The spatial heterogeneity in the temporal occurrence of pseudo-normalization of MR apparent diffusion coefficient values for ischemic lesions may be related to morphological and functional vascular remodeling. As the area of accelerated pseudo-normalization tends to expand faster and more extensively into the chronic stage, detailed vascular characterization of such areas is necessary. During the subacute stage of transient middle cerebral artery occlusion rat models, the morphological size of the macrovasculature, microvascular vessel size index (VSI), and microvessel density (MVD) were quantified along with functional perfusion measurements of the relative cerebral blood flow (rCBF) and mean transit time (rMTT) of the corresponding areas (33 cases for each parameter). When compared with typical pseudo-normalization lesions, early pseudo-normalization lesions exhibited larger VSI and rCBF (p < 0.001) at reperfusion days 4 and 7, along with reduced MVD and elongated rMTT (p < 0.001) at reperfusion days 1, 4, and 7. The group median VSI and rCBF exhibited a strong positive correlation (r = 0.92), and the corresponding MVD and rMTT showed a negative correlation (r = −0.48). Light sheet fluorescence microscopy images were used to quantitatively validate the corresponding MRI-derived microvascular size, density, and cerebral blood volume.

缺血性病变的 MR 表观扩散系数值在时间上出现伪正常化的空间异质性可能与形态和功能性血管重塑有关。由于加速伪正常化区域趋向于更快更广泛地扩展到慢性阶段，因此需要对这些区域进行详细的血管表征。在瞬时大脑中动脉闭塞大鼠模型的亚急性阶段，对大血管的形态大小、微血管大小指数 (VSI) 和微血管密度 (MVD) 以及相对脑血流量 (rCBF) 的功能灌注测量进行量化和相应区域的平均通过时间（rMTT）（每个参数 33 个案例）。与典型的伪正常化病变相比，早期假正常化病变在再灌注第 4 天和第 7 天表现出较大的 VSI 和 rCBF (p < 0.001)，同时在再灌注第 1、4 和 7 天时 MVD 降低和 rMTT 延长 (p < 0.001)。组中位数 VSI 和 rCBF表现出强正相关（r = 0.92），相应的MVD和rMTT表现出负相关（r = -0.48）。光片荧光显微镜图像用于定量验证相应的 MRI 衍生的微血管大小、密度和脑血容量。48)。光片荧光显微镜图像用于定量验证相应的 MRI 衍生的微血管大小、密度和脑血容量。48)。光片荧光显微镜图像用于定量验证相应的 MRI 衍生的微血管大小、密度和脑血容量。