儿童屈光参差性弱视的fMRI研究

目的利用血氧水平依赖性功能性磁共振成像（BOLD—fMRI）技术研究儿童屈光参差性弱视大脑视觉皮层功能受到的影响。资料与方法以1．5T磁共振成像系统采集8例儿童屈光参差性弱视的枕叶视皮层兴趣区BOLD-fMRI数据,比较其弱视眼与健眼,及弱视眼屈光矫正前后皮层激活强度及范围的不同,分析其改变特点及机制。结果弱视眼皮层神经元的反应水平及激活范围在Brodmann 17、18、19区均明显小于对侧眼,并且这种差别在Brodmann 18、19区更加明显。弱视眼矫正屈光不正后皮层活动水平明显增高,激活范围明显增大。结论屈光参差性弱视各级视觉皮层均发生了明显的功能损害,高级别纹外皮层可能比低级别纹状皮层损害更加明显;弱视眼矫正屈光不正可部分提高皮层活动能力及活动范围,屈光参差性弱视患者应尽早手术或配镜矫正。     

近视性屈光参差的功能性磁共振成像研究

目的利用血氧水平依赖性功能性磁共振成像(BOLD-fMR I)技术,探索人类近视性屈光参差是否对大脑皮层功能和结构造成影响。方法采用无磁MR I专用眼镜纠正屈光不正,以1.5T磁共振成像系统采集8例近视性屈光参差者枕叶视皮层兴趣区BOLD-fMR I数据,比较双眼皮层激活部位及范围的不同,及视力较差眼屈光纠正前后皮层激活情况的变化,分析其改变特点及机制。结果矫正屈光基础上,近视性屈光参差者双眼激活范围没有明显差异(P>0.05);视力较差眼屈光矫正前后皮层激活范围有明显差异(P<0.05)。结论人类近视性屈光参差可能没有发生明显的皮层功能损害及优势眼的转移;配镜可明显提高视力较差眼的皮层激活,应尽早配镜或手术矫正。     

屈光参差性弱视皮层功能损害fMRI视网膜脑图研究

目的 利用血氧水平依赖性功能磁共振成像(BOLD fMRI)视网膜脑图技术(retinotopic mapping),研究屈光参差性弱视皮层功能损害的发生机制. 资料与方法 以1.5T MRI系统采集8例单眼屈光参差性弱视患者枕叶视觉皮层对于视网膜脑图刺激和6 cpd空间频率黑白光点刺激的功能数据,比较弱视眼和健眼在初、高级视觉皮层功能区功能反应;对初、高级皮层间功能损害进行回归分析. 结果 弱视眼在V1、V2、V3、VP、V7区反应T值低于健眼( P＜0.05 ),在V3a、V4、V8区弱视眼与健眼T值无统计学差异;V1区与V2、V3、VP、V7区之间反应减低相关分析无统计学意义( P＞0.05 ). 结论 弱视患者初、高级视觉皮层均存在功能损害,两者之间无明显因果关系;在高级视觉皮层,背、腹侧传导通路均有功能损害;fMRI视网膜脑图技术为深入研究弱视初、高级视觉皮层功能损害的发病机制提供了新的方法.     

原发性开角型青光眼V1区皮层功能变化的功能MRI研究

目的 利用fMRI视网膜皮层映射技术研究原发性开角型青光眼(POAG)患者V1区皮层功能变化.方法 选取15例POAG患者及15名正常志愿者,利用视网膜皮层映射分区刺激和圆形黑白翻转棋盘格刺激采集fMRI数据.采用配对样本t检验比较POAG患者患侧眼与健侧眼V1区的fMRI反应、独立样本t检验比较健侧眼与匹配的正常人眼V1区的fMRI反应和激活.POAG患者患侧眼和健侧眼单独刺激时的V1皮层功能差异与视功能差异做线性相关分析.结果 (1)患侧眼接受刺激时V1区fMRI反应较健侧眼弱(t=4.757,P<0.01),患侧眼和健侧眼fMRI反应分别为(1.24±0.72)%、(2.18±0.93)%.患侧眼、健侧眼分别与其年龄、性别、眼侧别相匹配的正常人眼V1区fMRI反应进行比较:患侧眼较正常人眼反应弱(t=-3.011,P<0.01),患侧眼和匹配眼fMRI反应分别为(1.24±0.72)%、(2.01±0.65)%;健侧眼和匹配眼反应差异无统计学意义(t=0.742,P＞0.05),健侧眼和匹配眼分别为(2.18±0.93)%、(1.95±0.75)%.(2)患侧眼与健侧眼单独刺激的V1皮层功能差异与视功能差异存在线性负相关(r=-0.887,P<0.01).(3)患者的健侧眼与其年龄、性别、眼侧别相匹配的正常人眼比较,患者健侧眼V1激活较正常人眼小(t=-3.801,P<0.01),健侧眼和匹配眼V1激活面积指数分别为0.72±0.12、0.85±0.09.结论 青光眼存在皮层功能损害,而且青光眼皮层功能的损害与视觉功能的损害存在相关一致性;基于fMRI视网膜皮层映射分区的定位、定量测量是一种对青光眼视觉皮层功能变化临床随访、评估测量的有用方法,也是活体人青光眼视觉通路跨突触退变研究的潜在有用工具.     

