ESR MICROSCOPE SOFTWARE APPLICATION FOR SAMPLE T2 MEASUREMENT

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 对脉冲ESR显微镜(ESRM)检查样品的横向弛豫常数T2进行成像前测量，对于了解切片分辨率的Gz梯度要求、洛伦兹线形以及氧浓度、粘度和弛豫时间等影响是重要的。脉冲ESRM的一个重要优势是能够获取几种类型的图像对比度，这也需要样本的T2参数的先验知识。对于我们目前的主要ESRM工作模式，使用了相对简单的双脉冲自旋回波序列，从而避免了对短的、精确的矩形Gz脉冲梯度以及矩形Gx和Gy梯度的需要。对于该脉冲序列，知道样本T2是有利的，因为最佳脉冲间隔与其直接相关。 通过对我们最近设计的现有ESRM VI(LabVIEW虚拟仪器)应用程序的扩展，当预期的样本已插入ESRM探头谐振器时，现在可以在成像研究之前直接测量T2。只有脉冲序列在两种测量模式之间不同，在T2测量期间没有发生梯度脉冲。 在ESRM成像序列中，在脉冲序列定时和脉冲宽度保持不变的情况下，Gx和Gy脉冲梯度在其各自的强度范围内顺序步进。对于T2测量，？/2和？脉冲在宽度上保持不变，但脉冲间隔按顺序递减。在每个脉冲间隔步长处，记录回波信号(通常应用小的z梯度以稍微加宽回波信号)。当已经收集了完整的数据集时，提取回波信号的幅度并绘制与脉冲间隔时间对应的曲线图，并且对曲线图进行指数拟合，以得出T2横向弛豫时间参数的值。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Pre-imaging measurement of the transverse relaxation constant, T2, in samples intended for examination by pulse ESR Microscopy (ESRM) is important for understanding the Gz gradient requirement for slice resolution, the Lorentzian lineshape, and effects such as oxygen concentration, viscosity and relaxation times. An important advantage of pulse ESRM, the ability to acquire several types of image contrasts, also requires a priori knowledge of the sample's T2 parameter. For our current principal ESRM operating mode, a relatively simple two pulse spin-echo sequence is employed that avoids the need for short, precise rectangular Gz pulsed gradients and rectangular Gx and Gy gradients. For this pulse sequence, it is advantageous to know the sample T2 as the optimal pulse spacing is directly related to it. By means of an extension to the existing ESRM VI (LabView virtual instrument) application that we have recently devised, direct measurement of T2 can now be made prior to imaging studies when prospective samples have been inserted into the ESRM probe resonator. Only the pulse sequence differs between the two measurement modes, with no gradient pulsing occurring during the T2 measurement. In the ESRM imaging sequence, the Gx and Gy pulse gradients are stepped sequentially through their respective intensity ranges with the pulse sequence timing and pulse widths remaining constant. For the T2 measurement, the ¿/2 and ¿ pulses remain fixed in width but the interpulse spacing is sequentially stepped out. At each pulse spacing step, the echo signal is recorded (typically with a small z-gradient applied to somewhat broaden the echo signal). When the complete data set has been collected, the amplitudes of the echo signals are extracted and plotted against the pulse spacing time and the plot is exponentially fitted to derive the value of the T2 transverse relaxation time parameter.