Undecussated Superior Cerebellar Peduncles and Absence of the Dorsal Transverse Pontine Fibers: a New Axonal Guidance Disorder?

Axonal guidance disorders are a newly recognized group of diseases of the human central nervous system. These disorders are characterized by white matter tracts with abnormal course and failure to cross the midline or presence of ectopic white matter tracts. Diffusion tensor imaging (DTI) and fiber tractography are suitable neuroimaging tools to detect morphological abnormalities in the course, decussation, and location of white matter tracts. We report on a 6.5-year-old child with significant global developmental delay. Axial color-coded fractional anisotropy (FA)-maps revealed absence of (1) the midline “focal red dot” at the level of the pontomesencephalic junction representing absence of decussation of the superior cerebellar peduncles and (2) the dorsal component of the transverse pontine fibers. These findings are highly suggestive of an axonal guidance disorders. The complete neuroimaging phenotype of this child does not match well-known diseases with similar DTI findings. We show how DTI reveals important information of microstructural brain malformations that may go undetected or remains underestimated and consequently DTI may suggest the possible pathomechanism. We conclude that this child may be suffering from a not yet described subtype of an axonal guidance disorder.     

Comparative Evaluation of the Cerebral and Cerebellar White Matter Development in Pediatric Age Group using Quantitative Diffusion Tensor Imaging

Age-dependent changes in the normal cerebral white matter have been reported; however, there is no study on normal cerebellar white matter maturation in developing brain using diffusion tensor imaging (DTI). We performed DTI in 21 children who had normal neurological assessment along with no evidence of any abnormality on imaging. The aim of this study was to compare the age-related changes in fractional anisotropy (FA) and mean diffusivity (MD) quantified from cerebral white matter (splenium and genu of the corpus callosum and posterior limb of the internal capsule) and cerebellar white matter (middle cerebellar peduncles, superior cerebellar peduncles, and inferior cerebellar peduncles) regions in healthy children ranging in age from birth to 132 months. Log-linear regression model showed best fit to describe the age-related changes in FA and MD both for cerebral and cerebellar white matter. In cerebral white matter, an initial sharp increase in FA was observed up to the age of 24 months followed by a gradual increase up to 132 months. In cerebellar white matter, sharp increase in FA was observed up to 36 months, which then followed a gradual increase. However, MD showed a sharp decrease in cerebral white matter up to 24 months followed by a more gradual decrease thereafter, while in cerebellar white matter after an initial decrease (6 months), it followed a stable pattern. This study provides normative database of brain white matter development from neonates to childhood. This quantitative information may be useful for assessing brain maturation in patients with developmental delay of the cerebral and cerebellar white matter.     

Cerebellar white matter pathways are associated with reading skills in children and adolescents

Reading is a critical life skill in the modern world. The neural basis of reading incorporates a distributed network of cortical areas and their white matter connections. The cerebellum has also been implicated in reading and reading disabilities. However, little is known about the contribution of cerebellar white matter pathways to major component skills of reading. We used diffusion magnetic resonance imaging (dMRI) with tractography to identify the cerebellar peduncles in a group of 9‐ to 17‐year‐old children and adolescents born full term (FT, n = 19) or preterm (PT, n = 26). In this cohort, no significant differences were found between fractional anisotropy (FA) measures of the peduncles in the PT and FT groups. FA of the cerebellar peduncles correlated significantly with measures of decoding and reading comprehension in the combined sample of FT and PT subjects. Correlations were negative in the superior and inferior cerebellar peduncles and positive in the middle cerebellar peduncle. Additional analyses revealed that FT and PT groups demonstrated similar patterns of reading associations within the left superior cerebellar peduncle, middle cerebellar peduncle, and left inferior cerebellar peduncle. Partial correlation analyses showed that distinct sub‐skills of reading were associated with FA in segments of different cerebellar peduncles. Overall, the present findings are the first to document associations of microstructure of the cerebellar peduncles and the component skills of reading. Hum Brain Mapp 36:1536–1553, 2015. © 2014 Wiley Periodicals, Inc.     

