DIFFUSION CORRECTED RECONSTRUCTIONS OF PARTIAL PRESSURE OF OXYGEN

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 肺顺应性定义为每单位压力变化时肺体积的变化，是肺力学分析中使用的基本参数之一，了解这一参数对肺部疾病的研究和诊断具有重要意义。超极化(HP)3He磁共振测量局部氧分压有助于了解生理学和病理生理学条件下的肺功能。这源于肺稳态氧分压与其通气性灌注率之间的独特相关性；肺组织氧降解率与局部肺泡灌注率之间也存在类似的关系。因此，这些措施引起了肺病学家和生理学家的极大兴趣。目前的高压氧测量技术假定测量周期内高压气体的扩散对测量信号强度的影响可以忽略不计。我们发现，在许多情况下，这个假设是错误的，并且严重降低了测量精度；我们提出了第一个在扩散的HP造影剂存在的情况下测量区域氧压力的直接氧重建算法。给出了数值模拟和实验结果。

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. Pulmonary compliance  defined as the change in volume of the lung per unit change in pressure  is one of the fundamental parameters used in the analysis of lung mechanics, and knowledge of this parameter is important for the study and diagnosis of pulmonary diseases. Hyperpolarized (HP) 3He MRI measures of regional oxygen tensions provide important insight into lung function under physiologic and pathophysiologic conditions. This stems from the unique correlation between the lungs steady state oxygen tensions and its ventilation perfusion ratios; a similar relationship exists between the lungs the oxygen degradation rate and local alveolar perfusion. Thus these measures are of great interest to pulmonologists and physiologists. Current HP oxygen measurement techniques assume that diffusion of the HP gas during the measurement cycle affects the measured signal intensity negligibly. We show that under many conditions this assumption is false and severely degrades measurement accuracy; we present the first direct oxygen reconstruction algorithm for measuring regional oxygen tensions in the presence of a diffusing HP contrast agent. Numerical simulations and experimental results are presented as well.