Abstract
BackgroundReal-time cardiovascular magnetic resonance (CMR) assessment of ventricular volumes and function enables data acquisition during free-breathing. The requirement for high spatiotemporal resolution in children necessitates the use of highly accelerated imaging techniques.MethodsA novel real-time balanced steady state free precession (bSSFP) spiral sequence reconstructed using Compressed Sensing (CS) was prospectively validated against the breath-hold clinical standard for assessment of ventricular volumes in 60 children with congenital heart disease. Qualitative image scoring, quantitative image quality, as well as evaluation of biventricular volumes was performed. Standard BH and real-time measures were compared using the paired t-test and agreement for volumetric measures were evaluated using Bland Altman analysis.ResultsAcquisition time for the entire short axis stack (~ 13 slices) using the spiral real-time technique was ~ 20 s, compared to ~ 348 s for the standard breath hold technique. Qualitative scores reflected more residual aliasing artefact (p < 0.001) and lower edge definition (p < 0.001) in spiral real-time images than standard breath hold images, with lower quantitative edge sharpness and estimates of image contrast (p < 0.001).There was a small but statistically significant (p < 0.05) overestimation of left ventricular (LV) end-systolic volume (1.0 ± 3.5 mL), and underestimation of LV end-diastolic volume (− 1.7 ± 4.6 mL), LV stroke volume (− 2.6 ± 4.8 mL) and LV ejection fraction (− 1.5 ± 3.0%) using the real-time technique. We also observed a small underestimation of right ventricular stroke volume (− 1.8 ± 4.9 mL) and ejection fraction (− 1.4 ± 3.7%) using the real-time imaging technique. No difference in inter-observer or intra-observer variability were observed between the BH and real-time sequences.ConclusionsReal-time bSSFP imaging using spiral trajectories combined with a compressed sensing reconstruction showed good agreement for quantification of biventricular metrics in children with heart disease, despite slightly lower image quality. This technique holds the potential for free breathing data acquisition, with significantly shorter scan times in children.
Highlights
Real-time cardiovascular magnetic resonance (CMR) assessment of ventricular volumes and function enables data acquisition during free-breathing
Study population Between December 2017 and February 2018, 60 consecutive children referred for CMR and consented for additional research scans were included into this study
Patients were excluded from this study if: a) there was a requirement for general anesthetic (15 children excluded during the recruitment period), b) the subject had an irregular heart rate or difficulty performing breath-holds (11 children excluded), or c) the subject had single ventricular anatomy which was excluded to ensure that biventricular volumes could be evaluated in all patients (4 children excluded)
Summary
Real-time cardiovascular magnetic resonance (CMR) assessment of ventricular volumes and function enables data acquisition during free-breathing. The clinical standard method of evaluating ventricular volumes is cardiovascular magnetic resonance (CMR) – multi-slice cardiac gated balanced steady state free precession (bSSFP) cine imaging [1]. This technique is routinely used in children and has an important role to play in disease management [2]. The benefit of real-time CMR is that it can be acquired during free breathing and without cardiac gating This comes at the cost of lower spatial and temporal resolution, which can affect accuracy [3]
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