Diffusion tensor imaging measures of normal appearing white matter in patients who are aging,or have amnestic mild cognitive impairment,or Alzheimer’s disease

To evaluate whether cerebral white matter integrity is related to cognitive function, and whether diffusion tensor imaging (DTI) could differentiate amnestic mild cognitive impairment (aMCI) from Alzheimer’s disease (AD), 12 patients with AD, 12 with aMCI, and 12 controls were recruited for this study. Cognitive functions of all subjects were assessed using the Mini-Mental State Examination (MMSE) and AD Assessment Scale – Cognitive Subscale (ADAS-Cog). DTI studies were acquired, and fractional anisotropy (FA) and mean diffusivity (MD) values of normal-appearing white matter (NAWM) in multiple brain regions were obtained. Results showed that MMSE and ADAS-Cog subscores were significantly associated with white matter integrity of the temporal-parietal lobes. A decrease in FA values and an increase in MD values in multiple cortical regions were confirmed in patients with AD compared to controls. MD values in the posterior region of the corpus callosum in aMCI differed from those of early AD. Significant reductions of FA values in the NAWM of the parietal lobe was observed in aMCI compared to controls. Our data indicate that the microstructural white matter integrity in the temporal-parietal lobes is gradually impaired in the progressive process of AD, and that splenium MD values could be used as a biomarker differentiating aMCI from AD.     

Ultrastructural hippocampal and white matter alterations in mild cognitive impairment: a diffusion tensor imaging study

Mild cognitive impairment (MCI) is considered to be a transitional stage between normal aging and dementia. In Alzheimer's disease (AD), white matter structural pathology is due to Wallerian degeneration and central angiopathy. However, in MCI patients, the presence and extent of white matter alterations as a possible correlate of impaired memory function and as predictor of subsequent progression to AD is not clarified yet. Diffusion tensor imaging (DTI) reveals the ultrastructural integrity of cerebral white matter tracts. Therefore, it could detect pathological processes that modify tissue integrity in patients with MCI. In our prospective study, conventional and diffusion tensor MR scans were obtained from 14 patients with MCI, 19 patients with AD, and 10 healthy controls. Mean diffusivity (MD) and fractional anisotropy (FA) were measured in temporal, frontal, parietal and occipital white matter regions as well as in the corpus callosum (genu and splenium) and the hippocampus. MCI patients showed higher MD values in the left centrum semiovale (p = 0.013; right: p = 0.026), in the left temporal (p = 0.006), the right temporal (p = 0.014) and the left hippocampal (p = 0.002) region as compared to the control group. FA values of MCI patients and controls did not differ significantly in any region. Compared to controls, AD patients had increased MD values in the left centrum semiovale (p = 0.012), the left parietal (p = 0.001), the right parietal (p = 0.028), the left temporal (p = 0.018), the right temporal (p = 0.011) and the left hippocampal region (p = 0.002). Decreased FA values were measured in the left temporal area (p = 0.017) and in the left hippocampus (p = 0.031) in AD patients compared to controls. FA and MD values did not differ significantly between AD and MCI patients. Elevated MD values indicating brain tissue alterations in MCI patients were found in regions that are typically involved in early changes due to AD, particularly the left hippocampus. The sensitivity of distinguishing MCI patients from controls was 71.4% (with a specificity set at 80%). Therefore, the DTI technique validates the MCI concept, and diffusion tensor MR measurement can be a helpful tool to quantify MCI pathology in vivo.     

