MR phase-contrast flow measurement with limited spatial resolution in small vessels: Value of model-based image analysis
MR phase-contrast flow measurement with limited spatial resolution in small vessels: Value of model-based image analysis
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DOI：
10.1002/(sici)1522-2594(199903)41:3
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发表时间：
1999-03-01
影响因子：
3.3
通讯作者：
Viergever, MA
中科院分区：
文献类型：
--
作者：
Hoogeveen, RM;Bakker, CJG;Viergever, MA
小血管中分辨率有限的磁共振相位对比容积流速（VFR）测量存在两个主要误差来源：a）部分容积伪影，导致VFR的系统性高估，以及B）与血管像素[感兴趣区域（ROI）]选择相关的误差，导致观察者间和观察者内的较大变异性。此外，有限的分辨率导致血管周围的吉布斯振铃，这对VFR测定产生不利影响。本文提出了一种基于模型的半自动方法，该方法有效地消除了部分体积效应和吉布斯振铃引起的误差，并最大限度地减少了感兴趣区域选择中的可变性引起的误差。该模型假设一个抛物线形的流量剖面和圆柱形的血管几何形状，纳入流入的影响，并考虑到点扩散函数的采集。该方法自动估计最大速度、血管半径和VFR。该方法在各种条件下在体模中进行了验证，并在体内进行了评价。远小血管与中度脉动流，它表明，获得准确的VFR和直径估计，几乎独立的ROI选择，即使在血管覆盖的几个像素。与传统的VFR分析方法相比，该方法的准确性和重现性都有显著提高. Magn Reson Med 41：520-528，1999. (C)1999 Wiley-Liss，Inc.
Magnetic resonance phase-contrast volume flow rate (VFR) measurement with limited resolution in small vessels is subject to two major sources of error: a) partial volume artifacts, causing systematic overestimation of the VFR, and b) errors related to the selection of vessel pixels [region of interest (ROI)], causing large inter-observer and intra-observer variability. Additionally, limited resolution results in Gibbs-ringing around vessels, which adversely affects VFR determination. In this paper, a semi-automatic model-based method is presented that effectively eliminates errors due to both partial volume effect and Gibbs-ringing and also minimizes errors from variability in the ROI selection. The model assumes a parabolic flow profile and cylindrical vessel geometry, incorporates inflow effects, and takes into account the point-spread function of the acquisition. The method automatically estimates maximum velocity, vessel radius, and VFR. The method is validated in phantoms under various conditions and evaluated in vivo. Far small vessels with moderately pulsatile flow, it is demonstrated that accurate VFRs and diameter estimates are obtained, virtually independent of the ROI selection, even in vessels covered by just a few pixels. Compared with conventional VFR analysis, both accuracy and reproducibility Improve significantly. Magn Reson Med 41:520-528, 1999. (C) 1999 Wiley-Liss, Inc.