The left atrial appendage (LAA) is a complex cardiovascular structure which can yield to thrombi formation in patients with non-valvular atrial fibrillation (AF). The study of LAA fluid dynamics together with morphological features should be investigated in order to evaluate the possible connection of geometrical and hemodynamics indices with the stroke risk. To reach this goal, we conducted a morphological analysis of four different LAA shapes considering their variation during the cardiac cycle and computational fluid dynamics (CFD) simulations in AF conditions were carried out. The analysis of main geometrical LAA parameters showed a huger ostium and a reduced motility for the cauliflower and cactus shapes, as well as a lower velocity values from the CFD analysis. Such findings are in line with literature and highlight the importance of coupling dynamics imaging data with CFD calculations for providing information not available at clinical level.

The multimodal and multidomain registration of medical images have gained increasing recognition in clinical practice as a powerful tool for fusing and leveraging useful information from different imaging techniques and in different medical fields such as cardiology and orthopedics. Image registration could be a challenging process, and it strongly depends on the correct tuning of registration parameters. In this paper, the robustness and accuracy of a landmarks-based approach have been presented for five cardiac multimodal image datasets. The study is based on 3D Slicer software and it is focused on the registration of a computed tomography (CT) and 3D ultrasound time-series of post-operative mitral valve repair. The accuracy of the method, as a function of the number of landmarks used, was performed by analysing root mean square error (RMSE) and fiducial registration error (FRE) metrics. The validation of the number of landmarks resulted in an optimal number of 10 landmarks. The mean RMSE and FRE values were 5.26 ± 3.17 and 2.98 ± 1.68 mm, respectively, showing comparable performances with respect to the literature. The developed registration process was also tested on a CT orthopaedic dataset to assess the possibility of reconstructing the damaged jaw portion for a pre-operative planning setting. Overall, the proposed work shows how 3D Slicer and registration by landmarks can provide a useful environment for multimodal/unimodal registration.

Background: Penetrating aortic ulcer (PAU) is an acute aortic syndrome characterized by a high rupture risk. There are several PAU-treatment procedures indicated for the management of this pathology associated with different effects on vessel morphology and hemodynamics. A deep evaluation of the different types of treatment may be helpful in decision making. Computational Fluid Dynamics (CFD) is a powerful tool for detailed inspection of cardiovascular diseases. The aim of this work was to implement a comparative analysis based on CFD evaluation of the effects of two type of PAU treatments. Methods: Thoracic endovascular aortic repair (TEVAR) with a left subclavian artery (LSA) branched aortic endograft (SBSG) and a hybrid approach including TEVAR and carotid-LSA bypass were considered. Aortic anatomical models were created from computed tomography (CT) images acquired before and after PAU treatment with SBSG for three patients. Starting from these models, a new aortic geometry corresponding to the outcome of the hybrid strategy was generated. Morphological analysis and CFD simulations were carried out for all aortic models to evaluate LSA outflow for the same predefined boundary conditions. Results: Reductions in LSA diameter were found between aortic models before and after the SBSG (18.2%, 20.8%, and 12.4% for CASE 1, CASE 2, and CASE 3, respectively). The flow rate at LSA changed between pre-configuration and aortic configuration after the PAU treatments: an averaged decrement of 1.08% and 7.5% was found for SBSG and the hybrid approach, respectively. The larger increase in pressure drop between the aortic arch and the LSA extremity was shown in the hybrid approach for all cases. Conclusions: CFD simulations suggest that SBSG preserves LSA perfusion more than a hybrid strategy and has less impact on thoracic aorta hemodynamics.