Diffusion tensor imaging based white matter changes and antioxidant enzymes status for early identification of mild cognitive impairment

Mild cognitive impairment (MCI) is an early stage of dementia. The changes in white matter integrity and antioxidant enzymes levels are crucial in onset and progression to Alzheimer’s disease (AD). To elucidate the changes in cognitive performance, white matter integrity, oxidative stress marker, for early detection of prodromal state of AD. Fifty cases of MCI and controls (55-75 years) were subjected to Mini Mental State Examination (MMSE), diffusion tensor imaging (DTI) followed by estimation of superoxide dismutase, glutathione peroxidase and lipid peroxidation in serum of MCI and control population. The MMSE scores of MCI subjects were (28±2 - 22.6±1) as compared with controls (28±1- 29±1). DTI metrics fractional anisotropy (FA) values in right and left frontal lobe, fornix, corpus callosum, while apparent diffusion coefficient (ADC) values in right temporal lobe, hippocampus head, corpus callosum right, and forcep major were significantly altered in MCI as compared with controls. Superoxide dismutase, glutathione peroxidase level were lower while lipid peroxidation marker malondialdehyde (MDA) was increased in patients with MCI as compared with controls. The study emphasized that changes in neuro-psychological performance, white matter integrity and antioxidant enzymes level provide early signature for diagnosis of MCI.     

White matter loss in the splenium of the corpus callosum in a case of posterior cortical atrophy: a diffusion tensor imaging study

There have been several functional imaging studies using PET and SPECT to investigate posterior cortical atrophy (PCA). These studies have suggested dysfunction of corticocortical connections which is consistent with the occipitoparietal stream. However, there are no reports suggesting disturbance of the white matter that interconnects the temporal, parietal and occipital cortices. We measured fractional anisotropy (FA) in the genu and splenium of the corpus callosum and created color maps using diffusion tensor imaging (DTI), which is a relatively new MRI technique that allows visualization of the directionality of water diffusion, in a patient with PCA and compared these findings with those in 5 typical Alzheimer disease (AD) patients. The PCA patient was a 75-year-old man presenting with progressive complex visual disorder who satisfied the clinical diagnostic criteria for PCA. In 5 typical AD patients, the FA index in the splenium was higher than that in the genu; however, in the PCA patient, the FA index in the splenium was significantly lower than that in the genu. A DTI-based color map of the PCA patient showed reduction of anisotropy and fiber volume in the splenium. These findings suggest that the splenium of the corpus callosum secondarily degenerated due to neuronal degeneration of the temporal, parietal and occipital cortices and suggest that reduction of the FA in the splenium is one of the characteristics of PCA.     

弥散张量成像对阿尔茨海默病脑白质改变的评价

目的分析阿尔茨海默病(Alzheimer's disease,AD)脑白质结构改变及与认知功能的关系。方法对37例AD组和32例对照组行简易精神状态量表(mini-mental State examinationn,MMSE)评估和DTI扫描。采用基于全脑体素分析法对两组全脑白质各向异性(fractional anisotropy,FA)图进行比较,采用t检验分析FA值差异,并评估AD组MMSE评分与FA值相关性。结果 AD患者出现FA值下降区域广泛分布在右侧额叶、颞叶、枕叶、丘脑及双侧扣带回、胼胝体、楔前叶、顶叶下回、顶下小叶、缘上回及海马旁回(其中P0.001,未经校正的P值);当使用经FWE校正的P0.05后,AD患者右侧扣带回、左侧胼胝体、颞叶下回及双侧顶叶下回、额叶下回、楔前叶区域FA值较对照组显著下降。AD患者FA值下降与MMSE量表评分呈正相关,(P0.001,未经校正)。结论 AD患者存在特定脑区白质结构改变,并与认知功能损害程度呈正相关。     

Secondary white matter degeneration of the corpus callosum in patients with intractable temporal lobe epilepsy: a diffusion tensor imaging study

