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Multigated blood-pool imaging using heart sounds
M W Groch1, J R Domnanovich, W D Erwin
1Rush Graduate College, Department of Medical Physics Rush Presbyterian-St Luke's Medical Center, Chicago, Illinois 60612.
Insights
A novel heart sound gating (HSG) method accurately triggers multigated blood-pool imaging using first (S1) and second (S2) heart sounds. This technique offers a reliable alternative to ECG gating for assessing left ventricular function, especially in challenging patient cases.
Area of Science:
- Cardiovascular Imaging
- Biomedical Engineering
- Nuclear Cardiology
Background:
- Multigated blood-pool (MGBP) imaging traditionally relies on electrocardiogram (ECG) gating for cardiac cycle synchronization.
- Limitations of ECG gating include signal interference and inaccuracies, particularly in patients with arrhythmias or rapidly changing heart rates.
Purpose of the Study:
- To develop and evaluate a novel heart sound gating (HSG) method for MGBP acquisition.
- To assess the feasibility of using first (S1) and second (S2) heart sounds as trigger points for MGBP.
- To compare the accuracy of HSG-MGBP with conventional ECG-gated MGBP in evaluating left ventricular function.
Main Methods:
- Development of specialized HSG circuitry to identify S1 and S2 sounds based on their timing.
- Application of HSG to trigger MGBP acquisition in twenty patients undergoing left ventricular function analysis.
- Comparison of left ventricular ejection fractions (LVEFs) calculated from HSG-MGBP and ECG-gated MGBP.
Main Results:
- HSG circuitry successfully identified individual S1 and S2 heart sounds, providing two distinct trigger points per cardiac cycle.
- LVEFs calculated using S1 and S2 heart sound triggers correlated well with those from conventional ECG-gated acquisitions.
- HSG demonstrated potential utility in patients with rapid heart rate variations and inadequate ECG signals.
Conclusions:
- Heart sound gating (HSG) provides a viable alternative trigger mechanism for MGBP imaging.
- HSG accurately defines end-systole (S1) and end-diastole (S2), enabling precise assessment of systolic ejection and diastolic filling.
- This method enhances MGBP applicability in complex clinical scenarios where ECG gating is suboptimal.
Abstract:
A method to trigger multigated blood-pool (MGBP) acquisition using both the first and second heart sound has been developed. The heart sound gating (HSG) circuitry identifies, individually, both the first (S1) and second (S2) heart sounds from their timing relationship alone, and provides two trigger points during the cardiac cycle. First heart sound gating may be performed to assess the systolic ejection portion of the cardiac cycle, with S2 gating utilized for reproduction of the diastolic filling portion of the cycle. Heart sound gating has been applied to twenty patients who underwent analysis of left ventricular function, and compared to conventional ECG-gated MGBP. Left ventricular ejection fractions calculated from MGBP studies using a first and a second heart sound trigger correlated well with conventional ECG gated acquisitions in patients adequately gated by HSG and ECG. Heart sound gating may be utilized in patients with rapidly changing heart rates, as S1 and S2 precisely define end-diastole and end-systole, respectively, and in situations when the ECG is inadequate for gating purposes.