Reproducibility of aortic annulus measurements by computed tomography

Objectives To evaluate a systematic approach for measurement of aortic annulus dimensions by cardiac computed tomography. Methods CT data sets of 64 patients were evaluated. An oblique cross-section aligned with the aortic root was created by systematically identifying the caudal insertion points of the three aortic cusps and sequentially aligning them in a double oblique plane. Aortic annulus dimensions, distances of coronary ostia and a suitable fluoroscopic projection angle were independently determined by two observers. Results Interobserver intraclass correlation coefficients (ICC) for aortic annulus diameters were excellent (ICC 0.89–0.93). Agreement for prosthesis size selection was excellent ( ĸ = 0.86 for mean, ĸ = 0.84 for area-derived and ĸ = 0.91 for circumference-derived diameter). Mean distances of the left/right coronary ostium were 13.4 ± 2.4/14.4 ± 2.8 mm for observer 1 and 13.2 ± 2.7/13.5 ± 3.2 mm for observer 2 ( p = 0.30 and p = 0.0001, respectively; ICC 0.76/0.77 for left/right coronary artery). A difference of less than 10° for fluoroscopic projection angle was achieved in 84.3 % of patients. Conclusions A systematic approach to generate a double oblique imaging plane exactly aligned with the aortic annulus demonstrates high interobserver and intraobserver agreements for derived measurements which are not influenced by aortic root calcification. Key Points • Systematic approach to generate a double oblique imaging plane for TAVI evaluation. • This method is straightforward and software independent. • An approach with high reproducibility, not influenced by aortic root calcification.