Which statement best describes gallium-67 imaging in infection and inflammation?

• A. It binds to hydroxyapatite and highlights bone turnover
• B. It is exhaled rapidly and not used clinically
• C. Gallium binds to white blood cells and localizes in inflammatory sites
• D. It binds to plasma proteins only and does not localize to infection

Answer: (C)

Gallium-67 imaging works because gallium behaves like ferric iron and rides on iron-transport proteins. In the bloodstream, gallium binds to transferrin and lactoferrin. In areas of infection or inflammation, there’s increased activity of white blood cells and more vascular permeability, so transferrin and lactoferrin—carrying gallium—accumulate at the site. Activated white blood cells can take up gallium, and bacteria themselves may take it up as an iron surrogate, leading to focal uptake at infectious or inflammatory foci. This is why the tracer highlights sites of infection and inflammation rather than binding to bone or being exhaled; it localizes where immune activity is occurring.