磁共振扩散张量成像序列对脊髓型颈椎病的诊断价值

目的:分析3.0T磁共振（MR）扩散张量成像（DTI）序列对脊髓型颈椎病（CSM）的诊断价值。方法:选择福建中医药大学附属康复医院收治的30例CSM患者纳入观察组,另选择同期体检人群中年龄匹配的30例健康志愿者为对照组,均运用常规MRI序列及DTI技术进行扫描,运用DTI技术测量FA及ADC值,进行图像后处理及数据分析,观察组患者根据MR平扫结果分为A组（n=10,单纯硬膜囊受压）、B组（n=14,颈髓受压,信号正常）和C组（n=6,颈髓受压,T2WI高信号）,分析各组FA及DA值差异,评价DTI诊断脊髓型颈椎病的诊断价值。结果:对照组脊髓C2-3、C3-4、C4-5、C5-6、C6-7节段的ADC值与FA比较差异无统计学意义（P>0.05）;对照组与A、B、C组的ADC值、FA值存在显著性差异（P<0.05）,B组、C组的ADC值显著高于对照组（P<0.05）,FA值显著低于对照组（P<0.05）,A组ADC值、FA值与对照组比较差异无统计学意义（P>0.05）;从A组到C组,ADC值呈升高趋势,FA值呈降低趋势,差异显著（P<0.05）;MR T2WI、DTI序列扫描FA值、MR DTI序列扫描ADC值诊断扫描诊断CSM的敏感度与特异度为20.00%（6/30）与80.00%（24/30）,80.00%（24/30）与20.00%（6/30）,66.67%（20/30）与30.00%（9/30）。结论:DTI较常规MRI能更早期而准确地诊断CSM,是一种显示CSM病变和观察病变修复过程的有效手段。     

Prognosis of cervical myelopathy based on diffusion tensor imaging with artificial intelligence methods

Diffusion tensor imaging (DTI) has been proposed for the prognosis of cervical myelopathy (CM), but the manual analysis of DTI features is complicated and time consuming. This study evaluated the potential of artificial intelligence (AI) methods in the analysis of DTI for the prognosis of CM. Seventy‐five patients who underwent surgical treatment for CM were recruited for DTI imaging and were divided into two groups based on their one‐year follow‐up recovery. The DTI features of fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity were extracted from DTI maps of all cervical levels. Conventional AI models using logistic regression (LR), k‐nearest neighbors (KNN), and a radial basis function kernel support vector machine (RBF‐SVM) were built using these DTI features. In addition, a deep learning model was applied to the DTI maps. Their performances were compared using 50 repeated 10‐fold cross‐validations. The accuracy of the classifications reached 74.2% ± 1.6% for LR, 85.6% ± 1.4% for KNN, 89.7% ± 1.6% for RBF‐SVM, and 59.2% ± 3.8% for the deep leaning model. The RBF‐SVM algorithm achieved the best accuracy, with sensitivity and specificity of 85.0% ± 3.4% and 92.4% ± 1.9% respectively. This finding indicates that AI methods are feasible and effective for DTI analysis for the prognosis of CM.     

脊髓型颈椎病高场强磁共振成像探讨

目的 研究脊髓型颈椎病(CSM)的MRI成像特点及其临床意义。方法 分析主诉有颈肩痛或／和肢体麻木、乏力就诊者134例，经诊断CSM者80例，并根据临床表现分组比较MRI表现。结果 非CSM者MRI表现出椎间盘变性或轻度突出、骨赘形成但不构成对脊髓压迫；CSM病例表现不同程度椎间盘突出、椎体后缘骨赘形成及硬膜囊和脊髓受压，其中69例(86．25％，)脊髓受压，11例(13．75％)脊髓受压变性。临床症状严重者，MRI表现出颈髓变性显著增多，术后脊髓变性信号仍存在。结论 高场强MRI可良好显示CSM中椎间盘退变突出、骨赘形成及脊髓受压变性，为临床诊断与外科治疗提供依据。     

High‐resolution diffusion tensor imaging of the human kidneys using a free‐breathing,multi‐slice,targeted field of view approach

