• The aortic annulus should be measured at midsystole from inner edge to inner edge (I-I).
• All other aortic root measurements (i.e., maximal diameter of the sinuses of Valsalva, the sinotubular junction, and the proximal ascending aorta) should be made at end-diastole, in a strictly perpendicular plane to that of the long axis of the aorta using the leading edge to leading edge (L-L) convention.
• Measurements of maximal diameter of the aortic root at the sinuses of Valsalva should be compared with age- and BSA-related nomograms or to values calculated from specific allometric equations.
• Accurate measurement of the aortic annulus before TAVI or TAVR is crucial. To date, there is no established gold-standard technique for measuring the aortic annulus before TAVI or TAVR. Three-dimensional TEE and MDCT are emerging as reliable and possibly preferred methods for aortic annulus measurements.