# Volume-controlled 19 F MR ventilation imaging of fluorinated gas

Yannick Crémillieux

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## To cite this version:

Yannick Crémillieux. Volume-controlled 19 F MR ventilation imaging of fluorinated gas. Journal of Magnetic Resonance Imaging, In press, 10.1002/jmri.28384. hal-03840728

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Submitted on 16 Nov 2022

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Distributed under a Creative Commons Attribution 4.0 International License
Yannick Crémillieux

Editorial for "Volume-controlled ¹⁹F MR ventilation imaging of fluorinated gas"

<table><tr><td>Journal:</td><td>Journal of Magnetic Resonance Imaging</td></tr><tr><td>Manuscript ID</td><td>Draft</td></tr><tr><td>Wiley - Manuscript type:</td><td>Editorial</td></tr><tr><td>Classification:</td><td>Non-proton imaging < Imaging Principles and Education < Basic Science, Lung < Body imaging < Clinical Science, Quality assurance and phantoms < Imaging technology and safety < Basic Science</td></tr><tr><td>Manuscript Keywords:</td><td>fluorine-19, ventilation imaging, lung MRI, inspiratory volume control</td></tr></table>
Over the last two decades, pulmonary MRI techniques have gained significant attractiveness to clinicians and radiologists for the regional quantification of pulmonary function with mapping of key parameters of pulmonary physiology such as ventilation, perfusion, gas exchange or pulmonary biomechanics¹.

The increasing clinical importance of MRI in the diagnosis of lung diseases and patient management is tied to several methodological advances and technological breakthroughs, including UTE-type sequences and hyperpolarization techniques for isotopes of rare gas helium-3 and xenon-129 ($^{129}$Xe). Together these new techniques have positioned MRI as an imaging modality of first choice for indications such as cystic fibrosis - driven by the absence of ionizing radiations - and as shown more recently for long COVID disease with the possibility to image dissolved $^{129}$Xe in red blood cell in patients².

Despite its high diagnostic value, demonstrated on numerous pathologies (COPD, asthma, cystic fibrosis), $^{129}$Xe MRI remains limited to a few leading clinical research centers in the world, due to its relative technical complexity and cost (need for polarizer, broadband imaging capabilities and dedicated RF coil).

Alternative approaches³,⁴ to the use of $^{129}$Xe for lung ventilation imaging exist, however. Among them, the use of inert fluorinated gases is the most advanced in terms of clinical applications and has the potential for large-scale deployment⁵. Despite inferior capabilities (lower SNR, no imaging of dissolved phase) to hyperpolarized gas, this approach offers a number of advantages in terms of cost (no polarizer needed) and ease of preparation and delivery of inhalable gas to the patient. As a matter of fact, fluorine-19 ($^{19}$F) MRI has already shown its applicability and potential for certain pulmonary pathologies such as COPD and asthma⁶,⁷. However, validation studies are still needed to strengthen the robustness of $^{19}$F MRI, establish its reproducibility and extend its attractiveness for the radiologists and clinicians.
The authors of the "Volume-controlled 19F MR ventilation imaging of fluorinated gas" paper⁸ aimed precisely at this kind of objective. In this study they investigated the use of a fluorinated gas delivery device and assessed its impact on the acquisition, the quantification and the repeatability of several ¹⁹F ventilation readouts. Additionally, they computed the correlation of ¹⁹F imaging parameters with predicted forced expiratory volume in one second (FEV₁ % pred) derived from pulmonary function testing.

For this purpose, 30 healthy volunteers and 26 COPD patients were examined using a normoxic mixture of perfluoropropane (C₃F₈) and oxygen. On the same imaging session, the subjects underwent successively a lung ventilation MRI protocol with and without the use of the volume-controlled gas delivery system. This MRI protocol was repeated for each subject one week later. The ¹⁹F MRI readouts assessed in this study were both static – the ventilated volume percentage at the initial first and last ¹⁹F images – and dynamic – time to fill, fractional ventilation and wash-in time.

The authors observed that, as a sign of improved reproducibility, the intraclass correlation coefficients between the first and second scan one week later increased for all the ¹⁹F MRI readouts when using gas delivery system. In the same way, they also reported that the coefficients of variation between first and second scan for static and dynamic imaging readouts were lower for COPD and healthy subjects when using the gas delivery system. Additionally, strong and moderate linear correlations between ¹⁹F MRI readouts and FEV₁% pred were strengthened when using the gas delivery system.

Overall, this study demonstrates on a relatively large population the feasibility and interest of using a gas delivery system for ¹⁹F lung MRI. This type of device can be particularly useful to standardize ¹⁹F acquisitions based on multiple time-resolved breaths that generate ventilation dynamic measurements. Furthermore, this device will be especially important for patients with
chronic lung diseases such as COPD or CF, where reliable follow-up is essential for patient management.

While the publication of XX et al represents an important step toward routine clinical practice of ¹⁹F lung MRI, it remains to be seen whether its imaging markers will provide clinically valuable information for the diagnosis and phenotyping of lung diseases, the evaluation of drug or treatment efficacy, and the understanding of lung disease onset and progression.

References

1. Hatabu H, Ohno Y, Gefter WB et al; Fleischner Society. Expanding Applications of Pulmonary MRI in the Clinical Evaluation of Lung Disorders: Fleischner Society Position Paper. Radiology 2020 297:286-301.

2. Grist JT, Collier GJ, Walters H et al. Lung Abnormalities Depicted with Hyperpolarized Xenon MRI in Patients with Long COVID. Radiology 2022 24:220069.

3. Mosbah K, Ruiz-Cabello J, Berthezène Y, Crémillieux Y. Aerosols and gaseous contrast agents for magnetic resonance imaging of the lung. Contrast Media Mol Imaging 2008 3:173-90.

4. Kruger SJ, Nagle SK, Couch MJ, Ohno Y, Albert M, Fain SB. Functional imaging of the lungs with gas agents. J Magn Reson Imaging. 2016 43:295-315.

5. Couch MJ, Ball IK, Li T, Fox MS, Biman B, Albert MS. ¹⁹F MRI of the Lungs Using Inert Fluorinated Gases: Challenges and New Developments. J Magn Reson Imaging. 2019 49:343-354.

6. Halaweish AF, Moon RE, Foster WM et al. Perfluoropropane gas as a magnetic resonance lung imaging contrast agent in humans. Chest 2013 144:1300-1310.
7. Gutberlet M, Kaireit TF, Voskrebenzev A et al. Free-breathing Dynamic <sup>19</sup>F Gas MR Imaging for Mapping of Regional Lung Ventilation in Patients with COPD. Radiology. 2018 286:1040-1051.

8. XXXX. Volume-controlled 19F MR ventilation imaging of fluorinated gas. J Magn Reson Imaging.