Magnetic resonance imaging of the child's brain

The most significant difference between magnetic resonance imaging (MRI) and computed tomography (CT) is that the former graphic representation of the cerebrospinal axis and its structures does not use ionizing radiation or the injection of contrast material. The physical principles of MRI and the very characteristic appearances of some pathological processes common in children require special study. Low-proton density areas are generally dark; the short T ₁ value is responsible for white matter appearing clear; inversion recovery sequences permit study of the progression of myelination.     

Magnetic resonance imaging in multiple sclerosis: the role of conventional imaging

Magnetic resonance imaging (MRI) of the brain and spinal cord plays a central role in establishing the diagnosis of multiple sclerosis (MS), in monitoring disease activity, and as a key outcome measure in clinical trials of new MS therapies. Conventional MRI continues to evolve, reflecting advances in imaging hardware and software. These advances have led to important new insights into MS disease pathophysiology and can be used to improve patient management. Despite these improvements, standard MRI continues to capture only a small portion of the underlying changes that occur during the course of the disease.     

遗忘型轻度认知功能损害患者大脑皮质结构磁共振成像的改变

目的 运用MRI及FMRIB software library(FSL)和Freesurfer软件包分析技术,研究遗忘型轻度认知功能损害(amnestic mild cognitive impairment,aMCI)患者全脑皮质结构改变情况.方法 对20例aMCI患者和20名年龄、性别、文化程度相匹配的健康志愿者,应用SEMENTS trio3.0 T MRI仪,采用高分辨扫描技术获取大脑精细结构立体像,然后应用FSL软件和Freesurfer软件包进行数据分析和后处理,计算出全脑不同部位皮质密度和厚度,比较aMCI组与健康对照组皮质结构特征的区别.结果 与健康对照组相比,aMCI组的左侧额叶、顶叶、颞叶皮质密度显著降低,右侧丘脑、颞叶及左侧岛叶皮质密度轻度降低;aMCI组左侧前扣带回[(2.19±0.24)mm]、顶下小叶[(2.27±0.15)mm],双侧海马旁回[(2.03±0.15)、(2.04±0.17)mm]、额上回[(2.42±0.34)、(2.40±0.28)mm]、额中回[(2.31±0.31)、(2.33±0.29)mm]、颞极[(3.41±0.68)、(3.30±0.56)mm]、颞横回[(2.04±0.12)、(2.01±0.11)mm]、中央前回[(2.20±0.11)、(2.31±0.19)mm]、中央后回[(1.88±0.11)、(1.82±0.09)mm]、缘上回[(2.53±0.33)、(2.55±0.23)mm]的皮质厚度显著降低(t=2.13～3.75,P＜0.05),其余部位无明显改变(t=0.09～1.88,P＞0.05).结论 aMCI患者大脑多个部位存在皮质结构改变,皮质厚度的变薄早于密度的降低.     

Quantitative magnetic resonance imaging of the corpus callosum in childhood onset schizophrenia

Corpus callosum size has been found to be abnormal in adult schizophrenia, and other studies have implicated abnormal interhemispheric communication in this disorder. To assess continuity with brain abnormalities in the later onset disorder and to further localize brain maldevelopment, this structure was examined in a unique sample of childhood onset schizophrenics. Anatomic brain magnetic resonance imaging scans were acquired for 25 patients (mean age 13.9 ± 2.1) who had onset of schizophrenia by age 12 (mean age at onset 9.9 ± 1.9) and 55 normal children. The midsagittal area of the corpus callosum was divided into seven sections. With no adjustment for brain volume, no diagnostic differences were observed. After adjustment for the smaller cerebral volume of the schizophrenics, larger total, anterior and posterior corpus callosum areas emerged for the schizophrenics. These findings provide further evidence for continuity between childhood onset and later onset schizophrenia and support other studies showing white matter sparing in the context of decreased cortical volume.     

RETRACTED ARTICLE: The sequential magnetic resonance images of tri-methyl tin leukoencephalopathy

Organotin compounds are commonly used in industrial and agriculture. It causes toxic effects on skin, eyes, respiratory system, gastrointestinal system, and nervous system. After cleaning a di-methyl tin tank, 43-year-old man showed a dizziness, disorientation, visual hallucination, and agitation. Through a measurement by liquid chromatography and inductively coupled plasma-mass spectrometry, di-methyl tin and tri-methyl tin was detected. Although magnetic resonance (MR) image 3 days after exposure showed no abnormal signal intensity, follow-up MR images 15 days after exposure revealed abnormal extensive signal intensities in the white matter that was not ever coincident with previous reports. It was hardly explainable that previous abnormal signal intensities of MR image nearly disappeared 4 months later. We present a case of a patient who developed acute toxic leukoencephalopathy from an acute inhalational exposure to methyl tin with sequential MR images showing an involvement of white matter that was not ever reported.     

