Non-invasive Evaluation of NAFLD with Indocyanine Green Clearance Test: a Preliminary Study in Morbidly Obese Patients Undergoing Bariatric Surgery

Fluorescence use in minimally invasive metabolic and bariatric surgery - a systematic review of the literature

PURPOSE

This review aims to explore and summarise current knowledge of indocyanine green (ICG) fluorescence application in metabolic and bariatric surgery (MBS) and assess its potential in improving patient safety.

METHODS

The review was prepared according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. Evidence from PubMed, ScienceDirect and Ovid MEDLINE databases was independently screened in October 2022. The primary information and outcomes were the type of fluorescence application with potential patient benefit and the complication rate. The secondary outcomes consisted of the kind of dye, the application protocol, and the equipment used.

RESULTS

Thirteen publications were included, with six prospective observational studies, five case reports and two retrospective cohort studies and involved a total of 424 patients. The publications were categorized into four groups based on the method of fluorescence application. Sixty-six percent of the cases used fluorescence for LSG, 32.3% used it for RYGB, 1.2% for revisional surgery, 0.2% during removal of an adjustable gastric band, and 0.2% for LSG combined with Rossetti fundoplication. ICG was used on its own in the majority of studies, although in one case, it was used in combination with methylene blue. ICG administration protocols varied significantly. Complications occurred in three patients (0.71%): leaks were diagnosed in two cases, and one patient required a blood transfusion.

CONCLUSION

The most popular type of use is intraoperative assessment of the blood supply. ICG application may reduce the risk of complications, with potential benefits in detecting ischemia and leaks, searching for bleeding in areas inaccessible to endoscopy, and non-invasive hepatopathy evaluation.

A Clinical-Radiomic Model for Predicting Indocyanine Green Retention Rate at 15 Min in Patients With Hepatocellular Carcinoma

Purpose:

The indocyanine green retention rate at 15 min (ICG-R15) is of great importance in the accurate assessment of hepatic functional reserve for safe hepatic resection. To assist clinicians to evaluate hepatic functional reserve in medical institutions that lack expensive equipment, we aimed to explore a novel approach to predict ICG-R15 based on CT images and clinical data in patients with hepatocellular carcinoma (HCC).

Methods

In this retrospective study, 350 eligible patients were enrolled and randomly assigned to the training cohort (245 patients) and test cohort (105 patients). Radiomics features and clinical factors were analyzed to pick out the key variables, and based on which, we developed the random forest regression, extreme gradient boosting regression (XGBR), and artificial neural network models for predicting ICG-R15, respectively. Pearson's correlation coefficient (R) was adopted to evaluate the performance of the models.

Results

We extracted 660 CT image features in total from each patient. Fourteen variables significantly associated with ICG-R15 were picked out for model development. Compared to the other two models, the XGBR achieved the best performance in predicting ICG-R15, with a mean difference of 1.59% (median, 1.53%) and an R-value of 0.90. Delong test result showed no significant difference in the area under the receiver operating characteristic (AUROCs) for predicting post hepatectomy liver failure between actual and estimated ICG-R15.

Conclusion

The proposed approach that incorporates the optimal radiomics features and clinical factors can allow for individualized prediction of ICG-R15 value of patients with HCC, regardless of the specific equipment and detection reagent (NO. ChiCTR2100053042; URL, http://www.chictr.org.cn).

Functional multispectral optoacoustic tomography imaging of hepatic steatosis development in mice

The increasing worldwide prevalence of obesity, fatty liver diseases and the emerging understanding of the important roles lipids play in various other diseases is generating significant interest in lipid research. Lipid visualization in particular can play a critical role in understanding functional relations in lipid metabolism. We investigated the potential of multispectral optoacoustic tomography (MSOT) as a novel modality to non-invasively visualize lipids in laboratory mice around the 930nm spectral range. Using an obesity-induced non-alcoholic fatty liver disease (NAFLD) mouse model, we examined whether MSOT could detect and differentiate different grades of hepatic steatosis and monitor the accumulation of lipids in the liver quantitatively over time, without the use of contrast agents, i.e. in label-free mode. Moreover, we demonstrate the efficacy of using the real-time clearance kinetics of indocyanine green (ICG) in the liver, monitored by MSOT, as a biomarker to evaluate the organ's function and assess the severity of NAFLD. This study establishes MSOT as an efficient imaging tool for lipid visualization in preclinical studies, particularly for the assessment of NAFLD.

Nonalcoholic Fatty Liver Disease and Cardiovascular Disease: Overlapping Mechanisms

Nonalcoholic fatty liver disease (NAFLD) denotes a condition with excess fat in the liver. The prevalence of NAFLD is increasing, averaging > 25% of the Western population. In 25% of the patients, NAFLD progresses to its more severe form: nonalcoholic steatohepatitis and >25% of these progress to cirrhosis following activation of inflammatory and fibrotic processes. NAFLD is associated with obesity, type 2 diabetes, and the metabolic syndrome and represents a considerable and increasing health burden. In the near future, NAFLD cirrhosis is expected to be the most common cause for liver transplantation. NAFLD patients have an increased risk of developing cardiovascular disease as well as liver-related morbidity. In addition, hepatic steatosis itself appears to represent an independent cardiovascular risk factor. In the present review, we provide an overview of the overlapping mechanisms and prevalence of NAFLD and cardiovascular disease.

