Optimization of liposomal indocyanine green for imaging of the urinary pathways and a proof of concept in a pig model

Yael Friedman-Levi, Liraz Larush, Michele Diana, Francesco Marchegiani, Jacques Marescaux, Noam Goder, Guy Lahat, Joseph Klausner, Sara Eyal, Shlomo Magdassi, Eran Nizri*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Background: Iatrogenic ureteral injury is an increasing concern in the laparoscopic era, affecting both patient morbidity and costs. Current techniques enabling intraoperative ureteral identification require invasive procedures or radiations. Our aim was to develop a real-time, non-invasive, radiation-free method to visualize ureters, based on near-infrared (NIR) imaging. For this purpose, we interfered with the biliary excretion pathway of the indocyanine green (ICG) fluorophore by loading it into liposomes, enabling renal excretion. In this work, we studied various parameters influencing ureteral imaging. Methods: Fluorescence intensity (FI) of various liposomal ICG sizes and doses were characterized in vitro and subsequently tested in vivo in mice and pigs. Quantification was performed by measuring FI in multiple points and applying the ureteral/retroperitoneum ratio (U/R). Results: The optimal liposomal ICG loading dose was 20%, for the different liposomes’ sizes tested (30, 60, 100 nm). Higher concentration of ICG decreased FI. In vivo, the optimal liposome size for ureteral imaging was 60 nm, which yielded a U/R of 5.2 ± 1.7 (p < 0.001 vs. free ICG). The optimal ICG dose was 8 mg/kg (U/R = 2.1 ± 0.4, p < 0.05 vs. 4 mg/kg). Only urine after liposomal ICG injection had a measurable FI, and not after free ICG injection. Using a NIR-optimized laparoscopic camera, ureters could be effectively imaged in pigs, from 10 min after injection and persisting for at least 90 min. Ureteral peristaltic waves could be clearly identified only after liposomal ICG injection. Conclusions: Optimization of liposomal ICG allowed to visualize enhanced ureters in animal models and seems a promising fluorophore engineering, which calls for further developments.

Original languageAmerican English
Pages (from-to)963-970
Number of pages8
JournalSurgical Endoscopy and Other Interventional Techniques
Issue number2
StatePublished - 1 Feb 2018

Bibliographical note

Publisher Copyright:
© 2017, Springer Science+Business Media, LLC.


  • Indocyanine green
  • Liposomes
  • Minimal invasive surgery
  • Ureteral injury


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