Hyperpolarized Xenon Functional Lung Imaging in COPD Patients Undergoing Targeted Lung Denervation

Targeted Lung Denervation (TLD) Therapy is intended to improve airway smooth muscle relaxation from the site of treatment all the way to the lung periphery, which may be beneficial in the treatment of patients with COPD. To better understand the physiological effects of this therapy, the investigators intend to conduct a functional magnetic resonance imaging study of the lung with HP 129Xe study in COPD patients undergoing this procedure. HP 129Xe provides valuable regional information about ventilation and gas exchange in both healthy and diseased lung.

This study will be assessing the treatment response using HP 129Xe MRI for patients undergoing Target Lung Denervation (TLD) in COPD patients. Subjects eligible to participate in this study are those who agree and have already consented to participate in the AIRFLOW-3 clinical trial for TLD treatment at Temple University Hospital. The intent of this study is to image lung function using HP 129Xe MRI in ten TLD subjects before and approximately three months post TLD procedure as an observational sub-study. Subjects willing to participate in this sub-study will have to consent to this study and plan for two MRI imaging sessions: one prior TLD and a follow-up at approximately three months post TLD procedure. As part of this companion protocol at Penn, the aim is to image each subject twice, using a total of 2.5L of HP 129Xe gas administered over approximately 50 breaths during each visit. Using the dynamic image set acquired, the investigators will characterize each imaging voxel (approximately 4mm x 4mm x 4mm) in terms of its tidal volume (in mm3), functional residual capacity (in mm3), fractional ventilation (efficiency of gas exchange via ventilation, unit less), and what is defined as "arrival time", which can be also shown as 'tidal volume hysteresis', and corresponds to the area enclosed when the local tidal volume is plotted against the inhaled gas volume. The latter parameter is zero in a region that inflates and deflates perfectly in sync with the inhaled gas volume but grows in magnitude when the two are out of sync: e.g., in cases obstructed ventilation or air trapping. The subject will be coached to maintain a reasonably steady breathing cadence of 10-15 breaths per minute, depending on their size and natural breathing rate, but will be otherwise unconstrained with respect to breath timing and volume. Each imaging session will take approximately 30 minutes, including positioning in the MRI and inhalation of a small HP 129Xe dose for scanner calibration. The proposed dynamic HP 129Xe MRI technique allows for the quantification of fractional ventilation (FV), tidal volume (TV), functional residual capacity (FRC), arrival time (τ), apparent diffusion coefficient (ADC), and dissolved phase HP 129Xe information. Obtaining all of these parameters in a single scan session reduces the necessary amount of imaging gas while increasing accuracy by correcting artifacts associated with collateral ventilation and the slow filling of parenchyma in diseased lungs. Following the two imaging sessions, data will be analyzed and compared, including comparison with other lung function measuring techniques.