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首页> 美国卫生研究院文献>Journal of Applied Physiology >Assessing potential errors of MRI-based measurements of pulmonary blood flow using a detailed network flow model
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Assessing potential errors of MRI-based measurements of pulmonary blood flow using a detailed network flow model

机译：使用详细的网络流量模型评估基于MRI的肺血流量测量的潜在误差

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MRI images of pulmonary blood flow using arterial spin labeling (ASL) measure the delivery of magnetically tagged blood to an image plane during one systolic ejection period. However, the method potentially suffers from two problems, each of which may depend on the imaging plane location: 1) the inversion plane is thicker than the imaging plane, resulting in a gap that blood must cross to be detected in the image; and 2) ASL includes signal contributions from tagged blood in conduit vessels (arterial and venous). By using an in silico model of the pulmonary circulation we found the gap reduced the ASL signal to 64–74% of that in the absence of a gap in the sagittal plane and 53–84% in the coronal. The contribution of the conduit vessels varied markedly as a function of image plane ranging from ∼90% of the overall signal in image planes that encompass the central hilar vessels to <20% in peripheral image planes. A threshold cutoff removing voxels with intensities >35% of maximum reduced the conduit vessel contribution to the total ASL signal to ∼20% on average; however, planes with large contributions from conduit vessels underestimate acinar flow due to a high proportion of in-plane flow, making ASL measurements of perfusion impractical. In other image planes, perfusion dominated the resulting ASL images with good agreement between ASL and acinar flow. Similarly, heterogeneity of the ASL signal as measured by relative dispersion is a reliable measure of heterogeneity of the acinar flow distribution in the same image planes.
机译：使用动脉自旋标记（ASL）的肺血流MRI图像可测量一个收缩期射血期间将磁性标记的血液输送到图像平面。但是，该方法可能会遇到两个问题，每个问题都可能取决于成像平面的位置：1）反转平面比成像平面厚，导致必须穿过血液才能在图像中检测到间隙。 2）ASL包括来自导管血管（动脉和静脉）的带标记血液的信号贡献。通过使用计算机模拟的肺循环模型，我们发现该间隙将ASL信号降低到矢状面无间隙时的ASL信号的64-74％和冠状动脉中无间隙的53-84％。导管血管的贡献随图像平面的变化而显着变化，范围从包围中央肺门血管的图像平面的总信号的约90％到周围图像平面的<20％。阈值截止值去除强度大于最大强度的35％的像素可将导管血管对总ASL信号的贡献平均降低至约20％；然而，由于平面内流量的比例很高，导管血管贡献较大的平面低估了腺泡流量，因此无法进行ASL灌注测量。在其他图像平面中，灌注在生成的ASL图像中占主导地位，ASL和腺泡流之间具有良好的一致性。类似地，通过相对色散测量的ASL信号的异质性是对同一图像平面中腺泡流分布异质性的可靠度量。

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