Background: Cine balanced steady-state free precession (SSFP), the preferred sequence for ventricular function, demands uninterrupted radio frequency (RF) excitation to maintain the steady-state during suspended respiration. This is difficult to accomplish in sedated children. In this work, we validate a respiratory triggered (RT) SSFP sequence that drives the magnetization to steady-state before commencing retrospectively cardiac gated cine acquisition in a sedated pediatric population.
Methods: This prospective study was performed on 20 sedated children with congenital heart disease (8.6 ± 4 yrs). Identical imaging parameters were used for multiple number of signal averages (MN) and RT cine SSFP sequences covering both the ventricles in short-axis (SA) orientation. Image quality assessment and quantitative volumetric analysis was performed on the datasets by two blinded observers. One-sided Wilcoxon signed rank test and Box plot analysis were performed to compare the clinical scores. Bland-Altman (BA) analysis was performed on LV and RV volumes.
Results: Scan duration for SA stack using RT-SSFP (3.9 ± 0.8 min) was slightly shorter than MN-SSFP (4.6 ± 0.9 min) acquisitions. The endocardial edge definition was significantly better for RT than MN, blood to myocardial contrast was better for RT than MN without reaching statistical significance, and inter slice alignment was comparable. BA analysis indicates that the variability of volumetric indices between RT and MN is comparable to inter and intra-observer variability reported in the literature.
Conclusions: The free breathing RT-SSFP sequence allows diagnostic images in sedated children with significantly better edge definition when compared to MN-SSFP, without any penalty for total scan time.