自身免疫性脑炎影像学特征的研究进展

自身免疫性脑炎（AE）的诊断取决于临床症状、影像学和抗体,确诊依赖抗体及免疫治疗反应,但抗体检测普及性差、抗体阴性及早期免疫治疗反应不明显不能除外该病。细胞内抗原相关的AE其头颅MRI常表现为颞叶内侧异常,而细胞表面抗原相关AE头颅MRI常为正常或颞叶内侧以外的区域异常,不同类型AE急性期FDG-PET表现不同,但晚期所有AE患者均可出现不同程度的脑萎缩,其中以海马萎缩多见。因此,影像学如头颅MRI检查在AE早期确诊中具有十分重要的作用。此外,FDG-PET具有高敏感性,在AE诊断中受到了越来越多的重视。本文总结分析不同类型AE的结构影像和代谢影像学表现,提高其在AE早期诊断和治疗中的应用。     

Automated measurement of medial temporal lobe atrophy by computed tomography

Objects Evaluation of medial temporal lobe (MTL) atrophy is usually performed by magnetic resonance imaging (MRI). In Japan, however, the availability of computed tomography (CT) is much higher than that of MRI. The evaluation of MTL atrophy using CT may be useful when MRI is unavailable. This project developed a technique to automatically measure MTL atrophy using axial CT imaging and assessed the sensitivity of this method for diagnosing dementia of Alzheimer type (DAT). Materials and methods Linear measurements were taken for the width of the temporal horn, the width of the MTL, and the interuncal distance and the area of the temporal horn were measured. The algorithm developed employs the gray level threshold and the snake technique to process axial CT images. The algorithm was evaluated on 85 patients. Results The efficacy of this automated method was verified by a quantitative comparison of computerdetermined and manually obtained MTL measures, and based on its sensitivity and specificity in differentiating patients with DAT from control subjects. Conclusions This fully automated method of measuring MTL atrophy using CT is feasible and effective in DAT diagnosis, and simple to perform clinically. This method may be a practical alternative for MRI in some settings.     

Dynamic imaging in mild traumatic brain injury: support for the theory of medial temporal vulnerability

OBJECTIVE: To determine whether patients with mild traumatic brain injury (TBI) and persistent postconcussive symptoms have evidence of temporal lobe injury on dynamic imaging. DESIGN: Case series. SETTING: An academic medical center. PARTICIPANTS: Twenty patients with a clinical diagnosis of mild TBI and persistent postconcussive symptoms were referred for neuropsychologic evaluation and dynamic imaging. Fifteen (75%) had normal magnetic resonance imaging (MRI) and/or computed tomography (CT) scans at the time of injury. INTERVENTIONS: Neuropsychologic testing, positron-emission tomography (PET), and single-photon emission-computed tomography (SPECT). MAIN OUTCOME MEASURES: Temporal lobe findings on static imaging (MRI, CT) and dynamic imaging (PET, SPECT); neuropsychologic test findings on measures of verbal and visual memory. RESULTS: Testing documented neurobehavioral deficits in 19 patients (95%). Dynamic imaging documented abnormal findings in 18 patients (90%). Fifteen patients (75%) had temporal lobe abnormalities on PET and SPECT (primarily in medial temporal regions); abnormal findings were bilateral in 10 patients (50%) and unilateral in 5 (25%). Six patients (30%) had frontal abnormalities, and 8 (40%) had nonfrontotemporal abnormalities. Correlations between neuropsychologic testing and dynamic imaging could be established but not consistently across the whole group. CONCLUSIONS: Patients with mild TBI and persistent postconcussive symptoms have a high incidence of temporal lobe injury (presumably involving the hippocampus and related structures), which may explain the frequent finding of memory disorders in this population. The abnormal temporal lobe findings on PET and SPECT in humans may be analogous to the neuropathologic evidence of medial temporal injury provided by animal studies after mild TBI.     

