Non-Contrast Three-Dimensional Magnetic Resonance Imaging for Pre-Procedural Assessment of Aortic Annulus Dimensions in Patients Undergoing Transcatheter Aortic Valve Implantation

ABSTRACTBackground:We sought to appraise the accuracy of non-contrast three-dimensional (3D) magnetic resonance imaging (MRI) in comparison with computed tomography (CT).Methods:This is a single-center prospective study enrolling 48 consecutive patients with severe aortic stenosis screened for transcatheter aortic valve implantation (TAVI), who underwent non-contrast 3D MRI and standard cardiac CT for pre-TAVI aortic annulus assessment. Systolic MRI dimensions were modelled, by adding a corrective factor (+7.5% of the area). Tests of correlation and agreement were performed.Results:The mean subjective MRI image quality was 3.2±0.8. According to CT, 20 patients (43.5%) had severe or massive annular calcifications. Bland–Altman plots and Passing and Bablock regression analysis showed no relevant differences of cross-sectional area measurements for corrected systolic MRI vs. systolic CT measurements (mean bias 0.09 cm2; 95% limits of agreement: -0.48 to 0.67). Higher bias was seen in patients with severe or massive annular calcifications. Disagreement between CT and MRI in terms of transcatheter valve size was reported in 3 patients (6.5%). All of them had severe or massive annular calcifications.Conclusion:In patients referred for TAVI, aortic annulus measurements using corrected systolic MRI compare favorably with those made at CT. Caution should be applied when choosing transcatheter valve size in the presence of severe or massive annular calcification as they reduce the accuracy of MRI measurements.