Resident in Small Animal Surgery University of California - Davis
Due to the complex anatomy of the lymphocenters of the head and neck and documented interindividual variability in the location of metastatic lymph node(s) (LN), further investigation of Sentinel LN mapping with widely available techniques is a timely topic. This prospective study was to investigate the feasibility of indirect CT lymphography (CTL) and intraoperative lymphography with methylene blue (IOL-MB) for SLN mapping in canine oral cancer and to report both agreement between the techniques and accuracy of identifying metastatic LN(s). Forty-two dogs with a primary or incompletely excised oral tumor had routine pre and post contrast CT scans of the head and neck and had CTL, IOL-MB, and tumor/cervical LN removal. This study demonstrates that the combination of CTL and IOL-MB techniques yield high detection rate of SLN (97.6%) with moderate agreement (Cohen’s kappa = 0.471), highlighting the importance of using a combination of modalities. Metastatic LNs were identified as the SLN in 6/7 dogs (8/11 LNs). The mean short-long axis ratio was significantly lower when two modalities had the same results than when they did not (p < 0.05). These findings may indicate that the enlarged LN or tumor burden from metastasis may have had altered lymphatic pressure, leading to false negative and disagreement between modalities. The main limitations included a small number of LN metastasis, and the difficulty of standardizing protocols for IOL-MB due to surgical and surgeon factors. This study also highlights SLN mapping should only be used for subclinical LN metastasis.