Combined MEG/EEG analysis of the interictal spike complex in mesial temporal lobe epilepsy

We studied the functional organization of the interictal spike complex in 30 patients with mesial temporal lobe epilepsy (MTLE) using combined magnetoencephalography (MEG)/electroencephalography (EEG) recordings. Spikes could be recorded in 14 patients (47%) during the 2- to 3-h MEG/EEG recording session. The MEG and EEG spikes were subjected to separate dipole analyses; the MEG spike dipole localizations were superimposed on MRI scans. All spike dipoles could be localized to the temporal lobe with a clear preponderance in the medial region. Based on dipole orientations in MEG, patients could be classified into two groups: patients with anterior medial vertical (AMV) dipoles, suggesting epileptic activity in the mediobasal temporal lobe and patients with anterior medial horizontal (AMH) dipoles, indicating involvement of the temporal pole and the anterior parts of the lateral temporal lobe. Whereas patients with AMV dipoles had strictly unitemporal interictal and ictal EEG changes during prolonged video-EEG monitoring, 50% of patients with AMH dipoles showed evidence of bitemporal affection on interictal and ictal EEG. Nine patients underwent epilepsy surgery so far. Whereas all five patients with AMV dipoles became completely seizure-free postoperatively (Class Ia), two out of four patients with AMH dipoles experienced persistent auras (Class Ib). This difference, however, was not statistically significant. We therefore conclude that combined MEG/EEG dipole modeling can identify subcompartments of the temporal lobe involved in epileptic activity and may be helpful to differentiate between subtypes of mesial temporal lobe epilepsy noninvasively.     

A hippocampal lesion detected by high-field 3 tesla magnetic resonance imaging in a patient with temporal lobe epilepsy

Nearly 80% of patients with temporal lobe epilepsy have some types of lesion identified by conventional 1.5 tesla (T) magnetic resonance imaging (MRI). We performed high-field 3 T MRI in a 5-year-old patient with recurrent complex partial seizures who was diagnosed as having right temporal lobe epilepsy based on the results of single photon emission computed tomography and ictal video-electroencephalogram monitoring, because 1.5 T MRI failed to detect any abnormalities in the suspected region. High-field 3 T MRI revealed a small high-intensity lesion on fast spin-echo short inversion time inversion-recovery images of the hippocampus, possibly responsible for the seizures. This is the first report detecting a hippocampal lesion by 3 T MRI, which could not be found by conventional 1.5 T MRI.     

Hippocampal shape analysis using medial surfaces

In magnetic resonance imaging (MRI) research, significant attention has been paid to the analysis of the hippocampus (HC) within the medial temporal lobe because of its importance in memory and learning, and its role in neurodegenerative diseases. Manual segmentation protocols have established a volume decline in the HC in conjunction with Alzheimer's disease, epilepsy, post-traumatic stress disorder, and depression. Furthermore, recent studies have investigated age-related changes of HC volume which show an interaction with gender; in early adulthood, volume reduction of the HC is found in men but not in women. In this paper, we investigated gender differences in normal subjects in young adulthood by employing a shape analysis of the HC using medial surfaces. For each subject, the most prominent medial manifold of the HC was extracted and flattened. The flattened sheets were then registered using both a rigid and a non-rigid alignment technique, and the medial surface radius was expressed as a height function over them. This allowed for an investigation of the association between subject variables and the local width of the HC. With regard to the effects of age and gender, it could be shown that the previously observed gender differences were mostly due to volume loss in males in the lateral areas of the HC head and tail. We suggest that the analysis of HC shape using medial surfaces might thus serve as a complimentary technique to investigate group differences to the established segmentation protocols for volume quantification in MRI.     

Challenges of High-resolution Diffusion Imaging of the Human Medial Temporal Lobe in Alzheimer Disease

ABSTRACT: The human medial temporal lobe performs an essential role in memory formation and retrieval. Diseases involving the hippocampus such as Alzheimer disease present a unique opportunity for advanced imaging techniques to detect abnormalities at an early stage. In particular, it is possible that diffusion imaging will measure abnormal microarchitecture beyond the realm of macroscopic imaging. However, this task is formidable because of the detailed anatomy of the medial temporal lobe, the difficulties in obtaining high-quality diffusion images of adequate resolution, and the challenges in diffusion data processing. Moreover, it is unclear if any differences will be significant for an individual patient or simply groups of patients. Successful endeavors will need to address each of these challenges in an integrated fashion. The rewards of such analysis may be detection of microscopic disease in vivo, which could represent a landmark accomplishment for the field of neuroradiology.     

