Three-dimensional oxygen-enhanced MRI of the human lung at 1.5T with ultra-fast balanced steady-state free precession.
OBJECTIVE
To assess the feasibility of 3D oxygen-enhanced (OE) MRI of the lung at 1.5T using multi-volumetric ultra-fast balanced steady-state free precession (ufSSFP) acquisitions.


METHODS
Isotropic imaging of the lung for OE-MRI was performed with an adapted 3D ufSSFP sequence using five breath-hold acquisitions ranging from functional residual capacity to tidal inspiration under both normoxic (room air) and hyperoxic (100% O2) gas conditions. For each O2concentration, a sponge model (which captures the parenchymal signal intensity variation as a function of the lung volume) was fitted to the acquired multi-volumetric datasets after semiautomatic lung segmentation and deformable image registration. From the retrieved model parameters, 3D oxygen-enhancement maps were calculated.


RESULTS
For OE ufSSFP imaging, the maximum parenchymal signal is observed for flip angles around 23° under both normoxic and hyperoxic conditions. It is found that the sponge model accurately describes parenchymal signal at different breathing positions, thereby mitigating the confounding bias in the estimated oxygen enhancement from residual density modulations. From the model, an average lung oxygen enhancement of 7.0% ± 0.3% was found in the healthy volunteers, and the oxygen-enhancement maps indicate a ventral to dorsal gravitation-related gradient.


CONCLUSIONS
The study demonstrates the feasibility of whole-lung OE-MRI from multi-volumetric ufSSFP in healthy volunteers. Magn Reson Med 79:246-255, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland.|Department of Biomedical Engineering, University of Basel, Basel, Switzerland.
Orso
O
Pusterla
Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland.|Department of Biomedical Engineering, University of Basel, Basel, Switzerland.
Grzegorz
G
Bauman
Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland.|Department of Biomedical Engineering, University of Basel, Basel, Switzerland.
Oliver
O
Bieri
D000328:Adult; D062485:Breath Holding; D005240:Feasibility Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008168:Lung / Q000000981:diagnostic imaging* / Q000187:drug effects; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000737:chemistry*; D015203:Reproducibility of Results; D012119:Respiration
D010100:Oxygen
lung MRI; lung functional imaging; oxygen-enhanced; ultra-fast steady-state free precession