Fractional anisotropy (FA) obtained by diffusion tensor imaging (DTI) can be used to image the kidneys without any contrast media. FA of the medulla has been shown to correlate with kidney function. It is expected that higher spatial resolution would improve the depiction of small structures within the kidney. However, the achievement of high spatial resolution in renal DTI remains challenging as a result of respiratory motion and susceptibility to diffusion imaging artefacts. In this study, a targeted field of view (TFOV) method was used to obtain high‐resolution FA maps and colour‐coded diffusion tensor orientations, together with measures of the medullary and cortical FA, in 12 healthy subjects. Subjects were scanned with two implementations (dual and single kidney) of a TFOV DTI method. DTI scans were performed during free breathing with a navigator‐triggered sequence. Results showed high consistency in the greyscale FA, colour‐coded FA and diffusion tensors across subjects and between dual‐ and single‐kidney scans, which have in‐plane voxel sizes of 2 × 2 mm² and 1.2 × 1.2 mm², respectively. The ability to acquire multiple contiguous slices allowed the medulla and cortical FA to be quantified over the entire kidney volume. The mean medulla and cortical FA values were 0.38 ± 0.017 and 0.21 ± 0.019, respectively, for the dual‐kidney scan, and 0.35 ± 0.032 and 0.20 ± 0.014, respectively, for the single‐kidney scan. The mean FA between the medulla and cortex was significantly different (p < 0.001) for both dual‐ and single‐kidney implementations. High‐spatial‐resolution DTI shows promise for improving the characterization and non‐invasive assessment of kidney function. © 2014 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd.     

Reproducibility of tract‐specific magnetization transfer and diffusion tensor imaging in the cervical spinal cord at 3 tesla

Damage to specific white matter tracts within the spinal cord can often result in the particular neurological syndromes that characterize myelopathies such as traumatic spinal cord injury. Noninvasive visualization of these tracts with imaging techniques that are sensitive to microstructural integrity is an important clinical goal. Diffusion tensor imaging (DTI)‐ and magnetization transfer (MT)‐derived quantities have shown promise in assessing tissue health in the central nervous system. In this paper, we demonstrate that DTI of the cervical spinal cord can reliably discriminate sensory (dorsal) and motor (lateral) columns. From data derived from nine healthy volunteers, two raters quantified column‐specific parallel (λ_||) and perpendicular (λ_?) diffusivity, fractional anisotropy (FA), mean diffusivity (MD), and MT‐weighted signal intensity relative to cerebrospinal fluid (MTCSF) over two time‐points separated by more than 1 week. Cross‐sectional means and standard deviations of these measures in the lateral and dorsal columns were as follows: λ_||: 2.13 ± 0.14 and 2.14 ± 0.11 μm²/ms; λ_?: 0.67 ± 0.16 and 0.61 ± 0.09 μm²/ms; MD: 1.15 ± 0.15 and 1.12 ± 0.08 μm²/ms; FA: 0.68 ± 0.06 and 0.68 ± 0.05; MTCSF: 0.52 ± 0.05 and 0.50 ± 0.05. We examined the variability and interrater and test‐retest reliability for each metric. These column‐specific MR measurements are expected to enhance understanding of the intimate structure‐function relationship in the cervical spinal cord and may be useful for the assessment of disease progression. Copyright © 2009 John Wiley & Sons, Ltd.     

脊髓型颈椎病动物模型制作的关注热点

文题释义：脊髓型颈椎病：指患者由于年老或外伤导致其颈部脊髓受压或局部血供不足引起的以颈痛为主,伴损伤平面以下感觉减退及运动功能障碍的综合征。 脊髓型颈椎病动物模型：通过模拟脊髓型颈椎病患者的发病机制,选取合适的实验动物作为造模对象,并以合理的制作方法完成造模。从而对模型进行跟踪观察和实验研究,以便为临床治疗提供更全面的数据分析。 背景：脊髓型颈椎病是颈椎病中最为严重的一种发病类型,而目前其组织病理学研究仍不十分明确,主要原因在于缺乏理想的动物模型。 目的：通过查阅文献回顾脊髓型颈椎病模型常用的制作方法,并对模型的不同制作进行分析评价,以促进脊髓型颈椎病动物模型的改进和完善。 方法：通过下列检索词：脊髓型颈椎病、颈脊髓压迫、动物模型,cervical spondylotic myelopathy、cervical spinal compression、animal model,由第一作者检索中国知网、万方、维普、PubMed、Medline、Embase数据库收录的从2000至2019年与脊髓型颈椎病动物模型制作相关的中、英文献,并筛选出来进行分析评价。 结果与结论：①当前脊髓型颈椎病动物模型的制作方法较多,大致可分为动态造模法和静态造模法两类,且各自优缺点并存;②拧入螺钉压迫法最为常见,具有可控性强、造模周期短的优点,但对于造模动物的颈髓损害较重且致死率高;而膨胀材料压迫法科技要求难度大,但成功率高、可靠性强,有待继续完善和推广;③文章结果证实,目前脊髓型颈椎病动物模型的各种制作方法仍存在着明显的不足,还需在先前学者造模的基础上不断完善,从而实现再现性好、可重复、可分级的动物模型,以便今后在临床上为脊髓型颈椎病的治疗提供更好的理论依据。 ORCID: 0000-0002-3931-7326(陈盛) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Tract‐specific and age‐related variations of the spinal cord microstructure: a multi‐parametric MRI study using diffusion tensor imaging (DTI) and inhomogeneous magnetization transfer (ihMT)