弱视视觉运动功能的功能磁共振研究

目的 采用功能磁共振成像（fMRI）技术分别对屈光不正及斜视性弱视在视觉运动刺激时的皮层反应进行观察，探索不同弱视的视觉运动受影响机制。方法 采用旋转光栅／静止光栅为视觉运动刺激源，在1．5T的磁共振仪下分别对7例临床诊断为屈光不正型弱视及10例斜视型的弱视患者在单眼刺激下行功能磁共振检查，SPM（statistical parametric mapping）软件进行数据处理，结果 采用单样本数据分析。并设定双眼间反应体素差异水平指数，采用Mann-Whitney秩和检验，用以判断双眼分别刺激时皮层反应的差异水平。结果 两组样本中，双侧枕叶视觉运动功能区域有不同程度的反应，弱视眼刺激较正常眼有额外的额叶反应。以中颞（MT）区为感兴趣区进行分析，7例屈光不正型弱视患者中，弱视眼反应水平相比正常眼均下降，10例斜视性弱视，除1例无任何反应外，5例弱视眼反应水平较正常眼下降，4例较正常增高。两组数据体素差异水平指数（1AD）之间有统计学差异（Z=2．382，P=0．017）。结论 单眼视觉运动刺激时，弱视眼比正常眼有更多的脑区参与反应。屈光不正型弱视皮层可能存在视觉运动功能的下降，斜视性弱视功能受损情况可能与弱视的程度有关；提示两种弱视的视觉运动功能受损情况不一致。     

准分子激光原位角膜磨镶术矫治儿童单纯远视性屈光参差

目的评价准分子激光原位角膜磨镶术(LASIK)矫治儿童单纯远视性屈光参差的临床疗效。方法采用Summit公司的SVSApexplus准分子激光系统,对22例远视儿童患者(7~15岁)绝对散光值低于1.25D的22只眼进行LASIK手术,最大预矫值 6.00D。术后1个月开始行弱视治疗。随访时间12个月以上。结果术前,球镜屈光度: 5.50~ 9.00( 6.25±0.43)D,柱镜屈光度:0.00~-1.25(-0.73±0.33)D,两眼等值球镜屈光度差值: 4.25~7.75( 6.13±0.51)D,裸眼远视力:0.05~0.3(0.12±0.10)D,裸眼近视力:0.1~0.5(0.19±0.14)D,矫正远视力:0.05~0.4(0.20±0.13)D,矫正近视力:0.1~0.6(0.27±0.16)D。术后12月,球镜屈光度:-0.50~ 0.75( 1·02±0.51)D,柱镜屈光度:0.00~-1.75(-0.52±0.51)D,两眼等值球镜屈光度差值:0.00~1.75(0.86±0.55)D,平均裸眼远视力:0.1~0.5(0.25±0.13)D,平均裸眼近视力:0.1~1.2(0.53±0.38)D,平均矫正远视力:0.1~0.6(0.29±0·17)D,平均矫正近视力:0.1~1.2(0.56±0.37)D。所有手术眼均未见最佳矫正视力丢失。结论LASIK矫治儿童单纯远视性屈光参差是安全、有效的,可明显减少双眼屈光参差度。术后辅以弱视治疗疗效显著。     

基于体素的形态测量学方法研究屈光参差性弱视患儿的相关区域脑结构

目的 利用基于体素的形态测量学(VBM)分析屈光参差性弱视患者全脑灰、白质体积变化.方法 采用1.5 TMR扫描仪对12例屈光参差性弱视患儿和年龄、性别相匹配的12名正常志愿者行3D快速扰相梯度回波(FSPGR)序列的全脑扫描.原始数据用统计参数图(SPM)5软件进行处理.结果 与正常对照组相比,弱视组脑灰质体积减少的脑区包括右侧楔叶、双侧枕中下回、右侧额中回、左侧颞中回、右侧颞上回、右侧楔前叶、右侧中扣带回(差异脑区体素＞ 10个).弱视组脑灰质体积增多的脑区包括右侧小脑半球、右侧海马旁回、左侧中央前回、左侧额上回(差异脑区体素＞ 10个).与对照组比较,弱视组脑白质体积减少的脑区包括双侧视放射区、双侧内囊,以右侧为著(差异脑区体素＞10).未见弱视组脑白质体积增多的脑区.结论 运用VBM方法可分析屈光参差性弱视患者全脑灰、白质体积变化,有助于从形态学的角度阐述屈光参差性弱视的可能神经机制.     

