Diffusion tensor imaging assesses white matter injury in neonates with hypoxic-ischemic encephalopathy

With improvements in care of at-risk neonates, more and more children survive. This makes it increasingly important to assess, soon after birth, the prognosis of children with hypoxic-ischemic encephalopathy. Computed tomography, ultrasound, and conventional magnetic resonance imaging are helpful to diagnose brain injury, but cannot quantify white matter damage. In this study, ten full-term infants without brain injury and twenty-two full-term neonates with hypoxic-ischemic encephalopathy （14 moderate cases and 8 severe cases） underwent diffusion tensor imaging to assess its feasibility in evaluating white matter damage in this condition. Results demonstrated that fractional anisotropy, voxel volume, and number of fiber bundles were different in some brain areas between infants with brain injury and those without brain injury. The correlation between fractional anisotropy values and neonatal behavioral neurological assessment scores was closest in the posterior limbs of the internal capsule. We conclude that diffusion tensor imaging can quantify white matter injury in neonates with hypoxic-ischemic encephalopathy.

Diffusion tensor imaging pipeline measures of cerebral white matter integrity: An overview of recent advances and prospects

Cerebral small vessel disease(CSVD)is a leading cause of age-related microvascular cognitive decline,resulting in significant morbidity and decreased quality of life.Despite a progress on its key pathophysiological bases and general acceptance of key terms from neuroimaging findings as observed on the magnetic resonance imaging(MRI),key questions on CSVD remain elusive.Enhanced relationships and reliable lesion studies,such as white matter tractography using diffusion-based MRI(dMRI)are necessary in order to improve the assessment of white matter architecture and connectivity in CSVD.Diffusion tensor imaging(DTI)and tractography is an application of dMRI that provides data that can be used to non-invasively appraise the brain white matter connections via fiber tracking and enable visualization of individual patient-specific white matter fiber tracts to reflect the extent of CSVD-associated white matter damage.However,due to a lack of standardization on various sets of software or image pipeline processing utilized in this technique that driven mostly from research setting,interpreting the findings remain contentious,especially to inform an improved diagnosis and/or prognosis of CSVD for routine clinical use.In this minireview,we highlight the advances in DTI pipeline processing and the prospect of this DTI metrics as potential imaging biomarker for CSVD,even for subclinical CSVD in at-risk individuals.

Age-related changes of lateral ventricular width and periventricular white matter in the human brain: a diffusion tensor imaging study

Introduction Aging is the accumulation of multidimensional deterioration of process- ing of biological, psychological, and social changes with expansion over time （Bowen and Atwood, 2004; Grady, 2012）. Aging-related changes are typically accompanied by decline in cognitive function, urinary control, sensory-motor function, and gait ability （Bradley et al., 1991; Bowen and Atwood, 2004; Hedden and Gabrieli, 2004; Grady, 2012; Moran et al., 2012）. In addition, a number of studies have suggested changes in brain structure with normal aging, such as decrease in cortical thickness or increase in ventricular width （Blatter et al., 1995; Tang et al., 1997; Uylings and de Brabander, 2002; Preul et al., 2006; Apostolova et al., 2012）. In particular, ventricular enlargement has been suggested as a structural biomarker for normal aging and progression of some illnesses, such as Alzheimer＇s disease （Blatter et al., 1995; Tang et al.,

