Functional lung assessment using hyperpolarised xenon gas magnetic resonance imaging

Thesis

Purpose

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality worldwide. The standard method for assessing lung function in COPD is spirometry, which provides global lung function information but is a poor predictor of disability and quality of life. The overall aim of this thesis is to develop utility of hyperpolarised xenon gas magnetic resonance imaging (HP ¹²⁹Xe-MRI) as a technique to evaluate regional lung function.

Methods

Studies were approved by the National Research Ethics Service (NRES). Eleven volunteers and 25 patients with COPD underwent HP ¹²⁹Xe-MRI, pulmonary function tests (PFTs) and quantitative computerised tomography (QCT). Gravitational-dependent gradients of HP ¹²⁹Xe-MRI were compared between prone and supine postures in healthy volunteers. Lobar quantification of HP ¹²⁹Xe-MRI was completed in COPD patients, who also underwent time-resolved HP ¹²⁹Xe-MRI and HP ¹²⁹Xe-MRI pre- and post-salbutamol to determine feasibility of detecting regional delayed ventilation and post-intervention change. The relationship between study measures was assessed using Pearson’s correlation coefficient.

Results

HP ¹²⁹Xe-MR ventilation gradients were more marked in the supine than prone posture in healthy volunteers, whereas diffusion-weighted gradients were more uniform. HP ¹²⁹Xe-MRI was successfully quantified according to pulmonary lobes and correlated with lobar lung anatomy (QCT) and global functional transfer capability (TLCO) (r=-0.61, p<0.005). Delayed ventilation was observed with time-resolved breath-hold HP ¹²⁹Xe-MRI. Differential regional ventilation change was detected with HP ¹²⁹Xe-MRI post-salbutamol.

Conclusion

These data demonstrate technical optimisation of HP ¹²⁹Xe-MRI in healthy volunteers and COPD patients. Successful generation of lobar HP ¹²⁹Xe-MRI parameters offers an automated analysis method that can be adopted into the clinical workflow. Finally proof-of-principle data have identified roles for HP ¹²⁹Xe-MRI in evaluating regional treatments and assessing therapeutic response. Future work will evaluate the role of HP ¹²⁹Xe-MRI in patient selection for lung volume reduction therapy and as a surrogate end-point in drug development studies.

Authors: Matin, T

• DOI: 10.5287/ora-d54baaenv
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Hyperpolarised xenon gas MRI; Functional lung imaging
• Subjects: Pulmonary function; Magnetic resonance imaging