多发性硬化颈髓病变磁化传递成像的临床应用

目的探讨3.0T磁共振扫描仪(Siemens Trio Tim)磁化传递成像(MTI)在多发性硬化(MS)颈髓病变中的应用价值及其与临床的关系。资料与方法对11例伴颈髓病变的MS患者和20名健康自愿者行颈髓常规MRI和MTI。测量健康自愿者C2～7水平、MS患者MS斑块及正常表观颈髓(NACC)的磁化传递率(MTR),对其进行对照研究,并分析MTR与扩展病残状态评分(EDSS)之间的相关性。结果健康自愿者颈髓平均MTR值为(27.12±0.27)%,C2～7水平间颈髓MTR值差异无统计学意义(P>0.05)。MS斑块组、NACC组及对照组间的MTR值差异均具有统计学意义(P<0.05)。MS斑块组的MTR值与EDSS值存在高度负相关(r=-0.754,P=0.007)。结论颈髓MTI能发现MS患者T2WI病灶以外的隐匿性损伤,为判断损害程度提供信息。     

磁化传递成像评估原发性骨质疏松症的价值北大核心CSCD

目的:探讨磁化传递成像(MTI)定量评估原发性骨质疏松症的应用价值。方法:回顾性分析159例行腰椎MR检查患者的资料,根据定量CT(QCT)结果分成骨质疏松组、骨量减低组和骨量正常组3组。测量腰2~4椎体磁化传递率(MTR)。比较组间MTR值的差异,绘制ROC曲线以分析MTR对骨质疏松及骨量减低的诊断效能。结果:随着骨密度的降低,椎体MTR值也减低,差异有统计学意义(P<0.001)。MTR值诊断骨量减低与骨质疏松的ROC曲线下面积(AUC)分别为0.875、0.944,MTR阈值分别为10.45、5.95,其诊断骨量减低、骨质疏松的灵敏度分别为78.90%、86.41%,特异度分别为86.84%、89.83%(P<0.001)。结论:MTI技术可以早期、灵敏地检测骨量变化,MTR值可作为骨质疏松症进展的生物学标志物。     

肌萎缩侧索硬化症的磁化传递成像研究

目的 探讨肌萎缩侧索硬化症(amyotrophic lateral sclerosis,ALS)锥体束和非锥体束区域的磁化传递成像(magnetization transfer imaging,MTI)特点以及锥体束的磁化传递率(MTR)与临床表现、常规MRI征象的关系.资料与方法 对20例ALS患者及16名健康自愿者(对照组)行常规头颅MRI及MTI.测量锥体束区5个位置及非锥体束区3个位置的MTR值.结果 确诊组ALS在锥体束5个位置上的MTR值均显著低于对照组(P＜0.01);疑似组ALS在其中3个位置上显著低于对照组(P＜0.01).确诊组ALS在胼胝体膝部的MTR值显著低于对照组(P＜0.05).患者组锥体束5个位置的MTR值与ALSFRS评分及病程间均无相关性.结论 MTI是诊断ALS有效且敏感的检查方法,ALS存在锥体束以外脑组织的变性改变.     

磁化传递成像观察多发性硬化大鼠中枢神经系统病灶

目的：探索应用3.0T临床型MR设备进行磁化传递成像（MTI）观察多发性硬化（MS）大鼠中枢神经系统病灶的可行性。方法：用髓鞘少突胶质细胞糖蛋白多肽35-55（MOG35-55）致敏Lewis大鼠制备MS动物模型实验性自身免疫性脑脊髓炎（EAE）大鼠10只,正常对照组大鼠4只。3.0T临床型MR扫描仪配备小正交腕关节线圈,分别对大鼠脑和脊髓行T2W、T1磁化传递和T1非磁化传递三维容积扫描。利用工作站专业软件获得磁化传递率（MTR）图像。结果：成功建立MOG35-55-EAE模型大鼠10只。大鼠脑和脊髓的MTR图像具有较高的空间分辨率和对比度。MOG35-55-EAE病灶在T2WI上呈高信号,在MTR图像上表现为MTR值下降,呈低信号,在T1WI上呈低信号或者等信号。MTR图像对MOG35-55-EAE病灶检出率高,病灶显示清晰。对照组大鼠MR扫描未见异常。结论：应用3.0T临床型MR设备可以获得高质量的MOG35-55-EAE大鼠脑和脊髓MTR图像。MTI有望成为小动物中枢神经系统脱髓鞘疾病实验研究的体外监测手段。     

