Identification of liver metastases with probe‐based confocal laser endomicroscopy at two excitation wavelengths

Abstract

BackgroundMetastasis of colorectal cancer to the liver is the most common indication for hepatic resection in a western population. Incomplete excision of malignancy due to residual microscopic disease normally results in worse patient outcome. Therefore, a method aiding in the real time discrimination of normal and malignant tissue on a microscopic level would be of benefit.Material and MethodsThe ability of fluorescent probe‐based confocal laser endomicroscopy (pCLE) to identify normal and malignant liver tissue was evaluated in an orthotopic murine model of colorectal cancer liver metastasis (CRLM). To maximise information yield, two clinical fluorophores, fluorescein and indocyanine green (ICG) were injected and imaged in a dual wavelength approach (488 and 660 nm, respectively). Visual tissue characteristics on pCLE examination were compared with histological features. Fluorescence intensity in both tissues was statistically analysed to elucidate if this can be used to differentiate between normal and malignant tissue.ResultsFluorescein (488 nm) enabled good visualisation of normal and CRLM tissue, whereas ICG (660 nm) visualisation was limited to normal liver tissue only. Fluorescence intensity in areas of CRLM was typically 53–100% lower than normal hepatic parenchyma. Using general linear mixed modelling and receiver operating characteristic analysis, high fluorescence intensity was found to be statistically more likely in normal hepatic tissue.ConclusionReal time discrimination between normal liver parenchyma and metastatic tissue with pCLE examination of fluorescein and ICG is feasible. Employing two (rather than a single) fluorophores allows a combination of qualitative and quantitative characteristics to be used to distinguish between hepatic parenchyma and CRLM. Lasers Surg. Med. 49:280–292, 2017. © 2016 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Functional shift with maintained regenerative potential following portal vein ligation

“…CLE is a novel optical imaging method with an endoscopic wire probe, primarily designed for non-invasive ‘live optical biopsy’ and improved decision making during clinical endoscopy for gastrointestinal and bronchoalveolar diseases 14 . From the wide variety of CLE application types, a few reports are available regarding the liver 31 , 32 . However, to the best of our knowledge, our study is the first known experimental application of CLE in the setting of selective probe-measurement of NLL regional function.…”

Autofluorescence‐based optical biopsy: An effective diagnostic tool in hepatology

“…However, we cannot avoid briefly considering a few examples of optical applications in hepatology based on exogenous dyes. Besides the use of 5‐ALA‐induced PPIX recalled above, indocyanine green and fluorescein have been investigated as contrast dyes that assist the intraoperative differentiation of hepatobiliary structures and tumours from the surrounding hepatic tissue . The perfusion of mouse liver with erythrocytes labelled with fluorescein isothiocyanate and dyes sensitive to oxygen has also been proposed in order to assess hemodynamic changes in diseased liver .…”

“…Besides the use of 5-ALA-induced PPIX recalled above, 56,57 indocyanine green and fluorescein have been investigated as contrast dyes that assist the intraoperative differentiation of hepatobiliary structures and tumours from the surrounding hepatic tissue. 10,13 The perfusion of mouse liver with erythrocytes labelled with fluorescein isothiocyanate and dyes sensitive to oxygen has also been proposed in order to assess hemodynamic changes in diseased liver. 12 The addition of trypan blue to the perfusion medium has been successfully used in a time-course analysis of hypoxic injury in isolated rat livers.…”

“…Given the vastness of optical diagnostic's potential, our report will be restricted almost exclusively to native biomolecules, with a brief mention of applications based on exogenous dyes . We will also exclude the many recombinant proteins with fluorescence properties, encoded by genetic engineering to track gene expression and cells, over which criticisms as regards their in vivo biomarker value have been recently reported .…”

“…Given the vastness of optical diagnostic's potential, our report will be restricted almost exclusively to native biomolecules, with a brief mention of applications based on exogenous dyes. [10][11][12][13][14] We will also exclude the many recombinant proteins with fluorescence properties, encoded by genetic engineering to track gene expression and cells, over which criticisms as regards their in vivo biomarker value have been recently reported. 15 A further and unavoidable limitation relates to the literature cited, restricted to historical reports on the first observations and initial phases of AF-based research, some intermediate works, and more recent activity that demonstrates the increasing importance given to optical biopsy applications in hepatology ( Figure 1).…”