BACKGROUND & AIMS: :Drug-target interactions (DTIs) play a crucial role in target-based drug discovery and development. Computational prediction of DTIs can effectively complement experimental wet-lab techniques for the identification of DTIs, which are typically time- and resource-consuming. However, the performances of the current DTI prediction approaches suffer from a problem of low precision and high false-positive rate. In this study, we aim to develop a novel DTI prediction method for improving the prediction performance based on a cascade deep forest (CDF) model, named DTI-CDF, with multiple similarity-based features between drugs and the similarity-based features between target proteins extracted from the heterogeneous graph, which contains known DTIs. In the experiments, we built five replicates of 10-fold cross-validation under three different experimental settings of data sets, namely, corresponding DTI values of certain drugs (SD), targets (ST), or drug-target pairs (SP) in the training sets are missed but existed in the test sets. The experimental results demonstrate that our proposed approach DTI-CDF achieves a significantly higher performance than that of the traditional ensemble learning-based methods such as random forest and XGBoost, deep neural network, and the state-of-the-art methods such as DDR. Furthermore, there are 1352 newly predicted DTIs which are proved to be correct by KEGG and DrugBank databases. The data sets and source code are freely available at https://github.com//a96123155/DTI-CDF.

背景与目标： ：药物-靶标相互作用（DTI）在基于靶标的药物发现和开发中起着至关重要的作用。 DTI的计算预测可以有效地补充用于确定DTI的实验性湿实验室技术，这通常是耗时和资源消耗的。但是，当前的DTI预测方法的性能存在精度低和假阳性率高的问题。在这项研究中，我们旨在开发一种新的DTI预测方法，以基于称为DTI-CDF的级联深林（CDF）模型来提高预测性能，该模型具有多个药物之间基于相似性的特征以及目标之间基于相似性的特征从异构图中提取的蛋白质，其中包含已知的DTI。在实验中，我们在三种不同的数据集实验设置下建立了10倍交叉验证的五个重复样本，分别是某些药物（SD），靶标（ST）或药物靶标对（SP）的相应DTI值。缺少训练集，但存在于测试集中。实验结果表明，与传统的基于集合学习的方法（例如，随机森林和XGBoost），深度神经网络以及最新的方法（例如，DDR）相比，我们提出的方法DTI-CDF的性能要高得多。此外，还有KEGG和DrugBank数据库证明是正确的1352个新预测的DTI。数据集和源代码可从https://github.com//a96123155/DTI-CDF免费获得。

BACKGROUND & AIMS: OBJECTIVES:To assess the reliability of diffusion tensor imaging (DTI)-based fibre tractography (FT), which is a prerequisite for clinical applications of this technique. Here we assess the test-retest reproducibility of the architectural and microstructural features of two clinically relevant tracts reconstructed with DTI-FT. METHODS:The corticospinal tract (CST), arcuate fasciculus (AF) and its long segment (AFl) were reconstructed in 17 healthy subjects imaged twice using a deterministic approach. Coefficients of variation (CVs) of diffusion-derived tract values were used to assess the microstructural reproducibility. Spatial correlation and fibre overlap were used to assess the architectural reproducibility. RESULTS:Spatial correlation was 68 % for the CST and AF, and 69 % for the AFl. Overlap was 69 % for the CST, 61 % for the AF, and 59 % for the AFl. This was comparable to 2-mm tract shift variability. CVs of diffusion-derived tract values were at most 3.4 %. CONCLUSIONS:The results showed low architectural and microstructural variability for the reconstruction of the tracts. The architectural reproducibility results encourage the further investigation of the use of DTI-FT for neurosurgical planning. The high microstructural reproducibility results are promising for using DTI-FT in neurology to assess or predict functional recovery.

背景与目标： 目的：评估基于弥散张量成像（DTI）的纤维束成像（FT）的可靠性，这是该技术临床应用的先决条件。在这里，我们评估了用DTI-FT重建的两个临床相关道的结构和微结构特征的重测重现性。
方法：采用确定性方法，对17例健康受试者进行了两次成像，分别重建了皮质脊髓束（CST），弓形筋膜（AF）及其长节（AF1）。扩散衍生管道值的变异系数（CV）用于评估微观结构的可重复性。空间相关性和纤维重叠被用来评估建筑的可重复性。
结果：CST和AF的空间相关性为68％，AF1的空间相关性为69％。 CST的重叠率为69％，AF的重叠为61％，AF1的重叠为59％。这相当于2毫米的道偏移变化。扩散源的CV值最多为3.4％。
结论：结果表明，重建道的建筑和微观结构变异性较低。结构的可重复性结果鼓励进一步研究DTI-FT在神经外科计划中的应用。在神经病学中使用DTI-FT评估或预测功能恢复具有很高的微结构可再现性结果。

BACKGROUND & AIMS: :Diffusion tensor MR imaging (DTI) can provide in vivo unique information on integrity of white matter structures (anisotropy) and connectivity (fiber tracking) in the human brain. This is made possible by means of non-invasive MR-based technique. The purpose of this article is to review the method and the current applications of diffusion tensor MR imaging. Studies of the past decade featuring relevant neuropsychiatric disorders as well as disorders in child psychiatry are reviewed. Furthermore, this report offers a summary of DTI-studies in children and adolescents showing alterations in brain or CNS structures including neurological, traumatological and oncological investigations. In particular, it focuses on the importance of this method with respect to exploration of normal and pathological brain development.