Can spherical deconvolution provide more information than fiber orientations? Hindrance modulated orientational anisotropy,a true‐tract specific index to characterize white matter diffusion

Diffusion tensor imaging (DTI) methods are widely used to reconstruct white matter trajectories and to quantify tissue changes using the average diffusion properties of each brain voxel. Spherical deconvolution (SD) methods have been developed to overcome the limitations of the diffusion tensor model in resolving crossing fibers and to improve tractography reconstructions. However, the use of SD methods to obtain quantitative indices of white matter integrity has not been extensively explored. In this study, we show that the hindrance modulated orientational anisotropy (HMOA) index, defined as the absolute amplitude of each lobe of the fiber orientation distribution, can be used as a compact measure to characterize the diffusion properties along each fiber orientation in white matter regions with complex organization. We demonstrate that the HMOA is highly sensitive to changes in fiber diffusivity (e.g., myelination processes or axonal loss) and to differences in the microstructural organization of white matter like axonal diameter and fiber dispersion. Using simulations to describe diffusivity changes observed in normal brain development and disorders, we observed that the HMOA is able to identify white matter changes that are not detectable with conventional DTI indices. We also show that the HMOA index can be used as an effective threshold for in vivo data to improve tractography reconstructions and to better map white matter complexity inside the brain. In conclusion, the HMOA represents a true tract‐specific and sensitive index and provides a compact characterization of white matter diffusion properties with potential for widespread application in normal and clinical populations. Hum Brain Mapp 34:2464–2483, 2013. © 2012 Wiley Periodicals, Inc.     

White matter integrity of the cerebellar peduncles as a mediator of effects of prenatal alcohol exposure on eyeblink conditioning

Fetal alcohol spectrum disorders (FASD) are characterized by a range of neurodevelopmental deficits that result from prenatal exposure to alcohol. These can include cognitive, behavioural, and neurological impairment, as well as structural and functional brain damage. Eyeblink conditioning (EBC) is among the most sensitive endpoints affected in FASD. The cerebellar peduncles, large bundles of myelinated nerve fibers that connect the cerebellum to the brainstem, constitute the principal white matter element of the EBC circuit. Diffusion tensor imaging (DTI) is used to assess white matter integrity in fibre pathways linking brain regions. DTI scans of 54 children with FASD and 23 healthy controls, mean age 10.1 ± 1.0 years, from the Cape Town Longitudinal Cohort were processed using voxelwise group comparisons. Prenatal alcohol exposure was related to lower fractional anisotropy (FA) bilaterally in the superior cerebellar peduncles and higher mean diffusivity (MD) in the left middle peduncle, effects that remained significant after controlling for potential confounding variables. Lower FA and higher MD in these regions were associated with poorer EBC performance. Moreover, effects of alcohol exposure on EBC decreased significantly after inclusion of these DTI measures in regression models, suggesting that these white matter deficits partially mediate the relation of prenatal alcohol exposure to EBC. The associations of greater alcohol consumption with these DTI measures are largely attributable to greater radial diffusivity, possibly indicating poorer myelination. Thus, these data suggest that fetal alcohol‐related deficits in EBC are attributable, in part, to poorer myelination in key regions of the cerebellar peduncles. Hum Brain Mapp 36:2470–2482, 2015. © 2015 Wiley Periodicals, Inc.     

Diffusion tensor imaging for measuring recovery from cerebellar peduncle injury due to intracerebral hemorrhage A case report

Diffusion tensor tractography (DTT) in diffusion tensor imaging (DTI) examination allows for the three-dimensional visualization of cerebellar peduncles. The present case-control study analyzed the relationship between functional recovery of intracerebral hematoma patient and cerebellar peduncle injury, as detected by DTI. The enrolled patient could not sit at 3 weeks after onset, but was able to walk independently and perform most daily activities after 4 months. The 3-week DTT images revealed that all six cerebellar peduncles were compressed by the hematoma, posterior portions of all three left cerebellar peduncles were shortened, and the left middle cerebellar peduncle was interrupted in the mid-portion. The 4-week DTT images showed that all compressed cerebellar peduncles were ameliorated, although injured posterior portions of the three left cerebellar peduncles did not recover. The fractional anisotropy value of the right inferior cerebellar peduncle increased from two standard deviations below the normal control value to within two standard deviations of the normal control value. These findings suggested that functional recovery was primarily due to decompression of compressed cerebellar peduncles, and not to recovery of injured cerebellar peduncles. DTI evaluations of cerebellar peduncles could be helpful when cerebellar peduncle injury is suspected.     

