Cleveland Zackary I, Pavlovskaya Galina E, Elkins Nancy D, Stupic Karl F, Repine John E, Meersmann Thomas
Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
J Magn Reson. 2008 Dec;195(2):232-7. doi: 10.1016/j.jmr.2008.09.020. Epub 2008 Sep 26.
Hyperpolarized (hp) (83)Kr (spin I=9/2) is a promising gas-phase contrast agent that displays sensitivity to the surface chemistry, surface-to-volume ratio, and surface temperature of the surrounding environment. This proof-of-principle study demonstrates the feasibility of ex vivo hp (83)Kr magnetic resonance imaging (MRI) of lungs using natural abundance krypton gas (11.5% (83)Kr) and excised, but otherwise intact, rat lungs located within a custom designed ventilation chamber. Experiments comparing the (83)Kr MR signal intensity from lungs to that arising from a balloon with no internal structure inflated to the same volume with krypton gas mixture suggest that most of the observed signal originated from the alveoli and not merely the conducting airways. The (83)Kr longitudinal relaxation times in the rat lungs ranged from 0.7 to 3.7s but were reproducible for a given lung. Although the source of these variations was not explored in this work, hp (83)Kr T(1) differences may ultimately lead to a novel form of MRI contrast in lungs. The currently obtained 1200-fold signal enhancement for hp (83)Kr at 9.4T field strength is found to be 180 times below the theoretical upper limit.
超极化（hp）（83）氪（自旋I = 9/2）是一种很有前景的气相造影剂，它对周围环境的表面化学、表面体积比和表面温度表现出敏感性。这项原理验证研究证明了使用天然丰度氪气（11.5%（83）氪）和位于定制设计通风室内的切除但其他方面完好的大鼠肺进行离体hp（83）氪磁共振成像（MRI）的可行性。将肺的（83）氪磁共振信号强度与用氪气混合物充气至相同体积的无内部结构气球产生的信号强度进行比较的实验表明，观察到的大部分信号源自肺泡，而不仅仅是传导气道。大鼠肺中的（83）氪纵向弛豫时间在0.7至3.7秒之间，但对于给定的肺是可重复的。尽管这项工作未探究这些变化的来源，但hp（83）氪T1差异最终可能导致肺部MRI造影的一种新形式。发现在9.4T场强下目前获得的hp（83）氪1200倍信号增强比理论上限低180倍。
