脑静脉窦血栓形成65例临床与影像学分析

目的 探讨脑静脉窦血栓形成(CVST)的病因、临床表现及影像学特点.方法 回顾性分析65例CVST患者的临床表现、头颅CT、MRI、磁共振静脉血管造影及数字减影血管造影(DSA)特点.结果 本组65例CVST患者中,25例(38%)患者仅表现为单纯颅高压;头面部局部或全身感染者13例(20%);贫血4例(6%);服用避孕药史4例(6%);结缔组织及相关疾病4例(6%)(Behcet's病2例,系统性红斑狼疮2例),蛋白C缺乏2例(3%).9例急性患者的头颅CT平扫发现,2例存在"稠密三角征",3例存在"条带征".亚急性患者头颅MRI显示,静脉窦内主要为T1、T2高信号(33%,4/12).MRI发现急性、亚急性及慢性患者静脉性脑梗死的比例分别为38%(3/8)、33%(4/12)及18%(6/33).在行MRV检查的12例患者中,均发现静脉窦充盈缺损或中断(100%).DSA检查发现66%(40/61)累及2个或2个以上静脉窦,11%(7/61)累及大脑浅(深)静脉.结论 CVST病因复杂,起病形式多样,临床表现主要为颅高压等一些非特异性症状及体征;头颅CT及MRI分别对急性,亚急性CVST静脉窦内的血栓有较高的敏感性与特异性;MRV可快速、无创地诊断CVST.若以上检查仍不能明确诊断,应尽快行DSA检查,尤其是大脑浅(深)静脉血栓形成患者.     

Automated brain tissue assessment in the elderly and demented population: construction and validation of a sub-volume probabilistic brain atlas

OBJECTIVES: To develop an automated imaging assessment tool that accommodates the anatomic variability of the elderly and demented population as well as the registration errors occurring during spatial normalization. METHODS: 20 subjects with Alzheimer's disease (AD), mild cognitive impairment, or normal cognition underwent MRI brain imaging and had their 3D volumetric datasets manually partitioned into 68 regions of interest (ROI) termed sub-volumes. Gray matter (GM), white matter (WM), and cerebral spinal fluid (CSF) voxel counts were then made in the subject's native space for comparison against automated volumetric measures within three sub-volume probabilistic atlas (SVPA) models. The three SVPAs were constructed using 12 parameter affine (12 p), 2nd order (2nd), and 6th order (6th) transforms derived from registering the manually partitioned scans into a Talairach compatible AD population-based target. The three SVPA automated measures were compared to the manually derived measures in the 20 subjects' native space with a "jack-knife" procedure in which each subject was assessed by an SVPA they did not contribute toward constructing. RESULTS: The mean left and right GM ratio (GM ratio = [GM + CSF] / CSF) "r values" for the 3 SVPAs compared to the manually derived ratios across the 68 ROIs were 0.85 for the 12p SVPA, 0.88 for the 2nd SVPA, and 0.89 for the 6th SVPA. The mean left and right WM ratio (WM ratio = [WM + CSF] / CSF) "r values" for the 3 SVPAs being 0.84 for the 12p SVPA, 0.86 for the 2nd SVPA, and 0.88 for the 6th SVPA. CONCLUSION: We have constructed, from an elderly and demented cohort, an automated brain volumetric tool that has excellent accuracy compared to a manual gold standard and is capable of regional hypothesis testing and individual patient assessment compared to a population.     

儿童注意缺陷多动障碍研究进展

注意缺陷多动障碍(ADHD)是一种好发于学龄儿童的行为障碍综合征,严重影响到患儿的学习、生活,受到家长和社会的广泛重视。目前对该病的诊断多采用量表和问卷,缺乏客观性。从ADHD的病因和发病机制、临床诊断及神经成像等方面对儿童注意缺陷多动障碍研究进展进行回顾及综述,为ADHD的早期诊断及有效治疗开辟一条崭新的途径。     

The role of genetics for biomarker development in neurodegeneration

Research on biomarkers and genetics shares a number of objectives, including the identification of novel disease mechanisms, optimization of therapeutic studies, and improvement of diagnosis and prognosis. The latter is of particular relevance in neurodegenerative diseases where the underlying molecular processes often go on for decades until the first clinical symptoms appear. In this commentary we review the potential contribution that insight gained from genetic research may have on biomarker development in neurodegeneration. We argue that future progress will largely depend on a widespread application of novel high-throughput technologies now becoming available in both fields.     

