Compressed-Sensing Motion Compensation (CosMo): A Joint Prospective-Retrospective Respiratory Navigator for Coronary MRI

摘要

Prospective right hemi-diaphragm navigator is commonly used in free-breathing coronary MRI. The navigator results in an increase in acquisition time to allow for re-sampling of the motion-corrupted k-space data. In this study, we are presenting a joint prospective-retrospective navigator motion compensation algorithm called compressed-sensing motion compensation (CosMo). The inner k-space region is acquired using a prospective navigator; for the outer k-space, a navigator is only used to reject the motion-corrupted data without reacquiring them. Subsequently, those unfilled k-space lines are retrospectively estimated using compressed sensing (CS) reconstruction. We imaged right coronary artery (RCA) in 9 healthy adult subjects. An under-sampling probability map and sidelobe-to-peak ratio (SPR) were calculated to study the pattern of under-sampling, generated by navigator. RCA images were then retrospectively reconstructed using CosMo for gating windows between 3–10 mm and compared with the ones fully acquired within the gating windows. Qualitative imaging score and quantitative vessel sharpness were calculated for each reconstruction. The probability map and SPR show the navigator generates a random under-sampling k-space pattern. There were no statistically significant differences between the vessel sharpness and subjective score of the two reconstructions. CosMo could be an alternative motion compensation technique for free-breathing coronary MRI that can be used to reduce scan time.