磁共振弥散张量成像对正常成年人胼胝体性别差异的初步研究

目的:描述正常成年人胼胝体的微结构特征,探讨磁共振弥散张量成像(diffusion tensorimaqinq,DTI)对其微结构评价的价值。方法:对61例健康成年人(20-30岁:男30例,女31例)行脑部常规MRI和DTI扫描,DTI使用自旋回波一平面回波成像(SE-EPI)序列。在基底节层面,选定胼胝体膝部和压部为兴趣区,测量部分各向导性值(fractional anisotropy,FA)并做相应统计学处理。结果:在胼胝体膝部,男性的FA值为0.724±0.04,女性的FA值为0.698±0.05,男女胼胝体膝部的各向异性值存在显著性差异(P<0.05);胼胝体压部,男性的FA值为0.716±0.05,女性的FA值为0.695±0.05,男女胼胝体压部的各向异性值存在显著性差异(P<0.05)。结论:(1)正常成年男女胼胝体膝、压部神经纤维排列存在差异;(2)DTI可以无创地对活体白质纤维束排列进行定量研究。     

磁共振弥散张量成像在中枢神经系统中的临床应用

磁共振弥散张量成像是在磁共振成像基础上发展起来的,利用水分子的弥散来成像的影像学方法,可以定量观察活体组织的弥散特征,了解组织纤维的走行方向和完整性,为临床提供组织早期病变的微观结构和微观动力学信息;是无创性检查深部组织的有效方法,尤其是在脑白质病变的应用。     

脑小血管疾病磁共振波谱和张量成像分析

目的应用磁共振波谱(MRS)联合磁共振张量(DTI)研究脑小血管疾病(SVD)患者的白质损害程度,为SVD导致认知障碍提供进一步的研究。方法 SVD患者12例,正常对照组6例,采用MRS和DTI成像,感兴趣区(ROI)选择半卵圆中心层面,MRS成像测定ROI区乙酰天门冬氨酸(NAA)/肌酸(Cr)和胆碱(Cho)/Cr值。DTI成像获得平均弥散(MD)图和部分各向异性(FA)图,选择与MRS一致的白质ROI区进行测量。结果双侧MD值、左侧FA值两组间有统计学差异,而MRS参数NAA/Ch、Ch/Cr、NAA/Cr两组无统计学差异。结论通过MRS和DTI技术,可以无创敏感检测SVD患者较正常对照组颅内半卵圆中心白质结构有明显受损,但该区主要脑代谢物浓度改变并不明显,说明SVD认知障碍机制可能主要与白质结构受损有关,而与脑代谢可能关系不大。     

伴有颅内动脉狭窄的缺血性脑卒中患者脑血管储备能力研究

目的 对伴有颅内动脉狭窄的缺血性脑卒中患者采用口服乙酰唑胺实验研究颅内大动脉血流储备能力.方法 对17例经磁共振血管显影(magnetic resonance angiography, MRA)/或经颅多谱勒超声(transcranial doppler ultrasonography, TCD)证实颅内动脉狭窄大于50%的缺血性脑卒中患者,按TOAST分型为动脉粥样硬化性脑梗死,通过TCD共测定187条颅内大血管血流速度,2 d后再口服乙酰唑胺2 g, 2 h后再行TCD检查,比较乙酰唑胺前后颅内大血管血流速度改变情况.结果 乙酰唑胺实验可使颅内血管血流速度明显增加.右颈内动脉(right internal carotid artery,RICA)、右大脑中动脉(right middle cerebral artery,RMCA)和右大脑后动脉(right posterior cerebral artery,RPCA)在乙酰唑胺后血流速度增加但无统计学差异(P值分别为0.086,0.258,0.084),而其他颅内血管在乙酰唑胺后血流速度显著增加(P值都小于0.05).非狭窄血管较狭窄血管乙酰唑胺后血流速度增加,但无统计学差异(P=0.08).中度狭窄血管与重度狭窄血管乙酰唑胺后血流速度改变无差异(P=0.65).结论 乙酰唑胺前后TCD可以准确测定颅内大动脉的血管血流储备能力,颅内狭窄血管较非狭窄血管血流储备能力有下降的趋势,而中度和重度狭窄血管血流储备能力无明显差异,但仍有待进一步的研究.     