Imaging changes in patients with focal epilepsy are not only seen in areas where seizures arise but often also in remote locations. The mechanism for such changes is unknown. We aimed to investigate whether patients with temporal lobe epilepsy (TLE) have microstructural changes involving the posterior portion of the corpus callosum (CC), where it links the temporal lobes, using presurgical diffusion tensor imaging (DTI) sequences. Ten patients with medically intractable TLE (two mesial TLE, eight neocortical TLE) who had seizure-free surgical outcomes were compared with 10 healthy controls. The regions of interest were outlined at each Witelson region (WR). Fractional anisotropy (FA), apparent diffusion coefficient (ADC) and three principal diffusivity values (lambda1, lambda2, lambda3) were determined in each WR. We performed tractography originating at each WR. In the TLE patients, the FA values were lower at the splenium of the corpus callosum (WR 7) compared to controls (p<0.05). Analysis of Eigen values in that location revealed that lambda1 values were decreased while lambda2 and lambda3 values were increased (p<0.05). Tractography revealed the connection between both temporal lobes via WR 7. In conclusion, decreased FA values with decreased lambda1 and increased lambda2 and lambda3 at the splenium of CC suggest that the pathologic changes, Wallerian degeneration, extend to the corpus callosum in TLE patients. Seizure-induced damage may cause secondary white matter degeneration along the tapetum and through the splenium of the corpus callosum, a potential pathway of spread in temporal lobe seizures.     

Altered white matter microstructure identified with tract-based spatial statistics in irritable bowel syndrome: a diffusion tensor imaging study

The neural mechanisms underlying the pathophysiology of irritable bowel syndrome(IBS) are far from being completely understood. The purpose of the present study was to investigate potential white matter (WM) microstructural changes and underlying causes for WM impairment in IBS using diffusion tensor imaging. The present prospective study involved 19 patients with IBS and 20 healthy controls. Whole-brain voxel-wise analyses of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were performed by tract-based spatial statistics (TBSS) to localize abnormal WM regions between the 2 groups. We found that IBS patients had significantly reduced FA (P < 0.05) in the splenium of the corpus callosum, the right retrolenticular area of the internal capsule and the right superior corona radiata. We also found increased MD (P < 0.05) in the splenium and body of the corpus callosum, the right retrolenticular area of the internal capsule, the right superior corona radiata and the right posterior limb of the internal capsule. In addition, IBS patients had significantly increased AD (P < 0.05) in the splenium of the corpus callosum, the bilateral retrolenticular area of the internal capsule and the left posterior limb of the internal capsule. We conclude that the WM microstructure is changed in IBS and the underlying pathological basis may be attributed to the axonal injury and loss. These results may lead to a better understanding of the pathophysiology of IBS.     

胼胝体网络连接性与脑白质疏松认知功能损害的相关性

目的 通过弥散张量成像（diffusion tensor imaging,DTI）研究脑白质疏松（leukoaraiosis,LA）患者胼 胝体网络连接性改变,并探讨其与认知功能损害的关系。 方法 本研究为前瞻性单中心研究。纳入30例法泽卡斯量表（Fazekas scale）评分为2～3级的LA患 者及20例头部磁共振成像正常的对照组。依据是否存在认知功能损害将LA组再分为认知正常与轻 度认知功能损害2个亚组。所有被研究对象均进行脑血管危险因素登记、血液生化检查、认知功能 评估筛查及3.0T头部磁共振成像检查及DTI检查。认知评估采用中文版蒙特利尔认知评估（Montreal Cognitive Assessment,MoCA）量表及简易智力状况检查（Mini-mental State Examination,MMSE）量表。使 用PANDA软件处理DTI数据,提取胼胝体膝部、体部及压部的部分各向异性（fractional anisotropy,FA） 和平均扩散系数（mean diffusivity,MD）数值。采用Pearson相关分析研究DTI数据变化与认知功能损害 的关系。 结果 LA组与对照组的性别、年龄、受教育情况、脑血管病常规危险因素及血生化之间差异无 显著性,P >0.05。LA组的MMSE及MoCA分值低于对照组,P值分别为0.002和0.008。LA组胝体膝部 （P =0.000）、体部（P =0.000）、压部（P =0.026）3个部位的FA值均低于对照组,而MD值高于对照组,P 值分别为0.013、0.006及0.007。LA组MMSE及MoCA分值降低与胼胝体膝部、体部、压部的FA下降均成 正相关,但相关系数从膝部（r =0.78）到压部（r =0.41）呈现逐渐递减趋势。 结论 LA存在胼胝体网络连接性改变,胼胝体FA下降与认知功能损害密切相关。     

Microstructural white matter abnormality and frontal cognitive dysfunctions in juvenile myoclonic epilepsy