Being able to finely characterize the spinal cord (SC) microstructure and its alterations is a key point when investigating neural damage mechanisms encountered in different central nervous system (CNS) pathologies, such as multiple sclerosis, amyotrophic lateral sclerosis or myelopathy. Based on novel methods, including inhomogeneous magnetization transfer (ihMT) and dedicated SC probabilistic atlas post‐processing, the present study focuses on the in vivo characterization of the healthy SC tissue in terms of regional microstructure differences between (i) upper and lower cervical vertebral levels and (ii) sensory and motor tracts, as well as differences attributed to normal aging. Forty‐eight healthy volunteers aged from 20 to 70 years old were included in the study and scanned at 3 T using axial high‐resolution T₂*‐w imaging, diffusion tensor imaging (DTI) and ihMT, at two vertebral levels (C2 and C5). A processing pipeline with minimal user intervention, SC segmentation and spatial normalization into a reference space was implemented in order to assess quantitative morphological and structural parameters (cross‐sectional areas, scalar DTI and MT/ihMT metrics) in specific white and gray matter regions of interest. The multi‐parametric MRI metrics collected allowed upper and lower cervical levels to be distinguished, with higher ihMT ratio (ihMTR), higher axial diffusivity (λ_∥) and lower radial diffusivity (λ_⊥) at C2 compared with C5. Significant differences were also observed between white matter fascicles, with higher ihMTR and lower λ_∥ in motor tracts compared with posterior sensory tracts. Finally, aging was found to be associated with significant metric alterations (decreased ihMTR and λ_∥). The methodology proposed here, which can be easily transferred to the clinic, provides new insights for SC characterization. It bears great potential to study focal and diffuse SC damage in neurodegenerative and demyelinating diseases. Copyright © 2016 John Wiley & Sons, Ltd.     

Region‐specific impairment of the cervical spinal cord (SC) in amyotrophic lateral sclerosis: A preliminary study using SC templates and quantitative MRI (diffusion tensor imaging/inhomogeneous magnetization transfer)

In this preliminary study, our objective was to investigate the potential of high‐resolution anatomical imaging, diffusion tensor imaging (DTI) and conventional/inhomogeneous magnetization transfer imaging [magnetization transfer (MT)/inhomogeneous magnetization transfer (ihMT)] at 3 T, analyzed with template‐extracted regions of interest, to measure the atrophy and structural changes of white (WM) and gray (GM) matter spinal cord (SC) occurring in patients with amyotrophic lateral sclerosis (ALS). Ten patients with ALS and 20 age‐matched healthy controls were recruited. SC GM and WM areas were automatically segmented using dedicated templates. Atrophy indices were evaluated from T ₂*‐weighted images at each vertebral level from cervical C1 to C6. DTI and ihMT metrics were quantified within the corticospinal tract (CST), posterior sensory tract (PST) and anterior GM (aGM) horns at the C2 and C5 levels. Clinical disabilities of patients with ALS were evaluated using the Revised ALS Functional Rating Scale, upper motor neuron (UMN) and Medical Research Council scorings, and correlated with MR metrics. Compared with healthy controls, GM and WM atrophy was observed in patients with ALS, especially at lower cervical levels, where a strong correlation was also observed between GM atrophy and the UMN score (R  = ?0.75, p  = 0.05 at C6). Interestingly, a significant decrease in ihMT ratio was found in all regions of interest (p  < 0.0008), fractional anisotropy (FA) and MT ratios decreased significantly in CST, especially at C5 (p  < 0.005), and λ_// (axial diffusivity) decreased significantly in CST (p  = 0.0004) and PST (p  = 0.003) at C2. Strong correlations between MRI metrics and clinical scores were also found (0.47 < |R | < 0.87, p  < 0.05). Altogether, these preliminary results suggest that high‐resolution anatomical imaging and ihMT imaging, in addition to DTI, are valuable for the characterization of SC tissue impairment in ALS. In this study, in addition to an important SC WM demyelination, we also observed, for the first time in ALS, impairments of cervical aGM.     

