Longitudinal MRI evaluations of human global cortical thickness over minutes to weeks

Magnetic resonance imaging (MRI) was used to evaluate within-subject variability in global mean cortical thickness over test-retest intervals of minutes-weeks in five healthy adults. Within-subject measures of global mean thickness were consistent over these intervals. Test-retest assessments of absolute thickness differences and percent thickness differences indicated variations of, respectively, < or =0.05-0.06 mm and < or =+/-1.9-2.3%. There have been few evaluations of normal within-subject variations in cortical thickness. The present results suggest that within-subject variability in global mean cortical thickness can be low over test-retest intervals of minutes-weeks, and that longitudinal scans can establish useful baseline estimates of variability from which to assess changes due to injury, disease, or other experiences.     

Reduced subcortical brain volumes in nonpsychotic siblings of schizophrenic patients: A pilot magnetic resonance imaging study

Substantial evidence suggests that nonpsychotic relatives of schizophrenia patients manifest subtle abnormalities in communication, eye movements, event-related potentials, and neuropsychological processes of attention, reasoning, and memory. We sought to determine whether adult relatives without psychosis or schizophrenia spectrum diagnoses might also have structural brain abnormalities, particularly in subcortical regions found to be impaired in patients with schizophrenia itself. Subjects were six sisters of schizophrenic patients and eleven normal female controls. Sixty contiguous 3 mm coronal, T1-weighted 3D magnetic resonance images (MRI) of the entire brain were acquired on a 1.5 Tesla magnet. Cortical and subcortical gray and white matter was segmented using a semiautomated intensity contour mapping algorithm. Volumes were adjusted for total brain volumes. Adjusted gray matter subcortical volumes were significantly smaller in relatives than in controls in total hippocampus, right amygdala, right putamen, left thalamus, and brainstem. Relatives had significantly enlarged left and total inferior lateral ventricles. These results, though preliminary, suggest that some never-psychotic relatives of schizophrenic patients have abnormal brain structure. If replicated in a larger sample including both sexes, these results would suggest that the genetic liability to schizophrenia is also expressed as structural brain abnormalities. Am. J. Med. Genet. 74:507–514, 1997. © 1997 Wiley-Liss, Inc.     

Angelman and Prader-Willi syndrome: A magnetic resonance imaging study of differences in cerebral structure

Recent improvements in magnetic resonance imaging techniques now allow the developing brain to be visualized in sufficient detail to perform “in vivo neuropathology.” In this study we compared the cortical morphology in six children with Angelman and four with Prader-Willi syndrome. These two syndromes are of especial interest because, although they are both caused by deletions in the same region of chromosome 15, Angelman children are far more severely affected, and do not speak. We measured the length of the banks of the Sylvian fissure in a gapless series of thin sagittal images. Angelman children had a significantly larger proportion (75%) of anomalous fissures than the Prader-Willi children (12%). Anomalous cortical growth could result from mistimed expression and recognition of macromolecules involved in axonal guidance, target recognition, and pruning. We hypothesize that misrouting of long projection axons may be related to the Sylvian fissure anomalies and the language disorder in Angelman syndrome. © 1993 Wiley-Liss, Inc.     

Insights into the gyrification of developing ferret brain by magnetic resonance imaging

The developmental mechanisms underlying the formation of human cortical convolutions (gyri and sulci) remain largely unknown. Genetic causes of lissencephaly (literally 'smooth brain') would imply that disorders in neuronal migration cause the loss of cortical convolutions. However, prior studies have suggested that loss of sulci and gyri can also arise from impaired proliferation, disrupted lamination and loss of intracortical connections. To gain further insight into the mechanisms underlying the formation of cortical convolutions, we examined the progressive brain development of the gyrencephalic ferret. In this study, we used magnetic resonance imaging to follow the temporal and spatial pattern of neuronal migration, proliferation and differentiation in relation to the onset and development of cortical convolutions. In this manner, we demonstrate that the onset of gyrification begins largely after completion of neuronal proliferation and migration. Gyrification occurs in a lateral to medial gradient, during the period of most rapid cerebral cortical growth. Cortical folding is also largely complete prior to myelination of the underlying cortical axons. These observations are consistent with gyrification arising secondary to cortical processes involving neuronal differentiation.     

