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3：连续波电子顺磁共振成像。进度摘要：我们通过补充可以在高AC频率下工作的场扫地线圈修改了现有的300 MHz CW机器。我们测试了现有的梯度线圈进行高频操作，发现它们只能使用1 kHz的频率。通过使用0.33 kHz的场扫描，并以1 kHz旋转梯度（通过在两个正交梯度线圈中施加正弦梯度梯度，我们可以完成2D成像所需的左或右旋转梯度电流）。较低的频率快速扫描信号，三个较高频率梯度信号和用于数据采集的触发信号是使用国家仪器Labview软件和国家仪器PCI-6289多功能数据采集卡生成的。调整梯度信号的幅度，以导致以选定频率在XZ平面中旋转的圆极化梯度场。然后，可以在所需的步骤间隔以相对于快速扫描场进行编程相对于快速扫描场的相位。来自RF桥的EPR信号向下转换为基本频带，并使用低噪声低频放大器进行扩增，并使用商用数字化器 - 苏格里斯ACQIRIS AP100（ACQIRIS USA，MONROE，CA）双通道信号捕获。通过进一步在第三正交线圈中应用正弦电流，可以以相等的倾斜角度将旋转梯度平面倾斜，以覆盖以3D空间编码所需的谐振器中的梯度轨迹的整个半球。由于投影是通过扫描场和同时梯度旋转收集的，因此必须通过一个简单的矩阵改组程序重新组织观察到的信号，以提供传统的笛卡尔投影，然后将其用于通过过滤后的反向投影来生成图像。即使使用此适度的扫描频率，每个投影也可以在不到15毫秒内进行。我们可以在这种所谓的快速扫描梯度模态中收集2D和3D投影数据，比传统CW方法快50-100倍。本发明已受美国应用程序的保护。