A semi-empirical model to optimize continuous-flow hyperpolarized 129Xe production under practical cryogenic-accumulation conditions

Plummer, J.W.; Emami, Kiarash; Dummer, Andrew; Woods, Jason C.; Walkup, Laura L.; Cleveland, Zackary I.

doi:10.1016/j.jmr.2020.106845

Cited by 19 publications

(31 citation statements)

References 60 publications

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“…The device delivers a polarization level exceeding 55 % for 300 mL batches produced at a rate of 2 sL h −1 , equivalent to a DE production rate of ≈1 sL h −1 (85 % isotopically enriched 129 Xe). For device units operating in the field, research groups have reported polarization levels up to 40 % under similar conditions [41, 42] …”

Section: Continuous‐flow Seop Production Methodsmentioning

confidence: 99%

“…Fordevice units operating in the field, research groups have reported polarization levels up to 40 %u nder similar conditions. [41,42] 3.3. Other Key Developments in CF-SEOP Meersmann and co-workers [43] showed that the product of P Xe and Xe concentration increases with an increasing Xe partial pressure,and as aresult it is possible to operate even at near 100 %Xemole fraction.…”

Section: Methodsmentioning

confidence: 99%

“…A few approaches have been attempted to resolve this large disagreement. For example, Plummer and co‐workers simulated [41] the entire CF‐SEOP process (including 129 Xe cryo‐collection) and found that when Rb density and solid‐state 129 Xe T 1 were allowed to be freely floating parameters fit to experimental data, both values tended to be significantly less than literature expectations—potentially explaining much of the perceived underperformance of certain CF‐SEOP designs. Earlier, Freeman et al.…”

Section: Simulations Of Seop Processesmentioning

confidence: 99%

“…Af ew approaches have been attempted to resolve this large disagreement. Fore xample,P lummer and co-workers simulated [41] the entire CF-SEOP process (including 129 Xe cryocollection) and found that when Rb density and solid-state 129 Xe T 1 were allowed to be freely floating parameters fit to experimental data, both values tended to be significantly less than literature expectations-potentially explaining much of the perceived underperformance of certain CF-SEOP designs.Earlier, Freeman et al suggested that the discrepancy was aresult of anovel form of contamination in the SEOP cell manifested by Rb cluster formation. This hypothesis originated from the fact that small SEOP cells coupled with highpowered pump lasers give rise to very high power densities.…”

Section: Angewandte Chemiementioning

confidence: 99%

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Enabling Clinical Technologies for Hyperpolarized ¹²⁹Xenon Magnetic Resonance Imaging and Spectroscopy

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Hyperpolarization is a technique that can increase nuclear spin polarization with the corresponding gains in nuclear magnetic resonance (NMR) signals by 4–8 orders of magnitude. When this process is applied to biologically relevant samples, the hyperpolarized molecules can be used as exogenous magnetic resonance imaging (MRI) contrast agents. A technique called spin‐exchange optical pumping (SEOP) can be applied to hyperpolarize noble gases such as 129Xe. Techniques based on hyperpolarized 129Xe are poised to revolutionize clinical lung imaging, offering a non‐ionizing, high‐contrast alternative to computed tomography (CT) imaging and conventional proton MRI. Moreover, CT and conventional proton MRI report on lung tissue structure but provide little functional information. On the other hand, when a subject breathes hyperpolarized 129Xe gas, functional lung images reporting on lung ventilation, perfusion and diffusion with 3D readout can be obtained in seconds. In this Review, the physics of SEOP is discussed and the different production modalities are explained in the context of their clinical application. We also briefly compare SEOP to other hyperpolarization methods and conclude this paper with the outlook for biomedical applications of hyperpolarized 129Xe to lung imaging and beyond.

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Section: Continuous‐flow Seop Production Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Simulations Of Seop Processesmentioning

confidence: 99%

Section: Angewandte Chemiementioning

confidence: 99%

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Enabling Clinical Technologies for Hyperpolarized ¹²⁹Xenon Magnetic Resonance Imaging and Spectroscopy

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“…To date, most studies involving diffusion‐weighted HP gas MRI have employed 3 He because of its larger gyromagnetic ratio, historically higher achievable polarizations (>50%), and higher diffusivity 3–5 . However, 3 He is increasingly scarce and costly, and 129 Xe hyperpolarization technology has improved dramatically over the past decade, making 129 Xe practical for routine human imaging 3,4,12–14 . With respect to diffusion‐weighted imaging, HP 129 Xe ADC has been used to assess alveolar enlargement during normal aging and in a range of lung diseases, including idiopathic pulmonary fibrosis (IPF), 15 lymphangioleiomyomatosis (LAM), 16 and chronic obstructive pulmonary disease (COPD) 9,17 …”

Section: Introductionmentioning

confidence: 99%

Improving hyperpolarized ¹²⁹Xe ADC mapping in pediatric and adult lungs with uncertainty propagation

