Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by progressive dementia, and amnestic mild cognitive impairment (aMCI) has been defined as a transitional stage between normal aging and AD. Accumulating evidence has shown that altered functional connectivity (FC) and structural connectivity (SC) in the default mode network (DMN) is the prominent hallmarks of AD. However, the relationship between the changes in SC and FC of the DMN is not yet clear. In the present study, we derived the FC and SC matrices of the DMN with functional magnetic resonance imaging (fMRI) and diffusion-weighted imaging (DWI) data and further assessed FC and SC abnormalities within a discovery dataset of 120 participants (39 normal controls, 34 patients with aMCI and 47 patients with AD), as well as a replication dataset of 122 participants (43 normal controls, 37 patients with aMCI and 42 patients with AD). Disrupted SC and FC were found among DMN components (e.g., the posterior cingulate cortex (PCC), medial prefrontal cortex (mPFC), and hippocampus) in patients in the aMCI and AD groups in the discovery dataset; most of the disrupted connections were also identified in the replication dataset. More importantly, some SC and FC elements were significantly correlated with the cognitive ability of patients with aMCI and AD. In addition, we found structural-functional decoupling between the PCC and the right hippocampus in patients in the aMCI and AD groups. These findings of the alteration of DMN connectivity in neurodegenerative cohorts deepen our understanding of the pathophysiological mechanisms of AD.

目的 通过磁共振T2 mapping和磁共振软骨延迟增强成像(dGEMRIC)评估膝关节再生软骨的修复过程.资料与方法 对13例患者的20处再生软骨在基质诱导的自体软骨细胞移植术(MACI)后1、3、6、12个月进行磁共振T2 mapping和dGEMRIC检查,测量再生软骨和邻近正常软骨的T2值和纵向弛豫率差(ΔR1)值,比较术后各时间点再生软骨和正常软骨T2值和ΔR1值的差异,观察再生软骨T2值和ΔR1值在术后1、3、6、12个月的动态变化.结果 再生软骨区T2值和ΔR1值在MACI术后1、3、6、12个月呈逐渐下降趋势,且差异有统计学意义(P<0.01).MACI术后1、3、6个月,再生软骨T2值和ΔR1值高于正常软骨(P均<0.01).术后12个月,再生软骨的T2值和ΔR1值与正常软骨比较,差异无统计学意义(P均>0.05).结论 磁共振T2 mapping和dGEMRIC能作为评价再生软骨生物特性的有效方法,为临床软骨移植工作的疗效评价提供依据.

Background : Hippocampal atrophy is a characteristic of Alzheimer’s disease (AD). However, alterations in structural connectivity (number of connecting fibers) between the hippocampus and whole brain regions due to hippocampal atrophy remain largely unknown in AD and its prodromal stage, amnestic mild cognitive impairment (aMCI). Methods : We collected high-resolution structural MRI (sMRI) and diffusion tensor imaging (DTI) data from 36 AD patients, 30 aMCI patients, and 41 normal control (NC) subjects. First, the volume and structural connectivity of the bilateral hippocampi were compared among the three groups. Second, correlations between volume and structural connectivity in the ipsilateral hippocampus were further analyzed. Finally, classification ability by hippocampal volume, its structural connectivity, and their combination were evaluated. Results : Although the volume and structural connectivity of the bilateral hippocampi were decreased in patients with AD and aMCI, only hippocampal volume correlated with neuropsychological test scores. However, positive correlations between hippocampal volume and ipsilateral structural connectivity were displayed in patients with AD and aMCI. Furthermore, classification accuracy (ACC) was higher in AD vs. aMCI and aMCI vs. NC by the combination of hippocampal volume and structural connectivity than by a single parameter. The highest values of the area under the receiver operating characteristic (ROC) curve (AUC) in every two groups were all obtained by combining hippocampal volume and structural connectivity. Conclusions : Our results showed that the combination of hippocampal volume and structural connectivity (number of connecting fibers) is a new perspective for the discrimination of AD and aMCI.

