Study on the Automatic Accumulation-thawing Device of Hyperpolarized 129Xe

Due to the detection sensitivity provided by the high nuclear spin polarization, hyperpolarized 129Xe has been employed in animal and human magnetic resonance imaging (MRI). However, during the accumulation-thawing process of hyperpolarized 129Xe, multiple factors lead to the relaxation of spin polarization and would hinder the wider application of 129Xe. In this research, the spin relaxation mechanism of hyperpolarized 129Xe during the accumulation-thawing process is investigated by both theoretical model analysis and experimental measurements. Meanwhile, the stability of the homebuilt device for the accumulation-thawing is measured. Our results demonstrate that the thawing mode and the cold trap material significantly affect the polarization loss; the automatic device is very stable during long-term operation and shows a high degree of automation, resulting in a polarization recovery ratio of 85.6% ± 4.7%. This research greatly helps to improve the efficiency of hyperpolarized 129Xe in animal and human MRI.