Elsevier

Journal of Hepatology

Volume 58, Issue 2, February 2013, Pages 247-253
Journal of Hepatology

Research Article
Portal uptake function in veno-occlusive regions evaluated by real-time fluorescent imaging using indocyanine green

https://doi.org/10.1016/j.jhep.2012.09.028Get rights and content

Background & Aims

Although recent advances in preoperative imaging have enabled accurate estimation of the regional liver volume with venous occlusion, the extent of functional decrease in such regions remains unclear. In this study, the portal uptake function in postoperative veno-occlusive regions and non-veno-occlusive regions was evaluated by intraoperative fluorescent imaging after intravenous injection of indocyanine green (ICG).

Methods

In 22 liver resection patients and 23 recipients and 18 donors of liver transplantation, fluorescent intensity on the remnant liver or the liver graft was evaluated in real time following intravenous injection of ICG (0.0025 mg per 1 ml of remnant liver volume).

Results

Plateau ICG concentrations were significantly lower in the veno-occlusive regions (CVO) than in the non-veno-occlusive regions (CNon) in liver resection patients (median [range], 0.75 [0.29–2.0] μg/ml vs. 3.0 [0.46–6.4] μg/ml, p <0.001), donors (0.69 [0.29–1.9] μg/ml vs. 2.4 [0.46–6.4] μg/ml, p <0.001), and recipients (0.75 [0.34–1.8] μg/ml vs. 1.8 [0.54–6.4] μg/ml, p <0.001). Distributions of the CVO/CNon and the ratio of the hepatic uptake rate constant in the veno-occlusive regions to that in non-veno-occlusive regions were both around 40% (mean ± standard deviation, 0.36 ± 0.17 and 0.42 ± 0.16, respectively). When the functional remnant liver volume was calculated as a sum of non-veno-occlusive regions and veno-occlusive regions multiplied by CVO/CNon, its ratio to the total liver volume was correlated with the improved postoperative/preoperative ratio of prothrombin time.

Conclusions

Portal uptake function in veno-occlusive regions is approximately 40% of that in non-veno-occlusive regions. Intraoperative ICG-fluorescent imaging enables real-time evaluation of the extent of the functional decrease in veno-occlusive regions, enhancing accurate estimation of the hepatic functional reserve for determining the surgical indications and procedures.

Introduction

It is well known that hepatic venous outflow obstruction can cause decreased sinusoidal perfusion, sinusoidal congestion, and hepatocellular apotosis, leading to hepatic dysfunction in conditions such as veno-occlusive disease, Budd-Chiari syndrome, and congestive hepatopathy associated with cardiac diseases [1]. In surgical settings, venous occlusion in the remnant liver after resection or in the graft in partial liver transplantation can make portal veins function as a drainage vessel [2], resulting in necrosis [3], or insufficient regeneration [4] of such veno-occlusive regions, which can cause severe difficulty in postoperative management [5], [6]. In order to prevent postoperative hepatic dysfunction in veno-occlusive regions, stumps of the major hepatic vein tributaries are sometimes reconstructed during liver resection [7] and living donor liver transplantation [8], [9]. In particular, recent advances in imaging studies based on preoperative three-dimensional computed tomography (CT) have enabled accurate estimation of regional liver volumes with postoperative venous occlusion [10], [11], [12]. However, liver function in such veno-occlusive hepatic regions has been a “black box”. No matter how accurately we can estimate the liver volumes with venous occlusion, such information cannot be fully utilized for deciding the surgical indications and the need/lack of it for venous reconstruction, which requires clarification of the extent of functional decrease in the veno-occlusive regions.

In a previous study, Hashimoto et al. evaluated the extent of decrease in sinusoidal perfusion in veno-occlusive regions in the remnant liver after graft procurement, by estimating the intrahepatic concentrations of indocyanine green (ICG) by near-infrared spectroscopy [13]. Although they reported that the median value of the ratio of the hepatic ICG uptake constant in the veno-occlusive regions to that in the non-veno-occlusive regions was approximately 0.5, it ranged widely from 0.1 to 0.9, probably because of the large inter- and intra-individual variability in the degree of venous occlusion, which could not be revealed by fixed-point observation with the thin probe tip of spectroscopy. Recently, the fluorescent imaging technique utilizing ICG as the fluorescent source has been developed and applied to hepatobiliary surgery for intraoperative visualization of bile ducts [14], [15], [16], liver cancers [17], [18], and hepatic segments to be resected [19], [20]. In the present study, we evaluated the regional differences in the portal uptake function in the remnant livers or transplanted liver grafts by directly converting the fluorescence intensity (FI) values to estimated concentrations of ICG using a fluorescent imaging system, which enabled real-time visualization of the distribution of ICG to the entire liver surface.

Section snippets

Patients and methods

This study was conducted with the approval of the Institutional Ethics Review Board of Tokyo University and registered in the UMIN-CTR (UMIN000003656, https://center.umin.ac.jp/ctr/index.htm). Informed consent was obtained from all the patients.

Preoperative estimation of the regional LV with and without venous occlusion

Results of preoperative estimation of the regional LV are summarized in Table 1. The ratio of LVVO to RLV (or the graft volume in recipients) was significantly higher in the donors who underwent surgery for procurement of a left liver graft than in those who underwent surgery for procurement of a right liver graft (29.0 [15.8–34.0]% vs. 2.7 [1.5–24.3]%, p = 0.0013); it was also higher in the right liver graft than in the left liver graft (27.5 [10.8–61.4]% vs. 7.6 [2.6–18.7]%, p = 0.0006).

Discussion

Our results suggested that the portal uptake function in veno-occlusive regions is usually 30–40% of that in the non-veno-occlusive regions, in terms of both the hepatic uptake rate constant and the plateau concentration of ICG, which represent the efficacy of portal uptake function in the early phase and distribution of portal substance to hepatocytes in the equilibrium phase after ICG injection, respectively. In the exceptional patients with large communications among hepatic vein

Financial support

This work was supported by Grants from the Takeda Science Foundation, the Kanae Foundation for the Promotion of Medical Science, and the Ministry of Education, Culture, Sports, Science and Technology of Japan (No. 23689060).

Conflict of interest

The authors who have taken part in this study declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript.

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