Lymphatic transport will be examined using Near InfraRed Indocyanine Green fluorescence imaging (NIR-ICG) and magnetic resonance lymphography (MRL) of the upper extremities. The purpose of the study is to establish if NIR-ICG is a valid clinical outcome for quantifying lymphatic vessel drainage.

Lymphedema from various etiologies (i.e. infection, cancer, surgery, and rheumatoid arthritis) remains a major health concern. Efforts to develop effective treatments for this condition have been limited by the absence of quantitative outcome measures for lymphatic function. Published articles have supported the fact that human lymphatic contractions can be readily visualized after intradermal administration of micrograms of Indocyanine Green using laser-induced fluorescence. We recently demonstrated the feasibility of NIR imaging to quantify lymphatic drainage in the hands, wrists and forearms of healthy volunteers following intradermal web space ICG injection into the hand . To establish this emerging technology as a valid clinical outcome measure, however, we must address two major questions that confound interpretation of the imaging results: 1) are the ICG filled vessels lymphatic vessels and/or small veins?; and 2) does NIR-ICG imaging following web space injection fully capture lymphatic flow from the metacarpophalangeal (MCP) joints that are most commonly involved in RA? To answer these questions, healthy patients will be recruited to have intradermal and intra-articular injections of ICG and gadolinium followed by an imaging sessions (NIR or magnetic resonance imaging) to measure lymphatic contraction rates and flow.

Inclusion Criteria:

• Ability to provide written informed consent.
• Subjects must be 18 years old or older.

Exclusion Criteria:

• Active systemic disorders or inflammatory conditions (i.e., chronic infections with hepatitis B, hepatitis C or HIV) that would confound the study results.
• Known sensitivity to iodine because of residual iodide in indocyanine green
• Known sensitivity to gadolinium
• Any history of kidney disease
• Pregnant women should not participate; pregnancy tests will not be performed.

Information of any type may be shared with researchers at other institutions. Subjects will be made aware of this in the informed consent form.