To test the accuracy of real-time three-dimensional echocardiography （RT3DE） imaging system for evaluating left ventricular mass （LVM） in phantom and excised canine heart. Methods Ten left ventricular （LV） wall phantoms made of two rubber-bursas

ten excised canine hearts underwent RT3DE and two-dimensional echocardiography （2DE）. In RT3DE "full volume" imaging

the myocardial volume was mea-sured using 2

4

8

and 16-plane method with the analysis software of RT3DE. Mass was then calculated by multiplying the resulting myocardial volume by specific density of myocardial tissue. In 2DE the masses were measured by area-length meth-od. The true LV wall phantom mass was measured by water displacement and the canine LVM was weighed by anatomy

which served as a reference standard. We compared RT3DE or 2DE with true mass. Results In LV wall phantoms

RT3DE correlated with true masses strongly （r = 0.813-0.994） and weakly correlated between 2DE and true masses （r = 0.628）. In excised canine hearts

there is an excellent correlation between RT3DE and true masses （r = 0.764-0.991）

while 2DE value showed a lesser correlation （r = 0.514）. There are no difference between RT-3DE and true masses （P > 0.05） but different between 2DE and true masses （P < 0.05）. In different planes

there was no difference between 8-plane and 16-plane （P > 0.05） but different between 8-plane and 2

4-plane （P < 0.05）. Conclusion RT3DE can accurately quantify LVM and provide a new tool to evaluate LV function. For LVM by RT3DE

8-plane measurement method is the best choice for accuracy and convenience.