Serial Ultrasound of Solid Tumor Lesions to Detect Early Response to Cancer Immunotherapy

Inclusion Criteria: * 18 years of age or older * at least one solid tumor lesion greater than 1 cm in diameter (primary tumor and/or at metastatic site), amenable to ultrasound imaging * planned to be treated with ICI therapy (single agent or in combination with any other drug) * written informed consent. * prior use of any ICI is not necessarily excluded, and patients may be included with the approval of the Protocol Director Subjects may participate in the study more than once at the discretion of the Protocol Director, for example, if they receive different lines of treatment that all qualify for the study. Exclusion Criteria: * known hypersensitivity to sulfur hexafluoride lipid microsphere or its components, such as polyethylene glycol (PEG) * any comorbid condition that, in the opinion of the treating provider or the Protocol Directors, compromises the participant's ability to participate in the study * Examples: any mental condition that compromises the ability to follow a consent discussion, or to make informed decisions (except if represented by a Legally Authorized Representative \[LAR\]), or to have ultrasound exams.