MR薄层定位扫描与常规扫描检测脑转移瘤数量的对比研究

目的评估脑转移瘤患者治疗前常规增强MR扫描和伽玛刀治疗所采用的薄层增强MR扫描检测脑转移瘤数量之间的不同。方法转移瘤的数量在治疗前和治疗中两次扫描图像上分别由2名医生确定,研究分析的两次MR图像间隔时间为4周以内。常规的增强MR扫描为层厚6 mm间隔2 mm,伽玛刀定位增强MR扫描是采取对刚性固定框架进行3.0 mm薄层无间隔扫描。结果 1336名患者中41.2%的患者在伽玛刀定位时发现转移瘤的数量增加,而数目相同者占58.8%,检测出从单发转移增加到多发转移占13.8%。在结直肠癌、食道癌病例中,单发转移的比例为66.2%,高于其他恶性肿瘤患者。结论大约有40%的患者在伽玛刀定位薄层图像扫描中发现转移瘤的数目增加,脑转移瘤患者的薄层MR增强扫描应当常规使用。     

Molecular imaging using visible light to reveal biological changes in the brain

Advances in imaging have enabled the study of cellular and molecular processes in the context of the living body that include cell migration patterns, location and extent of gene expression, degree of protein-protein interaction, and levels of enzyme activity. These tools, which operate over a range of scales, resolutions, and sensitivities, have opened up broad new areas of investigation where the influence of organ systems and functional circulation is intact. There are a myriad of imaging modalities available, each with its own advantages and disadvantages, depending on the specific application. Among these modalities, optical imaging techniques, including in vivo bioluminescence imaging and fluorescence imaging, use visible light to interrogate biology in the living body. Optimal imaging with these modalities require that the appropriate marker be used to tag the process of interest to make it uniquely visible using a particular imaging technology. For each optical modality, there are various labels to choose from that range from dyes that permit tissue contrast and dyes that can be activated by enzymatic activity, to gene-encoding proteins with optical signatures that can be engineered into specific biological processes. This article provides and overview of optical imaging technologies and commonly used labels, focusing on bioluminescence and fluorescence, and describes several examples of how these tools are applied to biological questions relating to the central nervous system.     

MR imaging of the neonatal brain

The advent of modern neuroimaging tools and methods has revolutionized the evaluation of the brain in neonates. The development of magnetic resonance (MR)-compatible monitoring tools and incubators has alleviated concerns regarding transportation of these unstable infants. The development of dedicated neonatal imaging coils has increased signal-to-noise ratios dramatically in images of the neonatal brain; this has made high-quality anatomic imaging, diffusion tensor imaging, and proton MR spectroscopy feasible in a normal imaging time. In centers that are equipped properly for neonatal MR imaging, MR is now unquestionably the study of choice for neonates who have encephalopathy or suspected brain injury. This article discusses the application of modern MR techniques to some of the causes of encephalopathy in neonates.     

Magnetoencephalography can reveal deep brain network activities linked to memory processes

Recording from deep neural structures such as hippocampus noninvasively and yet with high temporal resolution remains a major challenge for human neuroscience. Although it has been proposed that deep neuronal activity might be recordable during cognitive tasks using magnetoencephalography (MEG), this remains to be demonstrated as the contribution of deep structures to MEG recordings may be too small to be detected or might be eclipsed by the activity of large‐scale neocortical networks. In the present study, we disentangled mesial activity and large‐scale networks from the MEG signals thanks to blind source separation (BSS). We then validated the MEG BSS components using intracerebral EEG signals recorded simultaneously in patients during their presurgical evaluation of epilepsy. In the MEG signals obtained during a memory task involving the recognition of old and new images, we identified with BSS a putative mesial component, which was present in all patients and all control subjects. The time course of the component selectively correlated with stereo‐electroencephalography signals recorded from hippocampus and rhinal cortex, thus confirming its mesial origin. This finding complements previous studies with epileptic activity and opens new possibilities for using MEG to study deep brain structures in cognition and in brain disorders.     

Temporal dynamics reveal atypical brain response to social exclusion in autism

Despite significant social difficulties, children with autism spectrum disorder (ASD) are vulnerable to the effects of social exclusion. We recorded EEG while children with ASD and typical peers played a computerized game involving peer rejection. Children with ASD reported ostracism-related distress comparable to typically developing children. Event-related potentials (ERPs) indicated a distinct pattern of temporal processing of rejection events in children with ASD. While typically developing children showed enhanced response to rejection at a late slow wave indexing emotional arousal and regulation, those with autism showed attenuation at an early component, suggesting reduced engagement of attentional resources in the aversive social context. Results emphasize the importance of studying the time course of social information processing in ASD; they suggest distinct mechanisms subserving similar overt behavior and yield insights relevant to development and implementation of targeted treatment approaches and objective measures of response to treatment.     