基于参考图像的压缩感知磁共振扩散张量成像

基于参考图像的压缩感知磁共振扩散张量成像方法,利用相邻方向的扩散加权图像差异较小的特点,采用压缩感知理论实现快速扩散张量成像,回顾性选取扩散张量图像数据进行实验研究,在采样率为50%的均匀分布辐射线欠采样方式下进行基于参考图像的压缩感知扩散张量图像重建,结果表明重建后的扩散加权图的平均结构相似性（MSSIM）和峰值信噪比（PSNR）分别为0.904±0.044、（37.92±3.89） dB,各向异性分数图的MSSIM和PSNR分别为0.992、41.64 dB。因此,该方法在保证重建图像质量的前提下,可显著缩短数据采集时间,减少由于时间过长引起的图像伪影等问题。     

Fast and accurate initialization of the free‐water imaging model parameters from multi‐shell diffusion MRI

Cerebrospinal fluid partial volume effect is a known bias in the estimation of Diffusion Tensor Imaging (DTI) parameters from diffusion MRI data. The Free‐Water Imaging model for diffusion MRI data adds a second compartment to the DTI model, which explicitly accounts for the signal contribution of extracellular free‐water, such as cerebrospinal fluid. As a result the DTI parameters obtained through the free‐water model are corrected for partial volume effects, and thus better represent tissue microstructure. In addition, the model estimates the fractional volume of free‐water, and can be used to monitor changes in the extracellular space. Under certain assumptions, the model can be estimated from single‐shell diffusion MRI data. However, by using data from multi‐shell diffusion acquisitions, these assumptions can be relaxed, and the fit becomes more robust. Nevertheless, fitting the model to multi‐shell data requires high computational cost, with a non‐linear iterative minimization, which has to be initialized close enough to the global minimum to avoid local minima and to robustly estimate the model parameters. Here we investigate the properties of the main initialization approaches that are currently being used, and suggest new fast approaches to improve the initial estimates of the model parameters. We show that our proposed approaches provide a fast and accurate initial approximation of the model parameters, which is very close to the final solution. We demonstrate that the proposed initializations improve the final outcome of non‐linear model fitting.     

任务态fMRI对脊髓型颈椎病严重程度及手术预后的评价

文题释义：血氧水平依赖功能磁共振：是一种非侵入性的检测方法。该技术依赖于脑血流和神经元激活的耦合,当大脑的某个区域处于活动状态时,流向该区域的血液会随之增加,超过了代谢需求时,顺磁性去氧血红蛋白浓度会相对下降,这一效应会减弱局部磁场的不均匀性,从而显示出成像信号的差异。  皮质重构：脊髓受到损伤后患者会出现脑皮质功能活动的改变。相对于正常健康人群,这种脑皮质活动的异常,类似于一种特殊的激活区域空间移位,被称之为皮质重构。神经组织的可塑性是脊髓损伤后脑皮质能够发生重构的重要原因。背景：血氧水平依赖功能磁共振(BOLD-fMRI)通过检测大脑功能区活动时血流变化而获得脑功能改变的客观信息。以往关于脊髓型颈椎病的任务态fMRI研究能够观察到患者感觉和运动皮质功能的重构。目的：运用任务态fMRI分析脊髓型颈椎病患者皮质激活的变化程度与临床症状严重程度及手术预后之间的关系。方法：2018年1月至2019年1月收集行颈椎后路减压手术治疗的脊髓型颈椎病患者82例(脊髓型颈椎病组)及健康志愿者45名(正常组)。所有对象均行颅脑fMRI扫描,动作任务均为右手对指任务。采用日本骨科学会(JOA)评分评估患者脊髓功能,术后6个月随访时将JOA评分改善率< 50%定义为手术预后不良。结果与结论：①脊髓型颈椎病组术后JOA评分较术前显著改善(P < 0.05);②脊髓型颈椎病组术前左侧中央前回的激活体积值较正常组显著升高(P < 0.05),左侧中央后回的激活体积值与正常组差异无显著性意义(P > 0.05);脊髓型颈椎病组术前左侧激活体积比值(中央前回/中央后回)较正常组显著升高(P < 0.05);③术后6个月随访时,脊髓型颈椎病组左侧中央前回的激活体积值较术前显著减低(P < 0.05),左侧中央后回的激活体积值与术前差异无显著性意义(P > 0.05),左侧激活体积比值较术前显著降低(P < 0.05);④相关性分析显示左侧中央前回、中央后回的激活体积值、激活体积比值与术前JOA评分、术后JOA评分改善率间均具有显著相关性(P < 0.05)。激活体积比值与术前JOA评分、术后改善率的相关系数绝对值最大;⑤受试者工作特征曲线分析发现术前激活体积比值预测预后不良的曲线下面积为0.803,界值为3.621;术前JOA评分预测预后不良的曲线下面积为0.751,界值为8;激活体积比值的预测效能高于JOA评分;⑥结果表明,脊髓型颈椎病患者任务态fMRI皮质左侧中央前回与中央后回的激活体积比值与临床症状严重程度(JOA评分)存在显著负相关。术前激活体积比值可有效预测脊髓型颈椎病患者术后脊髓功能恢复情况。ORCID: 0000-0002-9156-0702(宋彦澄)中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

