Comparison of dynamic changes in aortic diameter during the cardiac cycle measured by computed tomography angiography and transthoracic echocardiography

Objective: This study aimed to examine the relationship between dynamic changes in aortic diameter and corresponding measurement methods. Methods: Consecutive adult (nonaneurysmal) patients being surgically treated for heart disease (mean age, 51 +/- 11 years; range, 29-76 years; N = 25) were included in this study. All patients underwent transthoracic echocardiography (TTE), computed tomography angiography (CTA), and intraoperative ultrasound (IOUS). Anteroposterior diameters were measured at 1 cm above the junction of the aortic sinus, the proximal 1 cm of the innominate artery, and the midpoint of the two. Results: The average diameter of the proximal ascending aorta in systole/diastole measured by IOUS was 32.07 +/- 2.03/30.27 +/- 2.05 mm (paired t-test: difference, 1.80 +/- 0.46 mm; P < .001). The average diameters of the proximal ascending aorta measured by nonelectrocardiography-gated CTA and TTE were 31.45 +/- 1.97 mm and 29.7 +/- 1.84 mm, respectively. The average diameter of the mid and distal ascending aorta in systole/diastole measured by IOUS was 32.35 +/- 1.95/30.57 +/- 1.94 mm (paired t-test: difference, 1.78 +/- 0.44 mm; P < .001) and 32.32 +/- 1.92/30.67 +/- 1.90 mm (paired t-test: difference, 1.65 +/- 0.42 mm; P < .001), respectively. The average diameter of themid and distal ascending aorta measured by CTA was 31.74 +/- 1.92 mm and 31.59 +/- 1.96 mm, respectively. At each location, the difference in the aortic diameter between systole and diastole was statistically significant (all P values < .001; paired t-test). The minimum and maximum changes in the diameter between systole and diastole were 0.90 mm and 2.70 mm. In all, 96% (24/25) of the average diameters derived from IOUS and CTA at the three locations were within the concordance limit in systole, and 92% to 100% (23/25 to 25/25) were within the concordance limit in diastole. The average diameters derived from IOUS and TTE images of the proximal ascending aorta were within the bounds of the concordance limit 92% (23/25) of the time in systole and 100% (25/25) of the time in diastole. The average diameters derived from CTA and TTE images of the proximal ascending aorta were within the bounds of the concordance limit 88%(22/25) of the time. Pearson correlation coefficients between these groups ranged from 0.905 to 0.982 (all P values < . 01). Conclusions: The ascending aorta diameters measured by nonelectrocardiography-gated CTA and TTE were consistent with the IOUS measurements.