Diffusion tensor magnetic resonance imaging in brain white matter diseases

Objective To evaluate the usefulness of diffusion tensor MR imaging in brain white matter diseases. Methods A combined conventional and diffusion tensor MRI were obtained from 10 multiple sclerosis ,10 multiple lacunar infarction,3 cysticercosis,1 angiitis ,1 morphinist and 10 healthy control volunteers. After obtaining mean diffusivity (D) and fractional anisotropy images and image coregistration, the correlations of the lesions and the white matter pathways were investigated. D and AI values were measured form four big lesions which can be seen in T2WI and compared to contralateral white matter. Also D and AI value of four different anatomic locations of normal appearing white matter regions were measured in all patients and controls. Results Whereas the lesions of infarction, cysticercosis and angiitis were in and outside the white matter pathways, all plaques of multiple sclerosis were inside the whit matter pathways. The brain white matter lesions by 1 morphinist were beside the lateral ventricle with big patchy appearance, which was partly inside white matter. For MS, D value was higher in lesions than control white matter. But for other diseases, D value could be seen higher or lower compared to healthy side. AI values were lower in all lesions. D value was higher and AI was lower in normal appearing brain white matter when comparing MS to other cases or healthy control volunteers. Conclusion Diffusion tensor MR images can determine the correlations of the lesions and brain white matter pathways. The changes of D and AI values can improve specificity in differential diagnoses though quantitatively analyzing the tissue damage in lesions and normal appearing brain white matter.

White matter connectivity damage secondary to hippocampal and amygdala target injuries in acute limbic encephalitis Diffusion tensor image and voxel-based morphometry paired study

BACKGROUND： Limbic encephalitis is a rare syndrome that specifically affects the limbic system. Magnetic resonance imaging （MRI） has been typically used to detect brain changes in this disease. However, the mechanisms of limbic encephalitis-related white matter damage remain poorly understood. OBJECTIVE： To characterize white matter connectivity changes secondary to injuries of the limbic system in limbic encephalitis through combined application of diffusion tensor imaging （DTI） and voxel-based morphometry. DESIGN, TIME AND SETTING： A non-randomized, controlled, clinical, neuroimaging, DTI study was performed at the Department of Radiology, West China Hospital in December 2008. PARTICIPANTS： A male, 46-year-old, limbic encephalitis patient, as well as 11 age- and gender-matched healthy volunteers, were enrolled in the present study. METHODS： MRI was performed on the limbic encephalitis patient using a 3.0T MR scanner. Three-dimensional SPGR Tl-weighted images and DTI were acquired in the patient and controls. Data were analyzed using Matlab 7.0 and SPM2 software. MAIN OUTCOME MEASURES： Results from routine MRI scan with contrast enhancement of patient, as well as fractional anisotropy and mean diffusivity value map differences between patient and controls. RESULTS： Significant symmetric MRI signal intensity abnormalities were observed with routine MRI Affected bilateral hippocampi and amygdala exhibited hypointense signals in TIWI and hyperintense signals in T2 images. The DTI study revealed decreased fractional anisotropy values in the bilateral alveus and fimbria of the hippocampus, bilateral internal and external capsules, white matter of the right prefrontal area, and left corona radiate in the patient compared with normal controls （P 〈 0.001） Significantly increased fractional anisotropy, mean diffusivity, or decreased mean diffusivity were not observed in the patient, compared with controls. CONCLUSION： Secondary white matter damage to the hippocampal afveus and fimbria was apparent in the limbic encephalitis patient. In addition, other white matter fiber injuries surrounded the limbic structures, which were not attributed to secondary limbic system injuries.

Dynamic correlation of diffusion tensor imaging and neurological function scores in beagles with spinal cord injury

Exploring the relationship between different structure of the spinal cord and functional assessment after spinal cord injury is important. Quantitative diffusion tensor imaging can provide information about the microstructure of nerve tissue and can quantify the pathological damage of spinal cord white matter and gray matter. In this study, a custom-designed spinal cord contusion-impactor was used to damage the T_（10） spinal cord of beagles. Diffusion tensor imaging was used to observe changes in the whole spinal cord, white matter, and gray matter, and the Texas Spinal Cord Injury Score was used to assess changes in neurological function at 3 hours, 24 hours, 6 weeks, and 12 weeks after injury. With time, fractional anisotropy values after spinal cord injury showed a downward trend, and the apparent diffusion coefficient, mean diffusivity, and radial diffusivity first decreased and then increased. The apparent diffusion-coefficient value was highly associated with the Texas Spinal Cord Injury Score for the whole spinal cord（R = 0.919, P = 0.027）, white matter（R = 0.932, P = 0.021）, and gray matter（R = 0.882, P = 0.048）. Additionally, the other parameters had almost no correlation with the score（P 〉 0.05）. In conclusion, the highest and most significant correlation between diffusion parameters and neurological function was the apparent diffusion-coefficient value for white matter, indicating that it could be used to predict the recovery of neurological function accurately after spinal cord injury.