肝纤维化和肝硬化磁化传递成像与血清学指标相关性研究

目的 探讨肝纤维化和肝硬化病人磁化传递率(MTR)与血清学指标的相关性,以及对肝硬化早期诊断的价值.方法 分别对44例肝纤维化病人、49例肝硬化病人及46例正常对照组利用磁共振磁化传递成像(MTI)进行检查,并对MTR与血清学指标对照,采用Kruskal-Waills进行非参数统计分析,采用Pearson相关性检验及偏相关性检验进行相关性分析.结果 对照组、肝纤维化组、肝硬化组磁化传递率差别无统计学意义(H=3.558, P=0.169);肝纤维化组Pearson相关分析显示磁化传递率与透明质酸(HA)(r=0.724, P=0.000)和IV型胶原(r=0.425,P=0.038)正相关;偏相关显示磁化传递率仅与透明质酸(HA)相关(r=0.8748,P=0.000).结论 磁化传递率可间接反映肝纤维化胶原沉积情况,MTI技术和透明质酸等血清学检查指标相结合,在预测肝纤维化和肝硬化等弥漫性病变的早期诊断中有一定价值.     

正常成人大脑白质纤维磁共振弥散张量成像的定量研究

目的:运用弥散张量成像(DTI)定量研究正常成人脑白质不同解剖部位的各向异性特点.方法:对60名正常成人按年龄分成四组,均行DTI检查,分析其表面弥散系数(ADC)图及各向异性分数(FA)图的特点,并对不同解剖部位的脑白质进行ADC值及FA值的定量分析,通过统计学分析得出其弥散系数和各向异性特点.结果:不同年龄组间相同解剖部位脑白质ADC值及FA值的差异无统计学意义;不同解剖部位间FA值及ADC值的差异具有显著性.结论:DTI可清晰显示脑内白质的走行及方向,FA能准确定量分析正常成人不同部位脑白质纤维的各向异性程度.     

肝硬化患者脑改变的磁化传递成像定量研究

目的 利用磁化传递成像（MTI）评价肝硬化患者是否存在异常的脑改变,探讨其与静脉血氨值、苍白球指数（GPI）及神经心理学测试之间的相关性. 资料与方法 48例肝硬化患者和30名健康志愿者,在T1WI上分别测量壳核和苍白球的信号值计算GPI.在MTI中将感兴趣区（ROI）置于双侧顶叶白质、额叶白质、枕叶白质、尾状核头、壳核、苍白球、丘脑,计算右侧各部位的磁化传递率（MTR）. 结果 （1）患者组各部位的MTR明显低于正常对照组,差异有统计学意义（P均＜0.001）.苍白球的MTR降低最明显,约9%.（2）对于Child分级和肝性脑病（HE）分级,顶叶、额叶、壳核、苍白球及枕叶白质的MTR差异均有统计学意义（P均＜0.05）,两两比较后显示,上述部位的MTR在Child A和B级、A和C级之间差异有统计学意义,B和C级之间差异则无统计学意义;在肝硬化、轻微型肝性脑病（MHE）及HE 3组患者之间差异无统计学意义.（3）顶叶、额叶、壳核、苍白球及枕叶的MTR、GPI指标与Child分级呈负相关（P均＜0.05）,而仅苍白球的MTR与HE分级间呈负相关（r＝-0.291,P＝0.045）.（4）Pearson相关分析显示,顶叶、额叶、壳核、苍白球及枕叶的MTR、GPI与血氨之间没有相关性,与各神经心理学测试之间有相关关系（P均＜0.05）. 结论 肝硬化患者存在轻度脑水肿,其有随Child分级加重的趋势,由此,可部分解释肝硬化患者的认知功能改变.     

