Feasibility of Preoperative FDG PET/CT Total Hepatic Glycolysis in the Remnant Liver for the Prediction of Postoperative Liver Function

Assessing Liver Function in Rat Models of Acute Liver Failure Using Single-Photon Emission Computed Tomography and Cytokine Levels

OBJECTIVE

To evaluate liver function using dynamic hepatobiliary single-photon emission computed tomography (SPECT) in different rat models of acute liver failure.

METHODS

Twenty-four 6-8-week-old male Sprague-Dawley rats (weight 190-200 g) were evenly divided into four groups. Acute liver failure was induced by intraperitoneal injection of D-galactosamine (D-GalN, 600 mg/kg) and lipopolysaccharide (LPS, 10 µg/kg), common bile duct ligation surgery, and removing 70% of the liver mass. The fourth group served as the control without intervention. The time-activity curves for the liver and heart were generated from dynamic SPECT scans with 99mTc-ethylene hepatobiliary iminodiacetic acid (EHIDA). Image-derived functional parameters (5-minute heart/liver index [HLI5] and 15-minute receptor index [LHL15]) were calculated. Furthermore, correlations of image-derived parameters with serum interleukin-6 (IL-6) levels, liver aspartate aminotransferase (AST) and alanine transaminase (ALT) levels, and liver mRNA expression levels of tumor necrosis factor-α (TNF-α) and chemokine ligand-10 (CXCL-10) were analyzed.

RESULTS

All animals in the experimental groups exhibited varying degrees of liver damage. The SPECT images and indexes (HLI5 and LHL15) of the experimental groups significantly differed from those of the control group (P < 0.05). In the experimental groups, serum IL-6 levels and liver mRNA levels of TNF-α and CXCL-10 were significantly higher, while liver AST and ALT levels were significantly lower than those in the control group (P < 0.05).

CONCLUSION

Using SPECT with 99mTc-EHIDA, along with the calculated indexes and levels of various cytokines, presents a dependable method for assessing liver function.

Appraisal of multivariable prognostic models for post-operative liver decompensation following partial hepatectomy: a systematic review

BACKGROUND

Few reports have evaluated prognostic modelling studies of tools used for surgical decision-making. This systematic review aimed to describe and critically appraise studies that have developed or validated multivariable prognostic models for post-operative liver decompensation following partial hepatectomy.

METHODS

This study was designed using the CHARMS checklist. Following a comprehensive literature search, two reviewers independently screened candidate references for inclusion and abstracted relevant study details. Qualitative assessment was performed using the PROBAST tool.

RESULTS

We identified 36 prognostic modelling studies; 25 focused on development only, 3 developed and validated models, and 8 validated pre-existing models. None compared routine use of a prognostic model against standard clinical practice. Most studies used single-institution, retrospective cohort designs, conducted in Eastern populations. In total, 15 different outcome definitions for post-operative liver decompensation events were used. Statistical concerns surrounding model overfitting, performance assessment, and internal validation led to high risk of bias for all studies.

CONCLUSIONS

Current prognostic models for post-operative liver decompensation following partial hepatectomy may not be valid for routine clinical use due to design and methodologic concerns. Landmark resources and reporting guidelines such as the TRIPOD statement may assist researchers, and additionally, model impact assessment studies represent opportunities for future research.

Hepatectomy-Induced Alterations in Hepatic Perfusion and Function - Toward Multi-Scale Computational Modeling for a Better Prediction of Post-hepatectomy Liver Function

