ObjectiveTo discuss the accuracy and repeatability of left ventricular structural and functionalmeasurements in beagles by two-and three-dimensional contrast-enhanced transthoracic echocardiography（2 D c TTE and 3 Dc TTE）.MethodsM-mode images in parasternal long-axis view were obtained from 12 beagles

and the apical four-chamber

three-chamber and two-chamber views and the three-dimensional full-volume images of the left ventricle were collected byunenhanced and contrast-enhanced transthoracic echocardiography. The intimal display rates in apical four-chamber

three-chamber and two-chamber views of the left ventricular segment were evaluated by two-and three-dimensional echocardiography（2 DE and 3 DE）.Left ventricular end diastolic longitudinal diameter（LVLD）was measured by 2 DE and 2 D c TTE.Left ventricularend diastolic volume（LVEDV）

left ventricular end systolic volume（LVESV）and left ventricular ejection fraction（LVEF）weremeasured respectively by Teichholz method of M mode

biplane Simpson method of 2 DE and 2 D c TTE.Left ventricular three-dimensional full-volume images were processed and analyzed by Tom Tec software

LVEDV

LVESV

LVEF were measuredrespectively by 3 DE and 3 D c TTE.The measurements of pathological specimen were taken as the gold standard

the accuracies ofmeasuring LVLD and LVEDV by different methods were evaluated.All indexes were measured again by the same observer and different observers

and the repeatability of different methods for measuring different indexes was evaluated.Results（1） Theintimal display rate of the left ventricular segment was higher by 2 D c TTE and 3 D c TTE than those by 2 DE and 3 DE

2 D c TTE wasthe best（all P<0.05）.（2） The measurements of LVLD by 2 D c TTE was more relevent with the measurements by pathologicalspecimen than that by 2 DE（0.851 vs. 0.748）.The measurements of LVEDV by M mode

2 DE

2 D c TTE

3 DE and 3 D c TTE werecorrelated with the measurements by pathological specimen（r were 0.612

0.806

0.857

0.728

0.869

all P<0.05）.2 D c TTE and3 D c TTE could provide more accurate measurements

3 D c TTE was the most precise method.（3）For inter-and intraobservers

thecoefficient of variation of LVEDV

LVESV

LVEF by 2 D c TTE and 3 D c TTE were lower than those by M mode

2 DE and 3 DE.ConclusionContrast-enhanced transthoracic echocardiography can improve image quality of 2 DE and 3 DE with more accurateand repeatable measurements

providing a new method for clinical precise evaluation and dynamic monitoring of left ventricularstructure and function in beagles.