Name the valve morphology (fused type, raphe), then measure the aortic root and ascending aorta at standard levels — the dilated ascending aorta, not the valve, is what sets the surgical threshold.
Orient first
- The commonest congenital heart anomaly; right–left coronary cusp fusion is the usual type.
- Aortopathy affects the ascending aorta (and sometimes the root) independent of valve function.
- Coarctation travels with it — look at the isthmus on every study.
Acquire the study
- ECG-gated CT angiography of the thoracic aorta; multiphase (0–95% R-R) reconstruction when valve opening matters; double-oblique reformats.
The manoeuvre
- Short-axis reformat through the valve in systole: number of commissures, fused cusps, raphe, "fish-mouth" opening.
- Double-oblique measurements in mm, inner-to-inner edge, at the annulus, sinuses of Valsalva, sinotubular junction and mid-ascending aorta (at the pulmonary artery level).
- Valve calcification and coronary origins.
- Aortic arch and isthmus: coarctation, collaterals.
What confirms it
- Two functional cusps with a fused commissure (± raphe) on a systolic short-axis view.
What licenses you to exclude it
- Three separate commissures opening fully in systole exclude a bicuspid valve; a diastolic-only view cannot.
The classic misread
- Calling a raphe a third commissure on diastolic images — judge in systole.
- Measuring on axial slices instead of double-oblique planes (overestimates).
- Forgetting the coarctation.