Purpose: Previous neuroimaging studies provide growing evidence that patients with juvenile myoclonic epilepsy (JME) have both structural and functional abnormalities of the thalamus and frontal lobe gray matter. However, limited data are available regarding the issue of white matter (WM) involvement, making the microstructural WM changes in JME largely unknown. In the present study we investigated changes of WM integrity in patients with JME, and their relationships with cognitive functions and epilepsy-specific clinical factors. Methods: We performed diffusion tensor imaging (DTI) and neuropsychological assessment in 25 patients with JME and 30 control subjects matched for age, gender, and education level. Between-group comparisons of fractional anisotropy (FA) and mean diffusivity (MD) were carried out in a whole-brain voxel-wise manner by using tract-based spatial statistics (TBSS). In addition, both FA and MD were correlated with cognitive performance and epilepsy-specific clinical variables to investigate the influence of these clinical and cognitive factors on WM integrity changes. Key Findings: Neuropsychological evaluation revealed that patients with JME had poorer performance than control subjects on most of the frontal function tests. TBSS demonstrated that, compared to controls, patients with JME had significantly reduced FA and increased MD in bilateral anterior and superior corona radiata, genu and body of corpus callosum, and multiple frontal WM tracts. Disease severity, as assessed by the number of generalized tonic-clonic seizures in given years, was negatively correlated with FA and positively correlated with MD extracted from regions of significant differences between patients and controls in TBSS. Significance: Our findings of widespread disturbance of microstructural WM integrity in the frontal lobe and corpus callosum that interconnects frontal cortices could further support the pathophysiologic hypothesis of thalamofrontal network abnormality in JME. These WM abnormalities may implicate frontal cognitive dysfunctions and disease progression in JME.     

White matter integrity predicts delay discounting behavior in 9- to 23-year-olds: a diffusion tensor imaging study

Healthy participants (n = 79), ages 9-23, completed a delay discounting task assessing the extent to which the value of a monetary reward declines as the delay to its receipt increases. Diffusion tensor imaging (DTI) was used to evaluate how individual differences in delay discounting relate to variation in fractional anisotropy (FA) and mean diffusivity (MD) within whole-brain white matter using voxel-based regressions. Given that rapid prefrontal lobe development is occurring during this age range and that functional imaging studies have implicated the prefrontal cortex in discounting behavior, we hypothesized that differences in FA and MD would be associated with alterations in the discounting rate. The analyses revealed a number of clusters where less impulsive performance on the delay discounting task was associated with higher FA and lower MD. The clusters were located primarily in bilateral frontal and temporal lobes and were localized within white matter tracts, including portions of the inferior and superior longitudinal fasciculi, anterior thalamic radiation, uncinate fasciculus, inferior fronto-occipital fasciculus, corticospinal tract, and splenium of the corpus callosum. FA increased and MD decreased with age in the majority of these regions. Some, but not all, of the discounting/DTI associations remained significant after controlling for age. Findings are discussed in terms of both developmental and age-independent effects of white matter organization on discounting behavior.     

轻中型颅脑损伤后认知功能障碍的DTI研究

目的应用弥散张量成像(diffusion tensor imaging,DTI)技术探讨轻中型颅脑损伤病人不同部位脑白质微结构改变与其认知功能障碍的相关性。方法分析127例轻中型颅脑损伤病人的临床资料,伤后10 d采用蒙特利尔认知评估量表(Mo CA)评定有无认知功能障碍,并常规行头颅MRI检查,采集DTI数据,测量两侧额叶、颞叶内侧、顶叶,胼胝体膝部和压部,中脑部位的感兴趣区各向异性分数(FA值)、表观弥散系数(ADC值),并与Mo CA评估结果进行相关性分析。结果以Mo CA量表为标准评定,无认知功能障碍41例(32.28%,无认知障碍组),存在认知功能障碍86例(67.72%,认知障碍组),主要表现为视空间与执行功能、注意力和计算力、语言、抽象能力、延迟记忆的障碍。与无认知障碍的病人相比,认知障碍的病人两侧额叶、颞叶内侧、胼胝体膝部FA值降低,ADC值增加,差异具有统计学意义(P0.01)。结论轻中型颅脑损伤病人早期存在显著认知功能障碍,以视空间与执行功能、注意力和计算力、语言、抽象能力、延迟记忆障碍为主。颅脑损伤后早期认知功能障碍与病人额叶、颞叶、胼胝体白质受损密切相关。     

