Abstract Background Mitral annular calcification (MAC) is a degenerative process that leads to development of mitral regurgitation (MR). Its presence is associated with worse therapeutic results, due to technical challenges and risk of complications. The precise characterization has gained special importance in recent years. Due to the accuracy of the CT to detect calcium compared to transesophageal echocardiography (TEE), different prognostic scores based on this technique have been proposed. Purpose Our objective was to assess the usefulness of new tools based on 3D-TEE to determine the severity of MAC compared to CT in patients with MR. Methods Between 2019 -2022, patients with severe MR with different degrees of MAC were selected and evaluated by 3D-TEE and CT. Two independent expert observers blindly performed a quantitative standardized characterization of severity (1-10), applying the score proposed by Guerrero et al. based on four parameters: Calcium thickness, radial extension, involvement of trigones and leaflets both by CT (Figure 1, A) and advanced 3D-TEE tools (transillumination/True-Vue (Figure 1, B-C) and multiplanar/iSlice reconstruction (Figure 1, D). The agreement and correlation of both techniques were compared for each of the categories, as well as for the final classification of severity (Mild: 0-3, Moderate: 4-7, Severe 8-10). Results 38 patients were included (Mean age: 80±5.7 years), 76% women. The MAC score measured by TEE was 6.1±0.4 vs. 8±0.4 by CT (p=0.03) with a very good agreement between both techniques estimated by the ICC (r=0.9) with an average difference of 1.2±1.4. Regarding the qualitative estimation, the concordance was good except for the estimation of the of the leaflet’s calcification (Table 1). Conclusions The use of advanced 3D-TEE imaging tools provides an excellent estimation and extension of the severity of MAC compared to CT, slightly overestimating the severity. These tools not only bring qualitative but also quantitative information and could be a first approximation before performing CT. This result highlights the usefulness and necessity of using multimodality imaging in the evaluation of degenerative mitral regurgitation.Figure 1Table 1