Abstract: Due to the dynamic nature of brain studies in functional magnetic resonance imaging (fMRI), fast pulse sequences such as echo planar imaging (EPI) and spiral are often used for higher temporal resolution. Hundreds of frames of two- dimensional (2-D) images or multiple three-dimensional (3-D) images are often acquired to cover a larger space and time range. Therefore, fMRI often requires a much larger data storage, faster data transfer rate and higher processing power than conventional MRI. In Mercury Computer Systems' PCI-based embedded computer system, the computer architecture allows the concurrent use of a DMA engine for data transfer and CPU for data processing. This architecture allows a multicomputer to distribute processing and data with minimal time spent transferring data. Different types and numbers of processors are available to optimize system performance for the application. The fMRI reconstruction was first implemented in Mercury's PCI-based embedded computer system by using one digital signal processing (DSP) chip, with the host computer running under the Windows NT$+R$/ platform. Double buffers in SRAM or cache were created for concurrent I/O and processing. The fMRI reconstruction was then implemented in parallel using multiple DSP chips. Data transfer and interprocessor synchronization were carefully managed to optimize algorithm efficiency. The image reconstruction times were measured with different numbers of processors ranging from one to 10. With one DSP chip, the timing for reconstructing 100 fMRI images measuring 128 $MUL 64 pixels was 1.24 seconds, which is already faster than most existing commercial MRI systems. This PCI-based embedded multicomputer architecture, which has a nearly linear improvement in performance, provides high performance for fMRI processing. In summary, this embedded multicomputer system allows the choice of computer topologies to fit the specific application to achieve maximum system performance. !8
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机译：摘要：由于功能磁共振成像（fMRI）中大脑研究的动态性质，快速脉冲序列（例如回波平面成像（EPI）和螺旋波）经常用于更高的时间分辨率。通常要获取数百个二维（2-D）图像帧或多个三维（3-D）图像帧，以覆盖更大的空间和时间范围。因此，与常规MRI相比，fMRI通常需要更大的数据存储量，更快的数据传输速率和更高的处理能力。在Mercury Computer Systems基于PCI的嵌入式计算机系统中，计算机体系结构允许同时使用DMA引擎进行数据传输和CPU进行数据处理。这种体系结构允许多台计算机以最少的时间传输数据来分配处理和数据。可以使用不同类型和数量的处理器来优化应用程序的系统性能。 fMRI重建首先通过使用一个数字信号处理（DSP）芯片在Mercury基于PCI的嵌入式计算机系统中实现，并且主机在Windows NT + R $ /平台下运行。在SRAM或高速缓存中创建了双缓冲区，用于并发I / O和处理。然后使用多个DSP芯片并行执行fMRI重建。精心管理了数据传输和处理器间同步，以优化算法效率。图像重建时间是使用范围从1到10的不同数量的处理器测量的。使用一块DSP芯片，重建100幅测量128 fMUL 64像素的fMRI图像的时间为1.24秒，这已经比大多数现有的商用MRI系统快。这种基于PCI的嵌入式多计算机体系结构的性能几乎线性提高，为fMRI处理提供了高性能。总之，此嵌入式多计算机系统允许选择适合特定应用程序的计算机拓扑，以实现最大的系统性能。 ！8
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