Abstract Background Accurate imaging assessment of the aortic root (AR) is critical for prosthesis sizing in transcatheter aortic valve implantation. Multislice computed tomography (MSCT) is the gold standard for this purpose. 3D transesophageal (3D-TOE) reconstruction tools have recently been introduced, which automatically configures a geometric model of AR from 3D-TOE dataset and perform quantitative analyses of the AR. Purpose The aim of the study was to compare semi-automated measurements of AR obtained by eSie Valves (EV) (Siemens Medical Solution, California, USA) tool with MSCT. Methods We prospectively enrolled 26 consecutive patients (mean age 79.5 ± 7.5 years; 38% men) with severe symptomatic aortic stenosis (mean gradient 48.8± 13.6 mmHg) who underwent both 3D-TOE and MSCT as part of TAVI evaluation protocol. Volumetric datasets of the AR, acquired with 3D-TOE in mid-esophageal view, were analyzed with EV tool. EV tool automatically detected AR landmarks and, after user validation, created 3D model of AR providing values of area, perimeter, diameters of aortic annulus (AA) and coronary ostia heights (Fig 1). Results EV tool analysis on 3D-TOE volumetric data sets was feasible in all patients. Strong correlation between EV tool and MSCT assessment for AA major diameter (r = 0.79), AA minor diameter (r = 0.81), AA perimeter (r = 0.89) and AA area (r = 0.89) (all p< 0.0001) was found. On average EV tool underestimated MSCT measurements of AA major diameter (1.2 mm, 4.5%), AA minor diameter (2.6 mm, 11.3%), AA perimeter (4 mm, 5.2%) and AA area (65.3 mmq, 13.6%). Moderate correlation between the two methods, already in this initial sample, for right coronary artery ostium height (r = 0.53, p = 0.007) was discovered. Finally, weak correlation for left coronary artery ostium height (r = 0.33, p = 0.1) was revealed. EV tool measurements from two different volumetric datasets of the same patient showed an excellent reproducibility intraclass correlation coefficient (ICC) for AA area 0.94 and ICC for right coronary height 0.98. Conclusion With these initial results EV tool could be used in clinical practice for quick and reliable assessment of AA area, perimeter and diameters. A larger group of patients will be needed to assess the consistency of coronary ostia height evaluation by EV tool. Abstract P218 Figure. eSie Valve landmarks and 3D model of AR