Partial Rhombencephalosynapsis and Chiari Type II Malformation in a Child: a True Association Supported by DTI Tractography

Partial rhombencephalosynapsis (PRECS) has been recently reported in association with Chiari II (CII). However, its existence as a true malformation is challenged due to the anatomical changes potentially induced by CII. The aim of this report was to investigate the contribution of midbrain/hindbrain tractography in this setting. A 13-year-old boy with a known CII malformation and operated myelomeningocele was referred for brain imaging after a first complex partial seizure. In addition to the classical features of CII, MRI showed partially fused cerebellar hemispheres and multiple supratentorial abnormalities. Diffusion tensor imaging (DTI) color map and tractography showed absent transverse fibers on the midsection of the cerebellum, scarce fibers of the middle cerebellar peduncle (MCP), absence of the middle pontine crossing tract, and fibers running vertically in the medial part of the cerebellum. Vertical mediocerebellar fibers are a feature of classical RECS and the paucity or absence of MCP fibers is mainly described in CII. In our patient, DTI and FT therefore demonstrated structural characteristics of both RECS and CII confirming their potential coexistence and suggesting possible shared embryological pathway.     

Demonstration of Recovery of a Patient with a Cerebellar Peduncle Injury due to Intracerebral Hemorrhage: a Diffusion Tensor Imaging Study.

背景：扩散张量成像可以对小脑脚进行三维显影。 目的：采用扩散张量成像,观察一位由于颅内出血所致小脑脚损伤患者在三个月内的功能恢复。 设计,时间和地点：病例研究,2008年10月至2009年3月期间在岭南大学医学院理疗康复教研室进行。 受试者：一位72岁女性患者,九名对照者,对照者同患者的年龄和性别相符。 方法：采用1.5T敏感性编码头线圈进行扩散张量成像。 主要观察指标：采用DTI-Studio软件评价小脑脚,包括小脑上脚,小脑中脚和小脑下脚。 结果：患者在发病三周后不能平坐,但可以独立行走,发病后4周可以完成大部分日常活动。3周扩散张量成像显示,所有小脑脚被血肿压迫。左小脑脚的后侧缩短,尤其是左小脑中脚在中部阻断。4月扩散张量成像显示,所有被压缩的小脑脚复原。此外,3周扩散张量成像结果还显示,除去右小脑中脚之外,所有小脑脚的各项异性值同正常对照值相比,降低了2个标准差。4月扩散张量成像结果显示,右小脑小脚的各项异性值有所增加,比正常对照值高出2个标准差。尽管如此,其他小脑脚的各项异性值仍保持在正常对照值之下的2个标准差。结果显示,发病后3周时的小脑脚的神经元损伤（所有小脑上脚,左小脑中脚和所有小脑下脚）在发病后4月内康复不明显。 结论：患者的功能性恢复最初是由于被压迫的小脑脚的减压所致,而不是受伤小脑脚的恢复。笔者认为采用扩散张量成像评价小脑脚对小脚损伤的疑似病例有帮助。     

Investigating connectivity between the cerebellum and thalamus in schizophrenia using diffusion tensor tractography: a pilot study

Connections of the cortical-thalamic-cerebellar-cortical regions provide a framework for studying the neural substrates of schizophrenia. A novel diffusion tensor tractography method was used to evaluate the differences in white matter connectivity between 12 patients with schizophrenia and 10 controls. For the tract tracing, we focused on the connection between the cerebellum and the thalamus. Fractional anisotropy (FA) measures along the fiber tracks were compared between patients and the control sample. Fiber tracts located between the cerebellar white matter and the thalamus exhibit a reduced FA in patients with schizophrenia in comparison with controls. The FA values along the defined fiber tracts were not overall reduced but exhibited a reduction in the anisotropy in the region in the superior cerebellar peduncles projecting towards the red nucleus.     

