Accelerated reconstruction of 5D free-running MRI with variable projection-augmented Lagrangian (VPAL)

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Computational Science

Background:

• Ferumoxytol-enhanced 5D free-running cardiac MRI offers CTA-like image quality.
• Current reconstruction methods like ADMM are computationally intensive, limiting clinical application.
• Faster reconstruction is crucial for routine in-line 5D cardiac MRI.

Purpose of the Study:

• To evaluate the Variable Projection Augmented Lagrangian (VPAL) method for 5D free-running cardiac MRI reconstruction.
• To compare the computational efficiency and image quality of VPAL against the ADMM method.
• To determine if VPAL can enable faster, routine clinical use of 5D cardiac MRI.

Main Methods:

• Implemented VPAL to solve the optimization problem for spatial sparsity and temporal smoothness regularized MRI reconstruction.
• Compared VPAL with ADMM for reconstructing 5D cardiac MRI data.
• Evaluated reconstruction time and image quality using numerical simulations and clinical pediatric patient data.

Main Results:

• VPAL achieved significantly lower overall reconstruction times (10.0 ±3.7 hours) compared to ADMM (18.1 ±8.1 hours).
• VPAL's efficiency increased with more cardiac phases reconstructed.
• Image quality was comparable between VPAL and ADMM, with no compromise in qualitative or quantitative assessments (e.g., LVEF, border sharpness).

Conclusions:

• VPAL offers a computationally efficient alternative for 5D free-running CMR reconstruction.
• The method achieves comparable accuracy to ADMM while substantially reducing reconstruction time.
• VPAL facilitates more routine clinical application of high-quality 5D cardiac MRI.