## 4 Discussion and Conclusions  
In this paper, we have presented EVAR-eaSE software, a user-friendly tool that we have developed to ease the preoperative planning of EVAR procedure, particularly the AAA sac embolization (SE) using coils. As key advantage, the tool provides semi-automatic segmentation of patient CTA scans and the computation of aneurysm volumes, thus allowing time saving for clinicians, as well as the reduction of operator-dependency in preoperative planning procedures. The software is easy-to-use after a brief training, without the need of specific programming knowledge. Aneurysm volumes calculation is important to choose endovascular treatment modalities and to plan the optimal number of coils to be inserted for AAA SE. Many authors have previously reported the difficulty of determining true aneurysm volume [20; 21; 22; 23]. As noted by [PERSON] et al. [21] and [PERSON] et al. [22], volume calculations based on 2-dimensional images can be adversely affected by the lack of a fiduciary marker and irregular aneurysm shapes, as well as simplistic spherical or elliptical geometric models can be inaccurate. The developed EVAR-eaSE software provides segmentation, 3D modeling and automatic computation of the aneurysm volumes of interest for preoperative planning, starting from patient CTA scans. In the current version, the lumen volume segmentation is particularly efficient, since it may be achieved quickly and automatically with only two clicks by the user just selecting the first and the last slice in the patient scan. This result has been obtained following the example of previously reported \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Computed Volume [cm3]** & **Real** & \\  & **(by EVAR-eaSE)** & **Volume [cm3]** & **\% Difference** \\  & **(by Gauge)** & & \\ \hline
**Phantom 1** & 50.06 & 54.24 & \textasci{-7.7\%} \\ \hline
**Phantom 2** & 107.53 & 110.33 & \textasci{-2.5\%} \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparative results between mean “computed” volume (by EVAR-eaSE) and “real” volume (by gauge), for both radiological phantoms. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **AAA-Lumen Volume (LV)** & \\ \hline  & **3 Mensio** & **EVAR-eaSE** \\ \hline
**Mean (cm3)** & 89.73 & 85.38 \\ \hline
**SD (cm3)** & 25.70 & 25.25 \\ \hline Correlation (r) & 0.940 & \\ \hline \(p\)-value & \textasci{<0.001} & \\ \hline \multicolumn{3}{c}{**AAA-Total Volume (TV)**} \\ \hline  & **3 Mensio** & **EVAR-eaSE** \\ \hline
**Mean TV (cm3)** & 142.19 & 127.96 \\ \hline
**SD (cm3)** & 44.88 & 40.65 \\ \hline Correlation (r) & 0.954 & \\ \hline \(p\)-value & \textasci{<0.001} & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Paired samples correlation table between EVAR-eaSE and 3 Mensio volumetric computations, for 26 retrospective abdominal aortic aneurysm (AAA) cases. approaches for automatic blood vessel segmentation from CTA [24; 25] that use a pre-processing stage for obtaining better segmentation results. In our case, a dedicated contrast-enhanced algorithm was implemented based on contrast stretching for remapping the image so it can occupy the whole gray shade spectrum. This specific feature helps the surgeon to better identify in the segmentation window the number of EPV of the aneurysm, which represents a predictive risk factor for ELIlp. Comparing EVAR-eaSE with other commercial EVAR planning software or aneurysm volume calculators, the distinctive feature of our tool is the possibility to manage in an easy way the whole process of planning the SE during EVAR, this including: CTA patient scan segmentation and aneurysm volumes computation; setting of the endograft type and size for implant; computation of the endoluminal FV; and the optimal number of coils to be implanted. The software also provides calculation of a set of data useful for supporting EVAR planning (Table 1). A comparison of the EVAR-eaSE tool with other available software for aneurysm volume computation and SE planning, mainly in neurovascular field, is presented below in tabular format (Table 6).