Background There is increasing evidence in patients with Primary Spontaneous Pneumothorax (PSP) of emphysema-like change (ELC) and inflammation. Pulmonary function tests are global metrics, not sensitive to subtle disease. Computed tomography scans can provide detailed structural, but not direct functional, information. Hyperpolarised ¹²⁹Xenon magnetic resonance imaging (MRI) allows functional assessment of ventilation.

Methods Patients underwent ¹²⁹Xe MRI ventilation scan with a single breath-hold of 1L ¹²⁹Xe with ˜10% hyperpolarisation. Percentage ventilation of lung receiving ¹²⁹Xe hyperpolarized gas were analysed by lobe using a semi-automated software package.¹

Results Of 10 PSP patients, 8 (80%) were male, (median age 28.6 years), 5 (50%) were current or ex-smokers. Mean overall%Ventilation was 88.0% (SD 4.8%) and was correlated with forced expiratory volume in 1 s, (R2 0.41, p 0.045) and diffusing capacity, (R² 0.77, p<0.001). Regional differences were demonstrated between lobes. Smokers had a reduced%Ventilation (overall 3.9%), which was particularly marked in the upper lobes: right 9.0%, left 4.8%.

Conclusion This study demonstrates reduced% ventilation on ¹²⁹Xe MRI in patients post-PSP. These areas may represent the ELC, known to be associated with PSP, and were more marked in smokers. ¹²⁹Xe MRI is a non-ionising technique with the potential to visualise and characterise important subtle structural abnormalities. On-going work will assess pulmonary microstructure and gas transfer capacity to provide a comprehensive functional/structural evaluation on a regional basis, and its correlation with risk of PSP recurrence.

Reference

1. Matin, Radiology2017.