Quantitative lymph imaging for assessment of lymph function using indocyanine green fluorescence lymphography.

OBJECTIVES A new diagnostic imaging technique that can assess lymph function is needed as a screening test in daily practice. This study assessed the use of indocyanine green (ICG) fluorescence lymphography in subjects without leg oedema. METHODS 0.3ml of ICG (0.5 %) was injected subcutaneously at the dorsum of the foot. Subsequently, the movement of ICG dye from the injection site to the groin was traced by visualizing its fluorescence signal with an infrared light camera. The time for the dye to reach the knee and groin were measured (Transit time to knee: TT(K), Transit time to groin: TT(G)). TT(G) was measured while standing, lying at a supine position, standing with massage, and sitting while using a cycle ergometer exercise at an intensity of 50W at 50rpm in ten healthy volunteers at intervals of 14 days. RESULTS Mean TT(G) during standing was 357+/-289 and 653+/-564 seconds for the right and left legs respectively. Compared to TT(G) in the standing position, all other conditions shortened TT(G). In another seventeen subjects without leg oedema, we compared transit time obtained with ICG fluorescence lymphography to that with dynamic lymphoscintigraphy. A significant correlation between transit time measured with ICG lymphography and dynamic lymphoscintigraphy was identified (r(2)=0.64, p<0.01). CONCLUSIONS ICG fluorescence lymphography has the potential to become an alternative lymphatic imaging technique to assess lymph function.