Electric Potential Energy Optimized 3D Radial Sampling Trajectories for MRI

Authors

Christopher Huynh
Datta Singh Goolaub
Christopher K Macgowan

Publication Date

10-15-2024

Journal

Scientific Reports

DOI

10.1038/s41598-024-74437-x

PMID

39406755

PMCID

PMC11480509

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Golden, K-space sampling trajectories, 3D dynamic MRI, Optimization, Biomedical engineering, Computational science

Abstract

A novel method for creating “golden” 3D center-out radial MRI sampling trajectories was developed and analyzed. This method, called ELECTRO (ELECTRic potential energy Optimized), uses repulsive forces to minimize electric potential energy. An objective function , the electric potential energies of all subsets of consecutive readouts in a 3D radial trajectory, and its reduced form were minimized using a multi-stage optimization strategy. A metric called normalized mean nearest neighbor angular distance (NMNA) was proposed for describing distributions of points on a sphere. ELECTRO and other relevant golden trajectories were compared in silico using NMNA and point spread function analysis. Consecutive readouts from an ELECTRO trajectory were well spread out, with consistent NMNA values across sphere sizes (σNMNA = 0.005) and between regions on the sphere (NMNA ≈ 1.49). Conversely, the supergolden trajectory had poor consistency in NMNA values (σNMNA = 0.090) and clustering (NMNA = 1.28 at the pole with 40,000 readouts) that lead to artifact in the point spread function. Multi-stage optimization was faster than single-stage and obtained lower values of (e.g., 0.87 vs. 0.91, for a sphere size of 40). In conclusion, ELECTRO trajectories are more golden than other 3D center-out radial trajectories, making them a suitable candidate for dynamic 3D MR imaging.

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