脑默认网络临床应用及研究进展

脑默认网络（DMN）已成为神经放射学、认知神经科学等相关领域研究的焦点,其在静息状态下表现出大脑中线和外侧皮质区域功能活动相对活跃的特征,与人类认知及神经精神疾病存在着密切的关系。对该系统主要解剖位置、功能和临床意义及研究方法进展予以简述,并重点介绍其在阿尔茨海默病所致的痴呆、精神分裂症以及情感障碍疾病中的研究进展。     

Spatio-temporal pattern of vestibular information processing after brief caloric stimulation

Processing of vestibular information at the cortical and subcortical level is essential for head and body orientation in space and self-motion perception, but little is known about the neural dynamics of the brain regions of the vestibular system involved in this task. Neuroimaging studies using both galvanic and caloric stimulation have shown that several distinct cortical and subcortical structures can be activated during vestibular information processing. The insular cortex has been often targeted and presented as the central hub of the vestibular cortical system. Since very short pulses of cold water ear irrigation can generate a strong and prolonged vestibular response and a nystagmus, we explored the effects of this type of caloric stimulation for assessing the blood-oxygen-level-dependent (BOLD) dynamics of neural vestibular processing in a whole-brain event-related functional magnetic resonance imaging (fMRI) experiment. We evaluated the spatial layout and the temporal dynamics of the activated cortical and subcortical regions in time-locking with the instant of injection and were able to extract a robust pattern of neural activity involving the contra-lateral insular cortex, the thalamus, the brainstem and the cerebellum. No significant correlation with the temporal envelope of the nystagmus was found. The temporal analysis of the activation profiles highlighted a significantly longer duration of the evoked BOLD activity in the brainstem compared to the insular cortex suggesting a functional de-coupling between cortical and subcortical activity during the vestibular response.     

Active deep brain stimulation during MRI: a feasibility study.

The goal of this study was to evaluate the feasibility of active deep brain stimulation (DBS) during the application of standard clinical sequences for functional MRI (fMRI) in phantom measurements. During active DBS, we investigated induced voltage, temperature at the electrode tips and lead, forces on the electrode and lead, consequences of defective leads and loose connections, proper operation of the neurostimulator, and image quality. Sequences for diffusion- and perfusion-weighted imaging, fMRI, and morphologic MRI were used. The DBS electrode and lead were placed in a NaCl solution-filled phantom. The results indicate that there are severe potential hazards for patients. Strong heating, high induced voltage, and even sparking at defects in the connecting cable could be observed. However, it was demonstrated that under certain conditions, safe MR examinations during active DBS are feasible. Certain safety precautions are recommended in this report.     

Determination of regional cerebral function with FDG-PET imaging in neuropsychiatric disorders

Functional brain imaging using 18F fluorodeoxyglucose (FDG) and positron emission tomography (PET) has greatly enhanced our understanding of brain function both in normal conditions as well as in a wide variety of neuropsychiatric disorders. We review the uses of FDG PET in the diagnosis, management, and follow-up of patients with neuropsychiatric disorders. This article will also explore what FDG-PET imaging has revealed in these neuropsychiatric disorders and how these findings relate to both research and clinical applications.     

多巴胺能神经递质及受体显像的临床研究和应用进展

近年来神经递质显像发展极快,已从大量的基础研究进入临床应用的研究,目前中枢神经质显像中以多巴胺能神经递质及受体显像最为活跃,主要包括多巴胺受体、多巴胺能神经元神经递质和多巴胺转运蛋白显像等。     

Functional MRI in healthy subjects during acupuncture: different effects of needle rotation in real and false acupoints