作为一种常见的病因未明的严重精神疾病,精神分裂症对人类健康影响巨大,是全球性公共卫生问题.精神分裂症患者存在大脑结构、功能或代谢的异常,但目前尚未发现可用于疗效预测的生物学标记物或客观指标,临床治疗决策存在极大困难.研发生物标记物是走出精神分裂症疗效预测困境的切入点.神经影像学方法尤其是MRI可提取精神分裂症患者大脑结构和功能特征作为生物学标记物,提示精神分裂症可能的神经病理机制,进而辅助精神分裂症的疗效预测、判断患者病程及预后,有助于个体化精准治疗,提高治疗效果.本文对精神分裂症疗效预测的神经影像学标记物的研究进展进行综述.

OPINION article Front. Psychiatry, 11 September 2020Sec. Neuroimaging Volume 11 - 2020 | https://doi.org/10.3389/fpsyt.2020.565056

Background: Alzheimer's disease (AD) is the most common cause of dementia in older individuals, and amnestic mild cognitive impairment (aMCI) is currently considered the prodromal stage of AD. The hippocampus and fornix interact functionally and structurally, with the fornix being the major efferent white matter tract from the hippocampus. Objective: The main aim of this study was to examine the impairments present in subjects with AD or aMCI and the relationship of these impairments with the microstructure of the fornix and the functional connectivity (FC) and gray matter volume of the hippocampus. Methods: Forty-four AD, 34 aMCI, and 41 age- and gender-matched normal controls (NCs) underwent neuropsychological assessments and multimode MRI. We chose the bilateral hippocampi as the region of interest in which gray matter alterations and FC with the whole brain were assessed and the fornix body as the region of interest in which the microstructural integrity of the white matter was observed. We also evaluated the relationship among gray matter alterations, the abnormal FC of the hippocampus and the integrity of the fornix in AD/aMCI. Results: Compared to the NC group, the AD and aMCI groups demonstrated decreased gray matter volume, reduced FC between the bilateral hippocampi and several brain regions in the default mode network and control network, and damaged integrity of the fornix body (decreased fractional anisotropy and increased diffusivity). We also found that left hippocampal FC with some regions, the integrity of the fornix body, and cognition ability were significantly correlated. Therefore, our findings suggest that damage to white matter integrity may partially explain the reduced resting-state FC of the hippocampus in AD and aMCI. Conclusion: AD and aMCI are diseases of disconnectivity including not only functional but also structural disconnectivity. Damage to white matter integrity may partially explain the reduced resting-state FC in AD and aMCI. These findings have significant implications for diagnostics and modeling and provide insights for understanding the disconnection syndrome in AD.

目的 利用静息态功能磁共振成像(rs-fMRI)技术研究阿尔茨海默病(AD)及遗忘型轻度认知功能损害(aMCI)海马亚区与全脑功能连接(Fc)的特点.方法 选取2016年5月～2018年1月解放军总医院第二医学中心神经内科招募筛选的40例AD、37例aMCI和41例健康对照者(NC),并对其rs-fMRI数据进行分析.观察AD及aMCI中这些FC值与认知损害程度(MMSE评分)的相关性.结果 左侧海马前、后部与其共性脑区的FC值均表现为AD较aMCI、NC中下降,而右侧海马前、后部与其共性脑区间FC值的改变形式多样.这些FC值绝大部分与认知损害的程度呈正相关.结论 AD及aMCI中海马亚区与其共性脑区间FC值的改变模式具有左右差异.

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive dementia. Diffusion tensor imaging (DTI) has been used widely to delineate the white matter integrity/degeneration in AD. Automated fiber quantification (AFQ) method is a fully automated method, which can identify the major white matter fiber tracts and then evaluate the white matter properties. The main purpose of this study is to assess the white matter integrity and abnormities in a cohort of amnestic Mild Cognitive Impairment (aMCI) and AD patients as well as normal controls (NCs). We tested the utility of diffusion tensor imaging measures along white matter tracts as features to classify the AD from NCs using support vector machine. The results showed that we have detected credible and robust potential early biomarker that may be useful for clinical application in AD.