Assessment of cerebral blood volume in schizophrenia: A magnetic resonance imaging study

Brain atrophy has consistently been observed in schizophrenia, representing a 'gross' evidence of anatomical abnormalities. Reduced cerebral blood volume (CBV) may accompany brain size decrement in schizophrenia, as suggested by prior small SPECT studies. In this study, we non-invasively investigated the hemisphere CBV in a large sample of patients suffering from schizophrenia with perfusion-weighted imaging (PWI). PWI images were obtained, following intravenous injection of paramagnetic contrast agent (Gadolinium-DTPA), for 54 DSM-IV patients with schizophrenia (mean age+/-SD=39.19+/-12.20 years; 34 males, 20 females) and 24 normal controls (mean age+/-SD=44.63+/-10.43 years; 9 males, 15 females) with a 1.5T Siemens magnet using an echo-planar sequence (TR=2160 ms, TE=47 ms, slice thickness=5mm). The contrast of enhancement (CE), a semi-quantitative parameter inversely estimating the CBV, were calculated pixel by pixel as the ratio of the maximum signal intensity drop during the passage of contrast agent (Sm) by the baseline pre-bolus signal intensity (So) (CE=Sm/Sox100) for right and left hemisphere on two axial images. Specifically, higher CE values correspond to lower CBV and viceversa Compared to normal controls, patients with schizophrenia had significantly higher bilateral hemisphere CE values (p=0.02) and inverse CE laterality index (p=0.02). This study showed abnormally reduced and inverse hemisphere CBV in a large population of patients with schizophrenia. Hypothetically, chronic low CBV may sustain neural hypoactivation and concomitant increase of free radicals, ultimately resulting in neuronal loss and cognitive impairments. Thus, altered intracranial hemodynamics may accompany brain atrophy and cognitive deficits, being a crucial factor in the pathophysiology of schizophrenia.     

The association of MRI findings and neuropsychological functioning after the first recognized seizure

PURPOSE: To explore relationships between MRI abnormalities of the brain and neuropsychological functioning in children who were evaluated following their first recognized seizure. METHODS: Subjects were children aged 6 to 14 years with a first recognized seizure within the past 3 months who participated in a larger prospective study of child adaptation. The 249 children with neuropsychological testing and neuroimaging were studied. Children underwent neuropsychological examination an average of 2.8 months and MRI examination an average of 1.3 months after the first recognized seizure. On factor analysis four factors were found for neuropsychological function: LANG = Language, PS = Processing Speed, EC = Executive/ Construction, VMEM = Verbal Memory and Learning. For analysis, structural abnormalities found on MRI were classified as significant (yes/no) based on whether they were presumed to be related to the seizure condition. RESULTS: On MRI, 34 (14%) had structural abnormalities that were judged to be significant in that they were possibly related to their seizures. Children with significant abnormalities had significantly lower estimated IQ scores and significantly lower language, processing speed, executive/constructional ability, and verbal memory and learning factor scores than did children without significant abnormalities. CONCLUSIONS: Children who have structural brain abnormalities at onset have slightly lower cognitive functioning overall, and all neuropsychological domains seemed to be affected relatively equally. This pattern was apparent even when we restricted the analysis to children with intellectual functioning in the broadly normal range.     

Dissociable effects of phonetic competition and category typicality in a phonetic categorization task: an fMRI investigation

The current study used fMRI to explore the extent to which neural activation patterns in the processing of speech are driven by the quality of a speech sound as a member of its phonetic category, that is, its category typicality, or by the competition inherent in resolving the category membership of stimuli which are similar to other possible speech sounds. Subjects performed a phonetic categorization task on synthetic stimuli ranging along a voice-onset time continuum from [da] to [ta]. The stimulus set included sounds at the extreme ends of the voicing continuum which were poor phonetic category exemplars, but which were minimally competitive, stimuli near the phonetic category boundary, which were both poor exemplars of their phonetic category and maximally competitive, and stimuli in the middle of the range which were good exemplars of their phonetic category. Results revealed greater activation in bilateral inferior frontal areas for stimuli with the greatest degree of competition, consistent with the view that these areas are involved in selection between competing alternatives. In contrast, greater activation was observed in bilateral superior temporal gyri for the least prototypical phonetic category exemplars, irrespective of competition, consistent with the view that these areas process the acoustic-phonetic details of speech to resolve a token's category membership. Taken together, these results implicate separable neural regions in two different aspects of phonetic categorization.     

The neurocognitive basis of reading single words as seen through early latency ERPs: a model of converging pathways

This paper first provides a brief review of the functional neuroanatomy of reading single words, focusing on the lexical and phonological routes. Next, early (defined as peaking prior to 350 ms) reading event-related potential components are summarized. A comprehensive effort is made to organize existing observations into a coherent scheme and commentary is made on terminology. Proposals are made regarding the cognitive function reflected by each ERP component and the associated generator sites. The overall framework constitutes a neurocognitive model of reading and demonstrates how the high temporal resolution of event-related potentials can provide additional insights into the reading process beyond those available from behavioral and neuroimaging studies, with a special focus on how the two pathways implied in reading are coordinated. The present model suggests that there are two such coordinating operations, convergence processes during an initial information burst and resonance processes during an extended harmonization process that follows.