The cerebral activation pattern due to acupuncture is not completely understood. Although the effect of acupuncture on cerebral haemodynamics has been studied, no previous report has focused on different puncture and stimulation methods. We used functional MRI (fMRI) in 15 healthy subjects to investigate cortical activation during stimulation of two real acupoints (Liv3 and G40) and one sham point, needled in a random and, for the subjects, blinded order employing rotating and non-rotating methods, using a blocked paradigm on a 1.5 tesla imager. Compared to the non-rotating stimulation method, during rotating stimulation of the real acupoints, we observed an increase in activation in both secondary somatosensory cortical areas, frontal areas, the right side of the thalamus and the left side of the cerebellum; no such effects of the needling technique were seen while stimulating the sham point. The observation that rotating the needle strengthened the effects of acupuncture only at real acupoints suggests that, as claimed in Chinese traditional medicine, stimulation of these acupoints has a specific effect on cortical neuronal activity, absent with sham acupoints. These specific cerebral activation patterns might explain the therapeutic effects of acupuncture in certain subjects.     

Corticobasal degeneration: structural and functional MRI and single-photon emission computed tomography

We studied seven patients with corticobasal degeneration (CBD) from a clinical and imaging perspective. We describe the main morphological features of CBD and, using functional MRI, try to define the possible role of the parietal lobe in simple and complex learned motor sequences. We showed decreased activation of the parietal lobe contralateral to the more affected arm, when movements, simple or complex, are performed with that hand. Moreover we found that functional imaging can demonstrate parietal and motor cortex dysfunction before structural, and even single-photon emission computed tomography changes become evident.     

Utility of positron emission tomography-magnetic resonance imaging in musculoskeletal imaging

Differentiation between neoplastic and nonneoplastic conditions magnetic resonance imaging (MRI) has established itself as one of the key clinical tools in evaluation of musculoskeletal pathology. However, MRI still has several key limitations which require supplemental information from additional modalities to complete evaluation of various disorders. This has led to the development hybrid positron emission tomography (PET)-MRI which is rapidly evolving to address key clinical questions by using the morphological strengths of MRI and functional information of PET imaging. In this article, we aim to review physical principles and techniques of PET-MRI and discuss clinical utility of functional information obtained from PET imaging and structural information obtained from MRI imaging for the evaluation of musculoskeletal pathology. More specifically, this review highlights the role of PET-MRI in musculoskeletal oncology including initial diagnosis and staging, treatment planning and post-treatment follow-up. Also we will review utility of PET-MRI in evaluating musculoskeletal infections (especially in the immunocompromised and diabetics) and inflammatory condition. Additionally, common pitfalls of PET-MRI will be addressed.     

3.0磁共振成像在丘脑底核靶点定位中的应用研究

目的:探讨3.0T磁共振成像(magnetic resonance imaging,MRI)在丘脑底核(subthalamic nucleus,STN)靶点直视定位的可行性及其临床效果。方法:采用不同场强的MRI技术对23例帕金森病患者进行STN靶点定位脑深部电极植入术。采用T2加权扫描,层厚2 mm,间隔0.5 mm,TE 150～200 ms,TR 4000～5000 ms,FOV33 cm2。结果:术前3.0TMRI能清晰可视STN等重要结构,能够在直视下STN靶点直接定位。3.0T组术中均出现微毁损效应,临床效果满意,术后MRI复查显示电极均位于相关靶点内。结论:3.0TMR能清晰显示STN结构的低信号区,可直视靶点定位,电极位置准确可靠。     

非小细胞肺癌影像学分期研究进展

非小细胞肺癌是一种极为常见的癌症,早期非小细胞肺癌的影像学诊断尤为重要,对于该病诊断方法很多:普通CT、低剂量CT(LDCT)、核磁共振(MRI)、正电子发射计算机体层显像/x线计算机体层成像(PET/CT)、磁共振弥散加权成像(DWI),现就影像学技术在非小细胞肺癌分期中的应用现状及发展方向进行综述。     

Intraoperative functional MRI as a new approach to monitor deep brain stimulation in Parkinson's disease

This article deals with technical aspects of intraoperative functional magnetic resonance imaging (fMRI) for monitoring the effect of deep brain stimulation (DBS) in a patient with Parkinson's disease. Under motor activation, therapeutic high-frequency stimulation of the subthalamic nucleus was accompanied by an activation decrease in the contralateral primary sensorimotor cortex and the ipsilateral cerebellum. Furthermore, an activation increase in the contralateral basal ganglia and insula region were detected. These findings demonstrate that fMRI constitutes a promising clinical application for investigating brain activity changes induced by DBS.     

