Contrast-Assisted Ultrasound for Sentinel Lymph Node Detection in Spontaneously Arising Canine Head and Neck Tumors

We sought to evaluate a minimally invasive contrast-assisted ultrasound (US) technique for sentinel lymph node (SLN) localization.Microbubble contrast medium was injected into peritumoral tissues in 10 dogs with spontaneous head or neck tumors. Regional lymph nodes (LNs) were imaged up to 20 minutes after contrast administration using power Doppler US. Comparative lymphoscintigraphy studies were performed in all dogs by peritumoral injection of 99mTc-sulfur colloid administered around the primary lesion.US contrast enhancement of SLN revealed sentinel nodes and associated lymphatics in 8 of 10 dogs. In each instance in which contrast-enhanced LN was identified with US, a corresponding SLN was detected by lymphoscintigraphy. Multiple SLNs were present in 2 dogs. Regional lymph nodes were positive for metastasis in 1 dog and reactive in 9 dogs.Contrast-assisted US is effective in localizing SLN. This technique could reduce or eliminate many of the limitations of current SLN detection procedures.