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Rationale Hyperpolarized (HP) 129Xe‐MRI provides non‐invasive methods to quantify lung function and structure, with the 129Xe apparent diffusion coefficient (ADC) being a well validated measure of alveolar airspace size. However, the experimental factors that impact the precision and accuracy of HP 129Xe ADC measurements have not been rigorously investigated. Here, we introduce an analytical model to predict the experimental uncertainty of 129Xe ADC estimates. Additionally, we report ADC dependence on age in healthy pediatric volunteers. Methods An analytical expression for ADC uncertainty was derived from the Stejskal‐Tanner equation and simplified Bloch equations appropriate for HP media. Parameters in the model were maximum b‐value (bmax), number of b‐values (Nb), number of phase encoding lines (Nph), flip angle and the ADC itself. This model was validated by simulations and phantom experiments, and five fitting methods for calculating ADC were investigated. To examine the lower range for 129Xe ADC, 32 healthy subjects (age 6‐40 years) underwent diffusion‐weighted 129Xe MRI. Results The analytical model provides a lower bound on ADC uncertainty and predicts that decreased signal‐to‐noise ratio yields increases in relative uncertainty true(ϵADCtrue). As such, experimental parameters that impact non‐equilibrium 129Xe magnetization necessarily impact the resulting ϵADC. The values of diffusion encoding parameters (Nb and bmax) that minimize ϵADC strongly depend on the underlying ADC value, resulting in a global minimum for ϵADC. Bayesian fitting outperformed other methods (error < 5%) for estimating ADC. The whole‐lung mean 129Xe ADC of healthy subjects increased with age at a rate of 1.75 × 10−4 cm2/s/yr (p = 0.001). Conclusions HP 129Xe diffusion MRI can be improved by minimizing the uncertainty of ADC measurements via uncertainty propagation. Doing so will improve experimental accuracy when measuring lung microstructure in vivo and should allow improved monitoring of regional disease progression and assessment of therapy response in a range of lung diseases.

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Enabling Clinical Technologies for Hyperpolarized ¹²⁹Xenon Magnetic Resonance Imaging and Spectroscopy

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Prof. Eduard Y. Chekmenev received his PhD in Physical Chemistry (supervisor Prof. Richard J. Wittebort) in 2003 at the University of Louisville, KY (USA). He conducted postdoctoral research at the National High Magnetic Field Laboratory in Tallahassee, FL (with Prof. Timothy Cross), Caltech (Prof. Daniel P. Weitekamp) and HMRI in Pasadena, CA (USA) (with Dr.B rian D. Ross). In 2009, Dr.C hekmenev started his hyperpolarization program at Vanderbilt University (Nashville, TN) and he was tenured in 2015. In 2018, he moved to Wayne State University (Detroit, MI) to continue his research on MR hyperpolarization.Figure 1. Thermal equilibrium polarizationp roduces asmall excess of spins in one state. When the sample undergoes hyperpolarization, alarge excess of spins exists in one state producingaconsiderably stronger signal since more spins contribute.

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A semi-empirical model to optimize continuous-flow hyperpolarized 129Xe production under practical cryogenic-accumulation conditions

Cited by 19 publications

References 60 publications

Enabling Clinical Technologies for Hyperpolarized ¹²⁹Xenon Magnetic Resonance Imaging and Spectroscopy

Enabling Clinical Technologies for Hyperpolarized ¹²⁹Xenon Magnetic Resonance Imaging and Spectroscopy

Improving hyperpolarized ¹²⁹Xe ADC mapping in pediatric and adult lungs with uncertainty propagation

Enabling Clinical Technologies for Hyperpolarized ¹²⁹Xenon Magnetic Resonance Imaging and Spectroscopy

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A semi-empirical model to optimize continuous-flow hyperpolarized 129Xe production under practical cryogenic-accumulation conditions

Cited by 19 publications

References 60 publications

Enabling Clinical Technologies for Hyperpolarized 129Xenon Magnetic Resonance Imaging and Spectroscopy

Enabling Clinical Technologies for Hyperpolarized 129Xenon Magnetic Resonance Imaging and Spectroscopy

Improving hyperpolarized 129Xe ADC mapping in pediatric and adult lungs with uncertainty propagation

Enabling Clinical Technologies for Hyperpolarized 129Xenon Magnetic Resonance Imaging and Spectroscopy

Contact Info

Product

Resources

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Enabling Clinical Technologies for Hyperpolarized ¹²⁹Xenon Magnetic Resonance Imaging and Spectroscopy

Enabling Clinical Technologies for Hyperpolarized ¹²⁹Xenon Magnetic Resonance Imaging and Spectroscopy

Improving hyperpolarized ¹²⁹Xe ADC mapping in pediatric and adult lungs with uncertainty propagation

Enabling Clinical Technologies for Hyperpolarized ¹²⁹Xenon Magnetic Resonance Imaging and Spectroscopy