Intraoperative Localization of Rectal Tumors Using Liposomal Indocyanine Green

Shlomo Magdassi, Shoshi Bar-David, Yael Friedman-Levi, Ehud Zigmond, Chen Varol, Guy Lahat, Joseph Klausner, Sara Eyal, Eran Nizri*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Background: Tumor localization may pose a significant challenge during minimally invasive rectal resection. Near-infrared (NIR) imaging can penetrate biological tissue and afford tumor localization from the external surface of the rectum. Our aim was to develop an NIR-based tool for rectal tumor imaging that can be administered intravenously. Methods: We prepared indocyanine-green (ICG)-loaded liposomes by sonication. Liposomes were evaluated for their size and morphology. We then used an endoscopically induced rectal cancer in mice as a model for rectal cancer. After intravenous administration, tumors were evaluated for their fluorescence intensity. Tumor intensity was expressed in relation to the background signal, that is, tumor to background ratio (TBR). Results: Liposomes in various sizes could be prepared by adjusting sonication time. We selected 100-nm-sized liposomes for further experiments. Transmission electron microscopy showed spherical particles and confirmed the size measurements. The liposomes could be lyophilized and then rehydrated again before use without compromising their structure or signal. Fluorescence intensity was kept for 24 hours after solubilization. Testing the optimal time course for rectal tumor imaging revealed that early time course (up to 3 hours) yielded nonspecific imaging, whereas after long time course (24 hours), a very weak signal remained in the tissue. The optimal time window for imaging was after 12 hours from injection, with TBR = 8.1 ± 3.6 (P =.002). Free ICG could not achieve similar results. Conclusions: The liposomal ICG can be reproducibly prepared and kept in lyophilized form. Liposomal ICG could serve as a tool for intraoperative tumor localization.

Original languageAmerican English
Pages (from-to)139-144
Number of pages6
JournalSurgical Innovation
Issue number2
StatePublished - 1 Apr 2017

Bibliographical note

Publisher Copyright:
© SAGE Publications.


  • indocyanine green
  • laparoscopic resection
  • liposomes
  • near infrared imaging
  • rectal adenocarcinoma


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