Measurement of the Root and Ascending Aorta: Points, Cycle Phase, Leading-edge vs Inner-edge (BSE, ASE)
Measurement Points
The aortic root (AoR) and ascending aorta (AscAo) are measured from the parasternal long axis view (PLAX) at four levels:
- Aortic annulus (AoRing / annulus) — at the level of the attachment points of the aortic valve leaflets (RCC and NCC/LCC).
- Sinuses of Valsalva (SoV).
- Sino-tubular junction (STJ).
- Proximal segment of the ascending aorta (AoAsc prox) — 1 cm above the STJ.
If there is dilation above the level of the proximal ascending aorta, the maximum size must be measured and documented in the protocol (BSE, 2020). Optimal visualization may require a higher anatomical position of the probe (BSE, 2025).
Cardiac Cycle Phase
The aortic annulus is measured in mid-systole (at peak systole — Blagodir, 2024; midsystole — ASE, 2015). All other levels (sinuses of Valsalva, STJ, proximal ascending aorta) are measured at end-diastole, defined as the beginning of the QRS complex on the surface ECG (BSE, 2020; BSE, 2025).
Leading-edge vs Inner-edge
There are two measurement methods:
- I-I (inner-edge to inner-edge) — from inner edge to inner edge.
- L-L (leading-edge to leading-edge) — from leading edge to leading edge.
BSE recommends the inner-edge to inner-edge method for measuring aortic dimensions at end-diastole; the annulus is measured in mid-systole (BSE, 2020, 2025). ASE recommends measuring the annulus from inner-edge to inner-edge in midsystole, and the other root levels (maximum diameter of the sinuses of Valsalva, STJ, proximal ascending aorta) at end-diastole using the L-L convention, strictly perpendicular to the long axis of the aorta (ASE/EACVI, 2015).
Different cycle phases and anatomical landmarks (e.g., inner-edge vs leading-edge) yield different values, so the laboratory must specify the chosen method in the clinical protocol for comparability with other modalities and accurate dynamic monitoring (Baggish et al., 2014; BSE, 2020; BSE, 2025). Laboratories using L-L are advised to continue its use for consistency (BSE, 2020).
Normal Values (Blagodir, 2024)
| Level | Method / Phase | Women | Men |
|---|---|---|---|
| Aortic annulus (AoRing) | I-I, peak systole | 23 ± 2 mm | 26 ± 3 mm |
| Sinuses of Valsalva | L-L, end-diastole | 27–33 mm | 31–37 mm |
| Sino-tubular junction (STJ) | L-L, end-diastole | 23–29 mm | 26–32 mm |
| Proximal ascending aorta | L-L, end-diastole | 23–31 mm | 26–34 mm |
Indexing
According to BSE, aortic dimensions are measured in 2D from PLAX, and indices are obtained using the inner-edge to inner-edge method at end-diastole; all values are indexed to height (mm/m), not to body surface area (BSE, 2020).
Frequently asked questions
In which cycle phase should the aortic annulus and other levels be measured?
The aortic annulus is measured in mid/peak systole; the sinuses of Valsalva, STJ, and proximal ascending aorta are measured at end-diastole (beginning of QRS).
Which method does BSE recommend — inner-edge or leading-edge?
BSE recommends inner-edge to inner-edge (IE-IE) at end-diastole. Laboratories using leading-edge to leading-edge are advised to continue for consistency; the method is specified in the protocol.
How does ASE measure the aortic root?
ASE: the annulus is measured inner-edge to inner-edge in midsystole; the sinuses of Valsalva, STJ, and proximal ascending aorta are measured at end-diastole using the L-L convention, perpendicular to the long axis of the aorta.
To what should aortic dimensions be indexed?
According to BSE, values are indexed to height (mm/m), not to body surface area.
Where is the level of the proximal ascending aorta determined?
At the level 1 cm above the sino-tubular junction (STJ), from the PLAX position.