Figure 1
Schematic illustration depicting the varying measurement recommendations for CT and TTE at the aortic root and proximal ascending aorta. The American College of Cardiology (ACC) and American Heart Association (AHA) recently revised their measurement guidelines. The 2010 guideline suggested inner edge to inner edge measurement for TTE and external diameter measurement for CT [14, 15]. However, the updated 2022 ACC/AHA guideline now recommends leading edge to leading edge measurement in TTE and inner diameter measurements in CT imaging [12] (adapted from Isselbacher, E.M., et al. [12]).
Table 1
Mean aortic diameters based on CT.
| CT | ||||
|---|---|---|---|---|
| EXTERNAL DIAMETER, 2010 GUIDELINE | INTERNAL DIAMETER, 2022 GUIDELINE | |||
| Site | Aortic sinus | Ascending aorta | Aortic sinus | Ascending aorta |
| Mean and SD (mm) | 43.2 ± 5.8 | 36.2 ± 7.7 | 42.0 ± 5.8 | 35.1 ± 7.6 |
| EXTERNAL DIAMETER, 2010 GUIDELINE | INTERNAL DIAMETER, 2022 GUIDELINE | |||
| Site | Aortic annulus | Sinotubular junction | Aortic annulus | Sinotubular junction |
| Mean and SD (mm) | 33.2 ± 5.2 | 31.6 ± 6.7 | 32.2 ± 5.2 | 30.7 ± 6.9 |
Table 2
Mean aortic diameters based on TTE.
| TTE | ||||
|---|---|---|---|---|
| INNER EDGE, 2010 GUIDELINE | LEADING EDGE, 2022 GUIDELINE | |||
| Site | Sinus | Ascending aorta | Sinus | Ascending aorta |
| Mean and SD (mm) | 40.5 ± 5.6 | 35.0 ± 7.4 | 41.7 ± 5.5 | 36.2 ± 7.5 |
Figure 2
Bland-Altman plots depicting differences in diameter measurement at the aortic sinus (a) and at the level of the ascending aorta (b) applying both the 2010 AHA/ACC guideline and the 2022 AHA/ACC guideline. Dotted red line: clinically acceptable limit of agreement for difference (+/–2 mm). Green line: agreement bias. The frequency of measurement differences outside the acceptable clinical agreement limit of difference (outside the range of the lower and upper dotted red line) was significantly lower using the 2022 AHA/ACC guideline.
Table 3
Overview of the measurement differences between CT and TTE in the assessment of the aortic diameter, depending on the application of the current 2022 and the older ACC/AHA guideline from 2010. The agreement bias represents the average difference between the two applied modalities. The lower and upper tolerance range are calculated by adding and subtracting 1.96 times the standard deviation the agreement bias.
| MEASUREMENT DIFFERENCES BETWEEN CT AND TTE | ||||
|---|---|---|---|---|
| GUIDELINE VERSION | 2010 | 2022 | ||
| SITE | SINUS | ASCENDING AORTA | SINUS | ASCENDING AORTA |
| Measurement differences outside acceptable tolerance (n, %) | 67 (49%) | 56 (41%) | 35 (26%) | 40 (29%) |
| Agreement bias (mm) | –2.66 | –1.21 | –0.30 | 1.12 |
| Standard deviation of bias (mm) | 2.06 | 3.01 | 2.05 | 2.77 |
| Factor of 1.96 | 1.96 | 1.96 | 1.96 | 1.96 |
| Lower tolerance range | –6.7 | –7.1 | –4.3 | –4.3 |
| Upper tolerance range | 1.4 | 4.7 | 3.7 | 6.5 |
| Total (n) | 137 | 137 | 137 | 137 |