背景与目标： ：扩散张量MR成像（DTI）可以在人脑中提供有关白质结构完整性（各向异性）和连通性（纤维跟踪）的体内独特信息。借助于基于MR的非侵入性技术，这成为可能。本文的目的是回顾扩散张量MR成像的方法和当前应用。回顾了过去十年中有关神经精神疾病以及儿童精神病疾病的研究。此外，本报告提供了儿童和青少年DTI研究的摘要，这些研究表明大脑或CNS结构发生了变化，包括神经，创伤和肿瘤学研究。特别是，它着重于此方法在探索正常和病理性大脑发育方面的重要性。

BACKGROUND & AIMS: :Sport concussion is associated with disturbances in brain function in the absence of gross anatomical lesions, and may have long-term health consequences. Diffusion-weighted magnetic resonance imaging (MRI) methods provide a powerful tool for investigating alterations in white matter microstructure reflecting the long-term effects of concussion. In a previous study, diffusion tensor imaging (DTI) showed that athletes with a history of concussion had elevated fractional anisotropy (FA) and reduced mean diffusivity (MD) parameters. To better understand these effects, this study compared DTI results to neurite orientation dispersion and density imaging (NODDI), which was used to estimate the intracellular volume fraction (VIC ) and orientation dispersion index (ODI). Sixty-eight (68) varsity athletes were recruited, including 37 without a history of concussion and 31 with concussion >6 months prior to imaging. Univariate analyses showed elevated FA and decreased MD for concussed athletes, along with increased VIC and reduced ODI, indicating greater neurite density and coherence of neurite orientation within white matter. Multivariate analyses also showed that for athletes with a history of concussion, white matter regions with increased FA had increased VIC and decreased ODI, with greater effects among athletes who were imaged a longer time since their last concussion. These findings enhance our understanding of the relationship between the biophysics of water diffusion and concussion neurobiology for young, healthy adults. Hum Brain Mapp 38:4201-4211, 2017. © 2017 Wiley Periodicals, Inc.

背景与目标： 在没有严重的解剖病变的情况下，脑震荡与脑功能紊乱有关，并且可能对健康产生长期影响。扩散加权磁共振成像（MRI）方法为研究反映脑震荡的长期影响的白质微观结构变化提供了强大的工具。在先前的研究中，扩散张量成像（DTI）表明具有脑震荡史的运动员分数各向异性（FA）升高，平均扩散系数（MD）参数降低。为了更好地理解这些效应，本研究将DTI结果与神经突取向分散和密度成像（NODDI）进行了比较，后者用于估算细胞内体积分数（VIC）和取向分散指数（ODI）。招募了六十八（68）名大学运动员，其中包括37名无脑震荡史的运动员和31名脑震荡≥6个月的运动员。单因素分析显示，脑震荡运动员的FA升高，MD降低，VIC升高，ODI降低，表明白质内神经突密度更高，神经突取向连贯。多变量分析还显示，对于有脑震荡史的运动员，FA升高的白质区的VIC升高，ODI降低，自上次脑震荡起成像时间较长的运动员中，其影响更大。这些发现增强了我们对年轻健康成年人水扩散生物物理学与脑震荡神经生物学之间关系的理解。嗡嗡声大脑Mapp 38：4201-4211，2017.©2017 Wiley Periodicals，Inc.

BACKGROUND & AIMS: :In tropical spastic paraparesis, spinal cord atrophy is a well-known finding in magnetic resonance imaging. But in contrast to histological reports, focal lesions of the spinal cord have only been described in imaging reports in exceptional acute cases. Here, we looked for such focal lesions and for alterations of diffusion tensor imaging parameters of the long fibre tracts in the usual case of a long-standing and slowly progressive disease. We examined 10 symptomatic patients, 11 seropositive, but asymptomatic human T-lymphotrophic virus type 1 carriers and 18 seronegative volunteers as controls. Sagittal and transversal T2-weighted images were visually assessed for atrophy and focal cord lesions. The spinal cord cross-sectional areas and the segmental cord volumes were measured at all levels. High-resolution diffusion tensor imaging was performed in sagittal planes from the bregma down to the cervical spine. For tractography and calculation of fractional anisotropy and mean diffusivity, we used manufacturer-provided software. Two-thirds of patients showed focal lesions affecting the antero-lateral columns and in two cases also the dorsal columns. Compared to carriers and volunteers, patients presented a significant spinal cord atrophy and a reduction of fractional anisotropy (p < 0.05), correlating more to duration of symptoms than to clinical impairment. Because our carriers did not show a significant atrophy, focal lesions or a change of diffusion tensor imaging parameters, we need further long-term studies to see if these parameters at some stage may be used as early indicators of spinal cord affection in virus carriers.