Quantification of age- and gender-related changes in diffusion tensor imaging indices in deep grey matter of the normal human brain

This study aimed to demonstrate age-related and gender-related changes in diffusion tensor imaging (DTI) indices of deep grey matter (GM) nuclei of the normal human brain. DTI was performed on 142 subjects (age: 10-52 years). Regions of interest were placed on the caudate nucleus (CN), putamen, globus pallidus, frontal white matter (WM), occipital WM, anterior and posterior limb of internal capsule, genu of the corpus callosum and splenium in all participants. The quadratic regression model was used to describe age-related and gender-related changes in DTI indices for GM and WM. We observed increased fractional anisotropy (FA) values with age up to adulthood in GM, and a rise up to the third decade of life followed by a decrease in FA for WM. We observed higher FA values in males compared to females in CN and all WM regions. Decreased mean diffusivity with age was observed in GM and WM irrespective of gender. This normative data may be valuable in the diagnosis of neurodegenerative diseases.     

Age‐related topographic map of magnetic resonance diffusion metrics in neonatal brains

Accelerated maturation of brain parenchyma close to term‐equivalent age leads to rapid changes in diffusion‐weighted imaging (DWI) and diffusion tensor imaging (DTI) metrics of neonatal brains, which can complicate the evaluation and interpretation of these scans. In this study, we characterized the topography of age‐related evolution of diffusion metrics in neonatal brains. We included 565 neonates who had MRI between 0 and 3 months of age, with no structural or signal abnormality—including 162 who had DTI scans. We analyzed the age‐related changes of apparent diffusion coefficient (ADC) values throughout brain and DTI metrics (fractional anisotropy [FA] and mean diffusivity [MD]) along white matter (WM) tracts. Rate of change in ADC, FA, and MD values across 5 mm cubic voxels was calculated. There was significant reduction of ADC and MD values and increase of FA with increasing gestational age (GA) throughout neonates'' brain, with the highest temporal rates in subcortical WM, corticospinal tract, cerebellar WM, and vermis. GA at birth had significant effect on ADC values in convexity cortex and corpus callosum as well as FA/MD values in corpus callosum, after correcting for GA at scan. We developed online interactive atlases depicting age‐specific normative values of ADC (ages 34–46 weeks), and FA/MD (35–41 weeks). Our results show a rapid decrease in diffusivity metrics of cerebral/cerebellar WM and vermis in the first few weeks of neonatal age, likely attributable to myelination. In addition, prematurity and low GA at birth may result in lasting delay in corpus callosum myelination and cerebral cortex cellularity.     

White Matter Abnormalities in Schizophrenia and Schizotypal Personality Disorder

Prior diffusion tensor imaging (DTI) studies examining schizotypal personality disorder (SPD) and schizophrenia, separately have shown that compared with healthy controls (HCs), patients show frontotemporal white matter (WM) abnormalities. This is the first DTI study to directly compare WM tract coherence with tractography and fractional anisotropy (FA) across the schizophrenia spectrum in a large sample of demographically matched HCs (n = 55), medication-naive SPD patients (n = 49), and unmedicated/never-medicated schizophrenia patients (n = 22) to determine whether (a) frontal-striatal-temporal WM tract abnormalities in schizophrenia are similar to, or distinct from those observed in SPD; and (b) WM tract abnormalities are associated with clinical symptom severity indicating a common underlying pathology across the spectrum. Compared with both the HC and SPD groups, schizophrenia patients showed WM abnormalities, as indexed by lower FA in the temporal lobe (inferior longitudinal fasciculus) and cingulum regions. SPD patients showed lower FA in the corpus callosum genu compared with the HC group, but this regional abnormality was more widespread in schizophrenia patients. Across the schizophrenia spectrum, greater WM disruptions were associated with greater symptom severity. Overall, frontal-striatal-temporal WM dysconnectivity is attenuated in SPD compared with schizophrenia patients and may mitigate the emergence of psychosis.Key words: DTI, MRI, schizotypal personality disorder, schizophrenia, psychosis, white matter, genu, cingulum, inferior longitudinal fasciculus     