Functional and structural aging of the speech sensorimotor neural system: functional magnetic resonance imaging evidence

The ability to perceive and produce speech undergoes important changes in late adulthood. The goal of the present study was to characterize functional and structural age-related differences in the cortical network that support speech perception and production, using magnetic resonance imaging, as well as the relationship between functional and structural age-related changes occurring in this network. We asked young and older adults to observe videos of a speaker producing single words (perception), and to observe and repeat the words produced (production). Results show a widespread bilateral network of brain activation for Perception and Production that was not correlated with age. In addition, several regions did show age-related change (auditory cortex, planum temporale, superior temporal sulcus, premotor cortices, SMA-proper). Examination of the relationship between brain signal and regional and global gray matter volume and cortical thickness revealed a complex set of relationships between structure and function, with some regions showing a relationship between structure and function and some not. The present results provide novel findings about the neurobiology of aging and verbal communication.     

Identification of rare copy number variants in high burden schizophrenia families

Over the last years, genome‐wide studies consistently showed an increased burden of rare copy number variants (CNVs) in schizophrenia patients, supporting the “common disease, rare variant” hypothesis in at least a subset of patients. We hypothesize that in families with a high burden of disease, and thus probably a high genetic load influencing disease susceptibility, rare CNVs might be involved in the etiology of schizophrenia. We performed a genome‐wide CNV analysis in the index patients of eight families with multiple schizophrenia affected members, and consecutively performed a detailed family analysis for the most relevant CNVs. One index patient showed a DRD5 containing duplication. A second index patient presented with an NRXN1 containing deletion and two adjacent duplications containing MYT1L and SNTG2. Detailed analysis in the subsequent families showed segregation of the identified CNVs. With this study we show the importance of screening high burden families for rare CNVs, which will not only broaden our knowledge concerning the molecular genetic mechanisms involved in schizophrenia but also allow the use of the obtained genetic data to provide better clinical care to these families in general and to non‐symptomatic causal CNV carriers in particular. © 2013 Wiley Periodicals, Inc.     

Investigation of feline brain anatomy for the detection of cortical spreading depression with magnetic resonance imaging

Cortical spreading depression (CSD) and peri‐infarct depolarisation (PID) are related phenomena that have been associated with the human clinical syndromes of migraine (CSD), head injury and stroke (PID). Nevertheless the existence of CSD in man remains controversial, despite the detection of this phenomenon in the brains of most, if not all, other animal species investigated. This failure to unambiguously detect CSD clinically may be at least partly due to the anatomically complex, gyrencephalic structure of the human brain. This study was designed to establish conditions for the study of CSD in the brain of a gyrencephalic species using the noninvasive technique of magnetic resonance imaging (MRI). The 3‐dimensional (3D) gyrencephalic anatomy of the cat brain was examined to determine the imaging conditions necessary to detect CSD events. Orthogonal transverse, sagittal and horizontal T₁‐weighted image slices showed that the marginal and suprasylvian gyri were the most appropriate cortical structures to study CSD. This was in view of (1) their simple geometry: (2) their lengthy extent of grey matter orientated rostrocaudally in the cortex: (3) their separation by a sulcus across which CSD spread could be studied and (4) the discontinuity in the grey matter in these regions between the right and left hemispheres dorsal to the corpus callosum. The structure suggested by the T₁‐weighted images was corroborated by systematic diffusion tensor imaging to map the fractional anisotropy and diffusion trace. Thus a single horizontal image plane could visualise the neighbouring suprasylvian and marginal gyri of both cerebral hemispheres, whereas its complex shape and position ruled out the ectosylvian gyrus for CSD studies. With the horizontal imaging plane, CSD events were reproducibly detected by animating successive diffusion‐weighted MR images following local KCl stimulation of the cortical surface. In single image frames, CSD detection and characterisation required image subtraction or statistical mapping methods that, nevertheless, yielded concordant results. In repeat experiments, CSD events were qualitatively similar in appearance whether elicited by sustained or transient KCl applications. Our experimental approach thus successfully describes cat brain anatomy in vivo, and elucidates the necessary conditions for the application of MRI methods to detect CSD propagation.     

Association study of schizophrenia with dopamine D3 receptor gene polymorphisms: Probable effects of family history of schizophrenia?

Using a case-control design, a reported association of schizophrenia with homozygosity at the dopamine D3 receptor gene locus was investigated in a group of patients (n = 53), with schizophrenia (DSM-III-R), and psychiatrically normal controls (n = 61), matched for ethnicity and area of residence. No significant differences in the distribution of alleles or genotypes between the two groups could be deteched. However, among patients with a family history of schizophrenia, as compared to controls without such family history, an association with allele 1 at this locus was noted (Odds ratio 12.4, C.I. 1.61, 96.35). © 1993 Wiley-Liss, Inc.     

