Thoracic Aorta Dimension Changes During Systole and Diastole: Evaluation with ECG-Gated Computed Tomography.

BACKGROUND

This study was conducted to characterize the differences in the dimensions between systole and diastole in thoracic aorta in Chinese population with electrocardiogram (ECG)-gated multidetector computed tomography angiography (CTA) scans.

METHODS

The CTAs of 56 patients (mean age 58.2 ± 17.9 years; 42 men, 14 women) both in systole and diastole were obtained on a 64-slice ECG-gated multidetector CT scanner. Four anatomic levels of the thoracic aorta were selected for analysis (Level A: 1 cm proximal to the innominate artery; Level B: 1 cm distal to the left common carotid artery; Level C: 1 cm distal to the left subclavian artery; and Level D: 10 cm distal to the left subclavian artery). On each level, the maximal and the minimal diameters were measured both in systole and diastole.

RESULTS

The paired sample t-test results showed a significant difference between the systolic and diastolic diameters in all individual subjects on every level. The diameter differences range between -1.7 mm (diastolic dimension is greater than systolic dimension) and 3.6 mm (systolic dimension is greater than diastolic dimension). The aortic diameters in diastolic phase are greater than in systolic phase in 18-22% subjects on different levels. A mean maximum diameter change of 2.68% (range -3.45% to 8.25%) and a mean minimum diameter change of 2.71% (range -5.05% to 8.38%) were found at Level A; a maximum diameter change of 2.89% (range -4.5% to 13.3%) and a minimum diameter change of 2.37% (range -5.2% to 14.9%) were found at Level B; a maximum diameter change of 2.81% (range -6.02% to 10.85%) and a minimum diameter change of 2.92% (range -7.14% to 9.62%) were found at Level C; and a maximum diameter change of 3.08% (range -1.76% to 10.36%) and a minimum diameter change of 2.93% (range -2.37% to 11.9%) were found at Level D.

CONCLUSIONS

Our study verifies that the dimensional differences in thoracic aorta between systolic and diastolic phase are significant. But the pulsatility of thoracic aorta in Chinese population might be different from published literature.