Page 51 - VOL 26 N. 72 - 2015

NEAR-INFRA-RED (NIR) FLUORESCENCE IMAGING OF LYMPHATIC VESSELS AND NODES
AFTER SUBCUTANEOUS (SC) INJECTION OF FREE INDOCYANINE GREEN (ICG) IN ONE ANIMAL MODEL: PRELIMINARY RESULTS
PIERRE BOURGEOIS 1, ROMAIN BARBIEUX 2, SOPHIE V ANKERCKHOVE 1, OLIVIER LEDUC 2 For the Group R&D Clinical Applications of Fluorescence Imagings
1 Department of Nuclear Medicine and Clinic-Unit of Lymphology, Institut Jules Bordet, Université Libre de Bruxelles, Belgium
2 Lympho-phlebology Unit, Department of occupational and environmental physiology, Haute Ecole P.H. Spaak, Brussels Belgium
Introduction: NIR fluorescence imagings of the lymphatic vessels (LV) and/or of the lymph nodes (LN) after the SC injection of free ICG are now largely proposed to show the Sentinel Lymph Nodes in human patients with various cancers and/or to study the lymphatic system in human patients with edema. However, there are few data in the literature about the kinetics of these fluorescences in the LV and LN. The aim of the presentation is to report the results of the analysis of the fluorescence imagings (in the LN and in the LV) obtained in one animal model from 2 hours up to 7 days after SC injection of free ICG in the hind limbs.
Material and methods: Five groups of 5 mices were injected to be analyzed after 1h, 4h, 24h, 72h and 7 days. In order to perform the injections, mice were anesthetized with ketamine 10% and xylasine 5%. At least 4 mices in each group were sub-cutaneously injected with 50μg ICG in 50μl either in one, or in the two hind limbs. All the mices woke up (except the group analyzed 1h after injection) and moved normally between injections and euthanasia (by CO2 asphyxia). Using our near-infrared imaging system (PhotoDynamic Eye = PDE – Hamamatsu), imagings were performed at these times: a) of the whole animals in dorsal decubitus when the mices were opened and the axillary and inguinal lymph nodes and the connecting lymphatic inguino axillary vessels were exposed and b) (ex vivo “fresh” and after their embedding in paraffin) of the axillary and inguinal dissected LN and of the (also dissected) skin flap containing the lymph vessel between these LN.
Results: From the simple visual analysis of the animal imagings, the lymphatic transport of the ICG in the LV between the inguinal LN and the axillary LN appeared to be transitory and no more detectable after 24 hours. On the other hand, the semi-quantitative evaluation of the fluorescence in these LN showed that nodal ICG fluorescence peaked during the first 24 hours after injection, plateau-ed between 24 and 72 hours and thereafter decreased with one mean half life estimated to 48 hours. The fluorescence also remained always higher in the inguinal (first-tier) LN than in the axillary (second tier) LN.
Conclusions: Although obtained in one animal model, our results seem in agreement with the scarce informations about what is observed in human patients: one transport of ICG in the LV limited in the time but a long lasting fluorescence in the LN.
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THE EUROPEAN JOURNAL OF LYMPHOLOGY - Vol. XXVI - Nr. 72 - 2015