What does the Edinburgh high‐risk study tell us about schizophrenia?

The Edinburgh High Risk Study concerns 162 young people aged 16 to 25 at ascertainment who have at least two close relatives with schizophrenia. They are compared with two control groups (1) of age‐matched well subjects and (2) of age‐matched subjects with first schizophrenic episodes. The interim results show that schizophrenia has developed in 10 high‐risk subjects and no controls and that all categories of psychopathology are more marked in the high‐risk subjects. Psychopathology shows no relationships with measures of genetic liability. Neuropsychological measures are most impaired in the individuals with first‐episode schizophrenia, with high‐risk subjects performing better and well controls better still. The greater the genetic liability of the high‐risk subjects, the poorer the neuropsychological performance. Neuropsychological impairments occurred in more high‐risk subjects than are expected to develop schizophrenia. Structural brain scans show significant differences between those with first‐episode schizophrenia, high‐risk subjects, and well controls. Brain structure is related to genetic liability in that high‐risk subjects with higher genetic liability have smaller right and left prefrontal lobes and smaller right and left thalami. In those high‐risk subjects with two scans, there was a significantly greater reduction in temporal lobe size in those with psychotic symptoms than in those without. It is suggested that in high‐risk subjects, the change from vulnerability to psychosis may be preceded by reduction in size and deteriorating function of the temporal lobe. © 2002 Wiley‐Liss, Inc.     

The amygdala in schizophrenia: a trimodal magnetic resonance imaging study

In schizophrenic psychoses, structural and functional alterations of the amygdala have been demonstrated by several neuroimaging studies. However, postmortem examinations on the brains of schizophrenics did not confirm the volume changes reported by volumetric magnetic resonance imaging (MRI) studies. In order to address these contradictory findings and to further elucidate the possibly underlying pathophysiological process of the amygdala, we employed a trimodal MRI design including high-resolution volumetry, diffusion tensor imaging (DTI), and quantitative magnetization transfer imaging (qMTI) in a sample of 14 schizophrenic patients and 14 matched controls. Three-dimensional MRI volumetry revealed a significant reduction of amygdala raw volumes in the patient group, while amygdala volumes normalized for intracranial volume did not differ between the two groups. The regional diffusional anisotropy of the amygdala, expressed as inter-voxel coherence (COH), showed a marked and significant reduction in schizophrenics. Assessment of qMTI parameters yielded significant group differences for the T2 time of the bound proton pool and the T1 time of the free proton pool, while the semi-quantitative magnetization transfer ratio (MTR) did not differ between the groups. The application of multimodal MRI protocols is diagnostically relevant for the differentiation between schizophrenic patients and controls and provides a new strategy for the detection and characterization of subtle structural alterations in defined regions of the living brain.     

局灶性皮质发育不良患者的磁共振波谱分析与临床相关性研究

目的:应用多体素氢质子磁共振波谱(MRS)研究局灶性皮质发育不良(FCD)患者脑代谢特点,并进一步探讨(癎)性发作的机制.方法:收集来自贵阳医学院附属医院和重庆医科大学临床学院神经科门诊及住院明确诊断的20例大脑FCD伴有(癎)性发作患者和20名健康受试者进行多体素MRS扫描,测量患者病灶区、病灶比邻区和远离病灶区皮质氮-乙酰门冬氨酸(NAA)与肌酸(Cr)的比值(NAA/Cr),并与对照组受试者相对应皮质区NAA/Cr值比较.结果:FCD患者病灶区、病灶比邻区较对照组皮质区NAA/Cr比值显著降低(P＜0.01),远侧病灶区皮质区与对照组皮质区NAA/Cr比值之间比较差异无统计学意义(P＞0.05);病灶区皮质NAA/Cr比值与临床(癎)性发作次数之间未见相关性.结论:多体素MRS可无创观察FCD患者脑代谢改变,为手术治疗FCD伴有难治性癫(癎)患者提供了一个重要的参考指标.     

