## 1 Introduction  
In the last decade, endovascular aneurysm repair (EVAR) has become the primary choice of treatment for abdominal aortic aneurysm (AAA) in suitable patients due to its lower perioperative morbidity and mortality [1, 2].  
Endoleaks, i.e., blood flow outside the lumen of the endograft but within the aneurysm sac, are the most frequent causes of reinterventions. Type II endoleaks (ELII), caused by a backflow of collateral arteries into the aneurysm sac, if persistent (ELIIp, \(\geq\)6 months), can be associated with an increased incidence of the adverse outcomes, including the sac growth, the reintervention rate,the need for conversion to open surgery and AAA ruptures [3; 4; 5]. Some authors have suggested routine intra-procedural AAA sac embolization (SE) using different materials (metallic coils, fibrin, or glue) to promote AAA sac thrombosis and to reduce the incidence of ELIIp [6; 7; 8; 9]. Previous studies have also shown that the presence of pre-treatment morphological factors, such as multiple patent aortic branch efferent vessels and AAA sac thrombus load, increase the risk of ELIIp after EVAR [4], [10; 11; 12]. In particular, a recent study [11] suggested that at least six efferent patent vessels (EPV) and/or a thrombus volume ratio (VR%, i.e., [AAA thrombus volume/AAA total volume] \(*\) 100) \(<\)40% of the AAA total volume can identify patients with an increased ELIIp risk, and may lead to a selective prevention with intraoperative SE. Another study [13] investigating for predictors of ELIIp prevention after intraoperative SE with coils during EVAR, identified a Concentration Coil (CCoil = number coils implanted/endoluminal AAA free sac volume) of 0.17 coil/cc as optimal value to obtain a complete AAA thrombosis.  
Currently, the preoperative evaluation of ELIIp risk based on the said morphological features (EPV, VR%), as well as the choice for the optimal number of coils for SE have not been standardized yet. Aortic aneurysm volumetric estimations, essential for optimal endograft sizing and SE planning, are typically carried by the surgeon using a commercial software for EVAR preoperative sizing and planning (3 MensioTM, Vascular Imaging, Bilthoven, Netherlands, [14; 15]), but they remain quite operator-dependent and time consuming. Moreover, some procedural steps, such as the estimation of the endoluminal AAA free sac volume available for coils insertion, and the computation of the number of coils to be used for achieving the optimal CCoil, cannot be directly provided by the software.  
While in neurovascular field, the SE procedure with coils is more standardized and specific software applications already exist to support surgeon in accurately computing the aneurysm volumes and in predicting the packing density with each coil selection [16; 17], for vascular surgery no software tool specifically dedicated to planning SE with coils during EVAR has yet been proposed.  
In this paper, the primary aim is to introduce 'EVAR-eaSE', a new software that we have developed to provide the surgeon with an easy, semi-automatic and quick tool to manage the whole process of planning SE during EVAR, including: patient scan segmentation, accurate calculation of aneurysm volumes, input of type and size of the interventional devices (endografts and coils), computation of various parameters useful for supporting the preoperative planning.  
After a description of the main functionalities and user interfaces of the new developed software, we present a preliminary evaluation of its accuracy performed on phantoms of known volumes, and a comparison with the commercial 3 Mensio EVAR planning software on a retrospective database of 26 AAA cases.