Diffusion Tensor Imaging and Its Application to Traumatic Brain Injury: Basic Principles and Recent Advances

Traumatic axonal injury is a progressive process evoked by shear forces on the brain, gradually evolving from focal axonal alteration and cumulating in neural disconnection. Clinical classifiers and conventional neuroimaging are limited in traumatic axonal injury detection, outcome prediction, and treatment guidance. Diffusion weighted imaging is an advanced magnetic resonance imaging (MRI) technique that is sensitive to the movement of water molecules, providing additional information on the micro-structural arrangement of tissue. Quantitative analysis of diffusion metrics can aid in the localization of axonal injury and/or de(dys)myelination caused by trauma. Diffusion MRI tractography is an extension of diffusion weighted imaging, and can provide additional information about white matter pathways and the integrity of brain neural networks. Both techniques are able to detect the early micro-structural changes caused by Traumatic Brain Injury (TBI), and can be used to increase understanding of the mechanisms of brain plasticity in recovery after brain injury and possibly optimize treatment planning of patients with Traumatic Brain Injury. This review focuses on the theoretical basis and applied advanced techniques of diffusion weighted imaging, their limitations and applications, and future directions in the application to TBI.

Diffusion tensor imaging of spinal microstructure in healthy adults： improved resolution with the readout segmentation of long variable echo-trains

Diffusion tensor imaging plays an important role in the accurate diagnosis and prognosis of spinal cord diseases. However, because of technical limitations, the imaging sequences used in this technique cannot reveal the fine structure of the spinal cord with precision. We used the readout segmentation of long variable echo-trains（RESOLVE） sequence in this cross-sectional study of 45 healthy volunteers aged 20 to 63 years. We found that the RESOLVE sequence significantly increased the resolution of the diffusion images and improved the median signal-to-noise ratio of the middle（C4–6） and lower（C7–T1） cervical segments to the level of the upper cervical segment. In addition, the values of fractional anisotropy and radial diffusivity were significantly higher in white matter than in gray matter. Our study verified that the RESOLVE sequence could improve resolution of diffusion tensor imaging in clinical applications and provide accurate baseline data for the diagnosis and treatment of cervical spinal cord diseases.

Characteristics of diffusion-tensor imaging for healthy adult rhesus monkey brains

Diffusion-tensor imaging can be used to observe the microstructure of brain tissue. Fractional ani- sotropy reflects the integrity of white matter fibers. Fractional anisotropy of a young adult brain is low in gray matter, high in white matter, and highest in the splenium of the corpus callosum. Thus, we selected the anterior and posterior limbs of the internal capsule, head of the caudate nucleus, semioval center, thalamus, and corpus callosum （splenium and genu） as regions of interest when using diffusion-tensor imaging to observe fractional anisotropy of major white matter fiber tracts and the deep gray matter of healthy rhesus monkeys aged 4-8 years. Results showed no laterality dif- ferences in fractional anisotropy values. Fractional anisotropy values were low in the head of cau- date nucleus and thalamus in gray matter. Fractional anisotropy values were highest in the sple- nium of corpus callosum in the white matter, followed by genu of the corpus callosum and the pos- terior limb of the internal capsule. Fractional anisotropy values were lowest in the semioval center and posterior limb of internal capsule. These results suggest that fractional anisotropy values in major white matter fibers and the deep gray matter of 4-8-year-old rhesus monkeys are similar to those of healthy young people.