背景与目标： ：在热带痉挛性截瘫中，脊髓萎缩是磁共振成像中的众所周知的发现。但是与组织学报告相反，仅在特殊急性病例的影像学报告中描述了脊髓的局灶性病变。在这里，我们寻找这种局灶性病变，以及在长期且缓慢进展的疾病的通常情况下，长纤维束的弥散张量成像参数的变化。我们检查了10例有症状的患者，11例血清阳性但无症状的人类1型T淋巴细胞营养性病毒携带者和18例血清阴性志愿者作为对照。视觉评估矢状和横断T2加权图像的萎缩和灶性脊髓损伤。在所有水平上测量脊髓的横截面积和节段的体积。在从前reg到颈椎的矢状面进行高分辨率扩散张量成像。对于束线照相法和分数各向异性和平均扩散率的计算，我们使用了制造商提供的软件。三分之二的患者表现出局灶性病变，影响前外侧柱，在两个病例中也影响到背侧柱。与携带者和志愿者相比，患者表现出明显的脊髓萎缩和分数各向异性的降低（p <0.05），与症状持续时间的相关性大于与临床损害的相关性。因为我们的携带者没有显示出明显的萎缩，局灶性病变或弥散张量成像参数的变化，所以我们需要进一步的长期研究，以查看这些参数在某个阶段是否可以用作病毒携带者脊髓感染的早期指标。

BACKGROUND & AIMS: OBJECTIVES:To investigate whether DTI allows assessment of renal impairment and pathology in patients with chronic glomerulonephritis. MATERIALS AND METHODS:Seventy-five patients and 20 healthy volunteers were enrolled in this study. Renal function and kidney biopsies were evaluated. For DTI, a respiratory-triggered coronal EPI sequence was performed (TR, 1400 ms; TE, 76 ms; diffusion direction, 6; NEX, 4; b values, 0 and 600 s/mm2; slices thickness, 6 mm, with no intersection gap). Renal ADC and FA values were calculated and compared between the groups. Correlations between ADC/FA and histopathology were evaluated. RESULTS:ADC values decreased with increased stages. ADC differences in renal parenchyma at different disease stages were found, with the exception of the control group compared with stage 1 patients; similar results were obtained for FA. ADC values in the cortex and medulla in stage 1-3 patients were both statistically different, similar to the FA values. A significant negative correlation was found between the percentage of glomerulosclerosis and FA in the renal cortex (r =  -0.74), similar to the degree of tubulointerstitial fibrosis with FA in the medulla (r = -0.76). CONCLUSIONS:ADC and FA values are correlated with the degree of renal impairment, the percentage of glomerulosclerosis, and area of interstitial fibrosis. KEY POINTS:• DTI can be used to assess renal function impairment in patients with chronic glomerulonephritis. • ADC and FA values were correlated with tubulointerstitial fibrosis and glomerulosclerosis. • Identification of renal impairment is helpful for timely treatment. • DTI can be used for non-invasive assessment of renal pathology.

背景与目标： 目的：探讨DTI是否可以评估慢性肾小球肾炎患者的肾功能损害和病理。
材料与方法：该研究纳入了75名患者和20名健康志愿者。评估肾功能和肾脏活检。对于DTI，执行呼吸触发的冠状EPI序列（TR，1400毫秒; TE，76毫秒;扩散方向，6; NEX，4; b值，0和600 s / mm2;切片厚度，6 mm，无相交间隙）。计算肾ADC和FA值，并在各组之间进行比较。评估了ADC / FA与组织病理学之间的相关性。
结果：ADC值随阶段增加而降低。发现在不同疾病阶段的肾实质中ADC的差异，对照组与1期患者相比有所不同。 FA的结果相似。 1-3期患者皮质和髓质中的ADC值均在统计学上不同，类似于FA值。在肾皮质中的肾小球硬化百分比与FA之间存在显着的负相关性（r = 0.7 -0.74），类似于髓质中FA引起的肾小管间质纤维化程度（r = -0.76）。
结论：ADC和FA值与肾功能不全的程度，肾小球硬化的百分比和间质纤维化的面积有关。
要点：•DTI可用于评估慢性肾小球肾炎患者的肾功能损害。 •ADC和FA值与肾小管间质纤维化和肾小球硬化相关。 •识别肾功能不全有助于及时治疗。 •DTI可用于肾脏病理的非侵入性评估。

