The diameter of the aortic root is measured (usually at the Sinuses of Valsalva).
For adults, guidelines (e.g., ACC/AHA 2022) also use absolute thresholds (e.g., ≥5.0 cm for bicuspid aortic valve, ≥5.5 cm for Marfan), but Z-scores are superior for young adults and small-body-size patients. aortic root z score
To get a Z-score, doctors first perform an imaging test, usually an , CT scan , or MRI . The diameter of the aortic root is measured
According to international guidelines (such as the Ghent criteria for Marfan Syndrome), an aortic root Z-score of (in the absence of other specific features) or ≥ 3.0 (in the presence of other features like lens dislocation) is a major criterion for diagnosis. ≥5.0 cm for bicuspid aortic valve