patient preparation and subject training for hyperpolarized xenon mri

Hyperpolarized Xenon-129 MRI를 이용한 폐 기능 평가

Hyperpolarized Xenon-129 (HXe) magnetic resonance imaging (MRI)1 is a technique that offers unique insights into lung structure, function, and gas exchange processes. By dramatically amplifying the magnetization of Xenon gas through spin-exchange optical pumping, HXe MRI achieves an order-of-magnitude improvement in signal-to-noise ratio compared to thermally polarized Xenon MRI2,3,4,5,6. This hyperpolarization enables the direct visualization and quantification of Xenon gas uptake into lung tissue and blood, which would otherwise be undetectable with conventional thermally polarized MRI7.
Chemical shift saturation recovery (CSSR) MR spectroscopy8,9,10,11,12,13 has proven to be one of the most valuable HXe MRI techniques. CSSR involves selectively saturating the magnetization of Xenon dissolved in lung tissue and blood using frequency-specific radiofrequency (RF) pulses. The subsequent recovery of the dissolved-phase (DP) signal as it exchanges with fresh hyperpolarized Xenon gas in the airspaces on a timescale of ms offers important functional information about the lung parenchyma.
Since its development in the early 2000s, the techniques behind CSSR spectroscopy have been progressively refined14,15,16,17,18,19,20,21,22,23. Further, advances in modeling Xenon uptake curves have enabled the extraction of specific physiological parameters, such as alveolar wall thickness and pulmonary transit times10,24,25,26. Studies have shown CSSR&#39;s sensitivity to subtle changes in lung microstructure and gas exchange efficiency in the form of pulmonary abnormalities found in clinically healthy smokers27, as well as in a range of lung diseases, including chronic obstructive pulmonary disease (COPD)18,27,28, fibrosis29, and radiation-induced lung injury30,31. CSSR spectroscopy has also been demonstrated to be sensitive to detect oscillations in the DP signal corresponding to pulsatile blood flow during the cardiac cycle32.
While significant progress has been made, practical challenges remain in implementing CSSR spectroscopy on clinical MRI systems. Scan times requiring single-dose breath holds approaching 10 s may be too long for pediatric subjects33,34 or patients with severe lung disease35,36. Additionally, the technique is susceptible to measurement biases if acquisition parameters such as the order of the saturation delay times or the efficacy of the dissolved-phase saturation are not properly optimized21. To address these limitations and make CSSR more accessible to the broader research community, clear, step-by-step protocols for both conventional breath hold and free-breathing acquisitions, currently under development, are needed.
The objective of this paper is to present a detailed methodology for performing optimized CSSR MR spectroscopy using HXe gas. The protocol will cover polarization and delivery of the Xenon gas, RF pulse calibration, sequence parameter selection, subject preparation, data acquisition, and key steps in data analysis. Examples of experimental results will be provided. It is hoped that this comprehensive guide will serve as a foundation for CSSR implementations across sites and help realize the full potential of this technique for quantifying lung microstructural changes in a range of pulmonary diseases.

저자 스포트라이트: 자유 호흡 과분극 Xenon-129 MRI를 통한 폐 질환 연구 발전

Quantitative Measure of Lung Structure and Function Obtained from Hyperpolarized Xenon Spectroscopy(과분극 크세논 분광법에서 얻은 폐 구조 및 기능의 정량적 측정)

Our research focuses on using hyperpolarizing on 129 MRI technology to assess pulmonary function and to investigate lung diseases. The main objective is to see how this imaging technique can lead to better detection, understanding, and tracking of different lung conditions. Most hyperpolarized lung MR imaging is performed during a breath hold.We believe that pulmonary function quantified under such an artificial condition, may not fully reflect gas exchange during regular respiration, and we are testing new free breathing measurements that do not require any breath hold. Current challenges include the optimization of the CSSR acquisition technique for consistency and accuracy in the face of physiological variation and patient compliance. Severely ill or pediatric patients struggle with maintaining lengthy breath holds.The CSSR heart technique appears particularly sensitive to changes in alveolar septal wall thickness. As we and others in the field of demonstrated, alveolar wall thickening can indicate the presence of interstitial edema, inflammation, or pulmonary fibrosis. All metrics derived from CSSR spectroscopy acquisitions are currently based on the temporal dynamics of the signal amplitudes.In the future though, we hope to include changes in peak shape and center frequency in the analysis to obtain a more complete picture of the ongoing gas exchange processes.

Hyperpolarized Xenon MRI에 대한 환자 준비 및 피험자 교육

먼저 생리학적 모니터링 시스템을 설정하여 이미징 중 호흡 곡선과 실시간 가스 분석을 기록합니다. 들숨-날숨 오디오 녹음을 사용하여 피험자를 안내하는 오디오 신호와 함께 MRI 룸 헤드폰을 연결하고 테스트합니다. 오디오 트랙의 재생 속도를 조정합니다. 숨을 들이쉬고 내쉴 수 있습니다.각 피험자의 정상 호흡수를 기준으로 합니다. 숨을 들이쉬고 내쉬십시오. 다음으로, 깨끗한 머리 받침대, 다리 지지대 베개 및 담요로 스캐너 침대를 준비합니다. 고정되지 않은 Xenon 129 가슴 조끼 코일을 MRI 스캐너의 테이블에 놓고 코일의 커넥터 플러그를 삽입합니다.자유 호흡 연구를 위해 이미징 중 동기화된 호흡을 위해 들숨-날숨 음성 녹음에 피험자를 소개합니다. 피험자를 MRI실로 안내하고 열린 크세논 조끼 코일 위에 놓인 스캐너 침대에 놓습니다. 피험자의 위치가 잡히면 벨크로 스트랩을 조여 조끼 코일이 닫히지만 피험자의 가슴을 조이지 않도록 합니다.자유 호흡 연구를 위해 폐렴이 있는 안면 마스크를 환자의 얼굴에 씌웁니다. 마스크가 너무 꽉 조이지 않고 코와 입에 꼭 맞도록 스트랩을 조입니다. 착용 후 마스크를 제거하고 나중을 위해 따로 보관하고 스트랩은 피험자의 머리 뒤에 남겨 둡니다.그런 다음 두 개의 맥박 산소 측정기를 두 검지 손가락에 놓고 연구 중에 심박수와 혈중 산소 포화도를 지속적으로 모니터링합니다. MRI 호환 헤드폰을 피사체의 귀에 착용합니다. MRI 스캐너 테이블을 자석 구멍으로 이동하여 피사체의 폐가 시야의 중앙에 위치하도록 합니다.

Research

JoVE Journal

Medicine

Patient Preparation and Subject Training for Hyperpolarized Xenon MRI

Quantitative Measure of Lung Structure and Function Obtained from Hyperpolarized Xenon Spectroscopy

Hyperpolarized Xenon-129 (HXe) magnetic resonance imaging (MRI) provides tools for obtaining 2- or 3-dimensional maps of lung ventilation patterns, gas ...

연구

의학

Polarizing Xenon-129 for Hyperpolarized Xenon Spectroscopy

Hyperpolarized Xenon Spectroscopy를 위한 Polarizing Xenon-129

Performing Hyperpolarized Xenon-129 Inhalation for Chemical Shift Saturation Recovery (CSSR) Measurement

CSSR(Chemical Shift Saturation Recovery) 측정을 위한 Hyperpolarized Xenon-129 흡입 수행