BACKGROUND & AIMS: :Tractography based on diffusion tensor imaging (DTI) data has been used as a tool by a large number of recent studies to investigate structural connectome. Despite its great success in offering unique 3D neuroanatomy information, DTI is an indirect observation with limited resolution and accuracy and its reliability is still unclear. Thus, it is essential to answer this fundamental question: how reliable is DTI tractography in constructing large-scale connectome? To answer this question, we employed neuron tracing data of 1772 experiments on the mouse brain released by the Allen Mouse Brain Connectivity Atlas (AMCA) as the ground-truth to assess the performance of DTI tractography in inferring white matter fiber pathways and inter-regional connections. For the first time in the neuroimaging field, the performance of whole brain DTI tractography in constructing a large-scale connectome has been evaluated by comparison with tracing data. Our results suggested that only with the optimized tractography parameters and the appropriate scale of brain parcellation scheme, can DTI produce relatively reliable fiber pathways and a large-scale connectome. Meanwhile, a considerable amount of errors were also identified in optimized DTI tractography results, which we believe could be potentially alleviated by efforts in developing better DTI tractography approaches. In this scenario, our framework could serve as a reliable and quantitative test bed to identify errors in tractography results which will facilitate the development of such novel tractography algorithms and the selection of optimal parameters.

背景与目标： ：最近，大量研究已将基于扩散张量成像（DTI）数据的牵引术作为一种工具来研究结构连接体。尽管DTI在提供独特的3D神经解剖学信息方面取得了巨大的成功，但它是一种间接的观察方法，其分辨率和准确性有限，其可靠性仍不清楚。因此，必须回答这个基本问题：DTI体层摄影术在构建大规模连接体中的可靠性如何？为了回答这个问题，我们以艾伦小鼠脑部连接图集（AMCA）发布的1772年小鼠大脑神经元追踪数据为基础，来评估DTI显像在推断白质纤维通路和区域间性能方面的表现。连接。通过与跟踪数据进行比较，已经首次在神经影像学领域中评估了全脑DTI描记法在构建大型连接体中的性能。我们的研究结果表明，只有优化的束线照相参数和适当的脑部碎裂方案规模，DTI才能产生相对可靠的纤维通路和大规模的连接组。同时，在优化的DTI影像学检查结果中也发现了相当多的错误，我们认为通过开发更好的DTI影像学检查方法可以潜在地减轻这种错误。在这种情况下，我们的框架可以用作可靠且定量的测试平台，以识别出物镜检查结果中的错误，这将有助于这种新颖的物镜检查算法的开发和最佳参数的选择。

BACKGROUND & AIMS: :Diffusion tensor imaging (DTI) is rarely applied in spinal cord injury (SCI). The aim of this study was to correlate diffusion properties after SCI with electrophysiological and neurological measures. Nineteen traumatic cervical SCI subjects and 28 age-matched healthy subjects participated in this study. DTI data of the spinal cord were acquired with a Philips Achieva 3 T MR scanner using an outer volume suppressed, reduced field of view (FOV) acquisition with oblique slice excitation and a single-shot EPI readout. Neurological and electrophysiological measures, American Spinal Injury Association (ASIA) impairment scale scores, and motor (MEP) and somatosensory evoked potentials (SSEP) were assessed in SCI subjects. Fractional anisotropy (FA) values were decreased in the SCI subjects compared to the healthy subjects. In upper cervical segments, the decrease in FA was significant for the evaluation of the entire cross-sectional area of the spinal cord, and for corticospinal and sensory tracts. A decreasing trend was also found at the thoracic level for the corticospinal tracts. The decrease of DTI values correlated with the clinical completeness of SCI, and with SSEP amplitudes. The reduced DTI values seen in the SCI subjects are likely due to demyelination and axonal degeneration of spinal tracts, which are related to clinical and electrophysiological measures. A reduction in DTI values in regions remote from the injury site suggests their involvement with wallerian axonal degeneration. DTI can be used for the quantitative evaluation of the extent of spinal cord damage, and eventually to monitor the effects of future regeneration-inducing treatments.

背景与目标： ：弥散张量成像（DTI）很少用于脊髓损伤（SCI）。这项研究的目的是使SCI后的扩散特性与电生理和神经学指标相关联。 19名外伤性宫颈SCI受试者和28名年龄相匹配的健康受试者参加了这项研究。使用Philips Achieva 3 T MR扫描仪获取脊髓的DTI数据，该扫描仪使用外部体积抑制，倾斜切片激励和单次EPI读数来获取缩小的视场（FOV）。在SCI受试者中评估了神经和电生理指标，美国脊髓损伤协会（ASIA）损伤量表评分，运动（MEP）和体感诱发电位（SSEP）。与健康受试者相比，SCI受试者的分数各向异性（FA）值降低。在上颈段，FA的降低对于评估脊髓的整个横截面以及皮质脊髓和感觉道而言是显着的。胸椎皮质脊髓束水平也有下降的趋势。 DTI值的降低与SCI的临床完整性和SSEP幅度相关。在SCI受试者中看到的DTI值降低可能是由于脊髓的脱髓鞘和轴突变性所致，这与临床和电生理指标有关。远离损伤部位的区域中DTI值的降低表明它们参与了瓦勒轴突变性。 DTI可用于定量评估脊髓损伤的程度，并最终监测未来诱导再生的治疗的效果。

