非痴呆型皮质下小血管性认知障碍患者的MRI、DTI表现

A Study of Conventional MR and Diffusion Tensor Imaging in Patiens with Vascular Cognitive Impairment no Dementia with Subcortical Small Vessel Disease

目的探讨常规磁共振成像(MRI)和扩散张量成像(DTI)在非痴呆型皮质下小血管性认知障碍(VCIND-SSVD)诊断中的价值。方法采用蒙特利尔认知量表(MoCA)、简易智能状态检查量表(MMSE)对26例非痴呆型血管性认知障碍和24例正常对照者的认知功能进行评价,通过常规MRI分析两组脑叶萎缩、皮质下白质疏松和腔隙性脑梗死等影像学参数的差异;通过DTI技术测量双侧额叶、顶叶、颞叶、枕叶、内囊前肢、内囊膝部及内囊后肢的分量各向异性(FA)和平均扩散率(MD)的差异;对VCIND-SSVD组患者MoCA总分及其子项评分与FA和MD进行相关分析。结果常规MRI显示脑叶萎缩、皮质下白质疏松和腔隙性脑梗死等影像学参数在两组间无明显差异,与认知功能无明显相关(均P>0.05)。VCIND-SSVD组双侧额叶FA值与对照组比较明显下降,差异有统计学意义(均P<0.01);VCIND-SSVD组双侧额叶MD值与对照组比较明显升高,差异有统计学意义(均P<0.01);两组间顶叶、颞叶、枕叶、内囊前肢、内囊膝部及内囊后肢的FA、MD值差异均无统计学意义(均P>0.05)。VCIND-SSVD组患者双侧额叶FA值下降程度与MoCA评分及注意力、语言功能、抽象概括能力、视空间与执行能力等子项评分均呈正相关,(r=0.43~0.71,P<0.05,<0.01),MD值升高程度与MoCA评分及注意力、语言功能、抽象概括能力、视空间与执行能力等子项评分均呈负相关(r=-0.43^-0.67,P<0.05,<0.01)。结论 VCIND-SSVD患者认知功能损害可能与双侧额叶白质损伤有关,DTI在VCIND早期诊断中起着重要的作用。

Objective To evaluate the roles of conventional magnetic resonance imaging（MRI） and diffusion tensor imaging（DTI） in vascular cognitive impairment no dementia with subcortical small vessel disease（VCIND-SSVD）. Methods Twenty-six VCIND-SSVD patients and 24 normal controls were studied.Evaluated the cognitive functions by Montreal cognitive assessment（MoCA） and mini-mental status examation（MMSE）,and investigated the brain structural MRI parameters including lobar atrophy,white matter leukoaraiosis and lacunar infarction.All patients and controls received conventional MRI and DTI examination.For each individual,regional fractional anisotropy（FA） and mean diffusivity（MD） in white matter of bilateral frontal lobe,parietal lobe,temporal lobe,occipital lobe,anterior limb of internal capsule,genu of internal capsules and posterior limb of internal capsule were measured and were compared between the two groups.Meanwhile,the correlations between scores of MoCA and its sub-items and FA and MD value were analyzed in VCIND-SSVD group.Results No significant diference was found by the brain structural MRI parameters including lobar atrophy,white matter leukoaraiosis and lacunar infarction between two groups（all P0.05）.Compared with control group,FA was significantly decreased and MD was significantly increased in white matters of bilateral frontal lobe（all P0.01）;No significant diference was found in FA and MD in bilateral parietal lobe,temporal lobe,occipital lobe,anterior limb of internal capsule,genu of internal capsules and posterior limb of internal capsule（all P0.05）.In VCIND-SSVD group,significant positive correlation was found between FA value in white matters of bilateral frontal lobe and the MoCA total score（left r=0.62,right r=0.59） as well as the sub-scores in tested items of attention（left r=0.71,right r=0.52）,language（left r=0.44,right r=0.43）,linguistic competence（left r=0.47,right r=0.54） and visuospatial or executive（left r=0.63,right r=0.61,all P0.05 or P0.01）.Significant negative correlation was identified between the MD value of bilateral frontal lobe and the MoCA total score（left r=-0.61,right r=-0.55）as well as the sub-scores in tested items of attention（left r=-0.67,right r=-0.50）,language（left r=-0.58,right r=-0.43）,linguistic competence（left r=-0.55,right r=-0.49）and visuospatial or executive（left r=-0.59,right r=-0.52 all P0.05 or P0.01）.Conclusions Cognitive impairment in patients with VCIND-SSVD maybe related to white matter lesion in bilateral front lobe.DTI plays an important role in early diagnosis of VCIND-SSVD.Conventional MRI plays an unimportant role in evaluation of cognitive functions of patients with VCIND-SSVD.