Self-gated fetal cardiac MRI with tiny golden angle iGRASP: A feasibility study.

PurposeTo develop and assess a technique for self-gated fetal cardiac cine magnetic resonance imaging (MRI) using tiny golden angle radial sampling combined with iGRASP (iterative Golden-angle RAdial Sparse Parallel) for accelerated acquisition based on parallel imaging and compressed sensing. Materials and MethodsFetal cardiac data were acquired from five volunteers in gestational week 29-37 at 1.5T using tiny golden angles for eddy currents reduction. The acquired multicoil radial projections were input to a principal component analysis-based compression stage. The cardiac self-gating (CSG) signal for cardiac gating was extracted from the acquired radial projections and the iGRASP reconstruction procedure was applied. In all acquisitions, a total of 4000 radial spokes were acquired within a breath-hold of less than 15 seconds using a balanced steady-state free precession pulse sequence. The images were qualitatively compared by two independent observers (on a scale of 1-4) to a single midventricular cine image from metric optimized gating (MOG) and real-time acquisitions. ResultsFor iGRASP and MOG images, good overall image quality (2.80.4 and 2.61.3, respectively, for observer 1; 3.60.5 and 3.40.9, respectively, for observer 2) and cardiac diagnostic quality (3.8 +/- 0.4 and 3.4 +/- 0.9, respectively, for observer 1; 3.6 +/- 0.5 and 3.6 +/- 0.9, respectively, for observer 2) were obtained, with visualized myocardial thickening over the cardiac cycle and well-defined myocardial borders to ventricular lumen and liver/lung tissue. For iGRASP, MOG, and real time, left ventricular lumen diameter (14.1 +/- 2.2mm, 14.2 +/- 1.9mm, 14.7 +/- 1.1mm, respectively) and wall thickness (2.7 +/- 0.3mm, 2.6 +/- 0.3mm, 3.0 +/- 0.4, respectively) showed agreement and no statistically significant difference was found (all P>0.05). Images with iGRASP tended to have higher overall image quality scores compared with MOG and particularly real-time images, albeit not statistically significant in this feasibility study (P>0.99 and P=0.12, respectively). ConclusionFetal cardiac cine MRI can be performed with iGRASP using tiny golden angles and CSG. Comparison with other fetal cardiac cine MRI methods showed that the proposed method produces high-quality fetal cardiac reconstructions. Level of Evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:207-217