血管性痴呆的扩散张量成像研究

Diffusion tensor imaging study of vascular dementia

目的应用扩散张量成像(DTI)技术,探讨皮质下缺血性血管性痴呆(SIVD)患者脑白质变化的特点及不同脑区DTI参数改变与认知的关系。方法对34例SIVD患者(SIVD组)及26例健康老年人(对照组)行DTI扫描,测量双侧前额叶、额叶深部、眶额内侧、下额叶、颞叶、顶叶、枕叶白质及T_2WI高信号区、T_2WI高信号周围正常白质区的分量各向异性(FA)、主各向异性(PA)及表观弥散系数(ADC)值。结果对照组左侧前额叶白质PA值大于右侧,ADC值小于右侧。SIVD组双侧前额叶、双侧额叶深部、下额叶、眶额内侧的FA值及PA值明显下降,平均ADC值升高;双侧顶叶的FA值下降,平均ADC值升高;双侧颞叶、枕叶平均ADC值升高;左侧下额叶、眶额内侧白质的FA与PA值较右侧小;左侧下额叶ADC值较右侧大。病变区及病变周围区的FA和PA值小于正常区,ADC值大于正常区。前额叶FA与简易智能状态检查表评分呈正相关。结论 SIVD患者脑白质FA、PA和ADC改变具有区域选择性,前部及左侧脑区损伤明显,后部及右侧相对保留白质的完整性。DTI是研究SIVD脑白质损伤的一种理想的方法。

Objective To investigate the abnormality of white matter（WM） using diffusion tensor imaging（DTI） in subcortical ischemic vascular dementia（SIVD） and the relationship between the DTI paremeters in different regions and cognitive status. Methods Thirty-four SIVD patients and 26 age-matched nondemented older adults were studied. All patients and controls received DTI examination. For each individual, regional fractional anisotropy（FA）, principal anisotropy （PA） and apparent diffusion coefficient（ADC） were measured from prefrontal WM,deep frontal WM, inferior frontal WM, medial orbitofrontal WM, temporal lobe WM, parietal lobe WM and oc- cipital lobe WM and within hyperintensities identified on TzWI and outside these lesions. Results PA value of left prefrontal WM was greater than right side in control group. In SIVD group,in addition to the areas of T2-weighted MR imaging hyperintense and perilesion areas, FA, PA decreased and ADC increased in prefrontal WM, deep frontal WM,inferior frontal WM, medial orbitofrontal WM. FA decreased and ADC increased in parietal lobes. ADC values increased in temporal lobe WM and occipital lobe WM. In SIVD group, FA and PA values of left inferior frontal WM and medial orbitofrontal WM were lower than those of right side,and ADC of left inferior frontal WM was greater than that of right side. Significant positive correlation was found between MMSE score and FA of prefrontal WM. Conclusion These results indicate that changes of FA, PA and ADC of WM have regional selection in SIVD,anterior regions and left side of brain are most vulnerable to small vascular disease injury, while posterior region and right side relatively remain intact.