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Hyperpolarized 129Xe MRI Research Core

Hyperpolarized 129Xe MRI Research Core diagram

Mission

Our mission is to develop and utilize regional and non-invasive quantitative biomarkers for evaluating the structure and function of the lungs using hyperpolarized 129Xe MRI.

xenon  hyperpolarizer Figure 1Xenon Hyperpolarizer used to prepare hyperpolarized 129Xe for MRI.

About Hyperpolarized 129Xe MRI

In hyperpolarized 129Xe MRI, the MRI signal intensity of xenon gas is enhanced more than 50,000-fold using spin-exchange optical pumping. This process is commonly known as "hyperpolarization".

Once hyperpolarized, xenon gas is dispensed into a dose bag and delivered to a subject lying in the MRI scanner. The subject breathes in this gas, and their lungs are imaged during a short breath-hold.

By tailoring our imaging methodology, we can image several important facets of pulmonary structure and function: Ventilation, Terminal Airspace Dimensions, and Gas Exchange.

Learn more about Hyperpolarized 129Xe MRI:

In hyperpolarized 129Xe ventilation imaging, the distribution of xenon gas within the lungs is imaged. Areas of the lungs that are poorly ventilated show up as dark areas in these images. These dark areas are quantified using a quantity called the ventilation defect percent (VDP). VDP has shown to correlate strongly with conventional pulmonary function tests such as FEV1 and Lung Clearance Index. Moreover, VDP has proven to be more sensitive to early lung function abnormalities than FEV1.

At KUMC, we are interested in improving both the imaging of ventilation and the quantification of these images. Ventilation imaging is commonly performed by imaging thick slices of the lungs, collecting a total of 10-14 imaging slices over the lungs in a 16 second breath-hold. We have developed a 3D spiral imaging sequence that is capable of acquiring up to 50 imaging slices of the lungs in 9 seconds. We can also acquire an image of the underlying anatomy in 4 seconds within the same breath-hold, which improves our ability to quantify VDP.

Hyperpolarized 129Xe ventilation images acquired using a 3D spiral sequence. Figure 2. Hyperpolarized 129Xe ventilation images acquired using a 3D spiral sequence. High-resolution images covering the entire lungs are able to be acquired within a 16 s breath-hold. Gas images are shown overlaid on an image of the underlying anatomy acquired within the same breath-hold.

Once in the lungs, hyperpolarized 129Xe continues to be in motion, diffusing throughout the terminal airspaces. This diffusive motion is restricted within the confines of the alveoli, which can be measured using diffusion-weighted MRI. The apparent diffusion coefficient (ADC) provides a sensitive marker of terminal airspace dimensions, with larger values of ADC reflecting increased airspace size (e.g. emphysema), and smaller values reflecting decreased airspace size (e.g. inflammation).

Because of the requirements for diffusion-weighted imaging, these scans typically require a longer breath-hold than ventilation imaging. At KUMC, we are interested in reducing scan times in order to make hyperpolarized 129Xe MRI more comfortable for all subjects. To that end, we have employed a similar 3D spiral sequence to that used for ventilation imaging to image hyperpolarized 129Xe diffusion within the lungs. This sequence allows us to quantify ADC in 30-40 image slices within the lungs.

Hyperpolarized 129Xe apparent diffusion coefficient (ADC) map acquired in a healthy subject using a 3D spiral, diffusion weighted imaging sequence. Figure 3. Hyperpolarized 129Xe apparent diffusion coefficient (ADC) map acquired in a healthy subject using a 3D spiral, diffusion weighted imaging sequence. Within the lung volume, there is a homogeneous distribution of ADC values, while gas within the larger airways exhibit elevated ADC due to relatively free diffusion of gas. ADC maps are shown overlaid on an image of the underlying anatomy acquired within the same breath hold.

Xenon gas is soluble in red blood cells (RBCs) and other pulmonary tissues ("Barrier"), which enables quantitative imaging of pulmonary gas exchange. In particular, the amount of xenon dissolved in RBCs and Barrier, as well as their ratio (RBC/Barrier) can be quantified with 3D spatial resolution in the lungs. Moreover, cardiogenic oscillations of the xenon signal dissolved in RBCs can be imaged, which may provide further insight into perfusion within the pulmonary microvasculature. These markers have proven to be sensitive to interstitial thickening and reduced RBC transport in patients with interstitial lung disease and pulmonary hypertension.

