Ellipsoidal Cartesian K-space Sampling with Variable Readout Duration for 3D MRI Acceleration

Motivation: Conventional Cartesian MRI acceleration techniques subsample the K-space in the phase encoding direction, but rarely in the readout direction. Goal(s): To develop a new technique that accelerates Cartesian MRI acquisition by subsampling K-space in the readout direction. Approach: The ellipsoidal K-space sampling with variable readout duration was proposed. T1-weighted and time-of-flight (TOF) MR angiography images were acquired with the proposed method and compared with conventional cylindrical sampling. Results: The proposed method reduces scan time while maintaining image quality. The acceleration ratio was 23.4% for T1-weighted, and 6% for TOF. Impact: Ellipsoidal sampling strikes a balance between efficiency and simplicity. It is compatible with other acceleration methods that subsample the phase encodings and provides a new insight for acceleration along the readout direction.