正常及退变髌软骨磁化传递率的定量研究

目的 探讨磁化传递率(MTR)对正常及退变髌软骨的定量研究价值.资料与方法 对正常组(n=54)、退行性骨关节炎(OA)轻度组(n=28)、OA中度组(n=25)、OA重度组(n=13)行MR磁化传递成像,测量各组髌软骨上、中、下三层平均MTR,并进行统计学分析.结果 正常髌软骨中间层面内、中及外侧部位MTR值差异无明显统计学意义(F=0.041,P=0.91>0.05).正常、轻度、中度、重度OA组中央层面髌软骨MTR分别为(35.64±4.79)%、(34.90±4.27)%、(32.99±6.54)%、(31.83±8.40)%,差异无统计学意义(F=2.419,P=0.07>0.05).随着退变程度加重,髌软骨中央层面MTR值轻度降低.结论 髌软骨MTR值在一定程度上反映了髌软骨组织成分的变化.     

婴幼儿发育迟缓的脑磁共振扩散张量成像研究

目的应用磁共振扩散张量成像(DTI)研究发育迟缓婴幼儿脑白质的各向异性(FA)值,探讨其与正常婴幼儿脑白质有无差异。资料与方法对40例发育迟缓和40例正常婴幼儿进行了常规MRI及DTI扫描,并以常规MRI表现将发育迟缓组分为常规MRI表现正常和常规MRI表现脑白质发育迟缓。分别测量5个深部脑白质与4个浅部脑白质的FA值,并对结果进行统计学比较。结果发育迟缓组各测量部位FA值低于对照组,除内囊后肢外差异均有统计学意义(P<0.05)。发育迟缓常规MRI表现正常患儿深部脑白质FA值低于正常组,但差异无统计学意义(P>0.05);浅部脑白质FA值低于正常组,差异有统计学意义(P<0.05);发育迟缓常规MRI表现发育迟缓脑白质FA值均低于正常组,差异有统计学意义(P<0.05)。结论应用DTI FA值的测量能定量诊断婴幼儿脑白质发育迟缓,尤其常规MRI正常的发育迟缓患儿浅部脑白质FA值低于对照组,可明确诊断发育迟缓。     

鼻咽癌放疗后颞叶脑放射性损伤的磁共振扩散张量成像的表现

目的 探讨扩散张量成像(diffusion tensor imaging,DTI)在早期放射性脑损伤中的应用价值.方法 23例鼻咽癌放疗后常规MR表现正常者和28例健康正常人均做DTI,在双侧颞叶脑白质区域测量各向同性扩散张量(ADCiso)值和各向异性指数值.结果 鼻咽癌放疗组ADCiso值(644.08±56.80)×10-6mm2/s,部分各向异性(FA)值0.394±0.074、相对各向异性(RA)值0.344±0.075及1减容积比(1-VR)值0.182±0.072均比正常对照组各值降低,与正常对照组比较差异有显著性意义(P<0.05).结论 DTI能探测到鼻咽癌放疗后常规脑MR表现所不能显示的改变,对放射性脑损伤的早期诊断提供了一种新的影像学诊断手段.     

磁化传递对比成像在大鼠肝硬化的初步应用

目的 探讨磁化传递对比（MTC）成像在大鼠肝硬化的初步应用价值。材料与方法 二乙基亚硝胺诱导的单纯性肝硬化Wistar大鼠6只,5只正常大鼠作为对照组;全部大鼠均行附加磁化传递（MT）脉冲前后SE序列T1WI及FSE序列T2WI扫描。测量感兴趣区平均信号强度、背景噪声,计算信噪比及磁化传递率（MTR）。结果 6只大鼠病理证实均为单纯性肝硬化。电镜下见肝硬化细胞间隔增宽,胶原纤维明显增多。T1WI上正常肝实质附加MT脉冲后信噪比（SNR）低于无MT脉冲图像（P=0．002）;肝硬化附加MT后SNR明显低于无MT时（P=0．000）;肝硬化的MTR显著高于正常肝实质（P=0．000）。T2WI上正常肝实质附加MT后SNR低于无MT时（P=0．021）;肝硬化附加MT后SNR显著低于无MT时（P=0．000）;肝硬化的MTR较正常肝实质明显增高（P=0．002）。结论 MTC成像能间接反映肝硬化组织中胶原成分变化,为肝硬化的诊断和分期提供依据,可作为评价肝硬化的有效手段。     

