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Computer-assisted · Children · Heart · Image processing · Magnetic resonance imaging · Respiration ·
Volumetry
Abstract:
Background Cardiac real-time magnetic resonance imaging (RT-MRI) provides high-quality images even during free-
breathing. Difficulties in post-processing impede its use in clinical routine.
Objective To demonstrate the feasibility of quantitative analysis of cardiac free-breathing RT-MRI and to compare image
quality and volumetry during free-breathing RT-MRI in pediatric patients to standard breath-hold cine MRI.
Materials and methods Pediatric patients (n= 22) received cardiac RT-MRI volumetry during free breathing (1.5 T; short axis;
30 frames per s) in addition to standard breath-hold cine imaging in end-expiration. Real-time images were binned retrospec-
tively based on electrocardiography and respiratory bellows. Image quality and volumetry were compared using the European
Cardiovascular Magnetic Resonance registry score, structure visibility rating, linear regression and Bland–Altman analyses.
Results Additional time for binning of real-time images was 2 min. For both techniques, image quality was rated good to
excellent. RT-MRI was significantly more robust against artifacts (P< 0.01). Linear regression revealed good correlations for
the ventricular volumes. Bland–Altman plots showed a good limit of agreement (LoA) for end-diastolic volume (left ventricle
[LV]: LoA -0.1 ± 2.7 ml/m2, right ventricle [RV]: LoA -1.9 ± 3.4 ml/m2), end-systolic volume (LV: LoA 0.4 ± 1.9 ml/m2,
RV: LoA 0.6 ± 2.0 ml/m2), stroke volume (LV: LoA -0.5± 2.3 ml/m2, RV: LoA -2.6± 3.3 ml/m2) and ejection fraction (LV:
LoA -0.5 ± 1.6%, RV: LoA -2.1 ± 2.8%).
Conclusion Compared to standard cine MRI with breath hold, RT-MRI during free breathing with retrospective respiratory
binning offers good image quality, reduced image artifacts enabling fast quantitative evaluations of ventricular volumes in
clinical practice under physiological conditions.
