title: Macro- and microscopic findings of ICG fluorescence in liver tumors.
abstract: BACKGROUND
  Reports detailing microscopic observations of indocyanine green (ICG) fluorescence imaging (IFI) in hepatocellular carcinoma (HCC) and metastatic liver cancer are rare. We were able to perform macro- and microscopic IFI results in postoperative paraffin-embedded tissue samples and formalin-fixed specimens from liver tumors.
  
  
  METHODS
  Between April 2010 and March 2014, 19 patients with HCC or liver metastases of colorectal tumors underwent liver resection. ICG solution was injected into the peripheral vein from 14 to 2 days prior to operation. We observed liver tumor IFI during the laparotomy and IFI in resected liver sections using a photo dynamic emission (PDE) camera. The IFI of paraffin-embedded tissue samples was observed using a charge-coupled device (CCD) camera. Moreover, we microscopically performed tissue section IFI using a fluorescence microscope with an ICG-B-NQF.
  
  
  RESULTS
  We performed that IFI characteristics depended on tumor type macroscopically and microscopically. In normal liver tissue, fluorescence consistent with the bile canaliculus was observed. HCC had heterogeneous IFI, forming a total or partial tumor and rim pattern. In metastatic carcinoma, we performed that non-tumor cells in the marginal region showed fluorescence and tumor cells in the central region did not fluoresce.
  
  
  CONCLUSIONS
  We confirmed that the variations of ICG fluorescence imaging patterns reflect different tumor characteristics in not only macroscopic imaging as previous reports but also microscopic imaging. Moreover, the ICG fluorescence method is useful for postoperative pathological detection of microscopic lesions in histopathological specimens. ICG fluorescence in paraffin-embedded tissue samples and formalin-fixed specimens is preserved in the long term.
authors.affiliation: Department of Surgery, Japan Labor Health and Welfare Organization, Kushiro Rosai Hospital, 13-12, Nakazono-cho, Kushiro, Hokkaido, 085-8533, Japan. shingoshimada1979@true.ocn.ne.jp.
authors.forename: Shingo
authors.initials: S
authors.lastname: Shimada
authors.affiliation: Department of Oral and Maxillofacial Surgery, Japan Labor Health and Welfare Organization, Kushiro Rosai Hospital, 13-12, Nakazono-cho, Kushiro, Hokkaido, 085-8533, Japan. s-ohtsubo@kushiroh.rofuku.go.jp.
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtsubo
authors.affiliation: Department of Surgery, Japan Labor Health and Welfare Organization, Kushiro Rosai Hospital, 13-12, Nakazono-cho, Kushiro, Hokkaido, 085-8533, Japan. kaz-og@js2.so-net.ne.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ogasawara
authors.affiliation: Department of Surgery, Seiwa Memorial Hospital, 1-5-1-1, Kotoni, Nishi-ku, Sapporo, Hokkaido, 063-0811, Japan. kusanomitsuo@me.com.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kusano
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D004396:Coloring Agents; D006801:Humans; D007208:Indocyanine Green; D008113:Liver Neoplasms / Q000473:pathology*; D008856:Microscopy, Fluorescence; D016612:Paraffin Embedding
chemical_list: D004396:Coloring Agents; D007208:Indocyanine Green