皮层下缺血性血管性痴呆胼胝体的扩散张量成像研究

目的：应用扩散张量成像（DTI）技术探讨皮层下缺血性血管性痴呆（SIVD）病人胼胝体各项异性及平均扩散率变化特点及其与认知状态或其他临床表现的关系。方法：对SIVD病人34例及同期进行体检的健康老年人26例进行DTI扫描，测量胼胝体前部和后部FA值、PA值及平均ADC值，并对结果进行统计分析。结果：健康对照组及SIVD组胼胝体后部FA及PA均大于前部（P〈0．05）；SIVD组胼胝体前后部FA及PA值均明显下降，ADC值均明显增加；胼胝体前部ADC与MMSE评分成负相关，r=-0．361，P=0，036。结论：应用DTI可显示SIVD病人胼胝体完整性破坏，髓鞘和轴索的损伤和丢失。胼胝体的DTI的各参数变化有助于SIVD的早期预防及治疗，阻止或逆转认知下降。     

MRI quantification of non‐Gaussian water diffusion in normal human kidney: a diffusional kurtosis imaging study

Our aim was to prospectively evaluate the feasibility of diffusional kurtosis imaging (DKI) in normal human kidney and to report preliminary DKI measurements. Institutional review board approval and informed consent were obtained. Forty‐two healthy volunteers underwent diffusion‐weighted imaging (DWI) scans with a 3‐T MR scanner. b values of 0, 500 and 1000 s/mm² were adopted. Maps of fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (D_⊥), axial diffusivity (D_||), mean kurtosis (MK), radial kurtosis (K_⊥) and axial kurtosis (K_||) were produced. Three representative axial slices in the upper pole, mid‐zone and lower pole were selected in the left and right kidney. On each selected slice, three regions of interest were drawn on the renal cortex and another three on the medulla. Statistical comparison was performed with t‐test and analysis of variance. Thirty‐seven volunteers successfully completed the scans. No statistically significant differences were observed between the left and right kidney for all metrics (p values in the cortex: FA, 0.114; MD, 0.531; D_⊥, 0.576; D_||, 0.691; MK, 0.934; K_⊥, 0.722; K_||, 0.891; p values in the medulla: FA, 0.348; MD, 0.732; D_⊥, 0.470; D_||, 0.289; MK, 0.959; K_⊥, 0.780; K_||, 0.287). Kurtosis metrics (MK, K_||, K_⊥) obtained in the renal medulla were significantly (p <0.001) higher than those in the cortex (0.552 ± 0.04, 0.637 ± 0.07 and 0.530 ± 0.08 in the medulla and 0.373 ± 0.04, 0.492 ± 0.06 and 0.295 ± 0.06 in the cortex, respectively). For the diffusivity measures, FA of the medulla (0.356 ± 0.03) was higher than that of the cortex (0.179 ± 0.03), whereas MD, D_⊥ and D_|| (mm²/ms) were lower in the medulla than in the cortex (3.88 ± 0.09, 3.50 ± 0.23 and 4.65 ± 0.29 in the cortex and 2.88 ± 0.11, 2.32 ± 0.20 and 3.47 ± 0.31 in the medulla, respectively). Our results indicate that DKI is feasible in the human kidney. We have reported the preliminary DKI measurements of normal human kidney that demonstrate well the non‐Gaussian behavior of water diffusion, especially in the renal medulla. Copyright © 2014 John Wiley & Sons, Ltd.     