Magnetic resonance imaging as a tool to examine the neuropathology of multiple sclerosis

Magnetic resonance imaging (MRI) has significantly extended the understanding of multiple sclerosis (MS), owing to its ability to sensitively depict the dynamics of the disease process in vivo. The subject of this review is the use of MRI in the post-mortem setting, with emphasis on how it may be used to improve the specimen selection process at autopsy. Lesions with active demyelination are highly interesting in the study of MS pathogenesis, but are rare in a typical autopsy material of chronic MS. The yield of MS lesions in autopsy specimen selection can be increased by the use of MRI-guided tissue sampling, as a significant proportion of abnormalities detected by post-mortem MRI are not macroscopically visible/palpable. The majority of these MRI abnormalities have been found to represent either discrete areas of microglial activation with no demyelination (so-called (p)reactive lesions), or active demyelinating MS lesions by further histopathological examination. The presence and extent of MS pathology outside of the focal demyelinated lesions is more readily appreciated by MRI-guided specimen sampling, as has been shown in the study of extensive areas of partial myelin loss in the spinal cord. A further advantage of MRI-guided specimen sampling is the ability to use three-dimensional and quantitative measures. The potential of correlating these with histopathological data may be further exploited in the future. The technical procedure for MRI-guided tissue sampling at autopsy is presented, and the limitations of the technique are discussed.     

Magnetic resonance imaging for the diagnosis of acute leukoencephalopathy in children treated with tacrolimus

The leukoencephalopathy induced by tacrolimus is increasingly recognised as an important cause of neurological complications after transplantation. Magnetic resonance imaging (MRI) is of major help in the differential diagnosis of infection or vascular injury. We describe two children with coma and seizures after transplantation, in whom the results of MRI with FLAIR (fluid-attenuated inversion-recovery) and DWI (diffusion-weighted images) were the main positive elements for the diagnosis of drug-induced toxicity. The results of DWI favoured the role of oedema and/or demyelination in the pathophysiology of this disorder. Unlike other reported patients, in whom all symptoms resolved, lesions persisted, albeit improved, on the control MRI, and both children demonstrated learning disabilities after several years of follow-up.     

Magnetic resonance imaging predictors of treatment response in first-episode schizophrenia

Identifying neurobiological predictors of response to antipsychotics in patients with schizophrenia is a critical goal of translational psychiatry. Few studies, however, have investigated the relationship between indices of brain structure and treatment response in the context of a controlled clinical trial. In this study, we sought to identify magnetic resonance (MR) imaging measures of the brain that predict treatment response in patients experiencing a first-episode of schizophrenia. Structural MR imaging scans were acquired in 39 patients experiencing a first-episode of schizophrenia with minimal or no prior exposure to antipsychotics participating in a double-blind 16-week clinical trial comparing the efficacy of risperidone vs olanzapine. Twenty-five patients were classified as responders by meeting operationally defined treatment response criteria on 2 consecutive study visits. Fourteen patients never responded to antipsychotic medication at any point during the clinical trial. MR imaging scans were also acquired in 45 age- and sex-matched healthy volunteers. Cortical pattern matching methods were used to compare cortical thickness and asymmetry measures among groups. Statistical mapping results, confirmed by permutation testing, indicated that responders had greater cortical thickness in occipital regions and greater frontal cortical asymmetry compared with nonresponders. Moreover, among responders, greater thickness in temporal regions was associated with less time to respond. Our findings are consistent with the hypothesis that plasticity and cortical thickness may be more preserved in responders and that MR imaging may assist in the prediction of antipsychotic drug response in patients experiencing a first-episode of schizophrenia.     

