A method for standardized computed tomography angiography-based measurement of aortic valvar structures
Aims: Reliable assessment of the aortic valvar apparatus (AVAp) is essential as it may facilitate consistent outcomes with percutaneous aortic valvar therapies. The commonly referenced aortic annulus is problematic since this measurement does not correspond to any actual anatomic structure. We aim to describe a reliable method of measuring relevant structures of the AVAp based on widely available computed tomography analyses. Methods and results: Retrospective analysis of computed tomograms of 75 patients with severe aortic stenosis (45 females, age 81.2 ± 7.8 years). Curved multiplaner reconstruction technique was used to measure average diameters of the 'Aortic Leaflets Basal Attachment Plane' (ALBAP), sinuses of Valsalva (SV), sinutubular junction (STJ), ascending aorta (AA), and distance from coronary arteries to the base of the cusps. Angulation between the AA and the left ventricle (LV) was measured in one plane that included the LV inflow long axis and the maximum visualization of the aortic root. Inter-rater reliability and absolute agreement among three raters were evaluated. Intra-class correlation coefficients for ALBAP, SV, STJ, and AA diameters were 0.90, 0.99, 0.95, and 0.94, respectively (P < 0.001) with 95 limits of agreement of the observed differences falling in the less than 1 mm range. Intra-class correlation coefficients were 0.82 for the angle and 0.61 and 0.78 for distances to the right and left coronary arteries (P < 0.001).Conclusion: This method showed a high degree of inter-rater reliability and absolute agreement for AVAp diameters. Agreement was lower for AA-LV angle and distance to coronary artery measurements, emphasizing the need for software improvements and standardized image acquisition protocols.