BACKGROUND & AIMS: BACKGROUND:After the demonstration of a corticoefferent propagation pattern in amyotrophic lateral sclerosis (ALS) by neuropathological studies, this concept has been used for in vivo staging of individual patients by diffusion tensor imaging (DTI) techniques, both in `classical` ALS and in restricted phenotypes such as primary lateral sclerosis (PLS). OBJECTIVE:The study was designed to investigate that microstructural changes according to the neuropathologically defined ALS alteration pattern in PLS patients could be confirmed to be identical to ´classical´ ALS patients. The novelty in this approach is that the results were independent of the subject samples and the data acquisition parameters (as was validated in two samples from two different centres). That way, reproducibility across (international) centres in addition to harmonisation/standardisation of data analysis has been addressed, for the possible use of MRI-based staging to stratify patients in clinical trials. METHODS:Tractwise analysis of fractional anisotropy (FA) maps according to the ALS-staging pattern was applied to DTI data (pooled from two ALS centres) of 88 PLS patients and 88 ALS patients with a 'classical' phenotype in comparison to 88 matched controls in order to identify white matter integrity alterations. RESULTS:In the tract-specific analysis, alterations were identical for PLS and ALS in the tract systems corresponding to the ALS staging pattern, independent of the subject samples and the data acquisition parameters. The individual categorisation into ALS stages did not differ between PLS and ALS patients. CONCLUSIONS:This DTI study in a two-centre setting demonstrated that the neuropathological stages can be mapped in vivo in PLS with high reproducibility and that PLS-associated cerebral propagation, although showing the same corticofugal patterns as ALS, might have a different time course of neuropathology, in analogy to its much slower clinical progression rates.

背景与目标： 背景：在通过神经病理学研究证实了肌萎缩性侧索硬化症（ALS）的皮质介导的传播方式之后，该概念已通过扩散张量成像（DTI）技术用于个别患者的体内分期，无论是在“经典” ALS中还是在限制性表型，例如原发性侧索硬化症（PLS）。
目的：本研究旨在调查根据神经病理学定义的ALS改变模式在PLS患者中的微结构变化可被证实与“经典” ALS患者相同。这种方法的新颖之处在于结果独立于主题样本和数据采集参数（已在来自两个不同中心的两个样本中进行了验证）。这样，除了可以统一/标准化的数据分析外，还解决了跨（国际）中心的可重复性问题，从而可以在临床试验中使用基于MRI的分期对患者进行分层。
方法：将根据ALS分期模式进行的分数各向异性（FA）图的逐行分析应用于88个PLS患者和88个具有'经典'表型的ALS患者的DTI数据（从两个ALS中心汇集），而与88个匹配对照组进行比较为了识别白质完整性改变。
结果：在特定于管道的分析中，对应于ALS分期模式的管道系统中PLS和ALS的变化是相同的，独立于受试者样本和数据采集参数。在PLS和ALS患者之间，进入ALS阶段的个体分类没有差异。
结论：这项在两个中心的DTI研究表明，神经病理学阶段可以在PLS中以高再现性进行体内定位，并且与PLS相关的脑部繁殖，尽管显示出与ALS相同的皮质型，但可能具有不同的时程。神经病理学，类似于它的临床进展速度要慢得多。

BACKGROUND & AIMS: :Subjective tinnitus is the perception of sound in the absence of an external source. Tinnitus is often accompanied by hearing loss but not everyone with hearing loss experiences tinnitus. We examined neuroanatomical alterations associated with hearing loss and tinnitus in three groups of subjects: those with hearing loss with tinnitus, those with hearing loss without tinnitus and normal hearing controls without tinnitus. To examine changes in gray matter we used structural MRI scans and voxel-based morphometry (VBM) and to identify changes in white matter tract orientation we used diffusion tensor imaging (DTI). A major finding of our study was that there were both gray and white matter changes in the vicinity of the auditory cortex for subjects with hearing loss alone relative to those with tinnitus and those with normal hearing. We did not find significant changes in gray or white matter in subjects with tinnitus and hearing loss compared to normal hearing controls. VBM analysis revealed that individuals with hearing loss without tinnitus had gray matter decreases in anterior cingulate and superior and medial frontal gyri relative to those with hearing loss and tinnitus. Region-of-interest analysis revealed additional decreases in superior temporal gyrus for the hearing loss group compared to the tinnitus group. Investigating effects of hearing loss alone, we found gray matter decreases in superior and medial frontal gyri in participants with hearing loss compared to normal hearing controls. DTI analysis showed decreases in fractional anisotropy values in the right superior and inferior longitudinal fasciculi, corticospinal tract, inferior fronto-occipital tract, superior occipital fasciculus, and anterior thalamic radiation for the hearing loss group relative to normal hearing controls. In attempting to dissociate the effect of tinnitus from hearing loss, we observed that hearing loss rather than tinnitus had the greatest influence on gray and white matter alterations.

