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Mark E. Wagshul Terry M. Button Haifang F. Li Zhengrong Liang Charles S. Springer Kai Zhong Arnold Wishnia 《Magnetic resonance in medicine》1996,36(2):183-191
Hyperpolarized 129Xe has been used to obtain gas phase images of mouse lung in vivo, showing distinct ventilation variation as a function of the breathing cycle. Spectra of 129Xe in the thorax show complex structure in both the gas phase (−4 to 3 ppm) and tissue-dissolved (190-205 ppm) regions. The alveolar gas peak shows correlated intensity and frequency oscillations, both attributable to changes in lung volume during breathing. The two major dissolved peaks near 195-200 ppm are attributed to lung parenchyma and to blood; they reach maximum intensity in 5-10 s and decay with an apparent T1 of 30 s. Another peak at 190 ppm takes 20-30 s to reach maximum; this must represent other well-vascularized tissue (e.g., heart and other muscles) in the thorax. The maximum integrated area of the tissue components reaches 30–80% of the maximum alveolar gas area, indicating that imaging at tissue frequencies can be achieved. 相似文献
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MR imaging of hyperpolarized (HP) nuclei is challenging because they are typically delivered in a single dose of nonrenewable magnetization, from which the entire image must be derived. This problem can be overcome with HP (129)Xe, which can be produced sufficiently rapidly to deliver in dilute form (1%) continuously and on-demand. We demonstrate a real-time in vivo delivery of HP (129)Xe mixture to rats, a capability we now routinely use for setting frequency, transmitter gain, shimming, testing pulse sequences, scout imaging, and spectroscopy. Compared to images acquired using conventional fully concentrated (129)Xe, real-time (129)Xe images have 26-fold less signal, but clearly depict ventilation abnormalities. Real-time (129)Xe MRI could be useful for time-course studies involving acute injury or response to treatment. Ultimately, real-time (129)Xe MRI could be done with more highly concentrated (129)Xe, which could increase the signal-to-noise ratio by 100 relative to these results to enable a new class of gas imaging applications. 相似文献
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John P. Mugler Bastiaan Driehuys James R. Brookeman Gordon D. Cates Stuart S. Berr Robert G. Bryant Thomas M. Daniel Eduard E. De Lange J. Hunter Downs Christopher J. Erickson William Happer Denise P. Hinton Neal F. Kassel Therese Maier C. Douglas Phillips Brian T. Saam Karen L. Sauer Mark E. Wagshul 《Magnetic resonance in medicine》1997,37(6):809-815
Using a new method of xenon laser-polarization that permits the generation of liter quantities of hyperpolarized 129Xe gas, the first 129Xe imaging results from the human chest and the first 129Xe spectroscopy results from the human chest and head have been obtained. With polarization levels of approximately 2%, cross-sectional images of the lung gas-spaces with a voxel volume of 0.9 cm3 (signal-to-noise ratio (SNR), 28) were acquired and three dissolved-phase resonances in spectra from the chest were detected. In spectra from the head, one prominent dissolved-phase resonance, presumably from brain parenchyma, was detected. With anticipated improvements in the 129Xe polarization system, pulse sequences, RF coils, and breathing maneuvers, these results suggest the possibility for 129Xe gas-phase imaging of the lungs with a resolution approaching that of current conventional thoracic proton imaging. Moreover, the results suggest the feasibility of dissolved-phase imaging of both the chest and brain with a resolution similar to that obtained with the gas-phase images. 相似文献
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Satoshi Iguchi Hirohiko Imai Yuki Hori Junichi Nakajima Atsuomi Kimura Hideaki Fujiwara 《Magnetic resonance in medicine》2013,70(1):207-215