眶内眼神经的断层解剖与MRI的对照研究

目的为眶内手术及MRI诊断提供解剖学基础。方法采用成人尸头6例(12侧)制成0.5mm的火棉胶连续切片;再选择健康志愿者15例(30侧)行MRI的水平位、冠状位扫描,对额神经、鼻睫神经和泪腺神经位置、走行和毗邻进行观察和识别,并与相应活体MRI图像对照研究。结果眶内眼神经的分支额神经、鼻睫神经和泪腺神经均经过眶上裂入眶;额神经发出眶上神经内外支和滑车上神经,鼻睫神经与眼动脉伴行,泪腺神经在外直肌上方前行。活体MRI眶内眼神经扫描,T1WI、T2WI及其各脂抑加权像上眶内眼神经呈中等信号。结论MRI检查时,宜选择水平位观察额神经并显示最佳,选择冠状位观察鼻睫神经及泪腺神经,鼻睫神经显示尚可,泪腺神经显示不清;与MRI对应的火棉胶连续切片能准确显示眶内眼神经的分支、走形,且其制备技术是研究眶内眼神经的一种简单、经济、切实、可行的方法。     

Age-related changes in iliac crest cortical width and porosity: a histomorphometric study

Although age-related changes in cancellous bone structure in human are relatively well characterized, few studies have addressed changes in cortical bone. We have investigated age-related changes in iliac crest bone biopsy specimens from 54 normal subjects, 23 men and 31 women, aged 18-90 years. A significant decrease in cortical width and area was seen (P =0.002 and <0.001 respectively), with no difference between sexes. Haversian canal density increased significantly with age by approximately 9% per decade (P = 0.032) but Haversian canal area tended to be lower, resulting in no overall age-related difference in cortical porosity. Haversian canal area was significantly higher in the endosteal section than in the periosteal section of the cortex (P = 0.019) but the Haversian canal density was lower, resulting in similar overall porosity in the two sections. In conclusion, our results demonstrate an age-related decrease in iliac crest cortical width in men and women and an increase in Haversian canal density, but no overall change in cortical porosity.     

Thinning,movement, and volume loss of residual cortical tissue occurs after stroke in the adult rat as identified by histological and magnetic resonance imaging analysis

Plasticity of residual cortical tissue has been identified as an important mediator of functional post-stroke recovery. Many studies have been directed toward describing biochemical, electrophysiological, and cytoarchitectural changes in residual cortex and correlating them with functional changes. Additionally, after neonatal stroke the thickness of residual tissue can change, the tissue can move, and tissue can fill in the stroke core. The purpose of the present study was to systematically investigate and document possible gross morphological changes in peri-infarct tissue after forelimb motor cortex stroke in the adult rat. Rats received a unilateral forelimb motor cortex stroke of equivalent size by pial strip devascularization or photothrombotic occlusion and were then examined using histology or magnetic resonance imaging (MRI) at 1 h, 1, 3, 7, 14, or 31 days post-stroke. Middle cerebral artery occlusion was used as a control stroke procedure. Decreases in cortical thickness, volume, and neural density were found to extend far beyond the stroke infarct and included most of the sensorimotor regions of the stroke and intact hemispheres. Movement of residual tissue towards the infarct was observed and confirmed using anatomical markers placed in intact cortical tissue at the time of stroke induction. The results are discussed in relation to the idea that extensive time-dependent morphological changes that occur in residual tissue must be considered when evaluating plasticity-related cortical changes associated with post-stroke recovery of function.     

Functional magnetic resonance imaging of the cortical response to photic stimulation in humans following optic neuritis recovery

Recovery from optic neuritis has been shown to be associated with an abnormal functional MRI (fMRI) response following exposure of the eye to an epoch based (ON-OFF design) flickering photic stimulus. Visual cortex activation is reduced during photic stimulation, whilst extra-occipital areas are extensively activated with a peak blood oxygen level dependent response during the OFF phase of the stimulus paradigm. We performed a further fMRI experiment to determine whether the abnormal extra-occipital response is a phase-specific phenomenon or whether it results from a delayed haemodynamic response. A cohort of patients that recovered from optic neuritis was studied, this time using a longer photic stimulation epoch (40 s). The extra-occipital response again peaked during the baseline condition, indicating that the phenomenon is phase dependent. Our results also reinforce the important findings of extra-occipital activation following optic neuritis which may represent an adaptive reorganization of the cerebral response.     