背景与目标： ：主观耳鸣是在没有外部来源的情况下对声音的感知。耳鸣常伴有听力障碍，但并非每个有听力障碍的人都会出现耳鸣。我们在三组受试者中检查了与听力损失和耳鸣相关的神经解剖学改变：患有耳鸣的听力损失者，没有耳鸣的听力损失者和没有耳鸣的正常听力对照者。为了检查灰质的变化，我们使用了结构MRI扫描和基于体素的形态测量（VBM），并使用扩散张量成像（DTI）来确定白质束方向的变化。这项研究的主要发现是，相对于耳鸣者和听力正常者，仅听力损失的受试者在听觉皮层附近既有灰白色变化，也有白质变化。与正常的听力对照者相比，我们没有发现耳鸣和听力丧失的受试者的灰色或白色物质显着变化。 VBM分析显示，相对于那些有听力损失和耳鸣的人，没有耳鸣的听力损失的人的前扣带回和上，内侧额回中的灰质减少了。感兴趣区域分析显示，与耳鸣组相比，听力损失组的颞上回额外减少。单独调查听力损失的影响，我们发现与正常听力对照相比，患有听力损失的参与者的上，内侧额回回中的灰质减少。 DTI分析显示，相对于正常听力对照，听力损失组右上，下纵筋膜，皮质脊髓束，额枕下束，枕上束膜和丘脑前部辐射的分数各向异性值均已降低。在试图从耳聋中分离出耳鸣的效果时，我们观察到耳聋而不是耳鸣对灰色和白色物质的变化影响最大。

BACKGROUND & AIMS: :Rank-2 tensors are unable to represent multi-modal diffusion associated with intra-voxel orientational heterogeneity (IVOH), which occurs where axons are incoherently oriented, such as where bundles intersect or diverge. Under this condition, they are oblate or spheroidally shaped, resulting in artefactually low anisotropy, potentially masking reduced axonal density, myelinisation and integrity. Higher rank tensors can represent multi-modal diffusion, and suitable metrics such as generalised anisotropy (GA) and scaled entropy (SE) have been introduced. The effect of tensor rank was studied through simulations, and analysing high angular resolution diffusion imaging (HARDI) data from two volunteers, fit with rank-2, rank-4 and rank-6 tensors. The variation of GA and SE as a function of rank was investigated through difference maps and region of interest (ROI)-based comparisons. Results were correlated with orientation distribution functions (ODF) reconstructed with q-ball, and with colour-maps of the principal and second eigenvectors. Simulations revealed that rank-4 tensors are able to represent multi-modal diffusion, and that increasing rank further has a minor effect on measurements. IVOH was detected in subcortical regions of the corona radiata, along the superior longitudinal fasciculus, in the radiations of the genu of the corpus callosum, in peritrigonal white matter and along the inferior fronto-occipital and longitudinal fascicula. In these regions, elevating tensor rank increased anisotropy. This was also true for the corpus callosum, cingulum and anterior limb of the internal capsule, where increasing tensor rank resulted in patterns that, although mono-modal, were more anisotropic. In these regions the second eigenvector was coherently oriented. As rank-4 tensors have only 15 distinct elements, they can be determined without acquiring a large number of directions. By removing artefactual underestimation of anisotropy, their use may increase the sensitivity to pathological change.

背景与目标： ：Rank-2张量无法表示与体素内取向异质性（IVOH）相关的多峰扩散，这种扩散发生在轴突不连贯取向的地方，例如束相交或发散的地方。在这种情况下，它们呈扁圆形或球形，导致人为地降低了各向异性，并可能掩盖了轴突密度降低，髓鞘形成和完整性降低的趋势。较高等级的张量可以表示多峰扩散，并且已经引入了诸如广义各向异性（GA）和比例熵（SE）之类的合适度量。通过模拟研究了张量等级的影响，并分析了来自两名志愿者的高角分辨率扩散成像（HARDI）数据，这些数据适合等级2，等级4和等级6的张量。通过差异图和基于感兴趣区域（ROI）的比较研究了GA和SE随等级变化的变化。结果与用q球重建的方向分布函数（ODF）以及主特征向量和第二特征向量的颜色图相关。模拟表明，等级4张量能够表示多峰扩散，等级增加对测量的影响较小。在冠状放射线的皮层下区域，沿上纵向束，call体属的放射线，三角质白质以及额枕下和纵束下部中检测到IVOH。在这些区域中，张量等级升高会增加各向异性。对于call体，扣带和内囊的前肢也是如此，其中张量等级的增加导致了模式，尽管是单峰的，但更具各向异性。在这些区域中，第二特征向量是连贯定向的。由于4级张量只有15个不同的元素，因此无需获取大量方向即可确定它们。通过消除人为因素对各向异性的低估，它们的使用可能会增加对病理变化的敏感性。

