Experimental non-alcoholic fatty liver disease causes regional liver functional deficits as measured by the capacity for galactose metabolism while whole liver function is preserved.

BACKGROUND: Increasing incidence of non-alcoholic fatty liver disease (NAFLD) calls for improved understanding of how the disease affects metabolic liver function. AIMS: To investigate in vivo effects of different NAFLD stages on metabolic liver function, quantified as regional and total capacity for galactose metabolism in a NAFLD model. METHODS: Male Sprague Dawley rats were fed a high-fat, high-cholesterol diet for 1 or 12 weeks, modelling early or late NAFLD, respectively. Each NAFLD group (n = 8 each) had a control group on standard chow (n = 8 each). Metabolic liver function was assessed by 2-[18F]fluoro-2-deoxy-D-galactose positron emission tomography; regional galactose metabolism was assessed as standardised uptake value (SUV). Liver tissue was harvested for histology and fat quantification. RESULTS: Early NAFLD had median 18% fat by liver volume. Late NAFLD had median 32% fat and varying features of non-alcoholic steatohepatitis (NASH). Median SUV reflecting regional galactose metabolism was reduced in early NAFLD (9.8) and more so in late NAFLD (7.4; p = 0.02), both significantly lower than in controls (12.5). In early NAFLD, lower SUV was quantitatively explained by fat infiltration. In late NAFLD, the SUV decrease was beyond that attributable to fat; probably related to structural NASH features. Total capacity for galactose elimination was intact in both groups, which in late NAFLD was attained by increased fat-free liver mass to 21 g, versus 15 g in early NAFLD and controls (both p ≤ 0.002). CONCLUSION: Regional metabolic liver function was compromised in NAFLD by fat infiltration and structural changes. Still, whole liver metabolic function was preserved in late NAFLD by a marked increase in the fat-free liver mass.

Time-dependent improvement of liver inflammation, fibrosis and metabolic liver function after successful direct-acting antiviral therapy of chronic hepatitis C.

Sofosbuvir-based direct-acting antiviral (DAA) therapy generally cures chronic hepatitis C (CHC) infections, however, the effects on the underlying liver disease and the potential rate of recovery are unclear. We aimed to investigate the effects of DAA therapy on liver inflammation, fibrosis, metabolic function and cognitive function and the time course in CHC patients with advanced liver disease. Seventy-one CHC patients with advanced liver disease were studied before, during and one year after successful sofosbuvir-based DAA therapy. Liver inflammation was assessed by plasma sCD163 and sMR levels (ELISA), fibrosis by liver stiffness (transient elastography), function by galactose elimination capacity (GEC) and cognitive performance by continuous reaction time (CRT). During DAA therapy, we observed a rapid sCD163 decline from baseline to end of treatment (6.9 vs 3.8 mg/L, P < .0001), whereas the change in sMR was more subtle (0.37 vs 0.30 mg/L, P < .0001). Liver stiffness decreased by 20% at end of treatment (17.8 vs 14.3 kPa, P < .0001), together suggesting rapid resolution of liver inflammation. One year after treatment, liver stiffness decreased by an additional 15% (P < .0001), suggestive of fibrosis regression. The GEC improved at follow-up (all: 1.74 vs 1.98 mmol/min), mainly at 12 weeks post-treatment, both in patients with cirrhosis (n = 56) and those with advanced liver fibrosis (n = 15) (P < .001). The CRT improved at one-year follow-up (1.86 vs 2.09, P = .04). In conclusion, successful DAA therapy of CHC proves beneficial in advanced liver disease, with an initial rapid resolution of liver inflammation and a subsequent gradual but steady improvement in liver fibrosis, metabolic liver function and reaction time.

Importance of breath tests for the evaluation liver function in patients with chronic kidney disease.

Breath tests for the evaluation liver metabolic function are a non-invasive diagnostic method with high sensitivity and specificity. Up today, the issue of liver damage in patients with chronic kidney disease has not been investigated sufficiently, although it might have significant clinical consequences. The following article describes the principles of breath tests, experiences with breath tests in patients with chronic kidney disease (CKD) and the results of our pilot study with methacetin breath tests in patients with CKD and in regular peritoneal dialysis treatment.

Functional hepatic deterioration determined by 13C-methacetin breath test is associated with impaired hemodynamics and late Fontan failure in adults.

