SPATIAL DISTRIBUTION OF PULMONARY FUNCTION OF THE RAT LUNG

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 已知大鼠肺中辐射诱导的功能丧失的程度取决于哪个区域受到辐射。 然而，对这些区域差异的根本原因知之甚少。 一种假设是，这种效应可能是由于照射前肺功能的非均匀分布造成的。为了确定局部功能的区域变化在多大程度上可以解释辐射诱导的功能丧失的区域变化，我们希望通过测量以下参数的空间分布来测量肺功能的分布： 1)通气：这将通过对气相超极化氙气进行成像来测量。 2)表面积与体积比：溶解在组织中的氙的MR频率与气相中的氙不同。通过在施加去极化射频脉冲后短时间内测量溶解的超极化氙的197 ppm信号，我们希望获得与可用气体交换表面成比例的信号。 3)红细胞中的气体吸收：当氙被红细胞吸收时，其MR频率经历第二次偏移至211 ppm。因此，红细胞的气体摄取可以通过在该频率上成像来特异性地测量。 该测量提供了毛细血管血容量的区域分布以及血气屏障健康。 4)全肺动态光谱显示197和211 ppm共振的恢复。 5)用于胸部体积估计的质子MRI：为了计算体积平均值，需要显示解剖结构的质子图像。从辐照实验中使用的所有区域的这些图像中，将获得治疗前值，并将其与可用的治疗后功能丧失数据相关联。 6)可选-使用Gd注射对厚肺板进行MR灌注 我们打算根据概述的方案扫描3-6只大鼠。确切的数字将取决于结果的可变性。 方案的第1-5部分与Driehuys PNAS提交文件中执行的部分相同。 如果对CIVM的学生和教师有益，项目6将作为研究的可选组成部分。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The magnitude of radiation-induced function loss in the rat lung is known to be dependent on which region is irradiated. However, the underlying cause of these regional differences is poorly understood. One hypothesis is that the effect may result from a non-uniform distribution of function over the lung, prior to irradiation. To determine the extent to which regional variations in local function can explain regional variations in radiation-induced function loss, we want to measure the distribution of function over the lung by measuring the spatial distribution of the following parameters: 1) Ventilation: This will be measured by imaging hyperpolarized Xenon gas in gas phase. 2) Surface-to-volume ratio: The MR frequency of Xenon dissolved in tissue differs from Xenon in gas phase. By measuring the 197ppm signal of dissolved hyperpolarized Xenon for short period after applying a depolarizing rf-pulse, we want to obtain signals proportional to the available gas-exchange surface. 3) Gas uptake in red blood cells: When Xenon is taken up in red blood cells, its MR frequency undergoes a second shift to 211ppm. Thus gas uptake by red blood cells can be measured specifically by imaging on this frequency. This measurement provides a regional distribution of capillary blood volume coupled with blood-gas barrier health. 4) Whole-lung dynamic spectroscopy showing recovery of the 197 and 211 ppm resonances. 5) Proton MRI for chest volume estimation: To allow the calculation of volume averages, proton images revealing the anatomy are needed. From these images for all regions used in the irradiation experiments, pre-treatment values will be obtained and correlated the available post-treatment function loss data. 6) Optional - MR perfusion of a thick slab of lung using Gd injection We intend to scan 3-6 rats according to the outlined protocol. Exact numbers will depend on the variability in the results. Parts 1-5 of the protocol are identical to those carried out in the Driehuys PNAS submission. Item 6 would be included as an optional component to the study if there is benefit to CIVM students and faculty.