BOLD技术与皮质电刺激定位语言功能区的比较

目的:将语言BOLD与术中皮质电刺激作点对点比较,评价其对语言功能区定位的准确性.材料和方法:12例左侧大脑半球近语言功能区手术病例术前采用词语联想任务进行BOLD扫描,融合在导航序列上进行神经导航手术.在局麻下进行术中皮质电刺激,与导航影像对应,采用完全吻合或相邻1cm以内两种不同的标准来比较BOLD激活区与电刺激阳性区的关系.结果:12例病人共刺激了145个点,其中阳性点27个.与ESM比较,以完全重叠为标准,BOLD敏感性48.1%,特异性83.1%;以相距小于1cm为标准,BOLD敏感性88.9%,特异性75%.良性或低级别肿瘤(9例)BOLD敏感性(95.2%)特异性(80.4%)均高于高级别恶性肿瘤(3例)(敏感性66.7%,特异性68.6%).结论:词语联想任务的BOLD-fMRI与ESM结果有较好的吻合,显示出一定的临床应用价值.     

针刺穴位脑功能磁共振成像的再研究

目的 利用功能磁共振成像（functional Magnetic Resonance Imaging,fMRI）针刺位于足少阴肾经上的太溪穴（KI3）及非穴位对照点进行多次脑fMRI,探讨针刺引起的脑功能变化.方法 选取健康志愿者10名,在不同时间进行4次完全相同的功能磁共振扫描,每次扫描间隔至少间隔两周.结果 针刺太溪穴及非穴位点均可以观察到脑功能的活动.针刺两点同一受试者在不同次实验中及同一次实验过程中不同个体间的BOLD信号均有较大变异,但同一次实验中所有志愿者组分析结果相对恒定;组分析结果显示针刺太溪与非穴位点引起的脑功能活动有明显差别.结论 应用fMRI来研究针刺脑功能活动,为了解针刺某特定穴位点特定个体脑激活模式,需行多个时相的功能磁共振扫描,以获得精确的脑激活模式图像.     

功能MRI在意识障碍的诊断和唤醒预测中的研究进展

功能MRI能够实时准确地发现静息和刺激状态下高级复杂神经活动,并对意识障碍的3个不同水平:昏迷、植物状态、微意识状态的诊断和鉴别诊断提供了客观依据。近年来功能MRI研究在部分临床无应答病人中发现了意识唤醒相关的局部脑区和脑功能网络。介绍功能磁共振成像在意识障碍和意识唤醒相关脑功能网络中的应用和研究进展。     

Variability in RF-induced heating of a deep brain stimulation implant across MR systems

PURPOSE: To compare the MRI-related heating per unit of specific absorption rate (SAR) profile of a conductive implant between two 1.5-Tesla/64 MHz MR systems using a transmit/receive (t/r) head coil configuration. MATERIALS AND METHODS: Deep brain stimulation (DBS) leads were configured within a gel-filled phantom of the human head and torso. Temperature variation at each of four contacts of the bilaterally-placed leads was monitored using fluoroptic thermometry. MRI was performed using the t/r head coils of two different-generation 1.5-Tesla MR systems from the same manufacturer. Temperature changes were normalized to SAR values for the head (DeltaT/SAR-H), and the slope of this DeltaT/SAR-H by time relationship was compared between the two scanners. RESULTS: The DeltaT/SAR-H for the implant ranged from 3.5 to 5.5 times higher on one MR system as compared to the other (P < 0.01) depending on the measurement site. CONCLUSION: The findings support previous observations that console-reported SAR does not constitute a reliable index of heating for elongated, conductive implants, such as the DBS hardware system tested. In contrast to our previous findings using a t/r body coil, the data presented here reveal marked differences between two MR systems using t/r head coils (the coil configuration was consistent with the implant manufacturer's imaging guidelines). J. Magn. Reson. Imaging 2006. (c) 2006 Wiley-Liss, Inc.     