婴幼儿脑白质发育的弥散张量磁共振成像

目的：应用弥散张量成像分析不同年龄段婴幼儿的不同部位脑白质的各向异性。材料和方法：将26例正常婴幼儿（年龄4d至24个月）分为4组：第一组7例，小于6个月；第二组8例，6—12个月；第三组6例，12—18个月；第四组5例，18—24个月。均进行常规头颅MR和弥散张量成像，并测量不同部位脑白质的FA值和ADC值。结果：随着年龄的增加，ADC值逐渐减低，FA值逐渐升高。不同组别大脑白质各部位的ADC值和FA值不同（P〈0．05）。结论：弥散张量成像可以反映活体脑白质的细微结构，可用于评价脑白质发育情况。     

Imaging age‐related cognitive decline: A comparison of diffusion tensor and magnetization transfer MRI

Purpose

To determine which MR technique was the most sensitive to age‐related white matter damage. We compared both diffusion tensor imaging (DTI) and magnetization transfer (MT) maps to determine which technique correlated most strongly with cognitive function in a middle‐aged and elderly community population.

Materials and Methods

In all, 64 healthy subjects (aged 50–90) underwent MRI and neuropsychology. Histograms were generated for white matter mean diffusivity (MD), fractional anisotropy (FA), and MT ratio (MTR). White matter hyperintensity volume (WMH) and brain volume were also determined. Composite neuropsychological scores were derived for 4 cognitive domains (executive function, working memory, episodic memory, and information processing speed).

Results

All MRI parameters correlated with age (FA r = 0.726, P < 0.001; MD r = ?0.619 P < 0.001, MTR r = ?0.566, P < 0.001, WMH r = 0.511, P < 0.001). All MRI parameters correlated with cognition, but DTI, and particularly FA, correlated most strongly. Adding DTI parameters explained more variance in cognition than WMH alone; the increase was greatest with FA, which alone explained 45%, 33%, and 25% of the variance in cognition for information processing speed, episodic memory, and executive function, respectively.

Conclusion

DTI appears the most sensitive imaging parameter to determine age‐related white matter damage. The stronger relationship with FA suggests that axonal damage is important in age‐related cognitive decline. J. Magn. Reson. Imaging 2009;29:23–30. © 2008 Wiley‐Liss, Inc.

     

Global estimation of myelination in the developing brain on the basis of magnetization transfer imaging: a preliminary study

BACKGROUND AND PURPOSE: In the developing brain, myelination occurs in an orderly and predetermined sequence. The aim of this study was to determine whether such changes can be tracked using volumetric magnetization transfer imaging. METHODS: Three-dimensional magnetization transfer imaging was performed in 50 children (age range, 0.6-190 months) with no evidence of developmental delay or structural abnormalities. Volumetric magnetization transfer ratio (MTR) parameters generated of the whole brain were mean MTR and height and location of the MTR histogram peak. Relationships between volumetric MTR parameters and age were assessed using nonlinear regression analysis. RESULTS: With age, all volumetric MTR parameters changed exponentially in a way that was best expressed by the function y = a + b.exp(-x/c) (P < .0001). The peak height of the MTR histogram was the parameter that changed most predictably and that continued to change for the longest period of time. CONCLUSION: With this preliminary study, we show that by using volumetric MTR analysis, it is possible to monitor changes in the developing brain, presumably the myelination progress. This method has a potential role for detecting myelination disorders in the pediatric population, for studying the natural history of these diseases, and for monitoring the effects of treatment.     

