The aortic annular diameter as measured on the posteroanterior projection of left ventricular cineangiograms was found to correlate well with the size of the sewing ring used to replace the diseased aortic valve in 22 consecutive patients. The exact size of the prosthesis which was used could be predicted in 73% of the patients. The average error between radiographic measurement of the annular diameter and the outer diameter of the sewing ring actually used was less than 1 mm when adjusted for the presence of heavy, annular calcification and concomitant mitral valve implantation.
Fishman NH, Bogren HG, Carlsson ES. Angiographic Estimation of the Size of the Aortic Valve Annulus. Arch Surg. 1970;101(6):717-720. doi:10.1001/archsurg.1970.01340300073013