Men may be more vulnerable to seizure-associated brain damage

BACKGROUND: Repetitive seizures may be associated with progressive neuronal damage measurable by quantitative MRI. OBJECTIVE: To investigate whether gender is a risk factor for this damage. METHODS: Sixty patients with refractory temporal lobe epilepsy (TLE) (28 men, 32 women) and 54 healthy controls (28 men, 26 women) were compared by quantitative MRI methods. RESULTS: Male patients had ipsilateral hemicranial volume loss of 12% (CI 8% to 16%) and contralateral volume loss of 7% (CI:3% to 11%) compared with male controls (p < or =0.004, analysis of variance). Female patients were 4% (CI:0.3% to 8%, p = 0.04) smaller than controls in the ipsilateral hemicranium, and not different contralaterally. The patient-to-control difference was greater in men than in women for the ipsilateral (p = 0.003) and contralateral hemicranial volume (p = 0.02). In men, 14% of the ipsilateral (F = 4.7, p = 0.004) and 16% of the contralateral (F = 5.1, p = 0.03) hemicranial volume loss could be attributed to generalized tonic clonic seizures. Compared with controls, patients averaged a 29% smaller ipsilateral and a 5% smaller contralateral hippocampus. CONCLUSION: Men with TLE have more brain atrophy than women with TLE. Seizure frequency is a factor contributing to reduced brain volumes in men but not in women. Men, therefore, may be more vulnerable to seizure-associated brain abnormalities.     

Proton MR spectroscopy of the brain.

Over the past five decades, MR spectroscopy has evolved from an analytical chemistry tool to a noninvasive clinical examination on FDA approved equipment with an AMA billing code. While proton MR spectroscopy has dominated current clinical studies, interest in other nucleii has arisen, particularly P-31 for the evaluation of membrane lipids, and C-13 for the evaluation of glutamate neurotransmission and excitotoxicity. Currently, the most common neuroradiological diagnostic indication is the differentation of suspected cerebral neoplasms for post-treatment effects, abcesses, subacute infarcts, demyelinating disease, and other non-neoplastic processes. Recent recommendations for monitoring multiple sclerosis treatment suggest an increasing role for MR spectroscopy in the future.     

What the reflex epilepsies reveal about the physiology of ideation

A review of the phenomena involved in reflex epilepsy illustrates that ideas have a neural substrate. The ideational substratum and, at times, associative links to other stimuli have physiological (epileptogenic) power. These phenomena can be applied to events in some psychopathological disorders.     

MR imaging of brain maturation

Magnetic resonance imaging (MRI) is the imaging tool of choice to evaluate brain maturation and especially brain myelination. Magnetic resonance imaging also provides functional insight through diffusion images and proton spectroscopy. In this review the MRI techniques are analyzed for both pre- and postnatal periods. The origin of MR signal changes is also detailed in order to understand normal myelination evolution and the consequences on brain maturation of the different pathologies encountered prior and after birth. Because MRI is "blind" in terms of signal on conventional sequences after 2 years of age, a particular attention is given to diffusion images and proton spectroscopy of the developing brain.     

MR spectroscopy of the brain in Leigh syndrome

Brain magnetic resonance spectroscopy in two patients with Leigh syndrome revealed the presence of lactate in gray and white matter brain tissue and relatively high choline levels in the white matter. The latter observation, most probably related to an ongoing demyelination process, underlines specific involvement of white matter metabolism in Leigh syndrome even in cases without involvement of the white matter as visualized on MRI. Magnetic resonance spectroscopy might thus be of help in differentiating Leigh syndrome from a range of other mitochondrial diseases, such as ophthalmoplegia and Kearns-Sayre syndrome, showing lack of lactate in brain tissues appearing normal on MRI.     

'Fortis/lenis' revisited one more time: the aerodynamics of some oral stop contrasts in three continents

The terms fortis and lenis are variously regarded as having one single underlying phonetic correlate or many. An exploratory analysis of acoustic and aerodynamic data on contrasting stop series in a number of European and non-European languages confirms that a significant variation in peak intra-oral pressure and in articulatory stricture duration are two of the main factors differentiating these series. Two central questions are: (1) Is the contrast in peak pressure controlled by lung volume decrement or by the degree of glottal aperture? (2) Is the gesture for the lenis sound a truncated or a re-scaled version of the gesture for the fortis sound? A more detailed examination of the data from the non-European languages suggests that glottal aperture, rather than respiratory effort is the main physiological parameter underlying the pressure variation, and that each member of the opposition has a specific target peak pressure, rather than the lenis peak pressure being truncated by the early release of the articulatory closure.     

