Three‐dimensional sector‐wise golden angle–improved k‐space uniformity after electrocardiogram binning

Abstract

PurposeTo develop and evaluate a 3D sector‐wise golden‐angle (3D‐SWIG) profile ordering scheme for cardiovascular MR cine imaging that maintains high k‐space uniformity after electrocardiogram (ECG) binning.MethodCardiovascular MR (CMR) was performed at 1.5 T. A balanced SSFP pulse sequence was implemented with a novel 3D‐SWIG radial ordering, where k‐space was divided into wedges, and each wedge was acquired in a separate heartbeat. The high uniformity of k‐space coverage after physiological binning can be used to perform functional imaging using a very short acquisition. The 3D‐SWIG was compared with two commonly used 3D radial trajectories for CMR (i.e., double golden angle and spiral phyllotaxis) in numerical simulations. Free‐breathing 3D‐SWIG and conventional breath‐held 2D cine were compared in patients (n = 17) referred clinically for CMR. Quantitative comparison was performed based on left ventricular segmentation.ResultsNumerical simulations showed that 3D‐SWIG both required smaller steps between successive readouts and achieved better k‐space sampling uniformity after binning than either the double golden angle or spiral phyllotaxis trajectories. In vivo evaluation showed that measurements of left ventricular ejection fraction calculated from a 48 heart‐beat free‐breathing 3D‐SWIG acquisition were highly reproducible and agreed with breath‐held 2D‐Cartesian cine (mean ± SD difference of −3.1 ± 3.5% points).ConclusionsThe 3D‐SWIG acquisition offers a simple solution for highly improved k‐space uniformity after physiological binning. The feasibility of the 3D‐SWIG method is demonstrated in this study through whole‐heart cine imaging during free breathing with an acquisition time of less than 1 min.