To investigate the correlation of functional connectivity (FC) and the integrity of connective fibres between hippocampus and thalamus in Alzheimer′s disease(AD) and amnestic mild cognitive impairment (aMCI). Methods Both resting?state functional magnetic resonance imaging (rs?fMRI) and diffusion tensor imaging (DTI) data of 40 AD patients, 37 aMCI patients and 41 normal control subjects matching with age and educational level were collected. These subjects were all recruited from outpatient Department of Neurology in the Second Medical Center of Chinese PLA General Hospital, as well as poster, from May 2016 to January 2018. The FC strength between bilateral hippocampus and thalamus, as well as the parameters representing integrity of connective fibres, including fractional anisotropy(FA) and mean diffusivity(MD),were analyzed. Also, the correlations between FC strength and FA or MD strength were analyzed in the study. Results Compared to that of normal control subjects, the FC strength between billateral hippocampus and thalamus in patients with AD, aMCI were not significantly different(P>0.05). The integrity of bilateral connective fibres between hippocampus and thalamus were damaged in AD patients when compared to normal control subjects(P<0.01). A positive correlation of connective fibres integrity with FC strength between hippocampus and thalamus was found in the left side(r=0.25,P<0.05) but rather in the right side. Conclusion In AD and aMCI patients, structural connectivity between left hippocampus and thalamus affects the functional connectivity between them.

目的 探讨老年人椎基底动脉延长扩张症(VBD)对后循环供血区脑血流量(CBF)的影响,分析老年人基底动脉形态学改变与后循环延迟血流的关系.资料与方法 纳入经磁共振血管成像诊断为VBD的24例老年患者(研究组)及正常老年人25例(对照组),测量三维准连续动脉自旋标记灌注成像[标记延迟时间(PLD)=1525 ms,PLD=2525 ms]MR扫描数据,利用SPM 12软件测量顶叶、枕叶、丘脑和小脑皮层的CBF值,并计算后循环延迟脑血流量,比较研究组及对照组延迟脑血流量的差异.结果PLD=1525 ms时,研究组后循环的CBF值低于对照组,双侧顶叶、枕叶、丘脑、小脑CBF值与对照组比较,差异有统计学意义(P<0.05、P<0.01);PLD=2525 ms时,研究组与对照组后循环的CBF值比较,差异无统计学意义(P>0.05);研究组后循环延迟的脑血流量比大于对照组,双侧顶叶、枕叶、丘脑、小脑延迟脑血流量比与对照组比较,差异有统计学意义(P<0.05、P<0.01).结论 VBD患者后循环血流速度减慢,延迟灌注现象显著,但不影响CBF最大灌注值.VBD患者后循环CBF较健康人无显著差异.

PURPOSE:To describe the sonographic (ultrasound-US) features of retained surgical sponges (RSSs) and compare them with the pathological findings.METHODS:Ultrasound features of RSSs in nine patients (seven women and two men) identified between June 1996 and July 2015 were retrospectively analyzed. Patient characteristics including gender and age, location of the sponge, time interval until diagnosis, clinical presentation, and patient complaints were evaluated.RESULTS:The US appearances of RSSs could be classified into three types. Type I (five cases): an echogenic arc with a strong posterior shadow; type II (two cases): US appearance mimicked a cystic teratoma; type III (two cases): a cystic mass with zigzag-shaped internal contents. CT and/or MRI showed a mass with density/signal intensity similar to that of the adjacent soft tissues.CONCLUSION:The characteristic US findings along with a history of surgery can help reach a correct diagnosis of RSS.

