Self‐gated cine phase‐contrast balanced SSFP flow quantification at 0.55 T

Abstract

AbstractPurposeTo implement cine phase‐contrast balanced SSFP (PC‐bSSFP) for low‐field 0.55T cardiac MRI by exploiting the intrinsic flow sensitivity of the bSSFP slice‐select gradient and the in‐plane phase‐cancelation properties of radial trajectories, enabling self‐gated and referenceless PC‐bSSFP flow quantification at 0.55 T.MethodsA free‐running, tiny golden‐angle radial PC‐bSSFP approach was implemented on 0.55T and 1.5T systems. Cardiac and respiratory self‐gating was incorporated to enable electrocardiogram‐free scanning during breath‐hold and free‐breathing. By exploiting the intrinsic in‐plane phase‐cancelation properties of radial acquisitions and background phase fitting, referenceless single‐point PC‐bSSFP was realized. In vivo data were acquired in the ascending aorta of healthy subjects at 0.55 T and 1.5 T during breath‐hold and free‐breathing. Flow data, SNR, and velocity‐to‐noise ratio were compared relative to data obtained with phase‐contrast spoiled gradient‐echo variants.ResultsVelocities acquired with PC‐bSSFP compared well with data from phase‐contrast spoiled gradient‐echo (RMSEv = 5.8 cm/s). PC‐bSSFP at 0.55 T resulted in high‐quality cine magnitude images and phase maps with sufficient SNR and velocity‐to‐noise ratio. Breath‐hold and free‐breathing PC‐bSSFP performed very similarly, with comparable flow quantification (RMSEv = 5.7 cm/s). Referenceless single‐point PC‐bSSFP results agreed well with two‐point PC‐bSSFP (−1.8 ± 5.2 cm/s) while reducing scan times 2‐fold.ConclusionPC‐bSSFP is feasible on low‐field 0.55T systems, producing high‐quality cine images while permitting simultaneous aortic flow measurements during breath‐hold and free‐breathing and without the need for electrocardiogram gating.