Detecting abnormalities of corpus callosum connectivity in autism using magnetic resonance imaging and diffusion tensor tractography

The corpus callosum (CC) has emerged as one of the primary targets of autism research. To detect aberrant CC interhemispheric connectivity in autism, we performed T1-weighted magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI)-based tractography in 18 children with high functioning autism (HFA) and 16 well-matched typically developing (TD) children. We compared global and regional T1 measures (CC volume, and CC density), and the DTI measures [fractional anisotropy (FA), apparent diffusion coefficient (ADC), average fiber length (AFL), and fiber number (FN)] of transcallosal fibers, between the two groups. We also evaluated the relationships between scores on the Childhood Autism Rating Scale (CARS) and CC T1 or DTI measurements. Significantly less white matter density in the anterior third of the CC, and higher ADC and lower FN values of the anterior third transcallosal fiber tracts were found in HFA patients compared to TD children. These results suggested that the anterior third CC density and transcallosal fiber connectivity were affected in HFA children.     

Magnetic resonance imaging of the cervical spinal cord in multiple sclerosis

Background: The spinal cord is a common site of involvement in multiple sclerosis (MS) where pathology contributes substantially to locomotor disability. Previous studies have demonstrated significant correlations between clinical disability and cervical cord atrophy, but not with cord T₂ lesion load. We evaluate cervical cord pathology using, for the first time, quantitative T₁ relaxation time (T₁), which shows histopathological specificity for tissue damage in the cerebral white matter. Method: Cervical cord T₁ was compared in 15 MS patients [8 relapsing-remitting (RR), 7 secondary progressive (SP)] and 6 healthy controls, and related to normalised upper cervical cord area (UCCa), cerebral white matter T₁, T₂ lesion load and disability measures including the Expanded Disability Status Scale (EDSS), Ambulation index (AI) and timed 25-foot walk. T1 maps of the brain and cervical cord were acquired using a high-resolution, 3-dimensional fast low-angle shot sequence. Dual-echo sequences were also obtained. Results: Median cervical cord T₁ [mean (standard deviation)] was significantly greater in RR [854 [28] ms] (p = 0.0006) and SP patients [927 [67] ms] (p < 0.0001) compared with controls [888 [61] ms], and in SP vs. RR patients (p = 0.002). In the overall patient cohort, it correlated significantly with median cerebral white matter T1 (r = 0.7, p = 0.0046), UCCa (r = −0.87, p < 0.0001), but not T2 lesion loads. Both median cervical cord T1 and UCCa (respectively) correlated significantly with the EDSS (r = 0.55, p = 0.03; r = −0.54, p = 0.04), AI (r = 0.77, p = 0.001; r = −0.60, p = 0.02) and timed 25-foot walk (r = 0.56, p = 0.03; r = −0.55, p = 0.04). Conclusion: Cervical cord T₁ distinguishes between MS subgroups and could also prove a useful surrogate outcome measure in MS. The relation of cervical cord T₁ to cerebral white matter T₁ suggests that cord pathology may be influenced by tissue damage upstream. Received: 13 June 2002, Received in revised form: 9 October 2002, Accepted: 18 October 2002 Supported by a research grant from The University of Nottingham. Correspondence to Lalitha Vaithianathar     

Regulation of protein synthesis in lymphoblasts from vanishing white matter patients

Leukoencephalopathy with vanishing white matter (VWM) is an inherited childhood white matter disorder, caused by mutations in the genes encoding eukaryotic initiation factor 2B (eIF2B). The present study showed that, while the eIF2B activity was reduced in VWM lymphoblasts, the expression levels of the eIF2B subunits were similar to control lymphoblast lines. The mutations in eIF2B did not affect the interaction with eIF2. Strikingly, no apparent differences for the regulation of protein synthesis, measured by [35S]-methionine incorporation, were found between control and VWM lymphoblasts. Western blotting showed that, in some VWM cells, exposure to heat shock caused a decrease in the expression of specific eIF2B subunits. Most importantly, the increase in phosphorylation of eIF2alpha in response to heat shock was lower in VWM lymphoblasts than in control cells. These findings could form part of the explanation for the episodes of rapid and severe deterioration in VWM patients that are precipitated by febrile infections.     

Magnetic resonance imaging evaluation of the effects of ageing on grey–white ratio in the human brain

A previous neuropathological report noted a non–linear pattern of change in cerebral grey–white matter ratio during ageing. In that report, grey–white ratio decreased from age 20 to age 50, then increased in elderly subjects. The objective of the current study was to attempt to replicate this pattern of age–related change in the grey–white ratio in living human subjects using quantitative magnetic resonance imaging segmentation analysis. We measured the grey–white ratio in 78 subjects between the ages of 19 and 77 years, using a computer segmentation algorithm with magnetic resonance images. In agreement with the previous neuropathological report. the current in vivo magnetic resonance study found that the grey–white ratio declined from age 20 to age 50, then increased in elderly subjects.     

