Buschle Lukas Reinhold, Ziener Christian H, Zhang Ke, Sturm Volker J F, Kampf Thomas, Hahn Artur, Solecki Gergely, Winkler Frank, Bendszus Martin, Heiland Sabine, Schlemmer Heinz-Peter, Kurz Felix T
German Cancer Research Center, Radiology, INF 280, 69120, Heidelberg, Germany.
Department of Neuroradiology, University Hospital Heidelberg, INF 400, 69120, Heidelberg, Germany.
MAGMA. 2018 Aug;31(4):531-551. doi: 10.1007/s10334-018-0677-9. Epub 2018 Feb 24.
Spin dephasing of the local magnetization in blood vessel networks can be described in the static dephasing regime (where diffusion effects may be ignored) by the established model of Yablonskiy and Haacke. However, for small capillary radii, diffusion phenomena for spin-bearing particles are not negligible.
In this work, we include diffusion effects for a set of randomly distributed capillaries and provide analytical expressions for the transverse relaxation times T2* and T2 in the strong collision approximation and the Gaussian approximation that relate MR signal properties with microstructural parameters such as the mean local capillary radius.
Theoretical results are numerically validated with random walk simulations and are used to calculate capillary radius distribution maps for glioblastoma mouse brains at 9.4 T. For representative tumor regions, the capillary maps reveal a relative increase of mean radius for tumor tissue towards healthy brain tissue of [Formula: see text] (p < 0.001).
The presented method may be used to quantify angiogenesis or the effects of antiangiogenic therapy in tumors whose growth is associated with significant microvascular changes.
血管网络中局部磁化的自旋去相位可通过Yablonskiy和Haacke的既定模型在静态去相位状态（其中扩散效应可忽略不计）下进行描述。然而，对于小的毛细血管半径，携带自旋粒子的扩散现象不可忽略。
在本研究中，我们纳入了一组随机分布毛细血管的扩散效应，并在强碰撞近似和高斯近似下提供了横向弛豫时间T2*和T2的解析表达式，这些表达式将磁共振信号特性与微观结构参数（如平均局部毛细血管半径）相关联。
理论结果通过随机游走模拟进行了数值验证，并用于计算9.4 T下胶质母细胞瘤小鼠脑的毛细血管半径分布图。对于代表性肿瘤区域，毛细血管图显示肿瘤组织的平均半径相对于健康脑组织增加了[公式：见原文]（p < 0.001）。
所提出的方法可用于量化肿瘤中血管生成或抗血管生成治疗的效果，这些肿瘤的生长与显著的微血管变化相关。
