Human pulmonary imaging and spectroscopy with hyperpolarized Xe-129 at 0.2T

Rationale and Objectives: Using a novel Xe-129 polarizer with high throughput (1-2 L/hour) and high polarization (similar to 55%), our objective was to demonstrate and characterize human pulmonary applications at 0.2T. Specifically, we investigated the ability of 129Xe to measure the alveolar surface area per unit volume of gas, S-A/V-gas. Materials and Methods: Variable spin echo time (TE) gradient and radiofrequency (RF) echoes were used to obtain estimates of the lung\u27s contribution to both T-2* and T-2. Standard multislice ventilation images were obtained and signal-to-noise ratio (SNR) determined. Whole-lung, time-dependent measurements of Xe-129 diffusion from gas to septal tissue were obtained with a chemical shift saturation recovery (CSSR) method. Four healthy subjects were studied, and the Butler et al CSSR formalism (J Phys Condensed Matter 2002; 14:L297-L304) was used to calculate S-A/V-gas. A single-breath version of the xenon transfer contrast (SB-XTC) method was implemented and used to image Xe-129 diffusion between alveolar gas and septal tissue. A direct comparison of CSSR and SB-XTC was performed. Results: T-2* = 135 +/- 29 ms amd T-2 = 326.2 +/- 9.5 ms. Maximum SNR = 36 for ventilation images from inhalation of IL 86% Xe-129 and voxel volume = 0.225 mL. CSSR analysis showed S-A/V-gas decreased with increasing lung volume in a manner very similar to that observed from histology measurements; however, the absolute value of S-A/V-gas was similar to 40% smaller than histology values. SB-XTC images in different postures demonstrate gravitationally dependent values. Initial comparison of CSSR with XTC showed fairly good agreement with expected ratios. Conclusions: Hyperpolarized Xe-129 human imaging and spectroscopy are very promising methods to provide functional information about the lung

Large production system for hyperpolarized Xe-129 for human lung imaging studies

Rationale and Objectives. Hyperpolarized gases such as Xe-129 and He-3 have high potential as imaging agents for functional lung magnetic resonance imaging (MRI). We present new technology offering Xe-129 production rates with order-of-magnitude improvement over existing systems, to liter per hour at 50% polarization., Human lung imaging studies with xenon, initially limited by the modest quantity and quality of hyperpolarized gas available, can now be performed with multiliter quantities several times daily. Materials and Methods. The polarizer is a continuolis-flow system capable of producing large quantities of highly-polarized 129Xe through rubidium spin-exchange optical pumping. The low-pressure, high-velocity operating regime takes advantage of the enhancement in the spin exchange rate provided by van der Waals molecules dominating the atomic interactions. The long polarizing column moves the flow of the gas opposite to the laser direction, allowing efficient extraction of the laser light. Separate sections of the system assure full rubidium vapor saturation and removal. Results. The system is capable of producing 64% polarization at 0.3 L/hour Xe production rate. Increasing xenon flow reduces output polarization. Xenon polarization was studied as a function of different system operating parameters. A novel xenon trapping design was demonstrated to allow full recovery of the xenon polarization after the freeze-thaw cycle. Delivery methods of the gas to an offsite MRI facility were demonstrated in both frozen and gas states. Conclusions. We demonstrated a new concept for producing large quantities of highly polarized xenon. The system is operating in an MRI facility producing liters of hyperpolarized gas for human lung imaging studies

Strangeness physics programs by S-2S at J-PARC

In the K1.8 beam-line at Hadron Experimental Facility of J-PARC, a new magnetic spectrometer S-2S is being installed. S-2S was designed to achieve a high momentum resolution of Δp/p = 6 × 10−4 in FWHM. Several strangeness-physics programs which require the high resolution will be realized by S-2S. The present article introduces J-PARC E70 (missing-mass spectroscopy of Ξ12Be) and E94 (missing-mass spectroscopy of Λ7Li, Λ10B, and Λ12C) experiments