# Laparoscopic Microwave Ablation: Which Technologies Improve the Results
## 4 LUS Evaluation
This approach has the goal of producing an ischemic zone centered on the vessel feeding the lesion thus increasing the area of necrosis [26]: in this way, it is desired to reduce the risk of partial necrosis or a local tumor progression that would require additional ablative therapy. The first step of the procedure is to detect with ultrasound the presence of the vessel feeding the lesion or otherwise of a contiguous vessel that could determine a heat ink effect: very often the use of color-doppler allows for the better identification of the vascular architecture. At this point, under ultrasound guidance, the electrode/antenna is positioned as close as possible to the vessel and its ablation is carried out by RFA (the ablation cycle lasts either 2-4 min) or MWA (60-90 s). At the end of ablation, the coagulative ablation of the area previously refurnished by the vessel ablated is evaluated using again the color doppler imaging or using intravenous ultrasound contrast agent. Furthermore, a discolored area on the liver surface could be also visualized. The use of ICG imaging after immediate injection can emphasize the absence of portal flow. Then, the nodule can be treated with the insertion of the electrode or antenna in the usual way. IHVO reduces the local recurrence after ablation with comparable results to surgical resection [2,43]. Another application of IOUS is the ability to characterize locally advanced HCC nodules, even with a diameter of less than 3 cm and this could justify the high recurrence rates after radical treatments, mainly due to new HCC tumors in the remaining liver. Several studies have established that the existence of microvascular infiltration and satellitosis could be a determinant of HCC recurrence after healing treatments [44; 45; 46] and therefore the relevance of recognizing the HCC nodule with these features before the histological analysis [47; 48]. In fact, if it was possible to identify the biological aggressiveness of the HCC nodule, a micro-invasive HCC (MI-HCC) could be treated in another way. In a previous study [49], we have shown that IOUS is able to identify some features which were typical of MI-HCC and these findings effectively matched with similar histopathologic criteria. These IOUS findings (Figure 6) are useful to identify the biological behavior of HCC and to foresee the likelihood of local recurrences and overall survival rates. The ability of IOUS to identify the micro-invasive pattern allows for the recognition of these high-risk patients also during laparoscopic ablation, a treatment without a pathological specimen to analyze. In patients with MI-HCC, IOUS (during the laparoscopic ablation treatment) can definitely demonstrate situations at higher risk of local recurrence, secondary to the microvascular infiltration, satellitosis and/or lesions adjacent to the major vessels as described elsewhere [50]. These IOUS' patterns could be a reason for overlapping needle insertions to secure a larger necrosis area comprehending the territory with the microvascular infiltration and/or satellitosis. In the future, wider use of laparoscopic contrast-enhanced IOUS could improve the success of the laparoscopic ablation treatment thanks to the intraoperative evaluation of the extension of the necrosis area and the presence or not of residual disease. In fact, apart from the capacity of laparoscopic contrast-enhanced IOUS in characterizing new nodules, it can be useful to evaluate necrosis extension after the ablative treatment during the same procedure. Residual viable neoplastic foci can be recognized by the presence of an enhancement portion on the outskirts of the ablated area, permitting a supplementary treatment in the same session. It is necessary to wait for 10-15 min after the first ablation to assess the residual enhancement portion through the contrast-enhanced IOUS because an immediate appraisal of the ablated area is unsatisfactory for the presence of artifacts due to gas formation or cavitation.