Contrast-enhanced versus non-enhanced three-dimensional echocardiography of left ventricular volumes

[Evaluation of the left ventricle with three-dimensional echocardiography: comparison with cardiac magnetic resonance]

OBJECTIVE

Three-dimensional echocardiography (3DE) is becoming increasingly common in clinical environments. However, the quality of the images depends on the acoustic window, and it can be difficult to identify the endocardial borders. The objective of this study was to evaluate the performance of 3DE in determining the volumes and left ventricular ejection fraction in unselected patients against the gold standard, cardiac magnetic resonance (CMR).

MATERIAL AND METHODS

In 47 unselected patients who underwent CMR, we performed 3DE using a real-time acquisition technique and semiautomatic border detection.

RESULTS

We excluded 4 patients (8.5%) because they had an extremely deficient acoustic window. In the remaining 43 patients, including those with a suboptimal acoustic window, we obtained the following correlations between 3DE and CMR: end-diastolic volume, 0.71; end-systolic volume, 0.77; ejection fraction, 0.74. Although the end-diastolic volume was systematically underestimated, no significant differences were observed in the ejection fraction. When the 11 patients with suboptimal acoustic windows were excluded, we observed a systematic underestimation of the end-diastolic and end-systolic volumes, which paradoxically gave rise to improved correlation coefficients (0.79, 0.92, and 0.84, respectively) and a more accurate ejection fraction.

CONCLUSIONS

Compared to CMR, 3DE systematically underestimates the ventricular volumes but enables adequate determination of the left ventricular ejection fraction regardless of the quality of the acoustic window.

Comparison of contrast enhanced three dimensional echocardiography with MIBI gated SPECT for the evaluation of left ventricular function

Background

In clinical practice and in clinical trials, echocardiography and scintigraphy are used the most for the evaluation of global left ejection fraction (LVEF) and left ventricular (LV) volumes. Actually, poor quality imaging and geometrical assumptions are the main limitations of LVEF measured by echocardiography. Contrast agents and 3D echocardiography are new methods that may alleviate these potential limitations.

Methods

Therefore we sought to examine the accuracy of contrast 3D echocardiography for the evaluation of LV volumes and LVEF relative to MIBI gated SPECT as an independent reference. In 43 patients addressed for chest pain, contrast 3D echocardiography (RT3DE) and MIBI gated SPECT were prospectively performed on the same day. The accuracy and the variability of LV volumes and LVEF measurements were evaluated.

Results

Due to good endocardial delineation, LV volumes and LVEF measurements by contrast RT3DE were feasible in 99% of the patients. The mean LV end-diastolic volume (LVEDV) of the group by scintigraphy was 143 ± 65 mL and was underestimated by triplane contrast RT3DE (128 ± 60 mL; p < 0.001) and less by full-volume contrast RT3DE (132 ± 62 mL; p < 0.001). Limits of agreement with scintigraphy were similar for triplane andfull-volume, modalities with the best results for full-volume. Results were similar for calculation of LV end-systolic volume (LVESV). The mean LVEF was 44 ± 16% with scintigraphy and was not significantly different with both triplane contrast RT3DE (45 ± 15%) and full-volume contrast RT3DE (45 ± 15%). There was an excellent correlation between two different observers for LVEDV, LVESV and LVEF measurements and inter observer agreement was also good for both contrast RT3DE techniques.

Conclusion

Contrast RT3DE allows an accurate assessment of LVEF compared to the LVEF measured by SPECT, and shows low variability between observers. Although RT3DE triplane provides accurate evaluation of left ventricular function, RT3DE full-volume is superior to triplane modality in patients with suspected coronary artery disease.

Contrast-enhanced versus non-enhanced three-dimensional echocardiography of left ventricular volumes

BACKGROUND

In three-dimensional echocardiography (3DE), individual endocardial trabeculae are not clearly visible necessitating left ventricular (LV) volumes to be measured by tracing the innermost endocardial contour. Ultrasound contrast agents aim to improve endocardial definition, but may delineate the outermost endocardial contour by filling up intertrabecular space. Although measurement reproducibility may benefit, there may be a significant influence on absolute LV volume measurements.

METHODS

Twenty patients with a recent myocardial infarction and good ultrasound image quality underwent 3DE using the TomTec Freehand method before and during continuous intravenous contrast infusion. LV volumes were measured offline using TomTec Echo-Scan software.

RESULTS

The use of contrast enhancement increased end-diastolic (110+/-35 vs. 144+/-53 ml; p<0.01) and end-systolic volume measurements (68+/-31 vs. 87+/-45 ml; p<0.01) significantly compared with non-contrast; the ejection fraction remained unchanged (40+/-13 vs. 41+/-14%, p=NS). Measurement reproducibility did not improve significantly, however.

CONCLUSION

Volumes measured by 3DE are significantly larger when ultrasound contrast is used. Possibly, intertrabecular space comprises a substantial part of the LV cavity. In the presence of an adequate apical acoustic window, ultrasound contrast does not improve LV volume measurement reproducibility. (Neth Heart J 2008;16:47-52.).