Whole lung morphometry with 3D multiple b-value hyperpolarized gas MRI and compressed sensing.

Area of Science:

• Medical Imaging
• Pulmonary Medicine
• Biophysics

Background:

• Three-dimensional (3D) diffusion-weighted (DW) MRI using hyperpolarized 3He gas allows for detailed lung morphometry.
• Acquisition time and breath-hold duration are limitations for clinical translation of 3D DW-MRI.

Purpose of the Study:

• To demonstrate the feasibility of 3D multiple b-value 3He DW-MRI for whole lung morphometry using compressed sensing (CS).
• To accelerate scan times for improved clinical applicability.

Main Methods:

• Retrospective undersampling of fully-sampled 3D 3He DW-MRI data was performed to simulate CS acquisition.
• Optimal undersampling patterns were determined by minimizing error in apparent diffusion coefficient (ADC) maps.
• Prospective CS acquisitions were validated against fully-sampled data in healthy volunteers and a COPD patient.

Main Results:

• Compressed sensing reconstructions showed no visual artifacts and preserved image features.
• Mean global ADC and mean alveolar dimension (LmD) values from CS acquisitions agreed well with fully-sampled data (3.4% and 5.1% difference, respectively).
• Observed differences were within the standard deviation and consistent with reported values for healthy and COPD lungs.

Conclusions:

• Accelerated CS acquisition enables 3D multiple b-value 3He DW-MRI in a single breath-hold.
• This technique facilitates whole lung morphometry mapping.
• CS-accelerated 3He DW-MRI holds promise for clinical lung imaging and research.