Diffusion tensor imaging study of the middle cerebellar peduncles in patients with schizophrenia

Recent evidence from neuroimaging studies suggests that neural dysfunction is involved in the pathophysiology of schizophrenia. Diffusion tensor imaging (DTI) is a technique that has the potential to detect subtle disruptions of neural connectivity. Fractional anisotropy (FA), which is measured by DTI, is a measure of the directionality of diffusion anisotropy. Decrease in FA indicates abnormalities of white matter due to increased water diffusion accompanied by an increase in extracellular space. In the literature, previous studies reported that patients with schizophrenia showed widespread lower FA in the white matter. These findings suggest that patients with schizophrenia have microstructural lesions in the cerebral white matter. We used DTI to determine whether neural connectivity was disturbed in the middle cerebellar peduncles in schizophrenic subjects. We found a significant FA reduction in the middle cerebellar peduncle in patients with schizophrenia. Therefore, neural disconnectivity between the cerebellum and cerebrum was considered present in patients with schizophrenia and may be involved in the pathology of schizophrenia. This review provides current findings regarding DTI study on the cerebellar peduncle in patients with schizophrenia.     

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.     

Reduced Anisotropy in the Middle Cerebellar Peduncle in Chiari-II Malformation

Besides supratentorial abnormalities, spina bifida menigomyelocele (SBM) is typically associated with Chiari-II malformation comprising a small cerebellum, which herniates downward due to a shallow posterior fossa. We used diffusion tensor imaging to probe additional microstructural alterations of the major cerebellar white matter tracts, the cerebellar peduncles. A region-of-interest approach was employed in six SBM patients and six matched controls to compare the fractional anisotropy (FA) within the superior, middle, and inferior cerebellar peduncle (SCP, MCP, and ICP, respectively). The FA in the MCP was significantly reduced in the SBM patients (0.44 vs. 0.65, p = 0.002), while there was no significant difference in the other cerebellar peduncles. In the context of numerous supratentorial white matter abnormalities in SBM such as callosal dysplasia, the most likely explanation of reduced FA in the MCP is a reduced fiber density.     

Diffusion tensor imaging: tract based spatial statistics study in essential tremor

IntroductionEssential tremor (ET) is a common movement disorder with motor and non-motor symptoms. We aimed to investigate the neurodegenerative changes in the brain white matter of patients with ET using Diffusion Tensor Imaging (DTI).MethodsClinical and MRI data from 20 patients (5 women and 15 men; age-38.2 ± 16.5 yrs) with ET and 17 controls (3 women and 14 men; age-40.7 ± 16.5 yrs) were collected prospectively. The DTI data were analyzed using tract based spatial statistics (TBSS) software for tract wise analysis. Further region of interest (ROI) analysis was carried out in the genu of corpus callosum, anterior limb of internal capsule (ALIC), corticospinal tract (CS), and cerebellar peduncles. Effect of tremor severity, disease duration and age of onset on DTI metrics was also studied.ResultsPatients with ET in comparison to controls showed significant (P_corrected < 0.05) increase of mean diffusivityand radial diffusivity in right frontoparietal white matter. Axial diffusivity increase was seen in bilateral cerebral hemispheres, thalamus, brainstem and cerebellar hemisphere white matter. No significant change in fractional anisotropy of the white matter was seen. ROI analysis also revealed abnormalities in the ALIC and cerebellar peduncles. There was no correlation between the severity of white matter changes and clinical tremor severity score as well as disease duration.ConclusionsThis study provides in vivo evidence for axonal disintegration of the cerebral and cerebellar white matter fibres in patients with ET.     

Radial diffusivity in the cerebellar peduncles correlates with clinical severity in Friedreich ataxia

Friedreich ataxia (FRDA) is a common inherited ataxia, caused by an expanded GAA repeat sequence in the Frataxin (FXN) gene. The proprioceptive system, which enters the cerebellum through the cerebellar peduncles, is a primary focus of pathology. In this study, we investigate the relationship of clinical and genetic data with diffusion-tensor imaging (DTI) indices reflecting white matter integrity of the cerebellar peduncles. Nine FRDA patients underwent DTI. After between-subject registration using tract-based spatial statistics, a white matter atlas was used for computing average values of DTI indices in the regions of interest. These were the inferior, middle and superior cerebellar peduncles (ICP, MCP, SCP). For Bonferroni correction, significance threshold was set to p < 0.0056. We found that radial diffusivity (D^⊥) within the ICP significantly correlated with scores on the Friedreich Ataxia Rating Scale (FARS, Spearman’s ρ = 0.883, p = 0.0016, all two-sided) and, at trend level, with number of trinucleotide repeats (ρ = 0.812, p = 0.008). D^⊥ in the SCP correlated with scores on the Scale for the Assessment and Rating of Ataxia (SARA, ρ = 0.867, p = 0.0025). These findings support the role of DTI, and especially D^⊥, as an informative biomarker in FRDA.     

