on the Horizon Two teams of researchers are poised to bring new functional brain imaging technologies to the clinic. First, within a few years, physicians could have a way to monitor brain function at the bedsideofhospitalizedinfants,somethingthat is not currently possible with large functional magneticresonanceimaging(fMRI)machines. European researchers have developed a portable brain scanning technology called functional ultrasound imaging (fUSI). The fUSI system employs a flexible, noninvasive head mount and combines videoelectroencephalographic recording with ultrafast Doppler (UfD) imaging of brain microvasculature. The researchers previously developed the UfD technology, which produces up to 10 000 images per second, compared with 50 images per second in conventional ultrasound, enabling detection of small vessels or low blood flow in neonates. The variations in blood volume during the recordings are correlated with neuronal activity and could provide information on neonatal brain function in conditions such as hemodynamic failure, congenital heart defects, and sepsis, said Olivier Baud, MD, PhD, who co-led the development of fUSI while working at Robert Debré Children’s Hospital in Paris. In a proof-of-concept study in Science Translational Medicine, the investigators demonstrated fUSI’s ability to visualize cerebral bloodvolumechangesinresponsetochanges in brain activity during sleep states and seizures in neonates. Further study is needed on the safety of brain ultrasound scanning over long exposure times, the researchers said. Also on the horizon is a next-generation MRI scanner that can zoom in on brain regions as small as a poppy seed—a 20-fold increase in spatial resolution compared with current machines. Researchers at the University of California, Berkeley, will build a prototype machine over the next 2 years with a recently announced $13.43 million Brain Research Through Advancing Innovative Neurotechnologies (BRAIN) Initiative grant from the National Institutes of Health. The new technology, dubbed MR Corticography (MRCoG), will advance fMRI and diffusion imaging of cortical layers delineating distinct populations of neurons. “Each cortical layer is a part of specific circuitry,” explained principal investigator David Feinberg, MD, PhD, adjunct professor of neuroscience at UC Berkeley and president of Advanced MRI Technologies. “Therefore, the new scanner is designed to identify neuronal circuitry abnormalities for earlier and more specific diagnosis of abnormal brain conditions such as epilepsy, autism spectrum disorders, Alzheimer disease, chronic pain, and psychiatric disorders.” The gain in resolution comes from a combination of innovations including a larger number of smaller receiver coils, higherperformance gradient coils, faster imaging pulse sequences, and reduced noise in image reconstruction. “ B y a c h i e v i n g a r e s o l u t i o n t h a t approaches the size of fundamental organizational units of the human cortex, we will be able to study the cortical neural circuitry def ining the communications between cortical layers and columns,” Feinberg said. “This will help close the gap between our understanding of neural activity at the cellular levels and human behavior and cognition.”

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地平线上的功能性脑成像更新

在地平线上 两个研究小组准备将新的功能性脑成像技术带入临床。首先，在几年内，医生可能有办法在住院婴儿的床边监测大脑功能，这是目前大型功能性磁共振成像 (fMRI) 机器无法实现的。欧洲研究人员开发了一种称为功能超声成像 (fUSI) 的便携式脑部扫描技术。fUSI 系统采用灵活的无创头戴式安装，并将视频脑电图记录与脑微血管系统的超快多普勒 (UfD) 成像相结合。研究人员之前开发了 UfD 技术，每秒可生成多达 10 000 张图像，而传统超声每秒生成 50 张图像，能够检测到新生儿的小血管或低血流量。共同领导开发的 Olivier Baud 医学博士说，记录期间血容量的变化与神经元活动相关，并且可以提供有关新生儿脑功能的信息，例如血流动力学衰竭、先天性心脏缺陷和败血症等情况。 fUSI 在巴黎罗伯特·德布雷儿童医院工作时。在 Science Translational Medicine 的一项概念验证研究中，研究人员证明了 fUSI 能够将大脑血容量变化可视化，以响应睡眠状态和新生儿癫痫发作期间大脑活动的变化。研究人员说，需要进一步研究长时间曝光的脑超声扫描的安全性。同样即将出现的是下一代 MRI 扫描仪，它可以放大像罂粟籽一样小的大脑区域——与当前机器相比，空间分辨率提高了 20 倍。加州大学伯克利分校的研究人员将在未来 2 年内制造一台原型机，最近宣布了美国国立卫生研究院通过推进创新神经技术 (BRAIN) 计划拨款 1,343 万美元的大脑研究。这项被称为 MR 皮层造影术 (MRCoG) 的新技术将推进皮层层的 fMRI 和扩散成像，描绘不同的神经元群。“每个皮质层都是特定电路的一部分，”首席研究员、加州大学伯克利分校神经科学副教授兼高级 MRI 技术总裁 David Feinberg 医学博士解释说。“所以，新的扫描仪旨在识别神经元回路异常，以便更早、更具体地诊断异常脑部疾病，如癫痫、自闭症谱系障碍、阿尔茨海默病、慢性疼痛和精神疾病。” 分辨率的提高来自多项创新，包括数量更多的较小接收器线圈、更高性能的梯度线圈、更快的成像脉冲序列以及降低图像重建中的噪声。“通过接近人类皮层基本组织单位大小的分辨率，我们将能够研究定义皮层层和列之间通信的皮层神经回路，”范伯格说。