体模型,并使用四维磁共振速度成像序列和课题组自主研发的四维加速度成像序列对该模型进行扫描,扫描的空间分辨率有0.63 mm×0.63 mm×0.63 mm和0.89 mm×0.89 mm×0.89 mm两种,采集得到流体模型在两种不同空间分辨率下的速度和加速度数据,根据Naver-Stokes方程,使用中心有限差分方法计算得到流体模型狭窄两端的压力梯度,并以压力传感器测量的压力差为标准,计算Fréchet距离和最大相对误差以及进行回归分析等来对其准确性和相关性进行评估。结果两种空间分辨率下,直接加速度计算的压力梯度都比速度求导计算的压力梯度误差更小、准确性更高:在0.63 mm分辨率下,直接加速度计算和速度求导计算的压力梯度变化曲线与压力传感器得到的曲线之间的Fréchet距离d_(f)分别为0.84和1.32,最大相对误差(ε_(max))分别为13.9%和21.2%,在0.89 mm分辨率下d_(f)分别为1.33和1.60,ε_(max)分别为29.4%和33.2%。空间分辨率对压力梯度的计算有明显影响:0.63 mm和0.89 mm分辨率下,加速度与速度计算得到的压力梯度回归斜率k分别为0.72和0.62以及0.51和0.44,R^(2)分别为0.97和0.91以及0.91和0.72。结论四维磁共振血流加速度成像重建压力梯度具有很大潜力,得到的压力梯度的准确性比速度求导计算得到压力梯度的准确性更高,同时结果误差还随分辨率的增高而减小。
Objective To probe the reliability and accuracy of pressure gradient reconstructed using four-dimensional magnetic resonance blood flow acceleration imaging at different spatial resolutions.Methods A fluid model of vascular stenosis was constructed,and the model was scanned by the four-dimensional magnetic resonance velocity imaging sequence and acceleration imaging sequence independently developed by the research group.The spatial resolution of the scanning was 0.63 mm 0.63 mm 0.63 mm and 0.89 mm 0.89 mm 0.89 mm,respectively.The acceleration and velocity data obtained from magnetic resonance images were used to calculate pressure gradient of the fluid phantom through solving Navier-Stokes equation with using central finite difference over two different spatial resolutions.The Fréchet distance,the maximum relative error and regression analysis are calculated and used to assess the accuracy and relevance of pressure gradient with standard for the pressure difference of pressure transducer measurements.Results The pressure gradient calculated by direct acceleration has smaller error and higher accuracy than that calculated by velocity derivative at two spatial resolution:at dx=0.63 mm d_(f)=0.84 and 1.32,ε_(max)=13.9%and 21.2%for acceleration calculating and velocity derivative calculating,respectively;at dx=0.89 mm d_(f)=1.33 and 1.60,ε_(max)=29.4%and 33.2%for acceleration calculating and velocity derivative calculating,respectively.Spatial resolution has significant influence on the calculation of pressure gradient:linear regression analysis of results from acceleration calculating,k=0.72 and 0.51,R^(2)=0.97 and 0.91 at dx=0.63 mm and 0.89 mm,respectively;for results from velocity calculating,k=0.62 and 0.44,R^(2)=0.91 and 0.72 at dx=0.63 mm and 0.89 mm,respectively.Conclusion It has the great potential that pressure gradient is reconstructed by four-dimensional magnetic resonance blood flow acceleration mapping.It provides more accurate of pressure gradient calculating than that velocity derivative calculatin
作者
顾安燕
刘泽萍
刘红艳
刘洋
张卓能
骆彦德
谢国喜
Gu Anyan;Liu Zeping;Liu Hongyan;Liu Yang;Zhang zhuoneng;Luo Yande;Xie Guoxi(School of Biomedical Engineering,Guangzhou Medical University,Guangzhou 511436,China;Department of Imaging,The Sixth Affiliated Hospital,Guangzhou Medical University,Qingyuan 511518,China)
出处
《中华生物医学工程杂志》
CAS
2023年第3期241-247,共7页
Chinese Journal of Biomedical Engineering
基金
国家自然科学基金(81971607)。
