Continuous Wave Electron Paramagnetic Resonance Imaging

连续波电子顺磁共振成像

• 批准号: 7592719
• 负责人: murali cherukuri
• 金额: $ 42.37万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7592719
• 关键词: Amplifiers; Back; Computer software; Data; Data Collection; Detection; Dimensions; Electron Spin Resonance Spectroscopy; Frequencies; Goals; Image; Left; Measurement; Metabolic; Methods; Modality; Noise; Operative Surgical Procedures; Oxidation-Reduction; Oxygen saturation measurement; Phase; Physiologic pulse; Pulse taking; Rate; Relative (related person); Renal clearance function; Resolution; Rotation; Scanning; Scheme; Signal Transduction; Testing; Time; Width; Work; base; data acquisition; desire; improved; in vivo; instrument; programs; response

Project 3: Continuous Wave Electron Paramagnetic Resonance Imaging. Summary of Progress: We have modified our existing 300 MHz CW machine by supplementing a field sweep coil that can work at high AC frequencies. We tested the existing gradient coils for high frequency operation, and found that they can be used only up to a frequency of 1 kHz. By employing field sweeps at 0.33 kHz, and rotating gradients at 1 kHz (by applying sinusoidal gradients in two orthogonal gradient coils we could accomplish a left- or right-rotating gradient current corresponding to 2G/cm amplitude) required for 2D imaging. The lower frequency rapid scan signal, the three higher frequency gradient signals, and the trigger signals for data acquisition were generated using National Instruments LabView software and National Instrument PCI-6289 multifunction data acquisition card. The amplitudes of the gradient signals are adjusted to result in a circularly polarized gradient field rotating in the XZ plane at the selected frequency. The phase of the X and Z gradients can then be incremented programmatically relative to the rapid scan field at a desired step interval. The EPR signals from the RF bridge are down-converted to base band and amplified using a low noise low frequency amplifier and captured using a commercial digitizer-cum-summer Acqiris AP100 (Acqiris USA, Monroe, CA) dual channel Signal. By further applying a sinusoidal current in the third orthogonal coil, one can tilt the rotating gradient plane in equal tilt angles to cover an entire hemisphere of gradient trajectories centered on the resonator that is required for 3D spatial encoding. Since the projections are collected with the sweep field and simultaneous gradient rotation, one has to reorganize the observed signals by a simple matrix shuffling program to give the conventional Cartesian projections which are then used to generate the image by filtered back-projection. Even with this modest sweep frequency each projection could be carried out in less than 15 ms. We could collect 2D and 3D projection data in this so-called Rapid-scan-rotating gradient modality at least 50-100 times faster than the conventional CW approach. The invention has been protected by a US application.

项目三：连续波电子顺磁共振成像。进展总结：我们已经修改了我们现有的300兆赫连续波机，补充了一个可以在高交流频率下工作的场扫描线圈。我们测试了现有的梯度线圈用于高频操作，发现它们只能使用到1 kHz的频率。通过使用0.33 kHz的场扫描和1 kHz的旋转梯度（通过在两个正交梯度线圈中施加正弦梯度，我们可以实现对应于2G/cm振幅的左旋或右旋梯度电流）所需的二维成像。采用美国国家仪器公司LabView软件和美国国家仪器公司PCI-6289多功能数据采集卡生成低频快速扫描信号、三个高频梯度信号和数据采集触发信号。调整梯度信号的振幅，使圆极化梯度场以选定的频率在XZ平面上旋转。然后，X和Z梯度的相位可以在所需的步长间隔内相对于快速扫描场以编程方式递增。来自RF桥的EPR信号被下转换到基带，使用低噪声低频放大器放大，并使用商用数字化仪和夏季Acqiris AP100 （Acqiris USA, Monroe， CA）双通道信号捕获。通过在第三个正交线圈中进一步施加正弦电流，可以以相等的倾斜角倾斜旋转梯度平面，以覆盖以三维空间编码所需的谐振器为中心的梯度轨迹的整个半球。由于投影是通过扫描场和同步梯度旋转收集的，因此必须通过简单的矩阵洗牌程序重新组织观测到的信号，以获得传统的笛卡尔投影，然后通过滤波后的反投影生成图像。即使在这种适度的扫描频率下，每次投影也可以在不到15毫秒的时间内完成。我们可以用这种所谓的快速扫描旋转梯度模式收集2D和3D投影数据，比传统的连续波方法快至少50-100倍。这项发明已受到美国一项申请的保护。