Purpose: The purpose of this study is to reveal anatomical information of lymphatics in lower extremity using fresh human cadavers with indocyanine green (ICG) fluorescence lymphography (Figure 1: Shinaoka, et al, 2018, PRS), especially classification of lymphatic groups and origins of each group, and finally to establish protocol of injection sites in lymphography.
Material and methods: One hundred lower extremities from fifty-three fresh human cadavers were used for this study. We injected indocyanine green fluorescence (ICG) solution subcutaneously at totally 19 points on border line between dorsum and planta. Injection points were designed according to anatomical landmarks of foot. Immediately after the ICG injection, gentle hand massage was applied on injection points. Fluorescent images were obtained using a near infrared ray (NIR) camera system.
Results: Lymphatic system in lower extremity were classified to the four lymphatic groups according to anatomical features (Figure 2); anteromedial (blue), anterolateral(green), posterolateral(red), and posteromedial group (purple). Anteromedial, anterolateral, and posteromedial groups accompany with trunk and branch of great saphenous vein and posterolateral route accompany with small saphenous vein. Mapping of origins of these four groups was made and show the points which can selectivity visualize each group.
Conclusion: We investigated the anatomy of lymphatics in the lower extremity using 100 cadaveric lower extremities and classified the lymphatic anatomy into four groups. We elucidated correlation between each group and its original sites in the foot. According to these anatomical findings, the refined new protocol was proposed including four proper injection sites for comprehensive assessment of the lymphatic system in the lower extremity in clinical settings.