Diffusion kurtosis imaging of microstructural changes in brain tissue affected by acute ischemic stroke in different locations

The location of an acute ischemic stroke is associated with its prognosis. The widely used Gaussian model-based parameter, apparent diffusion coefficient(ADC), cannot reveal microstructural changes in different locations or the degree of infarction. This prospective observational study was reviewed and approved by the Institutional Review Board of Xiamen Second Hospital, China(approval No. 2014002).Diffusion kurtosis imaging(DKI) was used to detect 199 lesions in 156 patients with acute ischemic stroke(61 males and 95 females), mean age 63.15 ± 12.34 years. A total of 199 lesions were located in the periventricular white matter(n = 52), corpus callosum(n = 14), cerebellum(n = 29), basal ganglia and thalamus(n = 21), brainstem(n = 21) and gray-white matter junctions(n = 62). Percentage changes of apparent diffusion coefficient(ΔADC) and DKI-derived indices(fractional anisotropy [ΔFA], mean diffusivity [ΔMD], axial diffusivity [ΔD_a], radial diffusivity ΔDr, mean kurtosis [ΔMK], axial kurtosis [ΔK_a], and radial kurtosis [ΔK_r]) of each lesion were computed relative to the normal contralateral region. The results showed that(1) there was no significant difference in ΔADC, ΔMD, ΔD_a or ΔD_r among almost all locations.(2) There was significant difference in ΔMK among almost all locations(except basal ganglia and thalamus vs. brain stem; basal ganglia and thalamus vs. gray-white matter junctions; and brainstem vs. gray-white matter junctions.(3) The degree of change in diffusional kurtosis in descending order was as follows: corpus callosum > periventricular white matter > brainstem > gray-white matter junctions > basal ganglia and thalamus > cerebellum. In conclusion, DKI could reveal the differences in microstructure changes among various locations affected by acute ischemic stroke, and performed better than diffusivity among all groups.

Tri-linear interpolation-based cerebral white matter fiber imaging

Diffusion tensor imaging is a unique method to visualize white matter fibers three-dimensionally, non-invasively and in vivo, and therefore it is an important tool for observing and researching neural regeneration. Different diffusion tensor imaging-based fiber tracking methods have been already investigated, but making the computing faster, fiber tracking longer and smoother and the details shown clearer are needed to be improved for clinical applications. This study proposed a new fiber tracking strategy based on tri-linear interpolation. We selected a patient with acute infarction of the right basal ganglia and designed experiments based on either the tri-linear interpolation algorithm or tensorline algorithm. Fiber tracking in the same regions of interest （genu of the corpus callosum） was performed separately. The validity of the tri-linear interpolation algorithm was verified by quan- titative analysis, and its feasibility in clinical diagnosis was confirmed by the contrast between tracking results and the disease condition of the patient as well as the actual brain anatomy. Statis- tical results showed that the maximum length and average length of the white matter fibers tracked by the tri-linear interpolation algorithm were significantly longer. The tracking images of the fibers indicated that this method can obtain smoother tracked fibers, more obvious orientation and clearer details. Tracking fiber abnormalities are in good agreement with the actual condition of patients, and tracking displayed fibers that passed though the corpus callosum, which was consistent with the anatomical structures of the brain. Therefore, the tri-linear interpolation algorithm can achieve a clear, anatomically correct and reliable tracking result.

Association between scrub typhus encephalitis and diffusion tensor tractography detection of Papez circuit injury:A case report

BACKGROUND It is difficult to restore the cognitive functions of patients with impaired cognition caused by brain injury.Diffusion tensor imaging can visualize the integrity of neural tracts in the white matter(WM)three-dimensionally.It is unclear whether encephalitis following scrub typhus damages the WM.For the first time,we aimed to report diffusion tensor tractography(DTT)findings in a chronic patient with cognitive impairment following scrub typhus encephalitis,which revealed injury to the Papez circuit of the WM.CASE SUMMARY A 70-year-old male patient was affected by encephalitis caused by scrub typhus that occurred 23 years ago.He had poor cognition and his clinical examination findings were as follows:Mini-Mental Status Examination score,14;and handgrip strength(right/left,kg),32.3/31.3.DTT revealed serious injuries of the left thalamocingulate tract and right mammillothalamic tract in the Papez circuit,and a partial injury of the anterior part of the fornix.CONCLUSION Using DTT,we found a relationship between cognitive impairment and the integrity of the Papez circuit following scrub typhus.