Quantitative evaluation of cortical bone thickness and root proximity at maxillary interradicular sites for orthodontic mini-implant placement

Few studies have evaluated interradicular anatomy for cortical bone thickness and root proximity when placing a mini-implant for orthodontic anchorage. The purpose of this study was to provide a clinical guideline to indicate the best location, according to different insertion angles, for placement of a mini-implant with respect to the thickness of cortical bone and root proximity. CT images from 14 men and 14 women (mean age, 27 years; range, 23-35 years) were used to evaluate the buccal interradicular cortical bone thickness and root proximity from and mesial to the central incisor to the second molar. A measure of cortical bone thickness was performed at four different angles. Generally, thin cortical bone thickness was found in the central/central incisors and central/lateral incisors interradicular sites. Cortical bone thickness increased significantly as the insertion angle increased except for interradicular sites at the 2 mm level from the alveolar crest. The volume of cortical bone engagement increased significantly at the 4 and 6 mm levels from the alveolar crest with an insertion angle of 30 degrees and 45 degrees in most interradicular sites. The lateral incisor/canine and second premolar/first molar interradicular sites showed greater space between roots compared with other sites, although this was not statistically significant. Based on the findings of this study, we recommend that mini-implants be placed at the 4 and 6 mm levels from the alveolar crest with 30 degrees and 45 degrees angles for the majority of interradicular sites to ensure better cortical bone to mini-implant contact without root damage.     

Normal diameter of the thoracic aorta in adults: a magnetic resonance imaging study

To determine the evolution of the diameter of the thoracic aorta with age in order to detect dilatation more reliably by imaging, we performed a retrospective analysis of the MRI examinations of the normal thoracic aorta of 66 subjects aged 44.1±19.1 years (range 19.1–82.4 years) obtained between 1991 and 2000 on a Magnetom SP 42 1T apparatus (Siemens) using T1-weighted spin echo sequences with electrocardiographic synchronization. Sixteen measurements were made in the axial plane, the oblique sagittal plane in the axis of the aortic arch, and the oblique frontal plane perpendicular to the latter at the level of the ascending aorta, the arch and the descending thoracic aorta. We found an increase in the thoracic aorta diameter and a significant relationship between this diameter and the age of our subjects, wherever the measure was performed. However, there was no systematic correlation between aortic diameter and age. The aortic diameter evolved with age and a marked difference seemed to exist in measurements made in groups younger and older than 40 years. This study, conducted on a small population of 66 patients, thus helps to define a normal aortic diameter, thereby making the diagnosis of pathological dilatation of the aorta more reliable.

---

Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left of that page takes you directly to the supplementary material.

---

Diamètre normal de l'aorte thoracique chez l'adulte. Etude en imagerie par résonance magnétique

Résumé Pour déterminer l'évolution du diamètre de l'aorte thoracique en fonction de l'âge afin de pouvoir juger d'une éventuelle dilatation sur les examens d'imagerie, les auteurs ont analysé rétrospectivement des Imageries par Résonance Magnétique d'aortes thoraciques normales de 66 sujets âgés de 44,1±19,1 ans (19,1 à 82,4 ans) réalisés de 1991 à 2000 sur un appareillage Magnetom SP 42 de 1 T (Siemens, Erlangen) en séquences de spin écho pondérées en T1 avec synchronisation à l'électrocardiogramme; 16 mesures étaient effectuées dans les plans transversal, sagittal oblique dans l'axe de l'arc de l'aorte, et frontal oblique perpendiculaire au précédent au niveau de l'aorte ascendante, l'arc de l'aorte et l'aorte thoracique descendante. Il existait un accroissement significatif du diamètre de l'aorte sur les mesures effectuées en fonction de l'âge. En revanche il n'existait pas de corrélation systématique entre diamètre aortique et âge. Le diamètre aortique évoluait en fonction de l'âge de manière significative avec une différence qui paraissait nette entre la cohorte des sujets de moins de 40 ans celle des patients de plus de 40 ans. Cette étude, effectuée sur une courte série de 66 patients, permet donc d'approcher le diamètre aortique normal et d'aider au diagnostic de dilatation pathologique de l'aorte.

---

     

功能磁共振在大脑皮质发育障碍患者的初步应用研究

目的：应用功能磁共振（fMRI）探讨6名正常受试者及2例皮质发育障碍（DCDs）患者在进行汉语词汇加工过程中脑激活模式，探讨DCDs患者与正常受试者之间脑激活区域的差异与临床意义。方法：本实验采用听觉刺激，以汉语单词理解为语言作业任务。结果：①正常受试者均出现显著的脑区激活，传统语言脑区Wemicke和Broca区激活在双侧大脑半球基本是对称的。除传统语言脑区激活外，还出现其它脑区激活现象。②两例DCDs患者表现为基本语言功能区的激活，诸如Wemicke区和Broca区激活。但脑激活表现为显著的不对称性，甚至完全偏侧性。结论：fMRI能够对大脑DCDs患者功能重塑皮质进行定位，为DCDs伴难治性癫痫患者手术治疗，避免损伤重要功能区提供了有益的保障。