Transcatheter Aortic Valve Replacement: Performance of an Aortic Valvular Complex Model for Semi-Automated Quantification of Aortic Annulus Dimensions at Cardiac CT

Abstract

Ziele: To evaluate the accuracy and time-effectiveness of semi-automated model-based annulus computation compared to manual planimetry for assessment of aortic annulus dimensions prior to transcatheter aortic valve replacement (TAVR). Methode: Retrospectively ECG-gated dual-source cardiac CT data of 50 consecutive TAVR candidates with severe aortic stenosis (82.5 ± 5.8 years) were included. Data were reconstructed at 300 ms past the R-peak and were analyzed using an automatic 3D aortic valve model, fitted to CT data by discriminative learning methods and incremental search. It contains the aortic root's surface, commissures and hinges and allows for automated morphologic identification of the annulus plane, defined by the most basal hinge points of the aortic cusp. The encompassed aortic annulus contour is delineated based on gray-scales, with manual correction. Manual planimetric measurement using multiplanar reformations was used as the reference standard. Data were analyzed using linear regression and Bland Altman plots. Hypothetical prosthesis sizing (23 mm prosthesis for <22mm aortic annulus; 26mm: 22–25mm; 29mm: >25 mm) was compared using K-statistics. Ergebnis: Aortic valve hinge-points were correctly identified in 47/50 patients (94%). Mean effective annulus diameter was 24.5 ± 2.3 mm by model-based analysis and 24.6 ± 2.2 mm by manual assessment (p = n.s.). Excellent correlation was found between both methods (r = 0.98, p<0.01). Bland-Altman analysis revealed no systematic bias. Agreement for prosthesis sizing was found in 44/50 patients (K=0.80). Mean analysis time was significantly (p<0.001) reduced for model-based measurements (28 ± 11sec vs. 92 ± 13sec). Schlussfolgerung: Semi-automated morphologic aortic annulus quantification derived from an aortic valve model enables fast and accurate procedural planning in excellent agreement with manual planimetry and has the potential to improve cardiac imaging workflow in the evaluation of patients prior to TAVR.