BACKGROUND & AIMS: BACKGROUND:Diffusion tensor imaging (DTI) is a recent MRI technique demonstrating white matter tracts in the brain. Dementia is a neurodegenerative disease and this method has been used to demonstrate the loss of axonal fibers and myelin and decrease of fiber density in this condition. PURPOSE:To study a possible correlation between frontal lobe symptoms in patients with dementia and reduced fractional anisotropy (FA) in white matter/fascicles in the frontal lobes. MATERIAL AND METHODS:The study included 23 patients with dementia and frontal lobe symptoms and 20 controls (10 Alzheimer patients without frontal lobe symptoms and 10 normal controls). Clinical tests and MRI with DTI were performed. FA in subcortical white matter of both the frontal lobes was analyzed and correlated with clinical frontal score tests. RESULTS:We found a significant correlation between frontal score results and reduction in FA in the frontal lobes. The FA in the study group was significantly lower than the FA in the control group. CONCLUSION:The present study reveals that there is a probable correlation between the extent of frontal lobe symptoms and FA in fascicles/white matter tissue in the frontal lobes.

背景与目标： 背景：扩散张量成像（DTI）是一种最新的MRI技术，可显示大脑中的白质束。痴呆是一种神经退行性疾病，这种方法已被用来证明在这种情况下轴突纤维和髓磷脂的损失以及纤维密度的降低。
目的：研究痴呆患者额叶症状与额叶白质/纤维束分数各向异性（FA）降低​​之间的可能相关性。
材料与方法：该研究包括23例患有痴呆和额叶症状的患者和20例对照（10例无额叶症状的阿尔茨海默病患者和10例正常对照）。进行了DTI的临床检查和MRI。分析两个额叶的皮质下白质中的FA，并将其与临床额叶评分测试相关联。
结果：我们发现额叶评分结果与额叶FA的降低之间存在显着相关性。研究组的FA显着低于对照组的FA。
结论：本研究揭示额叶症状的程度与额叶的分枝/白质组织中的FA之间存在可能的相关性。

BACKGROUND & AIMS: In psychiatric research, there is a growing interest in the microstructural and functional characteristics of brain networks, which often form the basis of current etiological concepts. As a result of novel magnetic resonance imaging techniques, the pathogenic characteristics of neuronal activity and connectivity can be examined in a noninvasive, safe, and repeatable manner. Functional magnetic resonance imaging (fMRI) uses blood oxygenation level-dependent (BOLD) measures for identifying the gray matter contribution to cognition. Diffusion tensor imaging (DTI) reveals the course and structural integrity of white matter projections. Because DTI does not require special motivation and performance, group differences in psychiatry are more easily interpreted in terms of underlying pathology. To date few studies have tried to investigate both, i.e. dynamic and microstructural data in the sense of a modern multi-dimensional investigation approach. The combination of both techniques, however, seems to offer a promising vehicle to further extent our current understanding of mental disorders and to identify populations at risk. In addition to addressing findings in psychiatric research, the present article presents a technical overview of DTI and examines the limitations and potential applications of both techniques.

背景与目标： 在精神病学研究中，人们对大脑网络的微观结构和功能特征的兴趣日益浓厚，而大脑网络的微观结构和功能特征通常构成当前病因学概念的基础。作为新型磁共振成像技术的结果，可以以非侵入性，安全且可重复的方式检查神经元活动和连接性的致病特征。功能磁共振成像（fMRI）使用血液氧合水平依赖性（BOLD）措施来识别灰质对认知的贡献。扩散张量成像（DTI）揭示了白质投影的过程和结构完整性。由于DTI不需要特殊的动机和表现，因此根据潜在的病理学更容易解释精神病学方面的群体差异。迄今为止，很少有研究试图从现代多维研究方法的角度来研究动态和微观结构数据。然而，两种技术的结合似乎为进一步扩展我们目前对精神障碍的认识并确定处于危险中的人群提供了有希望的手段。除了解决精神病学研究的发现外，本文还介绍了DTI的技术概述，并研究了这两种技术的局限性和潜在应用。

BACKGROUND & AIMS: :Diffusion tensor imaging (DTI) metrics such as fractional anisotropy (FA) and mean diffusivity (MD) have been proposed as clinical trial markers of cerebral small vessel disease (SVD) due to their associations with outcomes such as cognition. However, studies investigating this have been predominantly single-centre. As clinical trials are likely to be multisite, further studies are required to determine whether associations with cognition of similar strengths can be detected in a multicentre setting. One hundred and nine patients (mean age =68 years) with symptomatic lacunar infarction and confluent white matter hyperintensities (WMH) on MRI was recruited across six sites as part of the PRESERVE DTI substudy. After handling missing data, 3T-MRI scanning was available from five sites on five scanner models (Siemens and Philips), alongside neuropsychological and quality of life (QoL) assessments. FA median and MD peak height were extracted from DTI histogram analysis. Multiple linear regressions were performed, including normalized brain volume, WMH lesion load, and n° lacunes as covariates, to investigate the association of FA and MD with cognition and QoL. DTI metrics from all white matter were significantly associated with global cognition (standardized β =0.268), mental flexibility (β =0.306), verbal fluency (β =0.376), and Montreal Cognitive Assessment (MoCA) (β =0.273). The magnitudes of these associations were comparable with those previously reported from single-centre studies found in a systematic literature review. In this multicentre study, we confirmed associations between DTI parameters and cognition, which were similar in strength to those found in previous single-centre studies. The present study supports the use of DTI metrics as biomarkers of disease progression in multicentre studies.

