Lu Hanbing, Yang Shaolin, Zuo Yantao, Demny Steven, Stein Elliot A, Yang Yihong
Neuroimaging Research Branch, National Institute on Drug Abuse (NIDA), Intramural Research Program, NIH, Baltimore, MD 21224, USA.
Magn Reson Imaging. 2008 Nov;26(9):1266-72. doi: 10.1016/j.mri.2008.02.020. Epub 2008 May 2.
In pharmacological magnetic resonance imaging (phMRI) with anesthetized animals, there is usually only a single time window to observe the dynamic signal change to an acute drug administration since subsequent drug injections are likely to result in altered response properties (e.g., tolerance). Unlike the block-design experiments in which fMRI signal can be elicited with multiple repetitions of a task, these single-event experiments require stable baseline in order to reliably identify drug-induced signal changes. Such factors as subject motion, scanner instability and/or alterations in physiological conditions of the anesthetized animal could confound the baseline signal. The unique feature of such functional MRI (fMRI) studies necessitates a technique that is able to monitor MRI signal in a real-time fashion and to interactively control certain experimental procedures. In the present study, an approach for real-time MRI on a Bruker scanner is presented. The custom software runs on the console computer in parallel with the scanner imaging software, and no additional hardware is required. The utility of this technique is demonstrated in manganese-enhanced MRI (MEMRI) with acute cocaine challenge, in which temporary disruption of the blood-brain barrier (BBB) is a critical step for MEMRI experiments. With the aid of real-time MRI, we were able to assess the outcome of BBB disruption following bolus injection of hyperosmolar mannitol in a near real-time fashion prior to drug administration, improving experimental success rate. It is also shown that this technique can be applied to monitor baseline physiological conditions in conventional fMRI experiments using blood oxygenation level-dependent (BOLD) contrast, further demonstrating the versatility of this technique.
在对麻醉动物进行的药理磁共振成像（phMRI）中，由于后续注射药物可能会导致反应特性改变（例如耐受性），通常只有一个时间窗口来观察急性给药后的动态信号变化。与功能磁共振成像（fMRI）信号可通过多次重复任务激发的组块设计实验不同，这些单事件实验需要稳定的基线，以便可靠地识别药物诱导的信号变化。诸如动物运动、扫描仪不稳定性和/或麻醉动物生理状况改变等因素可能会混淆基线信号。此类功能磁共振成像（fMRI）研究的独特特性需要一种能够实时监测磁共振成像信号并交互式控制某些实验程序的技术。在本研究中，介绍了一种在布鲁克扫描仪上进行实时磁共振成像的方法。定制软件与扫描仪成像软件并行在控制台计算机上运行，无需额外硬件。该技术的实用性在急性可卡因激发的锰增强磁共振成像（MEMRI）中得到了证明，其中血脑屏障（BBB）的暂时破坏是MEMRI实验的关键步骤。借助实时磁共振成像，我们能够在给药前以近实时的方式评估静脉注射高渗甘露醇后血脑屏障破坏的结果，提高了实验成功率。研究还表明，该技术可应用于使用血氧水平依赖（BOLD）对比的传统功能磁共振成像实验中监测基线生理状况，进一步证明了该技术的多功能性。
