Continuous Wave Electron Paramagnetic Resonance Imaging

项目3：连续波电子顺磁共振成像。仪器：当前光谱仪是一台工作在300 MHz和750 MHz的模拟光谱仪。大多数组件是模拟设备，它们对噪声和伪影有自己的贡献，这将影响信噪比。数字信号处理(DSP)技术正越来越多地被用于现代电信系统以及消费电子产品中，并且这些模块的成本已经变得很小。在可能的情况下，可以通过依赖于DSP策略来避免与射频电子设备中的几个模拟组件相关的噪声。我们计划开发一个基于DSP策略的通用EPR光谱仪平台，以提供在初始阶段标称工作频率为750 MHz的通用性。在此之后，我们计划在光谱仪中加入300 MHz的运行能力。在该系统中，可以集成快速扫描的直接检测和交流调制直流磁场的相敏检测等检测方案。该系统将使用数字合成器来产生所有的射频和控制信号，以及一个基于软件无线电的接收器。该系统的三个主要组成部分：射频源、接收器和磁场控制器处于不同的开发阶段。应用：这项技术在检测转基因动物的表型变化方面的力量，通过对野生型和血栓反应蛋白-1缺失的小鼠的研究得到了证明，这些小鼠的皮瓣上有手术创伤。TSP-1是一种公认的灌流和组织存活拮抗剂，可以限制手术后软组织的存活。用氧感应顺磁固体探头在皮瓣伤口的近端和远端验证了这一假设，并用EPR光谱监测了组织的氧分压。对野生型和TSP-1基因缺失小鼠的EPR研究、组织学分析和Western印迹分析表明，内源性TSP-1对一氧化氮引起的血管平滑肌松弛有抑制作用。其他研究采用长期植入氧敏感固体顺磁粒子，观察了4周的氧依赖谱线宽度，观察了核心体温对肌肉和乳腺组织pO2值的影响。研究表明，股骨肌肉在比乳房脂肪垫更高的氧分压下工作，也表明保持核心体温对于有效的生理监测的重要性。实验对象：既不是人体受试者，也不是人体组织。

Project 3: Continuous Wave Electron Paramagnetic Resonance Imaging.Instrumentation: The current spectrometer is an analog spectrometer which is operational at 300 and 750 MHz. Most components are analog devices which have their own contributions to noise and artifacts which will compromise the signal:noise ratio. DSP (digital signal processing) technology is increasingly being used in modern telecommunication systems as well as consumer electronics and cost of these modules has become small. The noise associated with several analog components in RF electronics can be avoided by relying on DSP strategies where possible. We plan to develop a general EPR spectrometer platform based on DSP strategy to confer versatility in operation with a nominal operating frequency of 750 MHz during the initial phase. Subsequent to this, we plan to incorporate capabilities in the spectrometer to operate at 300 MHz as well. In the proposed system, detection schemes such as direct detection with rapid scan as well as phase-sensitive detection using ac modulation of the dc magnetic field can be integrated. This system will use digital synthesizers to generate all RF and control signals and a 'Software Radio' based receiver. Three major components of this system: RF source, receiver and magnetic field controller are under various stages of development. Applications: The strength of this technique in detecting phenotypic changes of genetically modified animals is demonstrated by the studies using wild type and Thrombospondin-1 null mice with surgical wounds in the skin flap. TSP-1 is a putative antagonist of perfusion and tissue survival and can limit survival of soft tissue following surgery. This hypothesis was tested using oxygen sensing paramagnetic solid probes at proximal and distal sites to the wound on the skin flap and the tissue pO2 was monitored using EPR spectroscopy. EPR studies, histological analysis and western blot analysis on wild type and TSP-1 null mice showed that endogenous TSP-1 was inhibitory to the vascular smooth muscle relaxation by nitric oxide.Other studies examined the effect of core body temperature in mice on the pO2 values in muscle and mammary tissue using chronically implanted oxygen sensing solid paramagnetic particles whose oxygen dependent spectral line widths were monitored over a period of 4 weeks. The studies showed that the femoral muscles function at higher pO2 than the mammary fat pad and also indicated the importance of maintaining core body temperature for valid monitoring of physiology.Experimental Subjects:Neither human subjects nor human tissues.