RF instrumentation for same-breath triple nuclear lung MR imaging of (1)H and hyperpolarized (3)He and (129)Xe at 1.5T.

Madhwesha Rao,Jim M Wild

doi:10.1002/mrm.25680

Abstract

PurposeThe hyperpolarized gases 3He and 129Xe have distinct properties and provide unique and complementary functional information from the lungs. A triple‐nuclear, same‐breath imaging examination of the lungs with 1H, 3He, and 129Xe can therefore provide exclusive functional information from the gas images. In addition, the 1H images provide complementary co‐registered structural information in the same physiological time frame. The goal of this study was to design an RF system for triple nuclear lung MRI at 1.5T, consisting of a dual‐tuned transceiver coil for 3He and 129Xe, RF switches and a nested 1H receiver array.MethodsA dual‐tuned transmit‐receive dual‐Helmholtz RF coil for 3He and 129Xe was designed and constructed to work in unison with a nested 1H receiver array.ResultsTriple‐nuclear imaging (structural and ventilation) and apparent diffusion coefficient mapping of the human lungs was performed in the same breath‐hold using the integrated RF system. B1 maps and volumetric ventilation imaging using a three‐dimensional, balanced steady‐state free precession pulse sequence performed with both hyperpolarized 3He and 129Xe indicate good stand‐alone performance of the coil for the respective nucleus.ConclusionTriple‐nuclear same‐breath lung imaging with a dual‐tuned coil (3He and 129Xe) and a nested 1H array has been demonstrated with a custom RF system. Magn Reson Med 75:1841–1848, 2016. © © The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Highlights

Imaging the lungs with inhaled hyperpolarized gases 3He and 129Xe has been shown to provide functional information that cannot be accessed with proton (1H) MRI or other imaging modalities [1,2,3,4,5,6]
The capability to measure the diffusivity of both 3He and 129Xe gases in the same lung inflation level provides added information for measuring and modeling lung microstructure based on their measured apparent diffusion coefficients (ADC) [13]. 129Xe is denser and more viscous than 3He and as such has different fluid dynamic properties that define airflow in the airways, which can be measured with phase contrast MRI [14]. 129Xe has the added feature that it is soluble in blood and has a wide range of chemical shift, which enables quantification of perfusion and gas exchange in the lungs [8,9,15,16,17]
Same-breath ADC measurement of 3He and 129Xe performed in the same lung-inflation state is shown in Figure 2e and 2f

Summary

Introduction

Imaging the lungs with inhaled hyperpolarized gases 3He and 129Xe has been shown to provide functional information that cannot be accessed with proton (1H) MRI or other imaging modalities [1,2,3,4,5,6]. The two gases have distinct physical properties, which provide different but complementary functional information [7,8,9]. The capability to measure the diffusivity of both 3He and 129Xe gases in the same lung inflation level provides added information for measuring and modeling lung microstructure based on their measured apparent diffusion coefficients (ADC) [13]. Same-breath, multinuclear lung imaging with 3He-129Xe mixtures and 1H MRI provides a unique combination of functional and structural information that is spatio-temporally coregistered in the same physiological time frame [21,22]. In a recent study [23], we showed that the 1H lung

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