White matter correlates of slowed information processing speed in unimpaired multiple sclerosis patients with young age onset

Slowed information processing speed is among the earliest markers of cognitive impairment in multiple sclerosis (MS) and has been associated with white matter (WM) structural integrity. Localization of WM tracts associated with slowing, but not significant impairment, on specific cognitive tasks in pediatric and young age onset MS can facilitate early and effective therapeutic intervention. Diffusion tensor imaging data were collected on 25 MS patients and 24 controls who also underwent the Symbol Digit Modalities Test (SDMT) and the computer-based Cogstate simple and choice reaction time tests. Fractional anisotropy (FA), mean (MD), radial (RD) and axial (AD) diffusivities were correlated voxel-wise with processing speed measures. All DTI metrics of several white matter tracts were significantly different between groups (p < 0.05). Notably, higher MD, RD, and AD, but not FA, in the corpus callosum correlated with lower scores on both SDMT and simple reaction time. Additionally, all diffusivity metrics in the left corticospinal tract correlated negatively with SDMT scores, whereas only MD in the right superior fronto-occipital fasciculus correlated with simple reaction time. In conclusion, subtle slowing of processing speed is correlated with WM damage in the visual-motor processing pathways in patients with young age of MS onset.

     

Abnormal white matter integrity during pain-free periovulation is associated with pain intensity in primary dysmenorrhea

Neuroimaging studies have preliminarily described brain structural and functional differences that consist of the pain transmission and modulation systems in primary dysmenorrhea (PDM). However, whether PDM subjects have distinctive white matter (WM) alteration during the time when there is no painful menstruation is largely unknown. If that is the case, whether such specific variability is interconnected with the dysmenorrhic symptoms is unclear. In the current study, diffusion tensor imaging (DTI) was performed on 24 PDM females and 24 healthy control subjects. Optimized tract-based spatial statistics was employed to examine the between group differences in DTI measures including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). Visual analogue scale (VAS) was used to rate the intensity of the abdominal pain at periovulation and menstruation. In our results, PDM had lower FA coupled with higher MD and RD in widespread WM fibers including the splenium part of the corpus callosum, the posterior limb of the internal capsule, the anterior, superior and posterior corona radiata, and the posterior thalamic radiation (P < 0.05, FWE corrected). Further correlation analyses revealed close correlations between these DTI measures and VAS of the menstrual phase when the PDM showed serious abdominal pain. In the current study, we found PDM females had abnormal WM integrity involving pain transmission and modulation systems when they were at periovulation. Additionally, these WM abnormalities may closely associate with the intensity of painful menstruation. These observations complement the brain microstructural investigations for the pathophysiology of PDM.     

创伤后应激障碍患者扣带束及胼胝体纤维束FA值的初步研究

目的探讨创伤后应激障碍患者(PTSD)是否存在连合纤维束胼胝体及联络纤维扣带纤维束的超微结构异常。方法1.5T的MR成像仪下对12例PTSD患者及12名正常对照进行磁共振弥散张量成像(DTI),测量受试者胼胝体膝部、体部、压部、及双侧扣带水平部、后部等感兴趣区内主要白质纤维束的各向异性分数(FA)值,并进行组间比较。结果患者组双侧(左侧、右侧)扣带束水平部、胼胝体压部的FA值较对照组明显降低,差异均有统计学意义(t分别为3.26、-4.13、2.84,P均小于0.05)。结论PTSD患者的边缘系统纤维束可能存在结构异常。     