飞秒激光小切口基质透镜取出术治疗近视性屈光参差的临床研究

目的研究飞秒激光小切口基质透镜取出术(small incision lenticule extraction,SMILE)治疗近视性屈光参差的治疗效果。方法采用回顾性研究,近视患者19例30只眼,采用SMILE矫正,记录术前,术后1天,术后1周,术后1、3、6个月的裸眼视力、最佳矫正视力、屈光度、屈光参差程度进行对比研究。结果 30只眼术后裸眼视力均显著提高,术后1天、1周、1个月裸眼视力呈逐渐上升趋势(P0.05),而术后1、3、6个月裸眼视力稳定,差异均无统计学意义(P0.05);所有患者,按近视程度较高眼及近视程度较低眼分别统计,术后1天,1周,1、3、6个月的双眼裸眼视力之间无统计学差异(P0.05);术后3只眼最佳矫正视力提高一行,未出现最佳矫正视力下降的情况;所有患者术后屈光参差均得到有效矫正,术后1天,1周,1、3、6个月同一患者的近视程度较高眼与近视程度较低眼的屈光度无统计学差异(P0.05);术后双眼屈光度差值平均为(0.40±0.27)D。结论 SMILE治疗近视性屈光参差术后视力好、屈光状态稳定、不受术前双眼近视程度差异的影响,是一种安全、有效、稳定性好的屈光参差矫正方法。     

嗅觉脑功能MRI对阿尔茨海默病的早期诊断

目的 探讨嗅觉功能MRI早期诊断阿尔茨海默病(AD)的价值.资料与方法 14例正常老年人(NC)、11例轻度认知障碍(MCI)患者及12例AD患者进行MMSE、MOCA及CDR量表评分,采用西门子3.0T磁共振扫描仪、32通道头线圈以事件相关设计的方式进行嗅觉fMRI扫描,64位Matlab 7.11.0及SPM8软件进行数据处理,选择双侧初级嗅觉皮层(POC)为感兴趣区(ROI),统计ROI内激活体素数量并进行分析,比较3组间ROI内的激活体素数量,分析受试者ROI内的激活体素数量与MMSE和MOCA评分的相关性.结果 NC组、MCI组和AD组POC内激活体素数分别为201±114、88±102、45±60,AD组激活水平显著低于MCI组及NC组,MCI组显著低于NC组,差异有统计学意义(H=13.272,P＜0.01).控制年龄因素时,受试者初级嗅觉皮层内的激活范围与MMSE评分(r=0.447,P＜0.05)及MOCA评分(r=0.421,P＜0.05)呈正相关.结论 嗅觉功能MRI可以反映AD病理改变造成的嗅觉功能损害,可能成为早期诊断AD的新方法,具有重要研究价值.     

阿尔茨海默病与轻度认知障碍患者初级嗅觉皮层的形态与功能改变

目的 确定阿尔茨海默病(AD)与轻度认知障碍(MCI)患者中初级嗅觉皮层的萎缩程度,并且探讨解剖学萎缩与嗅觉功能减低的内在联系.方法 选取12例AD、8例MCI患者和20名正常志愿者(NC),进行标准的嗅觉功能和神经学评分,而后进行高分辨率MRI和嗅觉fMRI.于T_1WI上确定初级嗅觉皮层的边界,并测量常规初级嗅觉皮层的容积,将此容积保存为ROI.然后采用事件相关的实验设计进行嗅觉fMRI,测量初级嗅觉皮层ROI内的激活体素.3组间的初级嗅觉皮层体积和激活范围比较采用Kruskal-Wallis秩和检验,如存在统计学差异则进行Bonferroni法两两比较.解剖学体积与激活范围情况的相关性在控制年龄因素下进行偏相关性分析.结果 NC、MCI和AD组初级嗅觉皮层的体积范围分别为3024～4734、1409～4553和1561～3759 mm~3,中位数分别为3749、2752和2156 mm~3;激活体素范围分别为0～2360、0～2160和0～100 mm~3,中位数分别为430、40和0 mm~3,NC、MCI和AD组初级嗅觉皮层体积和激活体素依次降低,差异有统计学意义(H值分别为14.942、16.587,P值均<0.05).初级嗅觉皮层内的激活与皮层体积的萎缩存在弱相关性(r=0.364,P=0.023).结论 AD初级嗅觉皮层存在明显萎缩与功能障碍,可以为AD的嗅觉功能障碍研究提供神经病理学和神经功能学依据.     