Magnetization transfer analysis of cartilage repair tissue: a preliminary study

Purpose To evaluate the magnetization transfer ratio (MTR) after two different cartilage repair procedures, and to compare these data with the MTR of normal cartilage.Design and patients Twenty-seven patients with a proven cartilage defect were recruited: 13 were treated with autologous chondrocyte implantation (ACI) and 14 were treated with the microfracture technique (MFR). All patients underwent MRI examinations with MT-sequences before the surgical treatment, after 12 months (26 patients) and after 24 months (11 patients). Eleven patients received a complete follow-up study at all three time points (five of the ACI group and six of the MFR group). All images were transferred to a workstation to calculate MTR images. For every MT image set, different ROIs were delineated by two radiologists. Means were calculated per ROI type in the different time frames and in both groups of cartilage repair. The data were analyzed with unpaired t- and ANOVA tests, and by calculating Pearson’s correlation coefficient.Results No significant differences were found in the MTR of fatty bone marrow, muscle and normal cartilage in the different time frames. There was a significant but small difference between the MTR of normal cartilage and the cartilage repair area after 12 months for both procedures. After 24 months, the MTR of ACI repaired cartilage (0.31±0.07) was not significantly different from normal cartilage MTR (0.34±0.05). The MTR of MFR repaired cartilage (0.28±0.02), still showed a significant difference from normal cartilage.Conclusion The differences between damaged and repaired cartilage MTR are too small to enable MT-imaging to be a useful tool for postoperative follow-up of cartilage repair procedures. There is, however, an evolution towards normal MTR-values in the cartilage repair tissue (especially after ACI repair).     

兔坐骨神经牵拉伤MTR值与肢体功能的相关分析

目的：探讨兔坐骨神经急性牵拉伤后不同时间点牵拉远段神经磁化传递率（MTR）与肢体功能的相关关系。方法：选取20只新西兰大白兔,右后肢为损伤侧,建立坐骨神经牵拉伤模型;左后肢为假手术侧。随机将实验兔分为两组,A组（n=12）于术前1天、术后1和3天以及1、2、4、6和8周分别行双侧后肢磁化传递MRI扫描,测量牵拉远段神经及假手术侧神经的MTR值;同时对实验兔的肢体功能进行展趾反射和改良Tarlov评分,分析术后1～8周MTR值与肢体功能的相关性;B组（n=8）于上述各时间点进行病理学检查。结果：牵拉远段神经的MTR值于损伤后1天明显降低,2周时达最低值,4～8周逐渐升高至正常水平,各时间点MTR值与假手术侧相比差异均有统计学意义（P〈O．05）。牵拉伤后1天兔展趾反射及Tarlov评分降至最低;伤后1天～1周评分保持较低水平;伤后2～8周评分逐渐增高、肢体功能逐渐恢复。伤后1～8周牵拉远段神经MTR值与肢体功能评分呈正相关（r=0．638,P％0．01）。病理检查显示术后1周神经开始退变,2周时髓鞘退变最显著,4周后开始恢复。结论：牵拉远段神经的MTR值与肢体功能评分呈正相关,提示MTR值可用于监测伤后神经功能退变及再生的情况。     

正常青年人群脑磁共振扩散张量成像的定量研究

目的:运用扩散张量成像(DTI)方法研究正常青年人群不同脑组织及解剖部位的各向异性特点.方法:对40名正常青年人群行DTI成像,分析其表面扩散系数(ADC)图及各向异性分数(FA)图的特点,并对不同脑组织进行ADC及FA值的定量分析,通过统计学分析得出其扩散和各向异性特点.结果:扩散系数ADC不能区分脑灰质与脑白质(ADC分别为807.78±90.29,775.79±115.31×10-6mm2/s,P=0.098).而脑脊液、脑灰质与脑白质间的FA值间差异均具有显著性意义(P<0.05).不同解剖部位的脑白质间具有显著不同的各向异性(P<0.05).胼胝体压部的各向异性程度最高(0.73±0.09),其次为胼胝体膝部与内囊后肢(0.68±0.05,0.67±0.06),半卵圆中心与枕钳最低(0.53±0.09,0.53±0.09).脑灰质中以背侧丘脑具有最高的各向异性(0.31±0.04).结论:FA可准确定量正常青年人群不同脑组织的扩散特点,DTI可清晰显示脑内白质的方向及走行.