Background: Despite improved survival a substantial number of Fontan patients eventually develop late failure. Fontan-associated liver disease (FALD) is the most frequent end-organ dysfunction. Although impaired hemodynamics and Fontan failure correlate with FALD severity, no association between hepatic functional metabolic impairment and Fontan hemodynamics has been established. Hypothesis: Metabolic liver function measured by liver maximum function capacity test (LiMAx®) correlates with Fontan hemodynamics and Fontan failure. Methods: From 2020 to 2022, 58 adult Fontan patients [median age: 29.3 years, IQR (12.7), median follow-up time after Fontan operation: 23.2 years, IQR (8.7)] were analyzed in a cross-sectional study. Hemodynamic assessment included echocardiography, cardiopulmonary exercise testing and invasive hemodynamic evaluation. Fontan failure was defined based on commonly applied clinical criteria and our recently composed multimodal Fontan failure score. Results: LiMAx® test revealed normal maximum liver function capacity in 40 patients (>315 µg/h*kg). In 18 patients a mild to moderate impairment was detected (140-314 µg/h*kg), no patient suffered from severe hepatic deterioration (≤ 139 µg/kg*h). Fontan failure was present in 15 patients. Metabolic liver function was significantly reduced in patients with increased pulmonary artery pressure (p = 0.041. r = -0.269) and ventricular end-diastolic pressure (p = 0.033, r = -0.325), respectively. In addition, maximum liver function capacity was significantly impaired in patients with late Fontan failure (289.0 ± 99.6 µg/kg*h vs. 384.5 ± 128.6 µg/kg*h, p = 0.007). Conclusion: Maximum liver function capacity as determined by LiMAx® was significantly reduced in patients with late Fontan failure. In addition, elevated pulmonary artery pressure and end-diastolic ventricular pressure were associated with hepatic functional metabolic impairment.

Effect of stereotactic body radiotherapy on regional metabolic liver function investigated in patients by dynamic [18F]FDGal PET/CT.

PURPOSE: Stereotactic body radiotherapy (SBRT) is increasingly used for treatment of liver tumors but the effect on metabolic liver function in surrounding tissue is largely unknown. Using 2-deoxy-2-[18F]fluoro-D-galactose ([18F]FDGal) positron emission tomography (PET)/computed tomography (CT), we aimed to determine a dose-response relationship between radiation dose and metabolic liver function as well as recovery. PROCEDURES: One male subject with intrahepatic cholangiocarcinoma and five subjects (1 female, 4 male) with liver metastases from colorectal cancer (mCRC) underwent [18F]FDGal PET/CT before SBRT and after 1 and 3 months. The dose response was calculated using the data after 1 month and the relative recovery was evaluated after 3 months. All patients had normal liver function at time of inclusion. RESULTS: A linear dose-response relationship for the individual liver voxel dose was seen until approximately 30 Gy. By fitting a polynomial curve to data, a mean TD50 of 18 Gy was determined with a 95% CI from 12 to 26 Gy. After 3 months, a substantial recovery was observed except in tissue receiving more than 25 Gy. CONCLUSIONS: [18F]FDGal PET/CT makes it possible to determine a dose-response relationship between radiation dose and metabolic liver function, here with a TD50 of 18 Gy (95% CI 12-26 Gy). Moreover, the method makes it possible to estimate metabolic recovery in liver tissue.

Liver-related effects of chronic hepatitis C antiviral treatment.

More than five years ago, the treatment of hepatitis C virus infection was revolutionized with the introduction of all-oral direct-acting antiviral (DAA) drugs. They proved highly efficient in curing patients with chronic hepatitis C (CHC), including patients with cirrhosis. The new DAA treatments were alleged to induce significant improvements in clinical outcome and prognosis, but the exact cause of the expected benefit was unclear. Further, little was known about how the underlying liver disease would be affected during and after viral clearance. In this review, we describe and discuss the liver-related effects of the new treatments in regards to both pathophysiological aspects, such as macrophage activation, and the time-dependent effects of therapy, with specific emphasis on inflammation, structural liver changes, and liver function, as these factors are all related to morbidity and mortality in CHC patients. It seems clear that antiviral therapy, especially the achievement of a sustained virologic response has several beneficial effects on liver-related parameters in CHC patients with advanced liver fibrosis or cirrhosis. There seems to be a time-dependent effect of DAA therapy with viral clearance and the resolution of liver inflammation followed by more discrete changes in structural liver lesions. These improvements lead to favorable effects on liver function, followed by an improvement in cognitive dysfunction and portal hypertension. Overall, the data provide knowledge on the several beneficial effects of DAA therapy on liver-related parameters in CHC patients suggesting short- and long-term improvements in the underlying disease with the promise of an improved long-term prognosis.

