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  • br DISCUSSION br In our


    In our prospective cohort study of 31 surgical explo-rations, IOUS was of significant clinical value in 61% of the procedures by providing additional information at an early stage during the exploration. The vascular contact (or lack of contact) was correctly assessed with IOUS in 89% of the procedures, a 15% increase compared with the preoperative imaging. Although this increase is not significant, IOUS shows a trend toward better evaluation
    Fig. 2. Example of preoperative MRI images and IOUS images of complete response on Folfirinox. (a) Pre-Folfirinox scan: dynamic (post-contrast) MRI scan showing a borderline resectable tumor. Arrow: ductal pancreatic adenocarci-noma, definable mass. (b) Post-Folfirinox scan: dynamic (post-contrast) MRI scan showing the remnant of the tumor (*) No visible mass is seen, and without Galactose 1-phosphate  signal, only fibrotic irregular tissue is found. A stent is present in the ductus choledochus (CBD). (c) Intraoperative ultrasound: a hypoechoic irregular area (*) in the neck of the pancreas is seen without a definable mass. A stent is present in the ductus choledochus (CBD). Duod = duodenum; CBD = ductus chole-dochus; MRI = magnetic resonance imaging; PD = ductus pancreaticus.
    Intraoperative US for pancreatic cancer B. G. SIBINGA MULDER et al. 2025
    of vascular involvement. Because of the direct feedback of the radiologist to the surgeons during the procedures, surgeons were generally prepared earlier in the surgery with respect to what they could expect. Not only the extensiveness of the resection could be altered because of the IOUS assessment but also the vascular reconstruction could be advised and tumors treated with neoadjuvant therapy, as well as their responses, could be visualized with IOUS.
    The use of IOUS during surgery for pancreatic can-cer is not a new application, but IOUS is not routinely used during these procedures and has, surprisingly, scarcely been studied in the last few years. Therefore, the added value of IOUS is not recorded. In a Ukrainian study, 76 patients were retrospectively included, and the IOUS assessment changed the surgical strategy in 30% (Kolesnik et al. 2015). However, these changes were ret-rospectively determined and consisted mainly of the identification of additional hepatic metastases. In con-trast, all our procedures started with laparoscopic staging immediately prior to surgical exploration, thereby poten-tially identifying occult superficial liver metastases. Thereafter, patients were included in our prospective study for evaluation of their primary tumor with IOUS. In our group, no occult metastases were found during the open exploration following laparoscopy.
    IOUS can yield more information than the preoper-ative imaging scan by providing direct contact with the tissue and real-time imaging data. On the preoperative CT scan, the majority of tumors (63%) in our cohort appeared isodense, preventing direct visibility of the tumor using Archaebacteria imaging modality. In contrast, all tumors could be visualized with IOUS, and only 13% was suboptimally visualized. In addition, the rate of dis-cordance between preoperative imaging and microscopic examination was higher than between IOUS and micro-scopic examination with respect to vascular involve-ment. Interestingly, De Werra et al. (2015) reported an even higher discordance rate between preoperative imaging and pathology reports compared with our cohort (64% vs. 44%, respectively).
    In our patient cohort, the rate of R1 (non-radical) resection was 22%, which was lower than the global reported rate of approximately 60% (Neoptolemos et al. 2017). The resulting increase in the rate of R0 (radical) resection may have been the result of IOUS, thereby increasing the surgeon’s ability to directly visualize vas-cular involvement and/or ingrowth during surgical explo-ration. One factor that may explain the discordance rate between IOUS and the microscopy findings in our study is that IOUS failed to reveal the positive resection mar-gins of the gastroduodenal artery and the common bile duct in two patients because these margins were not assessed with IOUS and besides that, only a cluster of a