Image-Derived Volumetry During Forced Expiration Using a 3D Fermat Looped, Orthogonally Encoded Trajectory

Area of Science:

• Medical Imaging
• Pulmonology
• Biophysics

Background:

• Assessing lung function during forced expiration is crucial for diagnosing respiratory diseases.
• Current MRI techniques often lack the necessary spatio-temporal resolution for dynamic lung imaging.

Purpose of the Study:

• To develop and validate a nongated, 3D MRI method for high-resolution imaging of forced expiration.
• To achieve high spatio-temporal resolution and fidelity in depicting lung dynamics during exhalation.

Main Methods:

• An optimized undersampled 3D Fermat looped, orthogonally encoded trajectory (FLORET) was used for nonsegmented dynamic acquisitions during forced expiration.
• A model-based reconstruction pipeline promoting spatial and temporal total variation was implemented.
• The method was validated using a custom-built lung phantom and then applied to in vivo human measurements.

Main Results:

• The 3D FLORET MRI accurately depicted lung deflation dynamics in both phantom and in vivo experiments.
• Quantitative parameters such as deflation duration and volume change were successfully derived from segmented MR images.
• High temporal resolution (200 ms) and isotropic spatial resolution (5 mm) were achieved.

Conclusions:

• The 3D FLORET MRI technique enables high-resolution, nongated 3D depiction of forced expiration.
• This approach offers potential for improved assessment of lung dynamics and respiratory diseases.
• The method demonstrates high temporal and spatial resolution suitable for dynamic lung imaging.