High hepatic macrophage activation and low liver function in stable Wilson patients - a Danish cross-sectional study.

BACKGROUND: Hepatic macrophage (Kupffer cell) hyperplasia is often described in Wilson's disease (WD). In many liver diseases, Kupffer cell activation is related to disease severity, liver function, and fibrosis but the importance in WD is unknown. Kupffer cell activation can be assessed by the P-concentration of soluble (s)CD163, metabolic liver function by the galactose elimination capacity (GEC), and fibrosis by Fibroscan. We investigated the associations between sCD163, selected inflammatory cytokines, GEC, and liver fibrosis in Danish WD patients. METHODS: In a cross-sectional design, we studied 29 stable and well-treated patients (male/female15/14) with a median age of 35 years (IQR 24-50). P-sCD163 and cytokines were measured by ELISA. The GEC was measured by intra-venous galactose loading. RESULTS: The median P-sCD163 value at 2.96 mg/L (1.97-3.93) was high in the normal range (0.7-3.9) and seven patients (24%) had a value above the upper normal value. sCD163 correlated with TNF-α, IL-6 and IL-8 (rho> 0.50, p < 0.005). A higher sCD163 value was closely associated with a lower GEC (rho = - 0.51, p = 0.02). sCD163 was not related to the liver fibrosis indices. CONCLUSIONS: Stable WD patients showed various degrees of Kupffer cell activation which was accompanied by loss of metabolic liver function. Neither activation nor liver function was related to liver fibrosis. The findings suggest that in WD inflammatory Kupffer cell activation may be involved in the loss of liver function over time. sCD163 may serve as a non-invasive biomarker of loss of liver function in WD, which the degree of fibrosis evidently may not. This study is registered at clinical trials with name: "sCD163 and sMR in Wilsons Disease - Associations With Disease Severity and Fibrosis", NCT02702765. Date of registration: 26.02.16. Date of enrolment of the first participant to the trial: 17.03.16. ULR: https://clinicaltrials.gov/ct2/show/NCT02702765 .

Hypothermic Machine Preservation of the Liver: State of the Art.

PURPOSE OF REVIEW: In this review, we highlight which livers may benefit from additional treatment before implantation and describe the concept of hypothermic machine liver perfusion. Furthermore, we explain why cold oxygenated perfusion concepts could potentially lead to a breakthrough in this challenging field of transplantation. Accordingly, we summarize recent clinical applications of different hypothermic perfusion approaches. RECENT FINDINGS: The impact of end-ischemic, hypothermic liver perfusion in liver transplantation is currently assessed by two multicenter, randomized controlled trials. Recently, new applications of hypothermic perfusion showed promising results and recipients were protected from severe intrahepatic biliary complications, despite the use of very extended criteria grafts including donation after circulatory death livers. SUMMARY: Hypothermic machine liver perfusion is beneficial for high-risk livers and protects recipients from most feared complications. Importantly, such easy approach is currently implemented in several European centers and new markers obtained from perfusate may improve the prediction of liver function in the future.

Metabolic liver function in humans measured by 2-18F-fluoro-2-deoxy-D-galactose PET/CT-reproducibility and clinical potential.

