## 4 Discussion  
With a population of 120 patients, the present study based on our initial experience with the CT-Navigation(tm) electromagnetic system demonstrates that the use of this system for PLB is efficient and safe compared to conventional CT methods. The technical and diagnostic success rates were very high (95.0% and 93.3%, respectively) with no significant \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **NAV Group** & **CT Group** & \(p\) \\ \hline No. of procedures & 60 & 60 & \\ No. of complications (\%) & Pneumothorax & 15 (25.0) & 19 (31.6) & 0.418 \\ Pneumothorax requiring chest tube & 0 (0.0) & 3 (5.0) & 0.244 \\ Thoracic wall hematoma & 0 (0.0) & 0 (0.0) & - \\ Hemothorax & 0 (0.0) & 0 (0.0) & - \\ Intra-alveolar hemorrhage & 21 (35.0) & 16 (26.7) & 0.323 \\ Hemoptiysis moderate or severe & 0 (0.0) & 0 (0.0) & - \\ Systemic air embolism & 0 (0.0) & 0 (0.0) & - \\ \hline \hline \end{tabular}  
No., number; %, percentage; \(p\) < 0.05 was considered as significant.  
\end{table} 
Table 5: Peri-procedural complications. difference when compared to the conventional CT method. The whole procedure duration was very similar between the two groups, with no significant difference. The total radiation dose exposure was significantly lower in the NAV-group (\(p<0.0001\)). Our results are consistent with previous reports in terms of diagnostic success for PLB [20]. In a study, which included 180 patients, [PERSON] et al. found a diagnostic success rate of 96% in the navigation group and 90% in the standard group [20]. Despite no significant difference being found in the total procedure duration between the two groups, the duration of step \(\Delta 2\), that corresponds to the time duration from the puncture to needle progression toward the targeted lesion, was significantly shorter in the NAV-group. This procedure stage is the most uncomfortable for the patient. The navigation system offers the ability to find the best trajectory quickly, decreasing the need for needle repositioning. In the same way as in the [PERSON] et al. study, preparation time (step \(\Delta 1\)) was longer in the NAV-group as compared to the CT-group [13]. It may be explained by the time required to install the device. The installation of the navigation system requires to be fully integrated into the workflow. The operators and the imaging technologists must be accustomed to the use of the equipment, with a real learning curve over time. In our study, the longer preparation time may also be linked to the number of radiologists and residents who participated in the interventions. Some used the navigation system only once before this study, which may increase the average preparation time. Additionally, the system enables us to explore many different trajectories in the 3D volume, allowing the radiologist to choose the best option, that may lengthen the preparation time. Although a previous study showed that using the electromagnetic guidance minimized the impact of operator experience [15], allowing unskilled operators to obtain as good results as the best trained interventional radiologists, the system can still slow down the procedure for the most trained operators and for simple procedures [1]. In our study, less intermediate control acquisitions were required in the NAV-group as compared to the CT-group. Nevertheless, this difference did not reach the level of statistical significance. In a prospective study comparing the CT-Navigation(tm) system to the conventional method, [PERSON] et al. showed a significant decrease in the number of control acquisitions [13]. However, our study focused only on percutaneous lung biopsies. The lack of synchronization with the respiratory movements could explain the number of intermediate control. Although these movements can be critical for the navigation systems as well as for the conventional method, the navigation system superimposes the supposed path of the needle on previously acquired images.