Xu Min, Liu Xiao, Li Ang, Fan Yubo, Sun Anqiang, Deng Xiaoyan, Li Deyu
Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China.
ScientificWorldJournal. 2014;2014:803276. doi: 10.1155/2014/803276. Epub 2014 Nov 17.
One assumption of DSC-MRI is that the injected contrast agent is kept totally intravascular and the arterial wall is impermeable to contrast agent. The assumption is unreal for such small contrast agent as Gd-DTPA can leak into the arterial wall. To investigate whether the unreal assumption is valid for the estimation of the delay and dispersion of the contrast agent bolus, we simulated flow and Gd-DTPA transport in a model with multilayer arterial wall and analyzed the bolus delay and dispersion qualified by mean vascular transit time (MVTT) and the variance of the vascular transport function. Factors that may affect Gd-DTPA transport hence the delay and dispersion were further investigated, such as integrity of endothelium and disturbed flow. The results revealed that arterial transmural transport would slightly affect MVTT and moderately increase the variance. In addition, although the integrity of endothelium can significantly affect the accumulation of contrast agent in the arterial wall, it had small effects on the bolus delay and dispersion. However, the disturbed flow would significantly increase both MVTT and the variance. In conclusion, arterial transmural transport may have a small effect on the bolus delay and dispersion when compared to the flow pattern in the artery.
动态对比增强磁共振成像（DSC-MRI）的一个假设是，注入的造影剂完全保留在血管内，且动脉壁对造影剂不可渗透。对于像钆喷酸葡胺（Gd-DTPA）这样的小造影剂而言，该假设并不现实，因为Gd-DTPA会渗入动脉壁。为了研究这个不现实的假设对于估计造影剂团注的延迟和弥散是否有效，我们在一个具有多层动脉壁的模型中模拟了血流和Gd-DTPA的传输，并分析了由平均血管通过时间（MVTT）和血管传输函数方差所限定的团注延迟和弥散情况。我们进一步研究了可能影响Gd-DTPA传输从而影响延迟和弥散的因素，如内皮的完整性和紊乱血流。结果显示，动脉壁的跨壁传输会对MVTT产生轻微影响，并适度增加方差。此外，尽管内皮的完整性会显著影响造影剂在动脉壁中的积聚，但对团注延迟和弥散的影响较小。然而，紊乱血流会显著增加MVTT和方差。总之，与动脉中的血流模式相比，动脉壁的跨壁传输对团注延迟和弥散的影响可能较小。