The impact of myelination on axon sparing and locomotor function recovery in spinal cord injury assessed using diffusion tensor imaging

The dysmyelinated axons of shiverer mice exhibit impaired conduction characteristics, similar to early postnatal axons before myelination, whereas the patterns of neuronal activity and connectivity are relatively comparable with those of wild‐type myelinated axons. This unique dysmyelination pattern is exploited in the present study to determine the role of compact myelin in the loss and recovery of function following traumatic spinal cord injury (SCI). We applied in vivo diffusion tensor imaging (DTI) and post‐mortem immunohistochemistry analysis to examine changes in myelin and axonal integrity, and evaluated these changes in concert with the analysis of locomotor function from 1 to 4 weeks following a mid‐thoracic contusion injury in homozygous shiverer and heterozygous littermate mice. The DTI biomarkers, axial and radial diffusivities, are noninvasive indicators of axon and myelin integrity in response to SCI of both myelinated and dysmyelinated spinal cord. We show that myelin is critical for normal hind limb function in open field locomotion. However, when the functional outcome is limited during chronic SCI, the extent of recovery is associated with residual axonal integrity and independent of the extent of intact myelin at the lesion epicenter. Copyright © 2013 John Wiley & Sons, Ltd.     

User‐independent diffusion tensor imaging analysis pipelines in a rat model presenting ventriculomegalia: A comparison study

Automated analysis of diffusion tensor imaging (DTI) data is an appealing way to process large datasets in an unbiased manner. However, automation can sometimes be linked to a lack of interpretability. Two whole‐brain, automated and voxelwise methods exist: voxel‐based analysis (VBA) and tract‐based spatial statistics (TBSS). In VBA, the amount of smoothing has been shown to influence the results. TBSS is free of this step, but a projection procedure is introduced to correct for residual misalignments. This projection assigns the local highest fractional anisotropy (FA) value to the mean FA skeleton, which represents white matter tract centers. For both methods, the normalization procedure has a major impact. These issues are well documented in humans but, to our knowledge, not in rodents. In this study, we assessed the quality of three different registration algorithms (ANTs SyN, DTI‐TK and FNIRT) using study‐specific templates and their impact on automated analysis methods (VBA and TBSS) in a rat pup model of diffuse white matter injury presenting large unilateral deformations. VBA and TBSS results were stable and anatomically coherent across the three pipelines. For VBA, in regions around the large deformations, interpretability was limited because of the increased partial volume effect. With TBSS, two of the three pipelines found a significant decrease in axial diffusivity (AD) at the known injury site. These results demonstrate that automated voxelwise analyses can be used in an animal model with large deformations.     

Diffusion abnormalities in temporal lobes of children with temporal lobe epilepsy: a preliminary diffusional kurtosis imaging study and comparison with diffusion tensor imaging

In this preliminary study, we aimed to investigate the abnormalities of water diffusion in children with temporal lobe epilepsy (TLE). Eight children with unilateral TLE (according to electroencephalography, EEG) and eight age‐ and sex‐matched controls were recruited. Diffusion tensor imaging (DTI)/diffusional kurtosis imaging (DKI) acquisitions were performed. Radial diffusivity (λ_⊥), axial diffusivity (λ_∥), mean diffusivity (MD) and fractional anisotropy (FA) maps were calculated for both DTI and DKI, and radial kurtosis (K_⊥), axial kurtosis (K_∥) and mean kurtosis (MK) maps were calculated for DKI only. Mann–Whitney test showed that, for white matter in the temporal lobe, DKI‐derived λ_∥, MD and K_∥ were significantly different in bilateral temporal lobes and EEG‐abnormal and EEG‐normal sides of the temporal lobe between patients and controls, whereas DTI showed no abnormalities. For gray matter, DKI detected significantly higher MD and MK in the same three comparisons, whereas DTI detected abnormalities only in the comparison between bilateral temporal lobes and between EEG‐normal sides in cases and left–right matched sides in controls. No significant difference was observed between EEG‐abnormal and EEG‐normal sides in cases. These preliminary results indicate that DKI is more sensitive than DTI for the detection of diffusion abnormalities in the temporal lobes of children with TLE, even when EEG signals are normal. These findings pave the way for the application of DKI for in‐depth studies on TLE in children. Copyright © 2012 John Wiley & Sons, Ltd.     