老年人脑白质病变的头颅MRI分型演变及其意义

脑白质病变在无残障的老年人头颅磁共振成像MRI上常可见到,但发生率各家报道差异很大。这种情况与研究设计以及脑白质病变评价方法的选择密切相关。既往大部分研究将其分为脑室旁和深部脑白质病变,但这种两分法不能很好反映脑白质病变的病理生理改变。新近有学者提出了更符合病理机制的分型方法：即脑室旁、近脑室、深部、近皮层脑白质病变。这种分型有助于提高脑白质病变研究的同质性,有助于及早进行针对性的病因干预。     

Parkinsonian features in hereditary diffuse leukoencephalopathy with spheroids (HDLS) and CSF1R mutations

Atypical Parkinsonism associated with white matter pathology has been described in cerebrovascular diseases, mitochondrial cytopathies, osmotic demyelinating disorders, leukoencephalopathies leukodystrophies, and others. Hereditary diffuse leukoencephalopathy with spheroids (HDLS) is an autosomal dominant disorder with symptomatic onset in midlife and death within a few years after symptom onset. Neuroimaging reveals cerebral white matter lesions that are pathologically characterized by non-inflammatory myelin loss, reactive astrocytosis, and axonal spheroids. Most cases are caused by mutations in the colony-stimulating factor 1 receptor (CSF1R) gene.We studied neuropathologically verified HDLS patients with CSF1R mutations to assess parkinsonian features. Ten families were evaluated with 16 affected individuals. During the course of the illness, all patients had at least some degree of bradykinesia. Fifteen patients had postural instability, and seven had rigidity. Two patients initially presented with parkinsonian gait and asymmetrical bradykinesia. These two patients and two others exhibited bradykinesia, rigidity, postural instability, and tremor (two with resting) early in the course of the illness. Levodopa/carbidopa therapy in these four patients provided no benefit, and the remaining 12 patients were not treated. The mean age of onset for all patients was about 45 years (range, 18–71) and the mean disease duration was approximately six years (range, 3–11).We also reviewed HDLS patients published prior to the CSF1R discovery for the presence of parkinsonian features. Out of 50 patients, 37 had gait impairments, 8 rigidity, 7 bradykinesia, and 5 resting tremor. Our report emphasizes the presence of atypical Parkinsonism in HDLS due to CSF1R mutations.     

Magnetic resonance imaging to evaluate gastrointestinal function

Magnetic resonance imaging of gastrointestinal (GI) function has advanced substantially in the last few years. The ability to obtain high resolution images of the undisturbed bowel with tunable tissue contrast and using no ionizing radiation are clear advantages, particularly for children and women of reproductive age. Barriers to diffusion in clinical practice so far include the need to demonstrate clinical value and the burden of data processing. Both difficulties are being addressed and the technique is providing novel insights into both upper and lower GI disorders of function at an ever increasing rate.     

White matter magnetic resonance imaging hyperintensity in Alzheimer's disease: correlations with corpus callosum atrophy

We have previously demonstrated with MRI that as well as marked white matter involvement in late-onset Alzheimer's disease (AD), atrophy of the corpus callosum may also be present. This finding prompted us to study possible correlations between atrophy of the corpus callosum and white matter hyperintensity (WMH) and between white matter lesions and the severity of the disease. We compared the corpus callosum and white matter lesions on MRI from 15 AD patients and 15 controls. The white matter lesions were scored according to the Scheltens' rating scale. We found a significant reduction of the area of the corpus callosum and more severe white matter lesions in AD patients than in controls. Both atrophy of the corpus callosum and the severity of lesions depended mainly on the diagnosis of senile dementia of the Alzheimer type and on age but not on the diagnosis of presenile AD. We demonstrated a negative correlation between white matter lesions scores and areas of corpus callosum in AD patients and no correlation between the white matter lesions and the severity of the disease. We demonstrated that white matter lesions including WMH and atrophy of the corpus callosum are more frequent in AD than in controls. The predominance of white matter lesions in senile AD may be explained by the combination of aging and disease processes.