MRI of hyperpolarized 129Xe dissolved in pulmonary tissues, and blood has the potential to offer a new tool for regional evaluation of pulmonary gas exchange and perfusion; however, the extremely short T and low magnetization density make it difficult to acquire the image. In this study, an ultrashort echo‐time sequence was introduced, and its feasibility to quantitatively assess emphysema‐like pulmonary tissue destruction by a combination of dissolved‐ and gas‐phase 129Xe lung MRI was investigated. The ultrashort echo‐time has made it possible to acquire dissolved 129Xe images with reasonably high spatial resolution of 0.625 × 0.625 mm2 and to obtain T of 0.67 ± 0.30 ms in a spontaneously breathing mouse at 9.4 T. The regional dynamic alveolar gas uptake as well as subsequent transport by pulmonary blood flow was also visualized. The ratio of 129Xe magnetization that diffused into the septa relative to the gas‐phase magnetization F was regionally evaluated. The mean F value of elastase‐treated mice was 2.28 ± 0.46%, which was significantly reduced from that of control mice 3.41 ± 0.48% (P = 0.0052). This reflects the reduced uptake efficiency due to alveolar tissue destruction and is correlated with the histologically derived alveolar surface‐to‐volume ratio. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
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Nishard Abdeen Albert Cross Gregory Cron Steven White Thomas Rand David Miller Giles Santyr 《Magnetic resonance in medicine》2006,56(2):255-264
We used the dual capability of hyperpolarized 129Xe for spectroscopy and imaging to develop new measures of xenon diffusing capacity in the rat lung that (analogously to the diffusing capacity of carbon monoxide or DLCO) are calculated as a product of total lung volume and gas transfer rate constants divided by the pressure gradient. Under conditions of known constant pressure breath-hold, the volume is measured by hyperpolarized 129Xe MRI, and the transfer rate is measured by dynamic spectroscopy. The new quantities (xenon diffusing capacity in lung parenchyma (DLXeLP)), xenon diffusing capacity in RBCs (DLXeRBC), and total lung xenon diffusing capacity (DLXe)) were measured in six normal rats and six rats with lung inflammation induced by instillation of fungal spores of Stachybotrys chartarum. DLXeLP, DLXeRBC, and DLXe were 56 +/- 10 ml/min/mmHg, 64 +/- 35 ml/min/mmHg, and 29 +/- 9 ml/min/mmHg, respectively, for normal rats, and 27 +/- 9 ml/min/mmHg, 42 +/- 27 ml/min/mmHg, and 16 +/- 7 ml/min/mmHg, respectively, for diseased rats. Lung volumes and gas transfer times for LP (TtrLP) were 16 +/- 2 ml and 22 +/- 3 ms, respectively, for normal rats and 12 +/- 2 ml and 35 +/- 8 ms, respectively, for diseased rats. Xenon diffusing capacities may be useful for measuring changes in gas exchange associated with inflammation and other lung diseases. 相似文献
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Uncovering a third dissolved‐phase 129Xe resonance in the human lung: Quantifying spectroscopic features in healthy subjects and patients with idiopathic pulmonary fibrosis
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Scott H. Robertson Rohan S. Virgincar Elianna A. Bier Mu He Geoffrey M. Schrank Rose Marie Smigla Craig Rackley H. Page McAdams Bastiaan Driehuys 《Magnetic resonance in medicine》2017,78(4):1306-1315
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Kai Ruppert Jaime F Mata James R Brookeman Klaus D Hagspiel John P Mugler 《Magnetic resonance in medicine》2004,51(4):676-687
With the use of polarization-transfer pulse sequences and hyperpolarized (129)Xe NMR, gas exchange in the lung can be measured quantitatively. However, harnessing the inherently high sensitivity of this technique as a tool for exploring lung function requires a fundamental understanding of the xenon gas-exchange and diffusion processes in the lung, and how these may differ between healthy and pathological conditions. Toward this goal, we employed NMR spectroscopy and imaging techniques in animal models to investigate the dependence of the relative xenon gas exchange rate on the inflation level of the lung and the tissue density. The spectroscopic results indicate that gas exchange occurs on a time scale of milliseconds, with an average effective diffusion constant of about 3.3 x 10(-6)cm(2)/s in the lung parenchyma. Polarization-transfer imaging pulse sequences, which were optimized based on the spectroscopic results, detected regionally increased gas-exchange rates in the lung, indicative of increased tissue density secondary to gravitational compression. By exploiting the gas-exchange process in the lung to encode physiologic parameters, these methods may be extended to noninvasive regional assessments of lung-tissue density and the alveolar surface-to-volume ratio, and allow lung pathology to be detected at an earlier stage than is currently possible. 相似文献