BACKGROUND: PET/CT with the radioactively labelled galactose analogue 2-18F-fluoro-2-deoxy-D-galactose (18F-FDGal) can be used to quantify the hepatic metabolic function and visualise regional metabolic heterogeneity. We determined the day-to-day variation in humans with and without liver disease. Furthermore, we examined whether the standardised uptake value (SUV) of 18F-FDGal from static scans can substitute the hepatic systemic clearance of 18F-FDGal (K met, mL blood/min/mL liver tissue/) quantified from dynamic scans as measure of metabolic function. Four patients with cirrhosis and six healthy subjects underwent two 18F-FDGal PET/CT scans within a median interval of 15 days for determination of day-to-day variation. The correlation between K met and SUV was examined using scan data and measured arterial blood concentrations of 18F-FDGal (blood samples) from 14 subjects from previous studies. Regional and whole-liver values of K met and SUV along with total metabolic liver volume and total metabolic liver function (total SUV, average SUV multiplied by total metabolic liver volume) were calculated. RESULTS: No significant day-to-day differences were found for K met or SUV. SUV had higher intraclass correlation coefficients than K met (0.92-0.97 vs. 0.49-0.78). The relationship between K met and SUV was linear. Total metabolic liver volume had non-significant day-to-day variation (median difference 50 mL liver tissue; P = 0.6). Mean total SUV in healthy subjects was 23,840 (95% CI, 21,609; 26,070), significantly higher than in the patients (P < 0.001). CONCLUSIONS: The reproducibility of 18F-FDGal PET/CT was good and SUV can substitute K met for quantification of hepatic metabolic function. Total SUV of 18F-FDGal is a promising tool for quantification of metabolic liver function in pre-treatment evaluation of individual patients.

2-[(18)F]fluoro-2-deoxy-D-galactose PET/CT of hepatocellular carcinoma is not improved by co-administration of galactose.

INTRODUCTION: PET with [(18)F]fluoro-2-deoxy-D-galactose ((18)F-FDGal) is a promising imaging modality for detection of hepatocellular carcinoma (HCC). However, it can be difficult to distinguish small intrahepatic HCC lesions from surrounding liver tissue. Ut the competitive inhibition that galactose shows towards hepatic (18)F-FDGal metabolism, we tested the hypothesis that co-administration of galactose, at near-saturating doses, inhibits (18)F-FDGal metabolism to a greater extent in non-malignant hepatocytes than in HCC cells. This would increase the tumor to background ratio in the (18)F-FDGal PET scans with co-administration of galactose. METHODS: Three patients known to have HCC underwent two (18)F-FDGal PET/CT scans on consecutive days, one with and one without simultaneous constant intravenous infusion of galactose. On both days, (18)F-FDGal was injected in the beginning of a 45-min dynamic PET scan of the liver followed by a static PET scan from mid-thigh to the top of the skull starting 60-70min after (18)F-FDGal administration. Parametric images of the hepatic metabolic function expressed in terms of hepatic systemic clearance of (18)F-FDGal were generated from the dynamic PET recordings. RESULTS: Co-administration of galactose did not give significantly better discrimination of the HCC lesions from background. Parametric images of the hepatic metabolic function did not add additional useful information to the detection of HCC lesions compared to the static images of radioactivity concentrations. CONCLUSION: Co-administration of galactose did not improve the interpretation of the (18)F-FDGal PET/CT images and did not improve the detection of intrahepatic HCC lesions, either using static or parametric images.

Metabolic liver function measured in vivo by dynamic (18)F-FDGal PET/CT without arterial blood sampling.

BACKGROUND: Metabolic liver function can be measured by dynamic PET/CT with the radio-labelled galactose-analogue 2-[(18)F]fluoro-2-deoxy-D-galactose ((18)F-FDGal) in terms of hepatic systemic clearance of (18)F-FDGal (K, ml blood/ml liver tissue/min). The method requires arterial blood sampling from a radial artery (arterial input function), and the aim of this study was to develop a method for extracting an image-derived, non-invasive input function from a volume of interest (VOI). METHODS: Dynamic (18)F-FDGal PET/CT data from 16 subjects without liver disease (healthy subjects) and 16 patients with liver cirrhosis were included in the study. Five different input VOIs were tested: four in the abdominal aorta and one in the left ventricle of the heart. Arterial input function from manual blood sampling was available for all subjects. K*-values were calculated using time-activity curves (TACs) from each VOI as input and compared to the K-value calculated using arterial blood samples as input. Each input VOI was tested on PET data reconstructed with and without resolution modelling. RESULTS: All five image-derived input VOIs yielded K*-values that correlated significantly with K calculated using arterial blood samples. Furthermore, TACs from two different VOIs yielded K*-values that did not statistically deviate from K calculated using arterial blood samples. A semicircle drawn in the posterior part of the abdominal aorta was the only VOI that was successful for both healthy subjects and patients as well as for PET data reconstructed with and without resolution modelling. CONCLUSIONS: Metabolic liver function using (18)F-FDGal PET/CT can be measured without arterial blood samples by using input data from a semicircle VOI drawn in the posterior part of the abdominal aorta.