Diffusion tensor MRI and fiber tractography of cerebellar atrophy in phenytoin users

PURPOSE: The usefulness of diffusion tensor magnetic resonance imaging (DT-MRI) is still in debate, and the development of clinically feasible scan protocol is encouraged. The purpose of this study was to investigate the afferent fiber system to the cerebellum in patients with phenytoin (PHT)-induced cerebellar atrophy in comparison with cerebellar atrophy of other etiologies by using DT-MRI. METHODS: Thirteen patients (M/F ratio, 7:6; mean age, 42.5 years) and age-matched normal controls (n = 8) participated in this study. The patient group consisted of epilepsy patients who had received PHT therapy (n = 9) and clinically diagnosed as having olivopontocerebellar atrophy (OPCA; n = 4). DT-MRI was performed by using diffusion weighting of b = 600 s/mm2, and fractional anisotropy (FA) and color-coded vector maps were generated. FA of the middle cerebellar peduncle (MCP), the cerebellum, and transverse pontine fibers (TPF) was measured and compared between PHT and OPCA patients. RESULTS: Normal subjects showed FA values of 0.81 +/- 0.07 in MCP, 0.69 +/- 0.04 in TPF, and PHT users showed FA values of 0.84 +/- 0.09 in MCP, 0.72 +/- 0.08 in TPF, and 0.21 +/- 0.04 in cerebellum. OPCA patients showed FA values of 0.39 +/- 0.11 in MCP, 0.46 +/- 0.12 in TPF, and 0.22 +/- 0.07 in cerebellum. PHT users showed a statistically significant reduction of FA only in cerebellum, whereas OPCA demonstrated significant decrease of FA in MCP, TPF, and cerebellum (one-way analysis of variance, p < 0.01). Three-dimensional reconstruction of fiber tracts demonstrated decreased volume and altered fiber integrity within the peduncles and transverse pontine fibers in the OPCA group, whereas fiber course patterns in PHT users were similar to those in controls. CONCLUSIONS: PHT users showed normal orientation and anisotropy of MCP and TPF, whereas OPCA demonstrated impaired values, suggesting that PHT directly affects the cerebellum. DT-MRI can demonstrate detailed fiber configurations in degenerative diseases of brainstem and cerebellum and provides insight into the pathomechanisms of cerebellar atrophy.     

Sensorimotor white matter projections and disease severity in primary Restless Legs Syndrome/Willis-Ekbom disease: a multimodal DTI analysis

BackgroundRestless Legs Syndrome, a potentially disabling sleep disorder, also known as Willis-Ekbom disease (RLS/WED), may be caused by loss of inhibitory modulation of descending central motor pathways, structural changes in the somatosensory cortex, abnormal connectivity between motor and sensory areas, as well as by subtle abnormalities in white matter micro-organization.ObjectiveTo compare diffusion-tensor imaging (DTI) metrics in areas associated with sensory or motor function, as well as sensorimotor integration, between subjects with primary mild-to-severe RLS/WED and controls.MethodsDTI metrics were assessed in 38 subjects with RLS/WED (14 mild to moderate, 24 severe to very severe) and 24 healthy age-matched controls with whole-brain Tract Based Spatial Statistics (TBSS), Region-of-interest (ROI) and probabilistic tractography based analyses. The ROIs corresponded to the corticospinal tract (CST) at the level of the cerebral peduncle; the superior, middle and inferior cerebellar peduncles. Subgroup analyses were made according to the severity of RLS/WED symptoms. The corticospinal tract was evaluated with probabilistic tractography. We also explored associations between significant findings and severity of symptoms with the Spearman's correlation coefficient.ResultsTBSS analysis revealed decreased axial diffusivity (AD) in the left posterior thalamic radiation in RLS/WED. In subjects with severe RLS/WED, AD was reduced in the left posterior corona radiata and this reduction was negatively correlated with severity of symptoms. ROI-based analysis showed that radial diffusivity (RD) was increased in the superior cerebellar peduncles of individuals with severe RLS/WED. Tractography did not show between-group or subgroup differences.ConclusionsOur results are consistent with subtle white matter changes, prominently in RLS/WED subjects with more severe symptoms, in areas related to sensory or motor function, as well as to sensorimotor integration, compared to controls. These findings support the hypothesis, raised by prior pathophysiological studies, of defective integration within these networks.     