内侧颞叶癫痫脑微结构变化磁共振研究进展

内侧颞叶癫痫（mTLE）是最常见的难治性癫痫,其发病机制不清,多与内侧颞叶及颞叶外脑区异常有关,如海马硬化和相关大脑皮层萎缩。随着磁共振及其后处理技术的进步,显示内侧颞叶及其与之相关区域的微结构变化,对mTLE的发病机制研究、术前准确定位及术后评估中有重要作用。本文对mTLE的脑微结构变化MRI的研究进展进行综述。     

Interaction between a verbal working memory network and the medial temporal lobe

The irrelevant speech effect illustrates that sounds that are irrelevant to a visually presented short-term memory task still interfere with neuronal function. In the present study we explore the functional and effective connectivity of such interference. The functional connectivity analysis suggested an interaction between the level of irrelevant speech and the correlation between in particular the left superior temporal region, associated with verbal working memory, and the left medial temporal lobe. Based on this psycho-physiological interaction, and to broaden the understanding of this result, we performed a network analysis, using a simple network model for verbal working memory, to analyze its interaction with the medial temporal lobe memory system. The results showed dissociations in terms of network interactions between frontal as well as parietal and temporal areas in relation to the medial temporal lobe. The results of the present study suggest that a transition from phonological loop processing towards an engagement of episodic processing might take place during the processing of interfering irrelevant sounds. We speculate that, in response to the irrelevant sounds, this reflects a dynamic shift in processing as suggested by a closer interaction between a verbal working memory system and the medial temporal lobe memory system.     

Medial temporal lobe amnesia: a case study for nursing.

Maintaining and enhancing cognitive function is a crucial but challenging intervention for patients with memory problems. Research on the medial temporal lobe (MTL) memory system has yielded much information that can guide nurses in planning, evaluating, and performing effective interventions. A patient, Mrs. N, with a diagnosis of anaplastic astrocytoma of the left medial temporal lobe provides an example. Information from research guides assessment of Mrs. N and affords development of specific patient-centered interventions to maintain function, cope, and compensate. Data have been gathered from the patient, relatives, and caregivers to compare with and augment existing research, because few nursing case studies of amnesia involving patients with left medial temporal lobe tumors are available for analysis.     

Memory and the medial temporal lobe: hemispheric specialization reconsidered

The role of the medial temporal lobe in learning and memory has been well established in research on humans and other animals. In humans, clinical and neuroimaging studies typically suggest material-specific lateralization in which the left and right temporal lobes are associated with verbal and nonverbal memory, respectively. It is often assumed that the temporal lobes are functionally alike, differing only in terms of the content to be learned. Here we present data that challenge this notion, showing that the type of material used during a memory task can influence fMRI activation patterns beyond the expected left-verbal/right-nonverbal dichotomy. Our results also suggest some degree of functional asymmetry in the medial temporal lobe that is independent of material type, pointing to underlying processing differences between the left and right temporal lobes.     

Functional inferences vary with the method of analysis in fMRI.

Neuroanatomic substrates of specific cognitive functions have been inferred from anatomic distributions of activated pixels during fMRI studies. With declarative memory tasks, interest has focused on the extent to which various medial temporal lobe anatomic structures are activated while subjects encode new information. The aim of this project was to examine how commonly used variations in fMRI data processing methods affect the distribution of activation in anatomically defined medial temporal lobe regions of interest (ROIs) during a complex scene-encoding task. ROIs were drawn on an MRI anatomic template formed from 3D SPGR scans of eight subjects combined in Talairach space. Separate ROIs were drawn for the posterior and anterior hippocampal formation, parahippocampal gyrus, and entorhinal cortex. Twelve different activation maps were created for each subject by using four correlation coefficients and three cluster volumes. Friedman's two-way ANOVA by ranks was used to test the hypothesis that the distribution of activated pixels among defined anatomic ROIs varied as a function of the data processing method. By simply varying the combination of correlation coefficient and cluster volume, significantly different distributions of activation within named medial temporal lobe structures were obtained from the same fMRI datasets (P < 0.015; P < 0.001). The number of subjects studied (n = 8) is in a range commonly found in the literature yet this clearly resulted in spurious associations between processing parameter variations and activation distribution. Using data processing methods that are independent of the arbitrary selection of cutoff values for thresholding activation maps may reduce the likelihood of obtaining spurious results.     

