Comparison of cine and real-time cardiac MRI in rhesus macaques

Figures

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  Figure 1. Qualitative comparison of cine MRI and RT-MRI. Compared to cine MRI (top), RT-MRI (bottom) exhibited a reduced image sharpness making the demarcation of the papillary muscles and the trabeculae challenging. Epicardial and endocardial delineations are marked in green and red, respectively. All images were acquired during expiration.

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  Figure 2. Comparison of cine MRI and RT-MRI. Correlation and Bland–Altman plots of LVWM, EDV, ESV, SV and EF comparing cine MRI and RT-MRI of the first study time point (test). RT-MRI significantly underestimates volumetric parameter by 20% to 40% when taking cine MRI as gold standard. However, regression analysis comparing estimated parameter by RT-MRI and cine MRI revealed a strong correlation. LVWM: Left Ventricular Wall Mass; EDV: End-Diastolic Volume; ESV: End-Systolic Volume; SV: Stroke Volume; EF: Ejection Fraction.

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  Figure 3. Function-time curve over consecutive heartbeats. The signal-time curve of the respiratory signal (normalized by mean of maximum for expiration and minimum for inspiration) and the extracted functional parameter (EDV, ESV, SV and EF) of a Real-Time experiment over consecutive cardiac cycles were exemplarily plotted for a mid-ventricular slice of two different animals. Both EDV and ESV systematically show a periodical behavior leading to highest volumes in inspiration and lowest at expiration. Although EDV and ESV show fluctuations up to 30% in each cardiac cycle the estimated EF has only a minor fluctuation up to 10%. EDV: End-Diastolic Volume; ESV: End-Systolic Volume; SV: Stroke Volume; EF: Ejection Fraction.

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  Figure 4. Comparison of inspiratory and expiratory ventricular function. Correlation and Bland–Altman plots of LVWM, EDV, ESV and EF for inspiration and expiration obtained by RT-MRI of the first study time point (test). Volumetric parameters (EDV, ESV and SV) were increased by at least 20% during inspiration compared to expiration. Additionally, a slight increase in EF was observed during inspiration. Nevertheless, a strong correlation between the two respiration phases exists. LVWM: Left Ventricular Wall Mass; EDV: End-Diastolic Volume; ESV: End-Systolic Volume; SV: Stroke Volume; EF: Ejection Fraction.

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  Figure 5. Semi-automatic extraction of cardiorespiratory phases. The cardiorespiratory phase was extracted from signal-time curves of region of interests manually drawn in the left ventricle (top left) and at the lung-liver interface (bottom left). The diastolic and systolic phases (black arrows) were extracted from the signal-time curve of the left ventricle using a peak detection algorithm. The inspiration and expiration are detected based on thresholds defined by the respiratory signal (separated by dashed lines). Representative end-diastolic and end-systolic images obtained during inspiration and expiration are shown on the right. The movement of the liver due to respiration is clearly visible (dashed lines).