Molecular imaging of the lungs

An emerging suite of new imaging techniques offer the ability to monitor and quantify molecular and cellular processes in the lungs noninvasively. These techniques take advantage of dramatic advances in both imaging technology as well as molecular and cell biology. Molecular imaging is being used with increasing regularity in research protocols, and forms of molecular imaging have found their way into the patient care setting (eg, positron emission tomography imaging in cancer). Such techniques will afford the basic scientist as well as the clinician an unprecedented opportunity for in vivo study of the lung biology that drives normal pulmonary physiology as well as pathophysiology.     

MR Imaging in the 21st Century: Technical Innovation over the First Two Decades

Clinical MRI systems have continually improved over the years since their introduction in the 1980s. In MRI technical development, the developments in each MRI system component, including data acquisition, image reconstruction, and hardware systems, have impacted the others. Progress in each component has induced new technology development opportunities in other components. New technologies outside of the MRI field, for example, computer science, data processing, and semiconductors, have been immediately incorporated into MRI development, which resulted in innovative applications. With high performance computing and MR technology innovations, MRI can now provide large volumes of functional and anatomical image datasets, which are important tools in various research fields. MRI systems are now combined with other modalities, such as positron emission tomography (PET) or therapeutic devices. These hybrid systems provide additional capabilities.In this review, MRI advances in the last two decades will be considered. We will discuss the progress of MRI systems, the enabling technology, established applications, current trends, and the future outlook.     

原发性闭角型青光眼视觉皮层激活的fMRI研究

目的应用功能磁共振成像(fMRI)研究原发性慢性闭角型青光眼患者视觉皮层激活情况。资料与方法20例原发性慢性闭角型青光眼患者(青光眼组)和20名健康成人(对照组)左、右眼分别行3.0 T MR血氧水平依赖(BOLD)功能磁共振成像(fMRI),将BOLD-fMRI原始数据经基于Matlab平台的SPM2软件进行数据的预处理和统计分析,分别对青光眼组、对照组左、右眼进行组内分析,获得组内平均激活图;病变组与对照组的左、右眼进行组间分析,获得组间比较激活图。结果 (1)与对照组比较,青光眼组左、右眼刺激时双侧视皮层激活范围、激活强度都明显减小,以右侧视皮层为著。(2)与对照组比较,青光眼组左、右眼刺激时大脑皮层均发现异常激活区域。结论 fMRI可以反映青光眼患者视觉皮层功能活动,能为青光眼发病机制的研究提供重要信息。     

功能MRI在脑梗死演变中的研究进展

近年来功能磁共振成像(fMRI)技术已取得一定程度的发展和应用。利用磁共振弥散成像(弥散加权成像和弥散张量成像)、灌注加权成像、磁共振波谱分析及血氧水平依赖技术等,可从分子或细胞水平、物质代谢角度等对不同发展阶段的脑梗死进行动态监测和研究,有利于早期诊断、指导治疗及预测预后。现就该领域研究及应用现状进行综述。     

前列腺癌MRI诊断技术研究进展

前列腺癌是世界上第二常见的男性恶性肿瘤, 我国前列腺癌的发病率亦呈逐年上升趋势。MRI有着良好的软组织分辨率及多方位成像优势, 能较好地显示前列腺的解剖结构及相邻的组织结构, 随着MRI技术的不断发展, 其对前列腺癌的诊断发挥着越来越重要的作用。该文从前列腺癌MRI常规序列的影像表现着手, 对各种功能MRI在前列腺癌的诊断和鉴别诊断中的应用进行了详细地论述, 如MR灌注加权成像、MR波谱、MR扩散加权成像、MR扩散张量成像、体素内不相干运动扩散加权成像、MR磁敏感加权成像等, 介绍了功能MRI相对于常规扫描的优势及其所能提供的更多的影像学资料, 通过系列半定量和定量数据, 能进一步提供前列腺癌的血流灌注、水分子扩散、微循环状态、物质代谢及生化成分变化等信息。