APPLICATION OF HYPERPOLARIZED XENON-129 VIA THE VASCULAR SYSTEM

该子项目是利用 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。 在过去的十年中，超极化（HP）129已在生物医学MRI中得到应用，并取得了令人兴奋的结果。通常，通过吸入将气体引入生物体中，这是用于对肺的气体空间进行成像的有效策略。由于肺泡气体交换，少量吸入的HP 129进入肺血并输送到其他器官。这已经被用来研究脑灌注。用于将氙局部递送到其他靶器官的更有效的方法可以包括将HP气体预溶解在合适的液体中或产生微泡并随后注射到血流中。对于初始实验，我们将使用同位素富集的129氚（82%）、Intradecid 30%（Pharmacia，克莱顿，NC）和如M ller等人，MRM 41，1058（1999）中所述的“振荡器”，以再现用作参考的先前实验。寻找用于局部递送的其他载体将包括将HP 129 β溶解在完全氧合的血液或血浆中以及将HP 129 β溶解在氘代盐溶液中。虽然氙在这些液体中的溶解度显著低于脂肪乳剂，但它们是令人感兴趣的，因为氙在通过肺时将释放到肺泡气相，如果将RF激励选择性地应用于气相共振，则可以将其用于灌注成像。此外，在延长的输注实验期间，此类系统可更好地耐受。用氘代盐水进行的实验更令人感兴趣，人们可以预期129 μ T1会大大延长。 除了以前使用的“摇动器”溶解HP 129外，另一种策略将涉及中空纤维膜以改善溶解过程。该技术还可以保持HP气体载体的连续注入的潜力。 为了进行比较，还将研究涉及将少量HP 129 β直接注射到静脉中的实验。关于在水中的Ostwald溶解度（L），每mL血液可以注入大约0.1 mL气体。如果f是静脉血流量（mL/sec），则可以以L x f的速率连续注入HP气体，前提是溶解过程在体内足够快，并且气体定量释放到肺泡。

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. During the past decade, hyperpolarized (HP) 129Xe has found application in biomedical MRI with exciting results. Typically, the gas is introduced into the organism by inhalation, which is an efficient strategy for imaging the gas space of the lungs. Due to the alveolar gas exchange, a small amount of inhaled HP 129Xe enters the pulmonary blood and is delivered to other organs. This has already been exploited to study brain perfusion. More efficient methods for the local delivery of xenon to other target organs may include pre-dissolving of the HP gas in a suitable liquid or the production of microbubbles with subsequent injection into the blood stream. For initial experiments, we will use isotopically enriched 129Xe (82%), Intralipid 30% (Pharmacia, Clayton, NC) and a 'shaker' as described in M¿ller et al. MRM 41, 1058 (1999) to reproduce previous experiments serving as a reference. The search for other vehicles for local delivery will include dissolving of HP 129Xe in fully oxygenated blood or plasma and dissolving of HP 129Xe in deuterated saline solution. Although the solubility of xenon in these liquids is significantly less than that of lipid emulsions, they are of interest because Xe will be released to the alveolar gas phase upon passing through the lungs, which can be exploited for perfusion imaging if RF excitation is selectively applied to the gas phase resonance. In addition, such systems may be tolerated better during prolonged infusion experiments. Experiments with deuterated saline are of further interest one may expect a drasticallyprolonged 129Xe T1. Insead of the previously used 'shaker' for dissolving HP 129Xe, another strategy will involve hollow-fiber membranes to improve the process of dissolving. This technique may also hold a potential for continuous infusion of the HP gas carrier. For comparison, experiments involving direct injection of small amounts of HP 129Xe into a vein will also be investigated. Regarding the Ostwald solubility (L) of Xe in water, roughly 0.1 mL of gas may be injected per mL of blood. If f is the venous blood flow in mL/sec, HP gas may be injected continuously at a rate of L x f provided that the dissolving process is sufficently rapid in vivo and the gas is quantitatively released to the alveoli.