Age-related white matter degradation rule of normal human brain： the evidence from diffusion tensor magnetic resonance imaging

Background Diffusion tensor imaging can evaluate white matter function in human brain.Fractional anisotropy is the most important parameter.This study aimed to find regional reduction of fractional anisotropy （FA） with aging in the whole brain and the changing rules of anisotropy with aging.Methods Fifty volunteers from 20 to 75 years old were divided into five consecutive age groups; a young group and four senior groups.FA values were calculated with diffusion tensor imaging （DTI） studio software.The difference of FA between the young group and the four senior groups were analyzed by analysis of voxel-level height threshold in Statistic Parametric Mapping （SPM）,and the regions with decreased FA were obtained.The FA values of these regions were then extracted using an in-house developed program,and a multiple linear regression model was built to assess the influence of age and sex on the FA values of these regions.Results Eight regions,including frontal lobe,postcentral gyrus,optic radiation,hippocampus,cerebella hemisphere,corona radiate,corpus callosum and internal capsule,were found to have decreased FA.There was a strong negative correlation between age and the FA in the frontal lobe,postcentral gyrus,optic radiation,hippocampus,and cerebella hemisphere,while a weaker negative correlation in the corona radiate,corpus callosum,and internal capsule was found.The FA reduction in the frontal lobe,postcentral gyrus,optic radiation,hippocampus and cerebella hemisphere were found earlier than in the corona radiate,corpus callosum and internal capsule.There was no correlation between sex and FA in these regions.Conclusions The FA in the subcortical white matter area reduces earlier than that in deep white matter.The areas with decreased FA continuously enlarge with aqing.The FAs in these regions have a strong negative correlation with age.

Diffusion tensor imaging on white matter in normal adults and elderly patients with hypertension

Diffusion-weighted magnetic resonance imaging （MRI） exploits the properties of randomlymoving water molecules in the presence of magnetic field gradients. Within tissue, diffusion of water molecules is restricted by cell membranes, small vessels, axon cylinders, membrane, chemical interactions of water and macromolecules. In the brain, water diffusion exhibits directionality in the orientation along the long axis of white matter. This is referred to as ＂diffusion anisotropy＂. Diffusion anisotropy can be measured via diffusion tensor imaging （DTI）. There is a class of anisotropy indices that reflect the degree of anisotropy of water diffusion which are related to the degree of architectural and structural coherence within each voxel of the tissue. Fractional anisotropy （FA） was the most frequently used index of anisotropy.

Microstructural white matter lesion in Alzheimer's disease: a diffusion tensor imaging study using voxel-based analysis

Objective To study the microscopic changes of white matter and the relationship between white matter changes and cognitive impairment in Alzheimer’s disease(AD)using voxel-based analysis of DTI.Methods Thirty-seven patients with probable AD,and 32 normal controls(NC)were all examined by MMSE scores,and un-

Correlation between white matter damage and gray matter lesions in multiple sclerosis patients