Quantitative morphology of the vertebral body cortex

Summary The vertebral bodies consist of two main structures, trabecular and cortical bone. The histological changes within the spine, especially in cortical bone, leading to osteoporotic fractures remain, however, poorly understood. Therefore, the complete front column of the spine was removed in 26 autopsy cases without skeletal diseases and in 11 cases with proven osteoporosis. A sagittal segment prepared through the center of all vertebral bodies was undecalcified embedded in plastic, ground to a 1-mm-thick block and stained using a modification of the von Kossa method. The analysis included measurement of the mean cortical thickness of both ventral and dorsal shell (from C3 to L5). The qualitative investigation of the structure of the cortical ring completed the analysis. The skeletally intact specimens had high cortical thickness values in the cervical spine (285 ± 22 μm), a decrease in the thoracic spine (244 ± 14 μm) and an increase in the lumbar spine (290 ± 15 μm). The mean thickness of the ventral shell is in general higher than the thickness of the dorsal shell. The cortical thickness of the spine showed no gender-specific differences (P = n.s.). There was a slight decrease in cortical thickness with age; however, this decrease and the correlation of cortical thickness to age was only significant below vertebral body T8 (r = 0.225 to 0.574; P_r < 0.05 to P_r < 0.005). Most interestingly, osteoporosis is characterized by a significant decrease in cortical thickness throughout the whole spine. This decrease in cortical thickness was more marked in the dorsal shell (P < 0.05) than in the ventral shell (ventral from C3 to T6 (P < 0.05) below T6 (P = n.s.). We therefore conclude that in osteoporosis, biomechanical competence is affected by both trabecular bone loss and decrease of cortical thickness. This suggests that, in addition to trabecular bone measurements, the cortical thickness is of special interest for diagnostic radiological examinations (CT) to yield clues about the risk of vertebral fractures.      

Radionuclide imaging of the adrenal cortex.

Adrenocortical scintigraphy provides information concerning cortical function that is not readily available by other means. The ability to map differential adrenal cortical function has great clinical utility and demonstrable cost-effectiveness in the evaluation of adrenocortical disease and in distinguishing benign from malignant lesions in patients with incidentally discovered adrenal masses.     

MR signal intensity of the perirolandic cortex in the neonate and infant

Our purpose was to study the magnetic resonance (MR) signal intensity of the perirolandic gyri perinatally and to correlate it with the histological findings in formalinfixed brains, focusing on myelination. MRI of 20 neurologically normal neonates and infants, of 37–64 weeks postconception (PCA), were studied retrospectively. We reviewed four formalin-fixed brains of infants 37–46 weeks PCA microscopically. The posterior cortex of the precentral gyrus (P-PRE) and the anterior cortex of the postcentral gyrus (A-PST) had different signal intensity from the adjacent surrounding cortex. On T1-weighted images P-PRE and A-PST gave higher signal 41–44 weeks PCA; on T2-weighted images, they gave lower signal 37–51 weeks PCA. Histological examination revealed very little myelination of the nerve fibres within both the P-PRE and the A-PST, while considerable myelination was present in the internal capsule and central corona radiata. The changes in signal intensity in the perirolandic gyri may reflect not only the degree of myelination but also the more advanced development of the nerve cells, associated with rapid proliferation and formation of oligodendroglial cells, synapses and dendrites. They could be another important landmark for brain maturation.     

Magnetic resonance imaging of the femoral neck cortex

Purpose: To determine the in vivo precision and accuracy of magnetic resonance imaging (MRI) in evaluating the thin (~mm) femoral neck cortex.

Material and Methods: Hip regions of 30 volunteers were scanned with standard 1.5T MRI twice with repositioning, and the images of the narrow-neck cross-sections were obtained. Two radiologists independently delineated periosteal and endosteal cortical boundaries, and several structural variables were determined. For precision, 95% limits of agreement and coefficients of variation were calculated. Accuracy was determined with phantoms.

Results: In vivo precision of the directly delineated measurements varied from 0.9% (periosteal circumference) to 1.6% (total area), while the precision of the calculated variables remained poorer, from 7.3% (cortical to total area ratio) to 15.1% (torsional rigidity). The root-mean-square error of the cortical thickness measurement was 0.15 mm.

Conclusion: Thin cortical bone at the narrowest location of the femoral neck can be delineated precisely and accurately with a standard clinical 1.5T MRI device. MRI provides a feasible tool for the assessment of mechanically important cortical bone at the femoral neck and may be of clinical utility in assessing hip fragility.