Background: Lung proton MRI (1H-MRI) offers a radiation-free alternative to CT for paediatric lung imaging. Recent advances have enabled high-resolution free-breathing (FB) imaging, allowing for combined structural and functional assessment within a single protocol.
Purpose: Optimise structure-function FB and short breath-hold 1H-MRI in children and neonates by:
1. Quantifying gas trapping from breath-hold expiratory 1H-MRI to detect early functional impairment.
2. Developing a simple, robust lung ventilation mapping approach using 3D FB ultra-short echo time (UTE) 1H-MRI.
3. Comparing UTE and zero echo time (ZTE) 1H-MRI for high-resolution 3D FB structural and functional lung imaging.
4. Optimising 2D FB 1H-MRI for functional lung imaging in neonates.
Methods:
1. Developed a post-processing workflow to quantify gas trapping from breath-hold 1H-MRI in people with Cystic Fibrosis (pwCF), compared with pulmonary function tests and 129Xe ventilation MRI.
2. Structural UTE images at end-tidal-expiration and inspiration were registered to generate 1H-MRI ventilation maps, evaluating repeatability in healthy volunteers and implementing in pwCF and neonates.
3. Structural UTE and ZTE were compared in healthy volunteers and pwCF. 1H-MRI ventilation was also compared.
4. Phase-resolved functional lung (PREFUL) MRI was implemented in neonates, with deep-learning (DL) reconstruction and real-time MRI introduced to improve image quality and temporal resolution.
Results:
1. Gas trapping could be visualised and quantified, with abnormal levels observed in pwCF with normal lung function.
2. UTE ventilation maps showed homogeneous ventilation in healthy volunteers, visualised abnormalities in pwCF and was feasible in neonates.
3. UTE demonstrated superior image quality to standard ZTE, though ZTE improved significantly with DL reconstruction. Ventilation mapping using ZTE data showed some feasibility.
4. Neonatal PREFUL was limited by motion, though DL reconstruction and real-time acquisition showed potential for improvement.
Conclusions: Breath-hold and FB lung 1H-MRI together provide a complementary structural and functional imaging package in children and neonates.