We observed the characteristics of white matter fibers and gray matter in multiple sclerosis patients, to identify changes in diffusion tensor imaging fractional anisotropy values following white matter fiber injury. We analyzed the correlation between fractional anisotropy values and changes in whole-brain gray matter volume. The participants included 20 patients with relapsing-remitting multiple sclerosis and 20 healthy volunteers as controls. All subjects underwent head magnetic resonance imaging and diffusion tensor imaging. Our results revealed that fractional anisotropy values decreased and gray matter volumes were reduced in the genu and splenium of corpus callosum, left anterior thalamic radiation, hippocampus, uncinate fasciculus, right corticospinal tract, bilateral cingulate gyri, and inferior longitudinal fasciculus in multiple sclerosis patients. Gray matter volumes were significantly different between the two groups in the right frontal lobe（superior frontal, middle frontal, precentral, and orbital gyri）, right parietal lobe（postcentral and inferior parietal gyri）, right temporal lobe（caudate nucleus）, right occipital lobe（middle occipital gyrus）, right insula, right parahippocampal gyrus, and left cingulate gyrus. The voxel sizes of atrophic gray matter positively correlated with fractional anisotropy values in white matter association fibers in the patient group. These findings suggest that white matter fiber bundles are extensively injured in multiple sclerosis patients. The main areas of gray matter atrophy in multiple sclerosis are the frontal lobe, parietal lobe, caudate nucleus, parahippocampal gyrus, and cingulate gyrus. Gray matter atrophy is strongly associated with white matter injury in multiple sclerosis patients, particularly with injury to association fibers.

磁共振波谱成像联合弥散加权成像在早产儿脑白质损伤诊断及预后评估中的应用

目的探讨磁共振波谱成像(MRS)联合弥散加权成像(DWI)在早产儿脑白质损伤早期诊断以及其预后评估中的应用价值。方法选取2021年1月-2023年1月102例脑白质损伤早产儿作为病例组,同期选取98例非脑白质损伤早产儿作为对照组,记录两组早产儿相关临床指标,并在出生后7d实施MRS、DWI检查,比较两组MRS代谢指标、DWI参数差异,使用点二列相关性检验MRS代谢指标、DWI参数与早产儿脑白质损伤的关系,并绘制受试者工作曲线(ROC)分析MRS联合DWI对早产儿脑白质损伤的早期诊断价值。予以病例组患儿长期随访,在矫正年龄6个月时使用Gesell发育诊断量表将患儿分为预后不良组与预后良好组,比较并分析2组患儿MRS代谢指标、DWI参数对早产儿脑白质损伤预后的评估价值。结果病例组N-乙酰天冬氨酸(NAA)、NAA/Cr、rADC明显低于对照组,肌酸(Cr)明显高于对照组,差异有统计学意义(P<0.05)。经点二列相关性检验显示NAA、NAA/Cr、rADC与早产儿脑白质损伤存在负相关关系(r<0,P<0.05);Cr与早产儿脑白质损伤存在正相关关系(r>0,P<0.05)。绘制ROC显示NAA、Cr、NAA/Cr以及rADC对早产儿脑白质损伤诊断具有较低的诊断价值,AUC分别为0.629、0.630、0.605、0.603;MRS联合DWI具有良好的诊断价值,AUC为0.713。随访结果显示102例患儿中21例为边缘状态,53例为发育异常,共74例为预后不良组,另28例发育良好为预后良好组。预后不良组患儿NAA、NAA/Cr、rADC明显低于预后良好组,Cr明显高于预后良好组,差异有统计学意义(P<0.05)。经点二列相关性检验显示NAA、NAA/Cr、rADC与脑白质损伤患儿预后不良存在负相关关系(r<0,P<0.05);Cr与预后不良存在正相关关系(r>0,P<0.05)。绘制ROC曲线显示NAA、NAA/Cr以及rADC对脑白质损伤患儿预后具有较低的评估价值,AUC分别为0.641、0.639、0.688;Cr、MRS联合DWI对脑白质损伤患儿预后具有良好的评估价值,AUC分别为0.755、0.833,以联合评估价值最高。结论MRS联合DWI对早产儿脑白质损伤以及其预后均有良好的评估价值。