背景与目标： ：由于张量成像（DTI）与认知等结果的关联，因此提出了诸如张量各向异性（FA）和平均扩散率（MD）的扩散张量成像（DTI）指标作为脑小血管疾病（SVD）的临床试验标记。但是，对此进行调查的研究主要是单中心的。由于临床试验可能是多地点的，因此需要进一步的研究来确定在多中心环境中是否可以检测到具有相似优势的认知。作为PRESERVE DTI子研究的一部分，从六个地点招募了119例有症状的腔隙性脑梗塞和融合性白质亢进（WMH）的MRI患者（平均年龄= 68岁）。处理完丢失的数据后，可以从五个扫描仪模型（Siemens和Philips）的五个位置进行3T-MRI扫描，同时进行神经心理学和生活质量（QoL）评估。从DTI直方图分析中提取FA中位数和MD峰高。进行了多个线性回归，包括标准化的脑容量，WMH病变负荷和n°腔隙作为协变量，以研究FA和MD与认知和QoL的关联。来自所有白质的DTI指标与整体认知（标准化的β= 0.268），心理柔韧性（β= 0.306），口语流利度（β= 0.376）和蒙特利尔认知评估（MoCA）显着相关（β= 0.273）。这些关联的程度与以前在系统文献综述中发现的单中心研究报告的程度相当。在这项多中心研究中，我们证实了DTI参数与认知之间的关联，其强度与以前的单中心研究中发现的相似。本研究支持在多中心研究中将DTI指标用作疾病进展的生物标记。

BACKGROUND & AIMS: :Diffusion MRI is sensitive to the microstructure of tissue and allows the study of structural plasticity over short time scales of only hours. The initial temporal and spatial progression of this process, however, has yet to be elucidated. With the aim of examining early temporal progression of structural plasticity, we subjected rats to short training periods on a task in the Morris water maze (MWM), a paradigm previously shown to induce rapid changes in diffusion tensor imaging (DTI) indices. Two groups of rats were each divided into subgroups that consecutively completed 1, 2 or 3 sets of short trials (up to 60s) in the MWM. Each set comprised 4 trials (1 from each quadrant of the WMW), with a specific time interval between sets. To assess the effect of the duration of the task on the evolving changes in DTI indices, we allowed a rest of 45min between sets in one group of rats and a 2-h rest in the other. All rats were scanned with a DTI protocol before and 45min after their last trial. We found that a few minutes of training in a new task sufficed to generate changes in diffusion indices. The earliest changes in DTI (measured after one set of trials) progressed with further training (measured after two sets), but within a few more minutes (after three sets) they reached a plateau. Lengthening the duration of the overall task by prolonging the time interval between sessions did not alter this pattern of change, suggesting that at least within this short time scale such changes are task-dependent, but not time dependent. Our results demonstrate the progression of structural neuroplasticity at different stages of exposure to a novel experience, and show that DTI can be used to trace, in vivo, the localization of structural plasticity induced by training.

背景与目标： ：扩散MRI对组织的微结构敏感，可以在短短几个小时的时间内研究结构可塑性。但是，该过程的初始时间和空间进展尚未阐明。为了检查结构可塑性的早期时间变化，我们在莫里斯水迷宫（MWM）中对大鼠进行了短时间的训练，该模型先前已证明可引起扩散张量成像（DTI）指数的快速变化。两组大鼠各分为亚组，它们连续完成MWM中的1组，2组或3组短期试验（最多60 s）。每组包括4次试验（来自WMW每个象限的1次试验），每组之间有特定的时间间隔。为了评估任务持续时间对DTI指数不断变化的影响，我们让一组大鼠之间休息45分钟，另一组大鼠休息2小时。在最后一次试验之前和之后45分钟，用DTI方案扫描所有大鼠。我们发现，对新任务进行的几分钟培训足以产生扩散指数的变化。 DTI的最早变化（一组试验后测量）随着进一步的训练（两组后测量）而进展，但又过了几分钟（三组之后），它们达到了平稳状态。通过延长会话之间的时间间隔来延长总体任务的持续时间并没有改变这种变化模式，这表明至少在此短时间内，这种变化是任务相关的，而不是时间相关的。我们的结果证明了在接触新知识的不同阶段结构神经可塑性的进展，并表明DTI可用于体内追踪由训练引起的结构可塑性的定位。