Dynamic Chest X-ray With Simultaneous Spirometry

Dynamic chest X-ray (DCR) records images of the chest in motion in a 'recording' over 10-20 seconds. This is essentially a video x-ray of the chest and associated structures involved in breathing. The images acquired by the DCR can be processed using computer algorithm and key quantitative measures derived (such as diaphragm movement speed and changes in lung field area). Due to the way the X-ray is acquired, this is relatively lower radiation than other video caption imaging available (such as fluoroscopy). The time component of the imaging (vs static imaging) also opens up possibilities for clinical utilisation beyond imaging techniques that are already available without losing clinical information that a conventional static x-ray provides. The direct visualization of the chest and lung field in motion may therefore provide clinically relevant information about respiratory function. It may be possible that relating DCR to conventional lung function testing allows it to be used as a surrogate tool for assessing pulmonary function. Alternatively, it may provide different parameters of lung function that don't directly correlate with conventional testing but are of themselves clinically relevant.

Cystic fibrosis (CF) is an autosomal recessive genetic condition resulting in viscid, dehydrated luminal secretions. It has multi-system consequences but is usually characterised by a cycle of recurring lung infections and inflammation resulting in progressive lung damage. A key clinical investigation for people with cystic fibrosis (pwCF), as well as many other chest conditions, is a spirometry breathing test. Despite this spirometry can be poorly tolerated in individuals with underlying respiratory conditions. Patient factors combined with the ease and speed of acquiring DCR may mean it is better tolerated than conventional pulmonary function techniques such as spirometry. No previous studies have directly compared DCR with simultaneous breathing tests (such as spirometry). This is important as there can be significant variability in two different breathing manoeuvres such as used in breathing tests like spirometry. This means direct comparison is difficult when the tests are performed sequentially.

This study aims to address this by performing simultaneous spirometry and DCR to establish how DCR compares with spirometry in a healthy population of individuals. Study investigators also aim to perform DCR with simultaneous spirometry in a cohort of people with cystic fibrosis (pwCF), this would allow for comparison between the two groups. Furthermore the DCR has been part of Liverpool Heart and Chest Hospital's (LHCH) annual review process for pwCF since 2019. Study investigators therefore intend to review how changes in DCR metrics over time relate to other key clinical parameters for pwCF such as spirometry values. A questionnaire on patient experiences of DCR will be provided to patients after completion of the examinations, to be filled in at the time of investigation acquisition.

Principal research objective: to understand how DCR relates to a conventional assessment of lung function testing in the form of spirometry in both pwCF and those with no underlying lung health problems.

Secondary research objective: to understand how the relationship between metrics recorded by DCR imaging over time and key clinical markers of CF recorded in the annual review process, such as lung function recorded by spirometry.