Pulse sequences for interventional magnetic resonance imaging

Interventional magnetic resonance imaging (iMRI) is different from diagnostic magnetic resonance imaging (MRI) in its spatial, temporal, and contrast resolution requirements due to its specific clinical applications. As a result, the pulse sequences used in iMRI often are significantly different than those used in the more conventional diagnostic arena. The focus of this article is to summarize how iMRI is different from diagnostic MRI, to describe a variety of MRI pulse sequences and sequence strategies that have evolved because of these differences, and to describe some MRI sequence strategies that are in development and may be seen in future iMRI applications.     

Calibrated fMRI in the medial temporal lobe during a memory-encoding task

Prior measures of the blood oxygenation level-dependent (BOLD) and cerebral blood flow (CBF) responses to a memory-encoding task within the medial temporal lobe have suggested that the coupling between functional changes in CBF and changes in the cerebral metabolic rate of oxygen (CMRO(2)) may be tighter in the medial temporal lobe as compared to the primary sensory areas. In this study, we used a calibrated functional magnetic resonance imaging (fMRI) approach to directly estimate memory-encoding-related changes in CMRO(2) and to assess the coupling between CBF and CMRO(2) in the medial temporal lobe. The CBF-CMRO(2) coupling ratio was estimated using a linear fit to the flow and metabolism changes observed across subjects. In addition, we examined the effect of region-of-interest (ROI) selection on the estimates. In response to the memory-encoding task, CMRO(2) increased by 23.1+/-8.8% to 25.3+/-5.7% (depending upon ROI), with an estimated CBF-CMRO(2) coupling ratio of 1.66+/-0.07 to 1.75+/-0.16. There was not a significant effect of ROI selection on either the CMRO(2) or coupling ratio estimates. The observed coupling ratios were significantly lower than the values (2 to 4.5) that have been reported in previous calibrated fMRI studies of the visual and motor cortices. In addition, the estimated coupling ratio was found to be less sensitive to the calibration procedure for functional responses in the medial temporal lobe as compared to the primary sensory areas.     

联合磁源性影像和磁共振波谱技术评估颞叶癫痫的价值

目的：探讨磁源性成像（MSI）和磁共振波谱（^1H—MRS）技术结合在颞叶癫痫诊断定位中的价值。方法：设健康对照者10例，特发颞叶癫痫患者8例，应用MEG定位痫性病灶，选取MEG异常区域、对侧相应区域和双颞叶内侧区域测量NAA／Cho值，并观察是否存在海马硬化。结果：8例患者MEG检查结果均异常，6例MEG异常相应区域MRS检查NAA／Cho值减少，符合率为62．5％；MRI显示海马硬化2例，MRI正常6例，颞叶内侧MRS扫描未见明显改变。结论：联合MSI和MRS技术可进一步提高颞叶癫痫致痫灶的定位准确性。     

Encoding activity in anterior medial temporal lobe supports subsequent associative recognition

The ability to bind information together, such as linking a name with a face or a car with a parking space, is a vital process in human episodic memory. To identify the neural bases for this binding process, we measured brain activity during a verbal associative encoding task using event-related functional MRI (fMRI), followed by an associative recognition test for the studied word pairs. Analysis of the encoding data sorted by the associative recognition accuracy allowed us to isolate regions involved in successfully creating associations. We found that encoding activity in bilateral anterior medial temporal lobe (MTL) regions was greater for successfully bound pairs, that is, those later recognized as intact, than for all other pairs. These findings provide evidence that the anterior medial temporal lobes support the successful binding of information in memory.     