Alzheimer's disease (AD) is characterized by progressive dementia, especially in episodic memory, and amnestic mild cognitive impairment (aMCI) is associated with a high risk of developing AD. Hippocampal atrophy/shape changes are believed to be the most robust magnetic resonance imaging (MRI) markers for AD and aMCI. Radiomics, a method of texture analysis, can quantitatively examine a large set of features and has previously been successfully applied to evaluate imaging biomarkers for AD. To test whether radiomic features in the hippocampus can be employed for early classification of AD and aMCI, 1692 features from the caudal and head parts of the bilateral hippocampus were extracted from 38 AD patients, 33 aMCI patients and 45 normal controls (NCs). One way analysis of variance (ANOVA) showed that 111 features exhibited statistically significant group differences (P < 0.01, Bonferroni corrected). Among these features, 98 were significantly correlated with Mini-Mental State Examination (MMSE) scores in AD and aMCI subjects (P < 0.01). The support vector machine (SVM) model demonstrated that radiomic features allowed us to distinguish AD from NC with an accuracy of 86.75% (specificity = 88.89% and sensitivity = 84.21%) and an area under curve (AUC) of 0.93. In conclusion, these findings provide evidence showing that radiomic features are beneficial in detecting early cognitive decline, and SVM classification analysis provides encouraging evidence for using hippocampal radiomic features as a potential biomarker for clinical applications in AD.

Alzheimer's disease (AD) is a worldwide progressive neurodegenerative disorder in the elderly. Previous research has indicated that Alzheimer's disease impairs white matter (WM) tracts. Anatomical and neuroimaging studies have indicated that WM tracts are associated with cognitive function. Whether the abnormal WM integrity in AD is associated with cognitive impairments and the clinical symptoms is still not clear. To this end, we investigated the relationship between the impairments in WM tracts and the decline of cognitive ability in AD. Diffusion tensor imaging (DTI) data were collected from 38 AD patients and 30 normal, cognitively healthy volunteers. The tract-based spatial statistics (TBSS) approach was used to compare the fractional anisotropy (FA) and mean diffusivity (MD) values between the two groups. WM tracts (cingulum, superior longitudinal fasciculus (SLF), uncinate fasciculus (UF), and inferior longitudinal fasciculus (ILF)) associated with cognition function were extracted for region of interest (ROI)-based analysis. Significantly decreased FA values and increased MD values of the cognition-related WM tracts were observed in the AD group compared with the normal cognition (NC) group. In addition, we further demonstrated that the decreased FA values and increased MD values of the cognition-related WM tracts were significantly correlated with MMSE scores. These results indicated that abnormal changes in WM integrity are observed following AD. Finally, we used support vector machine (SVM) with a repeated, stratified 10-fold cross-validated classifier to evaluate the ability of FA and MD values to discriminate disease. The accuracy of the SVM using cognition-related WM as classified features was higher than that using non-cognition-related tracts. Most importantly, our results showed the relationship between abnormal WM tracts and cognitive ability in AD. These findings further suggested that AD-related impairments in cognition-related WM tracts may influence the cognitive ability of AD patients.

Alzheimer's disease (AD) is a neurodegenerative disorder associated with the progressive dysfunction of cognitive ability. Previous research has indicated that the default mode network (DMN) is closely related to cognition and is impaired in Alzheimer's disease. Because recent studies have shown that different frequency bands represent specific physiological functions, DMN functional connectivity studies of the different frequency bands based on resting state fMRI (RS-fMRI) data may provide new insight into AD pathophysiology. In this study, we explored the functional connectivity based on well-defined DMN regions of interest (ROIs) from the five frequency bands: slow-5 (0.01-0.027 Hz), slow-4 (0.027-0.073 Hz), slow-3 (0.073-0.198 Hz), slow-2 (0.198-0.25 Hzs) and standard low-frequency oscillations (LFO) (0.01-0.08 Hz). We found that the altered functional connectivity patterns are mainly in the frequency band of slow-5 and slow-4 and that the decreased connections are long distance, but some relatively short connections are increased. In addition, the altered functional connections of the DMN in AD are frequency dependent and differ between the slow-5 and slow-4 bands. Mini-Mental State Examination scores were significantly correlated with the altered functional connectivity patterns in the slow-5 and slow-4 bands. These results indicate that frequency-dependent functional connectivity changes might provide potential biomarkers for AD pathophysiology.