A diffusion tensor imaging study of deep gray and white matter brain maturation differences between patients with spina bifida cystica and healthy controls

The aim of this study was to use diffusion tensor imaging (DTI) to identify differences in the maturation of deep gray matter (GM) and white matter (WM) between patients with spina bifida cystica (SBC) (n = 29) with normal-appearing brains on conventional MRI, and age-matched and sex-matched healthy control participants (n = 33). Changes in DTI metrics were calculated using a log–linear regression model. We observed increasing fractional anisotropy (FA) with age in the occipital, fornix, cingulum and middle cerebellar peduncles and decreasing FA with age in the genu and splenium of the corpus callosum (CC) and caudate nuclei in patients compared to controls. Increasing FA values in some of the WM structures probably represent faulty WM maturation, whereas decreasing FA values in the CC represents changes secondary to the affected WM fibers contributing to the CC. DTI changes in deep GM and WM in the absence of any abnormality on conventional MRI might provide the basis for cognitive decline in these patients.     

皮质下缺血性血管性认知损害扩散张量成像研究

目的通过扩散张量成像(DTI)探讨皮质下缺血性血管性认知损害患者白质微结构变化及其与认知功能之间的相关性。方法采集49例皮质下缺血性脑血管病患者[轻度血管性痴呆(VaD)10例、非痴呆型血管性认知损害(VCIND)20例、认知功能正常19例]DTI数据并观察皮质下白质微结构改变,分析VaD组患者DTI参数与认知功能间的相关性。结果与对照组相比,VaD组内侧前额叶、前扣带回、胼胝体干、双侧顶叶、右侧颞叶、双侧眶额叶,以及VCIND组右侧额下回、右侧海马、双侧楔前叶FA值减低(均P=0.000);与VCIND组比较,VaD组内侧前额叶、前扣带回、胼胝体、双侧顶叶、右侧颞叶FA值减低(P=0.000)。与对照组相比,VaD组内侧前额叶、胼胝体、双侧顶叶、双侧颞叶、前扣带回,以及VCIND组双侧楔前叶、右侧海马MD值升高(均P=0.000);与VCIND组相比,VaD组右侧内侧前额叶、前扣带回、胼胝体干、双侧顶叶、双侧颞叶MD值升高(均P=0.000)。VaD组内侧前额叶FA值与数字连线测验A时呈显著负相关(r=-0.782,P=0.007),双侧额下回MD值与数字连线试验A时程呈显著正相关(r=0.877,P=0.001)。结论 DTI对皮质下缺血性认知损害患者白质微结构改变更敏感,能够反映患者认知功能早期异常改变;内侧前额叶白质微结构的改变是影响患者执行能力的重要因素。     

Gender-specific effect of urate on white matter integrity in Parkinson's disease

ObjectivesTo investigate the potential protective influence of serum uric acid (UA) level on white matter (WM) microstructural changes in de novo Parkinson's disease (PD).MethodsWe enrolled a total of 184 patients with drug-naïve de novo PD and 59 age and gender-matched controls that underwent diffusion tensor imaging (DTI). Based on the distribution, serum UA levels were stratified into tertiles in PD patients by gender. Using tract-based spatial statistics (TBSS) analysis, fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were used to compare WM integrity between the groups.ResultsInteraction analysis showed that interaction effect on FA values between gender and UA levels in PD was significant in widespread WM areas, including frontal-parieto-temporal, corpus callosum, bilateral internal and external capsule, and thalamic regions. Multiple regression analysis revealed that FA values had a significantly positive correlation with UA levels across widespread WM areas in male patients. However, there was no significant correlation between DTI measures and UA levels in female patients. In a group comparison in male patients, PD with the lowest UA level (PD-L-UA) group showed significantly lower FA and higher MD and RD values in frontal-parieto-temporal WM regions than PD with the highest UA level (PD-H-UA) group. However, female patients did not show significant difference of DTI measures between PD-L-UA and PD-H-UA groups.ConclusionsThe present study demonstrated that the serum UA levels may have the potentially gender-specific close relationship with WM integrity in the early stage of PD.