Evidence-based evaluation of magnetic resonance imaging as a diagnostic tool in dementia workup

BACKGROUND: The diagnostic utility of magnetic resonance imaging in dementia workups has increased recently. The basic use is to exclude space-occupying processes in the brain. However, magnetic resonance imaging offers major opportunities for studying atrophy of specific brain areas. A great interest has been put in whether atrophy in the medial temporal lobe can serve as an early diagnostic marker for Alzheimer disease. METHODS AND RESULTS: In this evaluation, we used evidence-based techniques and reviewed more than 400 articles that address this issue. Our main finding is that a variety of methods in studying brain areas were used, and this made it difficult to extract conclusive information in a systematic way. CONCLUSION: However, we were able to conclude that atrophy of the hippocampus can distinguish patients with Alzheimer disease from healthy subjects, but there was a lack of evidence because of insufficient studies concerning the usefulness of medial temporal lobe atrophy as a diagnostic marker in a more general setting.     

3.0T磁共振波谱对颞叶癫痫的定侧诊断价值

目的：通过对颞叶癫痫的磁共振波谱研究,探讨3.0T超高场强MRS在颞叶癫痫的定侧诊断价值。方法对40例临床诊断颞叶癫痫患者及20例正常志愿者进行研究,所有实验对象行双侧海马的常规MRI和1H-MRS扫描,MR成像序列为轴位SE T1WI、T2WI,对双侧海马体部进行多体素波谱成像,将正常对照组MRS结果作为标准,评价颞叶癫痫患者MRS代谢物比值特点,分析MRS对颞叶癫痫定侧诊断价值。结果常规MRI诊断海马硬化共21例。癫痫组患侧、健侧与对照组间NAA/（Cho＋ Cr）、NAA/ Cho比值差异均有统计学意义（F分别=12.89、15.73,P均＜0.05）。癫痫组患侧与健侧、患侧与对照组NAA/（Cho＋Cr）、NAA/Cho差异均有统计学意义（q分别=7.32、8.47、7.33、8.47,P均＜0.05）;而癫痫组健侧与对照组差异无统计学意义（q分别=1.13、1.13,P均＞0.05）。结论常规MRI检查对颞叶癫痫的定侧具有一定的价值;3.0T超高场强MRS与常规MRI联合应用可以提高颞叶癫痫定侧的准确性。     

Too much of a good thing: Overtreatment in epilepsy

Disagreements between clinicians and patients when considering treatment often arise because patient and practitioner differ as to what they believe constitutes overtreatment. In this paper, I focus on tensions that can arise between practitioner and patients with a particular illness: temporal lobe epilepsy. I argue that some ill patients with temporal lobe epilepsy may believe that maintaining their current condition is preferable to suppressing it. Consequently, they view what practitioners tend to see as the right amount of treatment (that which eliminates seizures) as excessive. I argue that in some cases, these patients' beliefs are justified, but that failure to acknowledge this on the part of practitioners may lead to overtreatment in a number of ways.     

Evidence that juvenile myoclonic epilepsy is a disorder of frontotemporal corticothalamic networks

The purpose of this study is to determine regions of cerebral cortex activated during the onset and propagation of dense array electroencephalographic (dEEG) epileptiform discharges in patients with juvenile myoclonic epilepsy (JME), through the use of 256 channel, dense array scalp EEG recordings. Ten patients (16–58 years old) with the clinical diagnosis of JME comprised the study group. In all cases the MRI and neurological exams were normal, while standard EEG recordings documented typical “generalized” 4–6 Hz epileptiform patterns. Outpatient dEEG recordings captured epileptiform discharges in each patient. Localization of onset and spread of discharges in relation to a standard MRI model was accomplished by applying dipole fits and a distributed linear inverse method of cortically constrained source analysis. All patients showed epileptiform discharges that localized to sources that included orbitofrontal/medial frontopolar cortex, while basal–medial temporal lobe sources were observed in 5/10 subjects. In many ways similar to discharges of typical absence, epileptiform patterns in JME are usually irregular and frequently include temporal lobe structures as the dominant contributors to the discharges. We find that epileptiform discharges in patients with JME are not “generalized” in the sense of bilaterally synchronous diffuse onset. Rather, discharges have both localized onsets and a restricted cortical network during propagation that includes regions of frontal and temporal cortex.