## 4 Discussion  
Our study has shown that parameters derived from 3D modeling and 3D characterization of the tumor, i.e., the tumor volume (Vol) and the presence of shape irregularities expressed by the Conv index, together with CS invasion (particularly for Knosp grade 4) have an independent prognostic role in determining the extent of resection of a pituitary tumor through an EEA. Although modern technological advancements have permitted to improve the effectiveness of the transsphenoidal route, allowing surgeons to achieve a total removal rate between 50% and 80%, the persistence of remnants remains an issue, exposing the patient to a higher risk of progression/recurrence, persistence of endocrinopathies, or of compressive symptoms [18; 23; 42; 43; 44]. In the pre-surgical phase, it would be relevant to predict the risk of incomplete resection, both for correct patient counseling and to eventually plan post-operative treatments, such as medications for hyper-secretive tumors or radiotherapy. However, it is a common experience in routine clinical settings that some tumors being pre-operatively considered not radically resectable would have a better result than expected, and vice versa. Based on these considerations, multiple studies have recently investigated if pre-operative neuroradiological or clinical factors would be associated with a different extent of tumor removal [14; 15; 16; 17; 18; 19; 23]. Many parameters have been demonstrated to present a significant prognostic role, such as tumor invasiveness, particularly when the mass extensively grows into the CS, the occurrence of previous surgeries or radiotherapies, the hard or fibrous consistency of the tumor, and its size and diameter [14; 15; 16; 17; 19; 43; 44; 45; 46; 47; 48; 49]. Furthermore, a Swiss group has recently proposed a score (Zurich Pituitary Score), which considers the ratio between the ICD and HD of the tumor, and the presence of carotid encasement, to pre-operatively estimate the extent of tumor removal [23]. We have observed that 3D morphological features also have a prominent role in the determination of the tumor extension rate. Indeed, for tumors with a similar Vol and CS invasion degree, the tumor's 3D shape represents a relevant predictive factor. In our study, we have evaluated two 3D-based morphological features of pituitary adenoma, i.e., the Spher and the Conv. With the first, we aimed to consider how much the tumor shape would be similar to that of a sphere, resulting in a round lesion. The second index (Conv) reflects the presence of irregularities more than the Spher, as hollows or indentations, in the 3D tumor shape, identifying lesions with a multi-lobular aspect or an excavated shape. At the statistical analysis, the Conv resulted as the most significantly associated with the risk of an incomplete tumor removal. This can be explained considering that in some cases, as for \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Parameter** & **z** & **_p_** & **95\% Conf. Interval** & **Odds Ratio** \\ \hline Conv & \(-\)3.87 & 0.00 & 0.73 & 0.90 & 0.81 \\ Vol & 1.61 & 0.11 & 1.00 & 1.01 & 1.01 \\ \hline
**Parameter** & **z** & P & **95\% Conf. Interval** & **Odds Ratio** \\ \hline Conv & \(-\)3.02 & 0.03 & 0.73 & 0.93 & 0.83 \\ Knosp 2 & 1.61 & 0.073 & 0.80 & 136.7 & 10.48 \\ Knosp 3 & 1.81 & 0.108 & 0.66 & 65.31 & 6.56 \\ Knosp 4 & 2.62 & 0.070 & 0.86 & 54.33 & 6.82 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: The upper section of the table: univariate logistic regression for convexity (Conv) and volume (Vol). The lower section of the table: bivariate analysis showed that for tumors with a similar volume, the presence of irregularities in their shape (expressed by low Conv values) has a major role in the determination of the tumor resection extent. For Knosp grade, Odds Ratios referred to Knosp grade 1.  
ovoidal or flat-geoidal lesions which do not present relevant surgical challenges, the Spher may be low, even if the overall shape is quite regular (i.e., high Conv), and vice versa.