MR imaging in congenital disorders of the brain

MR imaging is an excellent tool for use in diagnosing congenital malformations of the brain. Such malformations cannot be reliably recognized or classified without an insight into the basic processes of the fetal development of the brain. Cortical malformations are classically divided into (1) malformations of neuronal proliferation, i.e. of stem cell proliferation in the periventricular germinal matrix zone, (2) disorders of neuronal migration, i.e. of the radial migration of the neurons from the periventricular germinal matrix zone to the cortical surface, and (3) disorders of cortical organization. Other cerebral malformations are agenesis or dysgenesis of the corpus callosum, encephaloceles, and various kinds of holoprosencephaly. Chiari malformation ans disorders on the Dandy-Walker spectrum are relatively common, primarily infratentorial disorders. Rarer infratentorial disorders are Joubert syndrome, rhombencephalosynapsis and Lhermitte Duclos syndrome.     

To reveal or not to reveal a secret

As the physiological birth of the human infant precedes the psychological birth, the technology that has enabled birth of a child through donor fertility treatments may precede the psychological birth of the parent to such a child. The clinical vignette describes the therapy of a man preoccupied with the secret that his children had been conceived by artificial insemination due to his own infertility. His quandary over whether to keep the secret or reveal it to those close to him, and if so, then when and how, sapped his emotional energy, dragged down his spirits, and unsettled his life. The preoccupation with the secret and the question whether to keep it or reveal it, constitutes an organizing and containing envelope for other concealed issues and unconscious conflicts seeking revelation: who am I and where did I come from? Unsatisfactory answers to these fundamental questions during the pre-oedipal and oedipal stages of development can create a difficult dilemma to overcome.     

MR analysis of brain function]

Magnetic resonance (MR) is a remarkably versatile technology applicable to various aspects of medical science. Currently, there are three categories of MR techniques available for probing human brain function in detail. The first category comprises the most widely utilized techniques which make use of the metabolic effects of brain activation, represented by BOLD functional magnetic resonance imaging (fMRI). The second category of techniques deals with apparent diffusion tensor in probing the cellular aspects of brain function and is represented by three dimensional anisotropy contrast (3DAC) axonograpy. The third category of techniques is the oldest and as yet the most underutilized. These techniques which include MR spectroscopy (MRS) and spectroscopic imaging (SI), are based on classical nuclear magnetic resonance (NMR) spectroscopy and are capable of providing biochemical information in vivo. Because of its inherently non-invasive nature, MR technologies are especially important for the field of pediatric neurology and developmental neuroscience.     

MR imaging of fetal brain malformations

Methods From the generally accepted data on the morphogenesis of the brain, the principles for the classification of brain malformations are given, and the salient features of each malformation which may be considered as independent from the developmental stage and therefore practical for MR imaging in the fetus after mid-gestation, are discussed.Results and discussion However, the correlation with the clinical results in 150 cases of malformations out of a series of more than 1,000 cases of MR fetal brain imaging, demonstrates that beside the main, well-defined malformative entities, a significant degree of uncertainty remains. As the indication of further imaging is mainly based on the ultrasonographic findings, cases that are not identified as abnormal by US are not submitted to MRI (partial commissural agenesis and malformations of cortical development). A striking discrepancy exists between the findings of US and those of MRI, in the specific instance of the disorders of the posterior fossa (cystic malformations versus mega cisterna magna versus cerebellar defects), which may be only partly corrected by the use of strict anatomic criteria. Similar difficulties are observed for the diagnosis of nondestructive microcephaly.Conclusion Long-term prospective longitudinal clinical-radiological studies of these groups of patients are needed.     

Electric brain responses reveal gender differences in music processing

The present study investigates gender differences in the functional organization of the brain for music processing. In the language domain, males appear to have greater left hemisphere control than females. Despite some overlap of neural structures and processes for the perception of music and language, gender differences of musical functions have so far not been reported. Data sets of three previous music experiments with event-related brain potentials (ERPs) were pooled and re-analyzed. Results demonstrate that an electrophysiological correlate of music-syntactic processing (ERAN, or music-syntactic MMN) is generated bilaterally in females, and with right hemispheric predominance in males. The present findings indicate that gender differences for the analysis of auditory information are not restricted to processes in the linguistic domain such as syntax, semantics, and phonology.