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Hersman FW Ruset IC Ketel S Muradian I Covrig SD Distelbrink J Porter W Watt D Ketel J Brackett J Hope A Patz S 《Academic radiology》2008,15(6):683-692
RATIONALE AND OBJECTIVES: Hyperpolarized gases such as (129)Xe and (3)He have high potential as imaging agents for functional lung magnetic resonance imaging (MRI). We present new technology offering (129)Xe 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 continuous-flow system capable of producing large quantities of highly-polarized (129)Xe 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. 相似文献
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S. Sivaram Kaushik Zackary I. Cleveland Gary P. Cofer Gregory Metz Denise Beaver John Nouls Monica Kraft William Auffermann Jan Wolber H. Page McAdams Bastiaan Driehuys 《Magnetic resonance in medicine》2011,65(4):1154-1165
Given its greater availability and lower cost, 129Xe apparent diffusion coefficient (ADC) MRI offers an alternative to 3He ADC MRI. To demonstrate the feasibility of hyperpolarized 129Xe ADC MRI, we present results from healthy volunteers (HV), chronic obstructive pulmonary disease (COPD) subjects, and age‐matched healthy controls (AMC). The mean parenchymal ADC was 0.036 ± 0.003 cm2 sec?1 for HV, 0.043 ± 0.006 cm2 sec?1 for AMC, and 0.056 ± 0.008 cm2 sec?1 for COPD subjects with emphysema. In healthy individuals, but not the COPD group, ADC decreased significantly in the anterior–posterior direction by ~22% (P = 0.006, AMC; 0.0059, HV), likely because of gravity‐induced tissue compression. The COPD group exhibited a significantly larger superior–inferior ADC reduction (~28%) than the healthy groups (~24%) (P = 0.00018, HV; P = 3.45 × 10?5, AMC), consistent with smoking‐related tissue destruction in the superior lung. Superior–inferior gradients in healthy subjects may result from regional differences in xenon concentration. ADC was significantly correlated with pulmonary function tests (forced expiratory volume in 1 sec, r = ?0.77, P = 0.0002; forced expiratory volume in 1 sec/forced vital capacity, r = ?0.77, P = 0.0002; diffusing capacity of carbon monoxide in the lung/alveolar volume (VA), r = ?0.77, P = 0.0002). In healthy groups, ADC increased with age by 0.0002 cm2 sec?1 year?1 (r = 0.56, P = 0.02). This study shows that 129Xe ADC MRI is clinically feasible, sufficiently sensitive to distinguish HV from subjects with emphysema, and detects age‐ and posture‐dependent changes. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
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Hirohiko Imai Atsuomi Kimura Satoshi Iguchi Yuki Hori Shoko Masuda Hideaki Fujiwara 《Magnetic resonance in medicine》2010,64(4):929-938
In the present study, a chemical shift saturation recovery method in hyperpolarized 129Xe MR spectroscopy measurements was applied to two groups of spontaneously breathing mice, an elastase‐induced emphysema model and a control group. Parameters detected were those related to lung structures and functions, such as alveolar septal thickness, h, the ratio of the alveolar septal volume relative to gas space volume, Vs/Va, and the transit time of blood through the gas exchange region, τ. To investigate the potential of these parameters as biomarkers, an attempt was made to detect physiologic changes in the lungs of elastase‐treated mice. Our results showed that Vs/Va was significantly reduced in elastase‐treated mice, reflecting emphysema‐like destruction of the alveolar wall. Compared with histologic results, this degree of reduction was shown to reflect the severity of wall destruction. On the other hand, significant changes in other parameters, h and τ, were not shown. This study is the first application of hyperpolarized 129Xe MR spectroscopy to a mouse model of emphysema and shows that the Vs/Va volume ratio is an effective biomarker for emphysema that could become useful in drug research and development through noninvasive detection of pathologic changes in small rodents. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc. 相似文献