阳性症状为主型精神分裂症首次发病患者前额叶和海马磁共振质子波谱成像研究

目的 探讨阳性症状为主型精神分裂症首次发病患者前额叶和海马的磁共振质子波谱(1H-MRS)变化特点,为其病因学探讨提供线索.方法 对22例首次发病精神分裂症阳性症状为主型患者(患者组)和11名年龄、性别、受教育时间均匹配的正常对照者(对照组),应用2D 1H-MRS成像技术检测2组双侧前额叶白质、前扣带回皮质、海马N-乙酰天门冬氨酸(NAA)、胆碱(Cho)、肌酸(Cr)3种代谢物,分别计算NAA/Cr和Cho/Cr的比值;采用配对t检验、独立样本t检验进行统计分析.结果 (1)患者组左侧额叶白质NAA/Cr和Cho/Cr分别为(1.63±0.30)和(1.23±0.26),均低于对照组[(2.10±0.30)、(1.54±0.25)],右侧额叶白质NAA/Cr(1.70±0.34)低于对照组(1.97±0.34),差异有统计学意义(P<0.01和P<0.05);(2)双侧前扣带回皮质NAA/Cr、Cho/Cr值与对照组差异无统计学意义(P>0.05);(3)患者组右侧海马NAA/Cr(1.59±0.27)高于对照组(1.24±0.17),差异有统计学意义(P<0.01);(4)对照组内左侧额叶白质Cho/Cr(1.54±0.25)高于右侧(1.35±0.18),左侧海马NAA/Cr(1.45±0.28)高于右侧(1.24±0.17),差异均有统计学意义(P<0.05);(5)患者组内左侧海马NAA/Cr和Cho/Cr分别为(1.43±0.27)和(1.39±0.38),均低于右侧[(1.59±0.27)、(1.56±0.39)],差异有统计学意义(P<0.05).结论 首发精神分裂症阳性症状为主型患者的1H-MRS代谢物与正常人存在差异,提示阳性症状为主型患者存在双侧前额叶白质、海马的神经功能障碍.

Abstract：

Objective To identify the possible alteration of brain functioning in prefrontal lobes and hippocampus in the first-episode positive symptoms of schizophrenia using proton magnetic resonance spectroscopy (1H-MRS). Methods 1H-MRS was performed on prefrontal white matter, anterior cingulated cortex and hippocampus in 22 patients and 11 age-, sex-, and education-matched right-handed healthy controls. The ratios of N-acetylaspartate (NAA)/creatine (Cr) and choline-containing compounds (Cho)/Cr were calculated. Results The NAA/Cr and Cho/Cr ratios in the left prefrontal white matter in patients were lower than that in normal controls (patients, NAA/Cr 1. 63 ±0. 30; Cho/Cr 1. 23 ±0. 26; controls, NAA/Cr 2. 10 ±0. 30; Cho/Cr 1. 54 ± 0. 25, P<0. 01) , and NAA/Cr in the right prefrontal white matter was lower in patients than in controls (patients 1. 70 ± 0. 34; controls 1. 97 ± 0. 34, P<0. 05). There were no significant difference in NAA/Cr, Cho/Cr for the bilateral anterior cingulated cortex between patients and controls (P>0. 05). The ratio of NAA/Cr in the right hippocampus was significantly higher in patients than that in controls (patients 1. 59 ± 0. 27; controls 1. 24 ± 0. 17, P<0. 01). In addition, in healthy controls,Cho/Cr was significantly higher in the left prefrontal white matter than in the right (left 1. 54 ± 0. 25; right 1. 35 ±0. 18, P<0. 05) , and NAA/Cr in the left hippocampus was significantly higher than in the right (left 1. 45 ± 0. 28; right 1. 24 ± 0. 17, P<0. 05). While NAA/Cr and Cho/Cr in the left hippocampus were significantly lower than in the right hippocampus in schizophrenia patients (left, NAA/Cr 1.43 ± 0. 27;Cho/Cr 1.39 ±0.38; right, NAA/Cr 1.59 ±0.27; Cho/Cr 1.56 ±0.39, P<0.05). Conclusion There is the significant difference of manifestation of 1H-MRS between schizophrenia patients with positive symptoms and normal controls, which reflects neuronal dysfunction in the prefrontal lobes and hippocampus.