缓解期双相情感障碍Ⅰ型患者白质纤维结构异常的扩散张量成像研究

目的:探讨缓解期双相情感障碍(BD)Ⅰ型患者脑白质神经纤维束的改变,及患者认知功能与脑白质病变的关系。方法:采用汉密尔顿抑郁量表(HAMD),杨氏躁狂量表(YMRS)和重复性成套神经心理状态量表(RBANS)对患者进行入组的筛查与认知评估。应用3.0T磁共振仪对76例缓解期BD-Ⅰ型患者以及66例年龄、性别相匹配的健康志愿者(对照组)行DTI扫描,使用PANDA软件包提取全脑白质纤维束的各向异性分数(FA)和平均扩散率(MD),采用独立样本t检验进行组间差异比较,及Pearson相关分析探讨BD组中各纤维束的FA与临床可重复神经心理状态测验(RBANS)评分间的相关性。结果:相较于对照组,BD-Ⅰ型组的左、右侧钩束、右侧上纵束、右侧下额枕束及左侧毯束的FA值降低,MD值升高,差异均具有统计学意义(P<0.01)。BD-Ⅰ型组的左、右侧钩束、右侧上纵束和右侧下额枕束的FA值与RBANS量表评估的总分及即刻记忆、延迟记忆、视觉广度和注意力四项因子的评分均具有正相关关系(r=0.32~0.44,P均<0.05)。结论:缓解期双相障碍BD I型患者多个脑白质神经纤维束微观结构受损,且与认知功能改变相关。

基于体素分析的首发青少年抑郁症全脑DTI研究

目的:运用磁共振弥散张量成像(DTI)技术探讨首发未治疗青少年抑郁症患者的脑白质微结构变化特点。方法:前瞻性纳入35例首发未治疗青少年抑郁症患者(抑郁症组)和年龄、性别及受教育程度相匹配的26例健康志愿者(对照组)进行DTI扫描,运用FSL软件计算全脑白质各向异性分数(FA),应用基于体素分析(VBA)方法比较两组间全脑白质FA差异,并分析抑郁症组脑白质微结构改变与临床数据的相关性。结果:抑郁症组17项汉密尔顿抑郁量表(HAMD-17)评分高于对照组(P<0.01)。与对照组相比,抑郁症组脑桥、左侧小脑前叶白质FA值升高(簇水平P<0.05,FWE校正),未发现白质FA值减低的脑区;脑桥FA值与HAMD-17评分呈负相关(r=-0.352,P=0.038)。结论:青少年抑郁症患者脑桥小脑环路受损,在疾病早期出现脑白质FA值升高,可能是神经纤维代偿性再生所致。

全面性发育迟缓患儿大脑白质纤维束微结构异常的扩散峰度成像研究

目的使用扩散峰度成像(diffusion kurtosis imaging,DKI)评估全面性发育迟缓(global developmental delay,GDD)患儿大脑白质纤维束微结构的改变。材料与方法这项前瞻性研究纳入了37例GDD儿童作为试验组和32例性别、年龄相匹配的健康儿童作为对照组。对所有参与者进行了DKI序列扫描,经过后处理得到扩散张量和峰度张量参数。使用基于束的空间统计学方法(tract-based spatial statistics,TBSS)比较了这些参数在两组之间的差异,并将组间有显著差异纤维束内的参数值与GDD儿童的神经发育得分进行Spearman相关分析。结果与对照组相比,GDD组右侧皮质脊髓束和右侧丘脑前辐射的平均扩散率(mean diffusivity,MD)均显著升高(P均<0.05);双侧丘脑前辐射、双侧皮质脊髓束和右侧上纵束的径向扩散系数(radial diffusivity,RD)也显著升高(P均<0.05)。此外,GDD组的径向峰度(radial kurtosis,RK)则显著降低(P均<0.05),包括双侧丘脑前辐射、双侧皮质脊髓束、双侧下额枕束、双侧上纵束、双侧下纵束、小钳、左侧钩状束和右侧扣带回。相关性分析发现,左侧下纵束和左侧钩状束的平均RK值与适应性行为得分呈正相关(r=0.349、0.486,P均<0.05);左侧钩状束的平均RK值与精细动作得分和个人-社交行为得分均呈正相关(r=0.365、0.590,P均<0.05)。结论DKI技术能够检测到GDD儿童大脑白质纤维束微结构的异常,为探索GDD潜在病理机制提供了有用的价值。