两种支撑体在脊髓型颈椎病椎体次全切减压融合术中应用的效果对比

目的　比较钛网与纳米羟基磷灰石/聚酰胺66（n-HA/PA66）颈椎支撑体植骨在颈椎椎体次全切、减压融合、前路钛板螺钉系统内固定术后,恢复维持颈椎曲度、椎间高度及融合率、沉降率的差异。 方法　75例确诊为两个相邻节段脊髓型颈椎病的患者行颈椎前路减压融合术,40例行钛网支撑体植骨,35例行n-HA/PA66颈椎支撑体植骨,均行椎前钉板系统内固定。比较两组手术时间、术中出血量、住院时间、JOA评分、颈椎曲度变化、融合节段椎间高度及植骨融合情况。分别摄术前、术后即刻、术后3、6、9个月颈椎标准侧位X线片,测量融合节段Cobb角、C2～7 Cobb角、D值评价颈椎的曲度,同时测量融合节段椎体前缘高度（HAB）、后缘高度（HPB）评价支撑体融合沉降情况,对各参数不同时期间差值分别行组间配对t检验。 结果　所有患者均获得随访,随访时间9~24个月（平均16.7个月）。两组患者术后的JOA评分明显高于术前,两组间JOA评分比较差异无统计学意义(P > 0.05)。两组患者术后即刻与术前D值差值有统计学意义(P <0.05),在术后3、6、9个月融合节段前后高上差异有统计学意义（P<0.05）,融合率上差异无统计学意义（P > 0.05）,而在术后6、9个月沉降率上差异有统计学意义（P < 0.05）,钛网组明显存在早期沉陷,影响融合节段椎间高度。 结论　n-HA/PA66颈椎支撑体相对于钛网支撑植骨具有提高融合率、并发症少等优点,可以有效保持颈椎生理曲度及椎间高度,是一种较为理想的支撑体植骨材料。     

Longitudinal diffusion tensor imaging in a rat brain glioma model

In order to investigate the properties of water motion within and around brain tumors as a function of tumor growth, longitudinal diffusion tensor imaging (DTI) was carried out in a rat brain glioma (C6) model. As tumors grew in size, significant anisotropy of water diffusion was seen both within and around the tumor. The tissue water surrounding the tumor exhibited high planar anisotropy, as opposed to the linear anisotropy normally seen in white matter, indicating that cells were experiencing stress in a direction normal to the tumor border. When tumors were sufficiently large, significant anisotropy was also seen within the tumor because of longer-range organization of cancer cells within the tumor borders. These findings have important implications for diffusion-weighted MRI experiments examining tumor growth and response to therapy. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Assessment of the diagnostic value of diffusion tensor imaging in patients with spinal cord compression: a meta-analysis

We investigated the diagnostic value of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of magnetic resonance diffusion tensor imaging (DTI) in patients with spinal cord compression (SCC) using a meta-analysis framework. Multiple scientific literature databases were exhaustively searched to identify articles relevant to this study. Mean values and standardized mean differences (SMDs) were calculated for the ADC and FA in normal and diseased tissues. The STATA version 12.0 software was used for statistical analysis. Of the 41 articles initially retrieved through database searches, 11 case-control studies were eligible for the meta-analysis and contained a combined total of 645 human subjects (394 patients with SCC and 251 healthy controls). All 11 studies reported data on FA, and 9 contained data related to the ADC. The combined SMDs of the ADC and FA showed that the ADC was significantly higher and the FA was lower in patients with SCC than in healthy controls. Subgroup analysis based on the b value showed higher ADCs in patients with SCC than in healthy controls at b values of both ≤500 and >500 s/mm². In summary, the main findings of this meta-analysis revealed an increased ADC and decreased FA in patients with SCC, indicating that DTI is an important diagnostic imaging tool to assess patients suspected to have SCC.