应用Xe-CT技术研究老年人脑白质损害(WML)的脑血管反应性(CVR)

Cerebrovascular reactivity(CVR) to acetazolamide in the elderly with different extent of white matter lesions(WML):an xenon-computed tomography study

目的观察老年人不同级别脑白质损害(white matter lesions,WML)的脑血管反应性(cerebrovascularreactivity,CVR)。方法根据头颅磁共振FLAIR序列显示的WML程度,应用Fazekas改良量表,将WML分为2个部位:皮层下深部白质区(subcortical deep white matter hyperintensity,SDWMH)及侧脑室周边区(periventricular hyperintensity,PVH);3个等级:0～1级;2级及3级。对所有研究对象给予1g乙酰唑胺静脉推注,应用氙气增强CT技术测定不同级别WML病损区域内负荷前后的局部脑血流(regional cerebral bloodflow,rCBF),观察其CVR。结果 33例对象纳入本研究,平均年龄(74.4±7.2)岁。不同级别SDWMH中,0～1级者负荷前rCBF(单位:mL.100g-1.min-1)为18.11,负荷后为32.99(P=0.000);2级者负荷前rCBF为14.60,负荷后为21.63(P=0.004);3级者负荷前rCBF为10.56,负荷后为10.63(P=0.448)。不同级别PVH中,0～1级者负荷前rCBF为23.55,负荷后为35.49(P=0.000);2级者负荷前rCBF为15.39,负荷后为16.03(P=0.032);3级者负荷前rCBF为10.35,负荷后为9.88(P=0.533)。结论无论是SDWMH,还是PVH,病损越严重,静息状态下rCBF越低;且乙酰唑胺负荷后rCBF增幅也越小,CVR越差。本研究结果提示,脑血流自动调节受损可能是老年WML的重要发病机制。

Objective To observe the relationship between the severity of white matter lesions （WML） and cerebrovascular reactivity（CVR）in normal elderly. Methods All participators were divided into 2 catigeries：subcortical deep white matter hyperintensity and periventricular hyperintensity （SDWMH） and periventricular hyperintensity （PVH）, and 3 grades： grade 0 - 1, grade 2 and grade 3, according to the severity of WML showing on the FLAIR sequence of MRI using modified Fazekas scale. The values of regional cerebral blood flow within lesions in all participators were measured using xenon contrast CT before and 20 minutes later after 1 g acetazolamide injection. Results A total of33 elderly peoples were enrolled in this study with the average age of （74.4 ＋ 7.2） years. In SDWMH group, regional cerebral blood flow （rCBF,mL · 100 g-1· min-1） was 18.11 vs 32.99 （P = 0. 000） in grade 0- 1;14.6 vs 21.63 （P =0.004） in grade 2;and 10.56 vs 10. 63 （P =0.448） before and after acetazotamide injection respectively. In PVH group, rCBF was 23.55 vs 35.49 （P = 0. 000） in grade 0 - 1 ~15.39 vs 16. 03（P= 0. 032） in grade 2; and 10. 35 vs 9. 88 （P = 0. 533）before and after acetazolamide injection, respectively. Conclusions The severity of WML both in SDWMH and in PVH is significantly associated with reduction of rCBF within lesions before and after acetazolamide injection and the poor CVR. This study shows that cerebral hemodynamics may play a key role on the pathogenesis of WML in the elderly.