Harmonizing and validating 129Xe gas exchange imaging across multiple sites is hampered by a lack of a quantitative standard that 1) displays the unique spectral properties of 129Xe observed from human subjects in vivo and 2) has short enough T1 times to enable practical imaging. This work describes and demonstrates the development of two dissolved-phase, thermally polarized phantoms that mimic the in-vivo, red blood cell and membrane resonances of 129Xe dissolved in human lungs. Following optimization, combinations of two common organic solvents, acetone and dimethyl sulfoxide, resulted in two in-vivo-like dissolved-phase 129Xe phantoms yielding chemical shifts of 212.4 ppm and 193.9 ppm. By doping the solutions with iron(iii) acetylacetonate, the longitudinal relaxation time was reduced T1 = 1.2 s for both phantoms at 3 T and 7 T. There was minimal change in chemical shift (+1.58 ppm) and T1 (+1.2 %) over 1 year. In a 2D Dixon-type acquisition with 3 mm2 in-plane resolution, 129Xe dissolved-phase images yielded signal-to-noise ratios 6 and 12 for the RBC and membrane phantoms, respectively. A simple scaling of these phantoms to clinically relevant volumes of several liters would result in an SNR of 7 for the RBC phantom acquired in less than one minute. These findings demonstrate the ability to fabricate robust, quantitative, thermally polarized dissolved-phase phantoms, which will be needed to validate and harmonize gas exchange imaging in multi-site clinical trials.
Keywords: (129)Xe; Dixon; Gas-exchange; Phantom.
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