At KUMC we are interested in demonstrating the reproducibility of gas exchange imaging, decreasing imaging time, and improving the quantitative analysis of images. We have a funded research study to assess the reproducibility of the RBC/Barrier ratio in patients with idiopathic pulmonary fibrosis and chronic hypersensitivity pneumonitis. We have also adapted previously reported imaging methods to decrease imaging time while maintaining similar image quality. This has enabled imaging of both gas exchange and the underlying anatomy within a single breath, which improves our ability to quantify gas exchange using these images.

Hyperpolarized 129Xe gas exchange images acquired in two subjects. Figure 4. Hyperpolarized 129Xe gas exchange images acquired in two subjects. In subject 1, Most voxels of Ventilation, Barrier, and RBC images fall near to the mean of a group of healthy subjects (green). Subject 2 exhibits normal ventilation, but mildly elevated Barrier signal (purples), and some decreased RBC signal (Red).

Our focus is to use hyperpolarized 129Xe MRI to quantify pulmonary structure and function, but we also have an interest in other imaging methods. Of particular interest is ultra-short-echo time (UTE) MRI, which can be used to acquire high-quality images of pulmonary structure. We are interested in using UTE MRI for the evaluation of lung structure in subjects for whom computed tomography (CT) imaging is challenging (e.g. pediatrics).

In addition, we are also interested in linking hyperpolarized 129Xe biomarkers to quantitative CT metrics. More information on quantitative CT soon to come.

Peter Niedbalski portraitDr. Peter Niedbalski 

Dr. Peter Niedbalski is a research assistant professor at KU Medical Center and oversees the operation of the Hyperpolarized 129Xe MRI Research Core.

 His background is in MRI and hyperpolarization physics, and his primary interests are in using novel MRI methods to understand early disease progression in a wide variety of pulmonary diseases.


Chase Hall portraitDr. Chase Hall

Dr. Chase Hall is an assistant professor at KU Medical Center and the associate director of the ILD and Rare Lung Disease Clinic.

In addition to his clinical duties caring for patients with interstitial lung disease, Dr. Hall is interested in the use of imaging to better understand and treat lung disease. Dr. Hall also is an expert in quantitative analysis of images and deep learning imaging processing methods and is a driving force behind the complete automation of our image processing pipelines.


Mario Castro portraitDr. Mario Castro

Dr. Mario Castro is the Chief of the division of Pulmonary, Critical Care, and Sleep Medicine at KUMC.

He has extensive experience using novel imaging methods, including hyperpolarized 129Xe MRI, in his translational asthma research.


Vick Singh portraitVick Singh

Manvir (Vick) Singh is a research assistant in the lab of Dr. Niedbalski.

Vick is in charge of the day-to-day operation of the hyperpolarization system, which includes preparing hyperpolarized 129Xe for all of our research studies.

  • 129Xe Gas Exchange Imaging in IPF and cHP: A Reliability Study.
  • Evaluating Lung Structure and Function in Survivors of COVID-19 using Hyperpolarized 129Xe MRI
  1. Hall CS, Quirk JD, Goss CW, et al. Single-session bronchial thermoplasty guided by 129Xe magnetic resonance imaging. A pilot randomized controlled clinical trial. Am J Respir Crit Care Med. 2020; 202(4):524-34.
  2. Niedbalski PJ, Bier EA, Wang Z, Willmering MM, Driehuys B, Cleveland ZI. Mapping cardiopulmonary dynamics within the microvasculature of the lungs using dissolved 129Xe MRI. J Appl Physiol. 2020; 129(2):218-29.
  3. Niedbalski PJ, Willmering MM, Robertson SH, et al. Mapping and correcting hyperpolarized magnetization decay with radial keyhole imaging. Magn Reson Med. 2019; 82(1):367-76.
  4. Willmering MM, Niedbalski PJ, Wang H, et al. Improved pulmonary 129Xe ventilation imaging via 3D-spiral UTE MRI. Magn Reson Med. 2020; 84(1):312-20.

Acknowledgments

The Hyperpolarized 129Xe MRI Research Core was established in August 2020. We are indebted to collaborators around the world who provided assistance in getting our site up and running. In particular, we would like to thank John Mugler for providing the imaging sequences that enabled us to acquire our first xenon images.

KUMC is a member site of the 129Xe MRI Clinical Trials Consortium, a group dedicated to the facilitation of clinical research, education, and awareness of the capabilities of 129Xe MRI.


Contact us

For any questions about the Hyperpolarized 129Xe MRI Research Core, please contact Dr. Peter Niedbalski: pniedbalski@kumc.edu

Internal Medicine

University of Kansas Medical Center
Internal Medicine
Pulmonary, Critical Care, and Sleep Medicine Division
Mailstop 3007
3901 Rainbow Boulevard
Kansas City, KS 66160
Phone: 913-588-6045