Abstract: Objective  Cardiac endsystolic and enddiastolic images were obtained by 64slice spiral CT ECG gating technique. Then, theborderline of the four heart chambers as the measurement baseline,  the normal range of the heart chambers were measured and analyzed,  and the characteristics were compared between the two phases.Methods  Retrospective analysis of cardiac endsystolic and enddiastolic CT images was performed on 133 healthy subjects.The 95% confidence interval (CI) of the left to right diameter (RL) and the anteroposterior diameter (AP) of the heart chambers were measured separately and analyzed statistically. And the endsystolic and enddiastolic measurements were compared and analyzed. Results  In the endsystolic phase,  the AP and RL of the left and right atrium were significantly greater than those in the enddiastolic phase (P<0.05). For left and right ventricles,  theRL and AP in enddiastolic phase were significantly larger than that in endsystolic (P<0.05). The RL ratio of Left/ right atrial,  the RL ratio of left / right ventricular and the AP ratio of left/right ventricular were greater than 1,  and in the endsystolic phase significantly greater than in the enddiastolic phase (P<0.05). The AP ratio ofleft/right atrium was less than 1,  with that in the endsystolic phase being significantly less than that in the enddiastolic phase (P<0.05).There was no significant difference in left atrium RL: AP between the two phases (P>0.05),  and the rest ratio of each cardiac cavity parameters had significant difference between the two phases.Left ventricular angle (β) between endsystolic and enddiastolic contrast was nosignificant difference (P>0.05). Conclusion  By means of measuring the cardiac diameters in the endsystolic and enddiastolic phases,  the characteristics and 95%CI were statistically analyzed with multislice spiral CT,  and the range and upper limit was obtained. Thus,  it provides a theoretical basis for further exploration of the use of nonenhanced chest CT images to observe the size of each cardiac cavity.

Key words: tomography, , Xray computed；heart；morphology