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Factors influencing the quantification of valvular regurgitation by gated equilibrium radionuclide angiography
Insights
This study refined the stroke volume ratio (SVR) calculation in patients without valve disease, finding a modified method significantly improved accuracy and reduced variability for this important cardiac measurement.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Medical Imaging Analysis
Background:
- The stroke volume ratio (SVR) is a key metric in cardiac function assessment.
- Accurate determination of SVR is crucial for clinical validity, particularly in patients without valvular regurgitation.
- Previous methods for SVR estimation may be influenced by factors like atrial activity overlap.
Purpose of the Study:
- To evaluate the clinical validity of the stroke volume ratio (SVR).
- To identify factors influencing SVR values.
- To compare two methods for SVR estimation in patients without valvular regurgitation.
Main Methods:
- SVR was determined in 41 patients free of valvular regurgitation using multigated blood pool scans.
- Two methods were employed: a classical left-to-right ventricular stroke count ratio and a modified method subtracting right atrial activity.
- Correlation analysis was performed with ejection fraction, left ventricular volumes, and end-diastolic volume ratios.
Main Results:
- The modified SVR method yielded significantly lower values (1.05 +/- 0.12) compared to the classical method (1.25 +/- 0.18) (P < 0.001).
- SVR was not correlated with ejection fraction or angiographically determined left ventricular volumes.
- A significant correlation was found between SVR and the left-to-right end-diastolic volume ratio (r = 0.48, P < 0.01).
Conclusions:
- Subtracting right atrial activity at end-systole may enhance the accuracy of SVR determination.
- In patients without valvular regurgitation, the left ventricular/right ventricular stroke volume ratio approaches unity with reduced variability.
- The Fourier phase approach can further reduce interobserver and intraobserver variability in SVR measurements.
Abstract:
To test the clinical validity of the stroke volume ratio (SVR) and the factors influencing its value we determined it in a population of 41 patients free of valvular regurgitation. The SVR was estimated from multigated blood pool scans in left anterior oblique position by two methods. The first method followed the classical formula of the left to right ventricular stroke count ratio. The second method used the same formula except that the right atrial activity emanating from the area of right atrioventricular overlap as traced at right ventricular end-systole, was subtracted from the right ventricular stroke count. The SVR averaged 1.25 +/- 0.18 (range 0.97-1.80) by the first technique and 1.05 +/- 0.12 (range 0.82-1.36) by the second (P less than 0.001). In our results the SVR is not correlated to either ejection fraction or angiographically determined left ventricular volumes. Conversely the SVR is correlated with the left to right end-diastolic volume ratio evaluated from radionuclide counts measured at right and left ventricular end-diastole (r = 0.48, P less than 0.01). This may be due to variations in the area of right atrioventricular overlap, depending on the size of the ventricular chamber. It is postulated that the accuracy of SVR determination could be enhanced by subtraction of the right atrial activity from the right ventricular activity at end-systole. In patients free of valvular regurgitation the LV/RV stroke volume ratio approaches unity and the variability of the results is smaller. Interobserver and intraobserver variability is reduced using the Fourier phase approach.