正常区域局部脑血流下降与老年脑白质损害严重程度的相关性

Relationship between reduction of regional cerebral blood flow in normal appearing white matter and the extent of age-related white matter lesions

目的 测量老年人脑白质损害（white matter lesions,WML）者WML区域及病灶周围表现正常的白质（normal appearing white matter,NAWM）区域的脑血流量,探讨NAWM区域局部脑血流（regional cerebral blood flow,rCBF）下降与WML严重程度的相关性.方法 采用Fazekas量表,根据MRI显示的WML严重程度将56名60岁以上的健康体检者分为0级、Ⅰ级、Ⅱ级及Ⅲ级4组.采用Xe-CT技术测量病损区及周边NAWM区域的rCBF.结果 共有56名年龄为（67.4±8.2）岁的老年人入组,侧脑室周边、右侧及左侧半卵圆区病损区域平均rCBF（ml·100 g-1·min-1）为：Ⅰ级：20.33±2.52、21.27±1.02、21.03±1.83;Ⅱ级：16.33±2.03、15.55±1.71、15.91±0.98;Ⅲ级：14.05±2.63、14.46±2.17、14.23±1.95.侧脑室周边、右侧及左侧半卵圆区病损周围NAWM平均rCBF（ml·100g-1 ·min-1 min-1）为：0级：20.79±2.78、22.26±1.9、22.15±2.4;Ⅰ级：21.12±2.95、22.17±1.50、22.25±2.13;Ⅱ级：18.02±2.41、19.45±1.94、19.62±1.54;Ⅲ级：16.38±3.22、18.18±2.84、16.74±2.97.组间分析发现,Ⅱ级和Ⅲ级WML患者各病损区的rCBF与Ⅰ级者相比,差异有统计学意义（P＜0.05）;Ⅱ级和Ⅲ级WML患者病损区与其周围NAWM rCBF相比,差异有统计学意义（P＜0.05）;Ⅱ级和Ⅲ级WML患者的NAWM与0级及Ⅰ级者相比,rCBF均有显著下降（P＜0.05）;0级与Ⅰ级之间NAWM的rCBF差异无统计学意义;病损区及其周围NAWM区域的rCBF在不同部位无明显差异.结论 慢性缺血不仅存在于病损区域,且存在于病损NAWM区域,缺血程度与病损严重性密切相关.慢性缺血在老年性WML发病机制中起着重要作用.

Objective To explore the relationship between reduction of regional cerebral blood flow in the normal appearing white matter （NAWM） and the extent of age-related white matter lesions （WML）.Methods We used Fazekas scale to divide all participants into four groups （normal,mild,moderate,severe） according to the extent of the lesions showed on MRI.Regional cerebral blood flow （rCBF） in the area of WML and NAWM was measured by xenon contrast CT examination.Results A total of 56 cases were selected.The average rCBF （ml · 100 g-1 · min-1） in the lesions （WML） around ventricle,in right centrum ovale and in left centrum ovale respectively was 20.33 ± 2.52,21.27 ± 1.02,21.03 ± 1.83 for mild; 16.33 ±2.03,15.55 ±1.71,15.91 ±0.98 for moderate; 14.05 ±2.63,14.46 ±2.17,14.23 ± 1.95 for severe.The average rCBF （ml · 100 g-1 · min-1） in the NAWM around ventricle,in right centrum ovale and in left centrum ovale respectively was 20.79 ± 2.78,22.26 ± 1.9,22.15 ± 2.4 for normal; 21.12 ± 2.95,22.17 ± 1.50,22.25 ± 2.13 for mild,18.02 ± 2.41,19.45 ± 1.94,19.62 ± 1.54for moderate; 16.38 ± 3.22,18.18 ± 2.84,16.74 ± 2.97 for severe.The decrease of rCBF in the severe and moderate lesion areas was more serious than that in the mild lesion areas and reached statistic significance （P ＜ 0.05） ; The decrease of rCBF in the severe and moderate lesion areas was more serious than that in the area of NAWM in the same grade and reached statistic significance （P ＜ 0.05）.The decrease of rCBF in the area of NAWM around severe and moderate lesion areas was more serious compared with that around mild lesion areas or normal areas （P ＜ 0.05） ; But the difference of rCBF in the area of NAWM around mild lesion areas and normal areas did not show any statistic significance.Conclusions Chronic ischemia was found to be existed not only in the lesions （WML） but also in the area of NAWM around the lesions,and was related to the extent of the lesions.Chronic ischemia may play a key role in the mechanism of aged-related WML.