Mixture and dissolution of laser polarized noble gases: Spectroscopic and imaging applications

Lung fixation for the preservation of air spaces.

The procedures for the fixation of entire lungs of small rodents are presented together with various techniques used to verify the structural integrity of the lung tissue. To achieve this, the lungs were dissected out from rats and mice killed by ether overdose. The specimens were rinsed with isotonic saline and fixation solution under low vacuum conditions. After fixation, they were dried using alcohol and stored in a noncollapsed state (i.e., state of inhalation). Light and scanning electron microscopy as well as magnetic resonance imaging using hyperpolarized 3He were employed to verify the intact state on interalveolar septa and walls of smaller bronchi as well as accessibility of the a…

Controlling diffusion of 3He by buffer gases: a structural contrast agent in lung MRI.

Purpose: To study the influence of admixing inert buffer gases to laser-polarized 3 He in terms of resulting diffusion coefficients and the consequences for image contrast and resolution. Materials and Methods: The diffusion coefficient of 3 He was altered by admixing buffer gases of various molecular weights ( 4 He, N2, and SF6). The influence of the pulse sequence and the diffusion coefficient on the appearance of MRI of (laserpolarized) gases was analyzed by comparison of basic theoretical concepts with demonstrative experiments. Results: Excellent agreement between theoretical description and observed signal in simple gradient echoes was observed. A maximum signal gain can be predicted …

Imaging of a mixture of hyperpolarized 3He and 129Xe.

Abstract With the use of hyperpolarized gases, a great number of experiments have been carried out in order to improve the diagnostics of the lung, both from a structural and a functional point of view. 3 He is best suited for structural studies, whereas 129 Xe gives more detailed information about the functionality of the lung because it enters the bloodstream. In this work, we propose the use of a gas mixture to perform consecutive analysis of lung structure and functionality upon the delivery of a single bolus of gas. We show images of a helium–xenon gas mixture in the presence of a small amount of liquid toluene in order to demonstrate how both nuclei can be detected independently, extr…