Simultaneous Perfusion and BOLD Imaging with Reduced Sus

BOLD和灌注信号的同时检测具有许多优点，包括两个功能图像的有效采集以及它们之间的时间和空间变化最小化。这些优点可能是特别重要的脑氧代谢率（CMRO 2）的测定灌注和BOLD测量的组合。然而，MR信号在具有严重场不均匀性的大脑区域中显著衰减，例如下额叶和侧颞叶和中颞叶。这种图像伪影极大地干扰了功能MRI技术的使用，特别是在神经精神和神经药理学疾病的研究中。 我们开发了一种同时BOLD和灌注成像技术，采用单次激发交错z-匀场EPI（SSI-EPI），以减少敏感性伪影，同时保持快速图像采集速度。灌注信号通过标记流入的动脉血液自旋获得，而BOLD对比度通过有效横向弛豫（T2*）加权获得。该技术已被应用于功能实验与神经精神范式（由威胁和中性词），以评估检测大脑激活的中颞叶的可行性。在人脑上的实验表明，与常规EPI相比，使用同步BOLD/灌注SSI-EPI序列获得的基线图像在腹侧前额叶、颞中叶和侧颞叶中具有显著改善的信号强度。正常受试者（n = 7）使用威胁词与中性词的功能灌注和BOLD图（p < 0.01）显示灌注和BOLD图中杏仁核周围区域的脑活动增加，与先前使用类似范例从H215 O PET获得的结果相似。由于其快速的采集速度和减少敏感性伪影，这种新技术应该是非常有用的事件相关的功能实验，神经精神和神经药理学研究。

Simultaneous detection of BOLD and perfusion signals has a number of advantages, including efficient acquisition of the two functional images and minimized temporal and spatial variations between them. These advantages may be particularly important in the determination of cerebral metabolic rate of oxygen (CMRO2) from a combination of perfusion and BOLD measurements. However, MR signals attenuate significantly in the brain regions with severe field inhomogeneities, such as inferior frontal lobe and lateral and meso temporal lobes. This image artifact greatly interferes with the use of functional MRI techniques, particularly in the study of neuropsychiatric and neuropharmacological disorders. We have developed a simultaneous BOLD and perfusion imaging technique with single-shot interleaved z-shim EPI (SSIZS-EPI) to reduce susceptibility artifacts while preserving fast image acquisition speed. Perfusion signal was obtained by labeling the in-flowing arterial blood spins, whereas BOLD contrast was achieved by effective transverse relaxation (T2*) weighting. This technique has been applied to functional experiments with a neuropsychiatric paradigm (composed of threat and neutral words) to assess the feasibility of detecting brain activation in the meso-temporal lobes. Experiments on human brain demenstrated that baseline images acquired with the simultaneous BOLD/perfusion SSIZS-EPI sequence had significantly improved signal intensities, compared with conventioanl EPI, in the ventral prefrontal lobe, meso-temporal lobes, and lateral temporal lobes. Functional perfusion and BOLD maps (p < 0.01) for normal subjects (n = 7) with threat words vs. neutral words showed increased brain activities in the peri-amygdalar regions in both perfusion and BOLD maps, similar to previous results obtained from H215O PET with a similar paradigm. With its fast acquisition speed and reduced susceptibility artifacts, this new technique should be very useful for event-related functional experiments for neuropsychiatric and neuropharmacological studies.