This is a prospective single-center interventional non-inferiority study where subjects are participating for one day for patients 18 years or older with melanoma, breast cancer or head \& neck cancer (including melanoma of head and neck area) and scheduled for a surgical SN procedure in the NKI-AvL without any contra-indication for Sonazoid contrast agent, such as an allergy to eggs or egg products. The primary objective is to assess the sensitivity of CEUS for intra-operative SN localization compared to the gold standard (99mTc nanocolloid). Secondary objectives are the specificity of CEUS for intra-operative SN localization, the time required to localize the SNs using CEUS and intraoperative usability of the CEUS-system. The primary endpoint is the sensitivity of the CEUS SN localization method. The conventional gamma probe will be used as ground truth comparison.