Objective To investigate the value of 3D pseudo-continuous arterial spin labeling (3D-pCASL) magnetic resonance perfusion technique in evaluating posterior circulation ischemia (PCI) of the elderly beyond 80 years old and to offer the evidence of PCI of the elderly for clinical diagnosis. Methods Totally 53 male subjects older than 80 years were recruited in this study,including 20 subjects with clinically diagnosed PCI and 33 normal subjects. All the subjects underwent routine brain magnetic resonance imaging and 3D-pCASL sequence on a 3.0T magnetic resonance imaging system with 8 channel brain coil. Two post-labeling delay (PLD) time (PLD=1525 ms and PLD=2525 ms) of 3D-pCASL were used in this study to increase the accuracy of cerebral blood flow (CBF) change of posterior circulation region. We used SPM12 software to measure mean CBF values of bilateral occipital lobes and bilateral cerebellums. Independent sample t-test and rank-sum test were performed to evaluate the difference of CBF changes of anterior circulation and posterior circulation in two groups at two PLD time,the difference of CBF changes of bilateral occipital lobes and bilateral cerebellums in two groups of two PLD time,and the difference of increment of CBF between two PLD interval between two groups. Results In case group,the CBF value of the anterior circulation was significantly higher than that of posterior circulation at both two PLD time points (PLD=1525 ms and PLD=2525 ms)(P=0.000,P=0.000);in control group,the CBF value of the anterior circulation was significantly higher than that of the posterior circulation only at PLD=1525ms (P=0.025). The CBF values at bilateral occipital lobes and bilateral cerebellums at two PLD time points (PLD=1525 ms and PLD=2525 ms) were significantly higher in case group than in control group(P=0.003,P=0.002,P=0.000,P=0.001,P=0.000,P=0.001,P=0.002,P=0.014,respectively). Compared with the control group,the difference was statistically significant in bilateral occipital lobes and cerebellums with a smaller △CBF between two PLD interval in case group (P=0.004,P=0.001,P=0.001,P=0.025). Conclusion Multiple PLD time points need to be used in 3D-pCASL in diagnosing PCI of the elderly because the posterior circulation is slow in these patients. 3D-pCASL technique is sensitive in detecting decreased CBF in posterior circulation and therefore can be used to predict posterior circulation stroke in the elderly.

Convergent evidence has been collected to support that Alzheimer’s disease (AD) is associated with reduction in hippocampal volume based on anatomical magnetic resonance imaging (MRI) and impaired functional connectivity based on functional MRI. Radiomics texture analysis has been previously successfully used to identify MRI biomarkers of several diseases, including AD, mild cognitive impairment and multiple sclerosis. In this study, our goal was to determine if MRI hippocampal textures, including the intensity, shape, texture and wavelet features, could be served as an MRI biomarker of AD. For this purpose, the texture marker was trained and evaluated from MRI data of 48 AD and 39 normal samples. The result highlights the presence of hippocampal texture abnormalities in AD, and the possibility that texture may serve as a neuroimaging biomarker for AD.

