Blood vessel imaging using radiofrequency-induced second harmonic acoustic response.

We introduce a contrast mechanism for visualizing blood vessels based on radiofrequency-induced second harmonic acoustic (RISHA) signals sensing blood conductivity. We develop a novel imaging system using commonly available inexpensive components, and demonstrate in vivo RISHA visualization of blood vessels based on low-power quasi-continuous radiofrequency excitation of tissue at frequencies of a few MHz. We show how the novel approach also implicitly enables radiofrequency-induced passive ultrasound imaging and can be readily applied to non-invasive imaging of blood vessels ex vivo and in vivo. We discuss the implications of non-invasive conductivity measurements in the context of biomedical applications.