The value of indocyanine green clearance assessment to predict postoperative liver dysfunction in patients undergoing liver resection

Postoperative liver dysfunction remains a major concern following hepatic resection. In order to identify patients who are at risk of developing liver dysfunction, indocyanine green (ICG) clearance has been proposed to predict postoperative liver function. All patients who underwent liver resection at the Medical University Vienna, Austria between 2006 and 2015 with preoperative ICG clearance testing (PDR, R15) were analyzed in this study. Postoperative liver dysfunction was analyzed as defined by the International Study Group of Liver Surgery. Overall, 698 patients (male: 394 (56.4%); female: 304 (43.6%)) with a mean age of 61.3 years (SD: 12.9) were included in this study, including 313 minor liver resections (44.8%) and 385 major liver resections (55.2%). One hundred and seven patients developed postoperative liver dysfunction after liver resection (15.3%). Factors associated with liver dysfunction were: male sex (p = 0.043), major liver resection (p < 0.0001), and preoperative ICG clearance (PDR (p = 0.002) and R15 (p < 0.0001)). Notably ICG clearance was significantly associated with liver dysfunction in minor and major liver resections respectively and remained a predictor upon multivariable analysis. An optimal cut-off for preoperative ICG clearance to accurately predict liver dysfunction was PDR < 19.5%/min and R15 > 5.6%. To the best of our knowledge, this is the largest study analyzing the predictive value of preoperative ICG clearance assessment in patients undergoing liver resection. ICG clearance is useful to identify patients at risk of postoperative liver dysfunction.

Intraoperative Indocyanine Green Angiography for Fat Necrosis Reduction in the Deep Inferior Epigastric Perforator (DIEP) Flap

BACKGROUND

Fat necrosis is a frequent complication (up to 62.5%) of microsurgical breast reconstruction using the deep inferior epigastric perforator (DIEP) flap. This could have important clinical and psychological repercussions, deteriorating the results and increasing reconstruction costs.

OBJECTIVES

The aim of this study was to demonstrate the intraoperative use of indocyanine green angiography (ICGA) to reduce fat necrosis in DIEP flap.

METHODS

Sixty-one patients who underwent unilateral DIEP flap procedures for breast reconstruction after oncological mastectomy were included (24 cases with intraoperative use of ICGA during surgery, 37 cases in the control group). The follow-up period was 1 year after surgery. The association between the use of ICGA and the incidence of fat necrosis in the first postoperative year, differences in fat necrosis grade (I-V), differences in fat necrosis requiring reoperation, quality of life, and patient satisfaction were analyzed.

RESULTS

The incidence of fat necrosis was reduced from 59.5% (control group) to 29% (ICG-group) (P = 0.021) (relative risk = 0.49 [95% CI, 0.25-0.97]). The major difference was in grade II (27% vs 2.7%, P = 0.038). The number of second surgeries for fat necrosis treatment was also reduced (45.9% vs 20.8%, P = 0.046). The ICG group had higher scores on the BREAST-Q.

CONCLUSIONS

Intraoperative ICGA is a useful technique for reconstructive microsurgery that might improve patient satisfaction and reduce the incidence of fat necrosis by half as well as reduce its grade, especially in small fat necrosis cases; consequently, ICGA could reduce the number of secondary surgeries for treatment of fat necrosis.

LEVEL OF EVIDENCE: 4

Noninvasive Evaluation of Liver Function in Morbidly Obese Patients

Background

More than half of the obese patients develop nonalcoholic fatty liver disease (NAFLD), which may further progress to nonalcoholic steatohepatitis (NASH) and cirrhosis. The aim of this study was to assess alterations in liver function in obese patients with a noninvasive liver function test.

Methods

In a prospective cohort study 102 morbidly obese patients undergoing bariatric surgery were evaluated for their liver function. Liver function capacity was determined by the LiMAx® test (enzymatic capacity of cytochrome P450 1A2). Liver biopsy specimens were obtained intraoperatively and classified according to the NAFLD Activity Score (NAS). NASH clinical score was additionally calculated from laboratory and clinical parameters.

Results

Median liver function capacity was 286 (IQR = 141) μg/kg/h. 27% of patients were histologically categorized as definite NASH, 39% as borderline, and 34% as not NASH. A significant correlation was observed between liver function capacity and NAS (r = −0.492; p < 0.001). The sensitivity and specificity of the LiMAx® test to distinguish between definite NASH and not NASH were 85.2% and 82.9% (AUROC 0.859), respectively. According to the NASH clinical scoring system, 14% were classified as low risk, 31% as intermediate, 26% as high, and 29% as very high risk. Liver function capacity is also significantly correlated with the NASH clinical scoring system (r = −0.411; p < 0.001).

Conclusions

Obese patients show a diminished liver function capacity, especially those suffering from type 2 diabetes. The liver function capacity correlates with histological and clinical scoring systems. The LiMAx® test may be a valuable tool for noninvasive screening for NASH in obese patients.