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Variability of myocardial signal on magnetic resonance images
A De Roos1, H L Kundel, P M Joseph
1Department of Diagnostic Radiology, University Hospital, Leiden, The Netherlands.
Abstract:
The diagnosis of myocardial disease by magnetic resonance (MR) imaging depends on accurate measurement of myocardial signal intensity. The authors performed 15 experiments in four rabbits at 1.9 T with spin-echo MR imaging to study the variability of myocardial signal intensity throughout the cardiac cycle and to measure myocardial T2 values. Variability in signal from the myocardium throughout the cardiac cycle was observed in all experiments. During systole, a significant increase in myocardial signal was noted, when data acquisition was performed with electrocardiogram (ECG)-gating and controlled ventilation (P = .02). An inverse relationship between myocardial signal and phase noise was found, indicating the motion-related nature of the variation of myocardial signal. A similar inverse relationship was observed in images obtained from a normal human volunteer. Ex vivo myocardial T2 values of rabbit myocardial tissue were significantly higher than the in vivo values (P = .003), reflecting residual motion despite cardiac gating and controlled ventilation.
Insights
Myocardial signal intensity varies during the cardiac cycle, especially during systole. This variability in cardiac MRI is linked to motion, impacting T2 value measurements.
Area of Science:
- Cardiovascular Imaging
- Magnetic Resonance Imaging (MRI)
- Biomedical Engineering
Background:
- Accurate diagnosis of myocardial disease using magnetic resonance (MR) imaging relies on precise measurement of myocardial signal intensity.
- Understanding signal intensity variations is crucial for reliable interpretation of cardiac MRI scans.
Purpose of the Study:
- To investigate the variability of myocardial signal intensity throughout the cardiac cycle during MR imaging.
- To measure myocardial T2 values in vivo and ex vivo.
- To identify factors contributing to signal intensity variations in cardiac MRI.
Main Methods:
- Conducted 15 experiments in four rabbits using spin-echo MR imaging at 1.9 Tesla.
- Utilized electrocardiogram (ECG)-gating and controlled ventilation during data acquisition.
- Acquired images from a normal human volunteer to compare findings.
Main Results:
- Observed significant variability in myocardial signal intensity throughout the cardiac cycle in all experiments.
- Noted a significant increase in myocardial signal during systole (P = .02) with ECG-gating and controlled ventilation.
- Found an inverse relationship between myocardial signal intensity and phase noise, suggesting motion-related variations.
- Demonstrated significantly higher ex vivo myocardial T2 values compared to in vivo values (P = .003), indicating residual motion.
Conclusions:
- Myocardial signal intensity exhibits significant variability during the cardiac cycle, particularly during systole.
- Motion artifacts, despite cardiac gating and ventilation, influence myocardial signal intensity and T2 measurements in MRI.
- These findings highlight the importance of accounting for motion-related variations in cardiac MRI for accurate myocardial disease diagnosis.