Abstract:

Objective  To investigate the relationship between blood perfusion, microstructural damage that in different subtypes of white matter hyperintensity (WMH) and white matter hyperintensity penumbra (WMH-P), and cognitive impairment.

Methods  The patients with cerebral small vessel disease (CSVD) patients with the WMH rating of modified Fazekas grade Ⅰ-Ⅱ at Tangshan Gongren Hospital from May 2021 to March 2023 were included. The 3.0 T MRI scan [three-dimensional arterial spin labeling (3D-ASL), diffusion kurtosis imaging (DKI) sequences] were conducted on these patients. The blood perfusion index [cerebral blood flow (CBF)] and the indexes [axial diffusivity (AD), mean diffusivity (MD), radial diffusivity (RD), axial kurtosis (AK), mean kurtosis (MK), radial kurtosis (RK), and fraction anisotropy (FA)] reflecting the microstructural changes within the deep white matter hyperintensity (DWMH) region of interest (ROI1) and its WMH-P (ROI1-1 in the inner layer and ROI1-2 in the outer layer), as well as periventricular white matter hyperintensity (PVWMH) (ROI2) and its WMH-P (ROI2-1 in the inner layer and ROI2-2 in the outer layer) of patients were analyzed. The cognitive function of patients was analyzed. The Spearman correlation was used to analyze the relationship between the above indexes reflecting blood perfusion changes and microstructural changes in different subtypes of WMH (DWMH and PVWMH) and its corresponding WMH-P and the severity of cognitive impairment.

Results  A total of 61 patients with CSVD were included, with an average age of (61±1) years. The RD value (r=0.296) in DWMH (ROI1) was positively correlated with the severity of cognitive impairment, while the MK value (r=－0.287) and the RK value (r=－0.315) were negatively correlated with the severity of cognitive impairment. The values of AD (ROI1-1: r=0.274; ROI1-2:
r=0.261), MD (ROI1-1: r=0.370; ROI1-2: r=0.387), and RD (ROI1-1: r=0.411; ROI1-2: r=0.430) in WMH-P were positively correlated with the severity of cognitive impairment, while the values of AK (ROI1-1: r=－0.270; ROI1-2: r=－0.297), MK (ROI1-1: r=－0.367; ROI1-2: r=－0.325), RK (ROI1-1:
r=－0.379; ROI1-2: r=－0.309), and FA (ROI1-1: r=－0.286; ROI1-2: r=－0.256) were negatively correlated with the severity of cognitive impairment. The MK value (r=0.354) and RK value (r=0.293) in PVWMH were positively correlated with the severity of cognitive impairment. There was no significant correlation between the indexes that reflecting the changes of microstructures in WMH-P and cognitive impairment. The CBF values in WMH and WMH-P were not significantly correlated with the severity of cognitive impairment.

Conclusions  In CSVD patients, the microstructural damages of DWMH, WMH-P of DWMH, and PVWMH were weakly correlated with cognitive impairment, but the microstructure in WMH-P of PVWMH was not correlated with cognitive impairment. In addition, blood perfusion in WMH and WMH-P was not correlated with cognitive impairment.

Key words: Three-dimensional arterial spin labeling; Diffusion kurtosis imaging; White matter hyperintensity; White matter hyperintensity penumbra; Cognition

摘要：

目的       探讨不同亚型脑白质高信号（white matter hyperintensity，WMH）及脑白质高信号半暗带（white matter hyperintensity penumbra，WMH-P）内血流灌注、微结构损伤与认知障碍的关系。

方法       前瞻性连续纳入2021年5月—2023年3月就诊于唐山市工人医院，WMH为改良Fazekas分级Ⅰ～Ⅱ级的脑小血管病（cerebral small vessel disease，CSVD）患者，进行包括三维动脉自旋标记（three-dimensional arterial spin labeling，3D-ASL）、弥散峰度成像（diffusion kurtosis imaging，DKI）序列在内的3.0 T MRI扫描。分析患者深部脑白质高信号（deep white matter hyperintensity，DWMH）感兴趣区（region of interest，ROI）（界定为ROI1）及其WMH-P感兴趣区（内层为ROI1-1，外层为ROI1-2），脑室旁脑白质高信号（periventricular white matter hyperintensity，PVWMH）感兴趣区（界定为ROI2）及其WMH-P感兴趣区（内层为ROI2-1，外层为ROI2-2）内血流灌注指标——脑血流量（cerebral blood flow，CBF），以及反映微结构改变的指标——轴向扩散系数（axial diffusivity，AD）、平均扩散系数（mean diffusivity，MD）、径向扩散系数（radial diffusivity，RD）、轴向峰度（axial kurtosis，AK）、平均峰度（mean kurtosis，MK）、径向峰度（radial kurtosis，RK）、各向异性分数（fraction anisotropy，FA）。评估患者的认知功能，用Spearman相关分析计算不同亚型WMH（DWMH和PVWMH）及其WMH-P内上述反映血流灌注和微结构改变的指标与认知障碍严重程度的相关性。

结果       共纳入61例CSVD患者，平均年龄（61±1）岁。DWMH（ROI1）内RD值（r=0.296）与认知障碍严重程度呈正相关，MK值（r=－0.287）、RK值（r=－0.315）与认知障碍严重程度呈负相关；其WMH-P内AD值（ROI1-1：r=0.274；ROI1-2：r=0.261）、MD值（ROI1-1：r=0.370；ROI1-2：r=0.387）、RD值（ROI1-1：
r=0.411；ROI1-2：r=0.430）与认知障碍严重程度呈正相关，AK值（ROI1-1：r=－0.270；ROI1-2：
r=－0.297）、MK值（ROI1-1：r=－0.367；ROI1-2：r=－0.325）、RK值（ROI1-1：r=－0.379；ROI1-2：
r=－0.309）、FA值（ROI1-1：r=－0.286；ROI1-2：r=－0.256）与认知障碍严重程度呈负相关。PVWMH（ROI2）内MK值（r=0.354）、RK值（r=0.293）与认知障碍严重程度呈正相关；其WMH-P内各微结构改变的指标与认知障碍严重程度的相关性均无统计学意义。WMH及WMH-P内CBF值与认知障碍严重程度的相关性均无统计学意义。

结论       CSVD患者DWMH及其WMH-P、PVWMH内微结构损伤与认知障碍存在弱相关性，但PVWMH周围WMH-P内的微结构与认知障碍无相关性；WMH及WMH-P内血流灌注与认知障碍无相关性。

关键词: 三维动脉自旋标记；弥散峰度成像；脑白质高信号；脑白质高信号半暗带；认知功能