目的 评估阿尔茨海默病(Alzheimer's disease,AD)及遗忘型轻度认知功能障碍(aMCI)患者海马及海马旁回的灰质体积改变及其与认知功能的相关性.方法 选择35例AD患者(AD组)、27例aMCI患者(aMCI组)及27例正常老年对照(NC组)的三维结构磁共振图像划分双侧海马、海马旁回感兴趣区,按照Y轴从前到后的顺序将各感兴趣区平均分为4部分,得到双侧海马头、双侧海马体1、双侧海马体2、双侧海马尾、双侧海马旁回头、双侧海马旁回体1、双侧海马旁回体2、双侧海马旁回尾16段,比较3组海马及海马旁回各段灰质体积,并分析其与神经心理量表的相关性.结果 AD组双侧海马及海马旁回各段灰质体积较NC组明显减小.aMCI合并AD组双侧海马前部、海马旁回中后部与简易智能精神状态检查量表呈正相关;aMCI组、aMCI合并AD组双侧海马及海马旁回各段灰质体积与延迟回忆和新词辨认等呈正相关.结论 海马及海马旁回灰质萎缩可以反映AD及aMCI患者情景记忆受损的程度,海马头部萎缩可以反映AD整体认知下降水平.

Alzheimer's disease (AD) and mild cognitive impairment (MCI) have been associated with impaired communication among large-scale brain networks. Given nature that interconnected subnetworks are responsible for daily behavior than a single pair of functional connectivity, it is valid to use a network-based statistic (NBS) method to exploit the clustering structure of connectivity alterations in AD/MCI. We explored abnormal network components using NBS based on resting-state functional magnetic resonance imaging (fMRI)connectivity in a sample of patients with AD (N = 35), MCI (N = 27) and age-matched healthy subjects (N = 27). The results demonstrated that patients had reduced functional connectivity strength in several components, including the default mode network, sensorimotor network, visual-sensory network, and visual-attention network. In patients with AD, the functional connectivity of these components of interest (COIs) exhibited greater attenuation than that in MCI subjects compared with normal cognition. A greater degree of cognitive impairment was correlated with a greater decrease in functional connectivity in the identified COIs. These results indicate that the neurodegenerative disruption of fMRI connectivity is widely distributed in several networks in AD/MCI. These profiles deepen our understanding of the neural basis of AD/MCI dysfunction and indicate the potential of resting-state fMRI measures as biomarkers or predictors of AD.

The purpose of our study was to investigate whether the whole-brain functional connectivity pattern exhibits disease severity-related alterations in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). Resting-state functional magnetic resonance imaging data were acquired in 27 MCI subjects, 35 AD patients, and 27 age- and gender-matched subjects with normal cognition (NC). Interregional functional connectivity was assessed based on a predefined template which parcellated the brain into 90 regions. Altered whole-brain functional connectivity patterns were identified via connectivity comparisons between the AD and NC subjects. Finally, the relationship between functional connectivity strength and cognitive ability according to the mini-mental state examination (MMSE) was evaluated in the MCI and AD groups. Compared with the NC group, the AD group exhibited decreased functional connectivities throughout the brain. The most significantly affected regions included several important nodes of the default mode network and the temporal lobe. Moreover, changes in functional connectivity strength exhibited significant associations with disease severity-related alterations in the AD and MCI groups. The present study provides novel evidence and will facilitate meta-analysis of whole-brain analyses in AD and MCI, which will be critical to better understand the neural basis of AD.

OBJECTIVE To assess the value of magnetic resonance imaging (MRI) T2 mapping in quantitative evaluation of cartilage repair following matrix-associated autologous chondrocyte transplantation (MACT). METHODS Six patients (with 9 plug cartilages) following MACT underwent MRI on a 3.0 Tesla MR scan system at 3, 6 and 12 months after the surgery. The full-thickness and zonal areas (deep and superficial layers) T2 values were calculated for the repaired cartilage and control cartilage. RESULTS The mean T2 values of the repaired cartilage after MACT were significantly higher than that of the control cartilages at 3 and 6 months (P<0.05), but not at 12 months (P=0.063). At 6 and 12 months, the T2 values of the superficial layers were significantly higher than those of the deep layers in the repaired cartilages (P<0.05). The zonal (deep and superficial layers) T2 values of the repaired cartilages decreased significantly over time at 6 and 12 months as compared to those at 3 months after the surgery (P<0.05). CONCLUSION MRI T2 mapping can serve as an important modality for assessing the repair of the articular cartilage following MACT.