Diffusion tensor imaging in the developing human cerebellum with histologic correlation

Diffusion tensor imaging was performed on 24 freshly aborted human fetuses with gestational age ranging from 20 to 37 weeks to observe age-related fractional anisotropy changes in cerebellar cortex and cerebellar white matter. Quantitative immunohistochemical analysis was performed for glial fibrillary acidic protein in each fetus molecular layer of cerebellar cortex and myelin basic protein expression was quantified in myelinated areas of the middle cerebellar peduncles. The cerebellar cortical fractional anisotropy reached its peak value at 28 weeks, and then decreased gradually until 37 weeks. The time course of glial fibrillary acidic protein expression paralleled that of fractional anisotropy in the cerebellar cortex from 20 weeks of gestation upto the gestational age at which the fractional anisotropy reached its peak value (28 weeks). In the middle cerebellar peduncles, the fractional anisotropy increased continuously upto 37 weeks of gestational age and showed a significant positive correlation with myelin basic protein immunostained fibers. The fractional anisotropy quantification can be used to assess the migrational and maturation changes during the development of the human fetal cerebellum supported by the immunohistochemical analysis.     

Diffusion tensor imaging and tractography of human brain development

Over the past decade, diffusion tensor imaging (DTI) has offered researchers and clinicians a new noninvasive window into the developing human brain, from preterm infants through adolescents and young adults. DTI improves on conventional MR imaging, such as T1-weighted and T2-weighted sequences, through its sensitivity to many microstructural features of neural organization. This has enabled visualization of the early cerebral laminar architecture in premature infants, of developing white matter before myelination, and of the microarchitecture of the cerebral cortex during preterm maturation. DTI provides reproducible quantitative measures, such as mean diffusivity and fractional anisotropy, that reflect the underlying tissue properties of gray matter and white matter and may therefore become useful as developmental milestones for the improved assessment of abnormal brain maturation. Furthermore, three-dimensional fiber tractography based on DTI can reveal the developing axonal connectivity of the human brain as well as aberrant connectivity in structural brain malformations. In this article, applications of DTI and fiber tractography to the study of human brain development are reviewed. The new insights into brain maturation afforded by DTI promise to improve the diagnostic evaluation of an array of congenital, metabolic, and neurodevelopmental disorders.     

带状灰质异位的磁共振弥散张量白质束成像研究

目的采用磁共振弥散张量白质束成像技术,观察带状灰质异位脑白质异常分布情况,探讨异位灰质的神经病理机制以及弥散张量白质束成像技术的应用价值。方法采用磁共振弥散张量白质束成像技术,对1例癫痫症状的带状灰质异位患者进行白质束描绘,观察其不同灰、白质的分布情况,并和1例正常人进行对比研究。结果弥散张量白质束成像技术很好地描绘了白质束结构。整体观察发现带状灰质异位患者脑白质整体结构紊乱,与正常人相比其联络弓状纤维稀疏、大部缺失,胼胝体纤维稀疏不整;局部分析发现内层灰质为主要的白质纤维发出处,而外层灰质仅发出细碎短小的纤维。结论对于带状灰质异位,异位的内层灰质不仅具有神经生理功能,并且可能起着主要作用,外层"正常"的灰质由于脑结构紊乱而丧失主要功能地位;灰质结构的紊乱导致白质纤维结构的缺失;弥散张量白质束成像技术可以很好地应用于带状灰质异位的神经机制研究。