Liver resection causes marked perfusion alterations in the liver remnant both on the organ scale (vascular anatomy) and on the microscale (sinusoidal blood flow on tissue level). These changes in perfusion affect hepatic functions via direct alterations in blood supply and drainage, followed by indirect changes of biomechanical tissue properties and cellular function. Changes in blood flow impose compression, tension and shear forces on the liver tissue. These forces are perceived by mechanosensors on parenchymal and non-parenchymal cells of the liver and regulate cell-cell and cell-matrix interactions as well as cellular signaling and metabolism. These interactions are key players in tissue growth and remodeling, a prerequisite to restore tissue function after PHx. Their dysregulation is associated with metabolic impairment of the liver eventually leading to liver failure, a serious post-hepatectomy complication with high morbidity and mortality. Though certain links are known, the overall functional change after liver surgery is not understood due to complex feedback loops, non-linearities, spatial heterogeneities and different time-scales of events. Computational modeling is a unique approach to gain a better understanding of complex biomedical systems. This approach allows (i) integration of heterogeneous data and knowledge on multiple scales into a consistent view of how perfusion is related to hepatic function; (ii) testing and generating hypotheses based on predictive models, which must be validated experimentally and clinically. In the long term, computational modeling will (iii) support surgical planning by predicting surgery-induced perfusion perturbations and their functional (metabolic) consequences; and thereby (iv) allow minimizing surgical risks for the individual patient. Here, we review the alterations of hepatic perfusion, biomechanical properties and function associated with hepatectomy. Specifically, we provide an overview over the clinical problem, preoperative diagnostics, functional imaging approaches, experimental approaches in animal models, mechanoperception in the liver and impact on cellular metabolism, omics approaches with a focus on transcriptomics, data integration and uncertainty analysis, and computational modeling on multiple scales. Finally, we provide a perspective on how multi-scale computational models, which couple perfusion changes to hepatic function, could become part of clinical workflows to predict and optimize patient outcome after complex liver surgery.

Different Risk Factors for Early and Late Recurrence After Curative Resection of Hepatocellular Carcinoma

BACKGROUND

Factors of early and late recurrence after curative resection of hepatocellular carcinoma (HCC) may be different. The aim of this study was to identify clinical factors, including liver stiffness measurement (LSM), which are associated with HCC recurrence after curative resection.

METHODS

Patients who underwent preoperative LSM and primary curative resection for HCC between October 2015 and May 2018 were retrospectively reviewed, with 1 year as the cut-off between early and late recurrence.

RESULTS

Recurrence was observed in 42/149 (28.2%) patients over a median follow-up of 38.3 months (early recurrence: 10 [6.7%] patients; late recurrence: 32 [21.5%] patients). Multivariate analysis identified LSM (P = 0.026) and tumor size (P = 0.010) as the only factors that were significantly associated with recurrence-free survival. Compared with patients without recurrence, those with early recurrence had larger tumor size (P = 0.035) and those with late recurrence had higher LSM (P = 0.024). Receiver-operating characteristic analysis indicated that the optimal LSM cut-off value for predicting HCC recurrence was 7.4 kPa.

CONCLUSION

Tumor size was associated with early HCC recurrence after curative resection and LSM was associated with late recurrence. LSM cut-off of 7.4 kPa is recommended in predicting recurrence.

Comparison of nuclear imaging techniques and volumetric imaging for the prediction of postoperative mortality and liver failure in patients undergoing localized liver-directed treatments: a systematic review

Background/aims

Although volumetric imaging by computed tomography (CT) is the gold standard for preoperative assessment of the future liver remnant, nuclear imaging studies have shown promising data. This systematic review summarized the results from trials investigating volumetric and nuclear medicine imaging for the prediction of postoperative mortality and liver failure (LF).

Methods

MEDLINE and Web of Science were searched for papers investigating nuclear imaging methods for the prediction of postoperative clinical outcomes in patients undergoing local, liver-directed treatments. Only papers investigating both preoperative nuclear imaging and CT or magnetic resonance imaging (MR) for the prediction of postoperative mortality and/or LF were included.

Results

Twenty-five trials were qualified for this review. All trials but two used technetium-based tracers for the nuclear imaging examination. Four papers used MR imaging and the remaining used CT for the volumetric evaluation. Overall, the studies were heterogeneous both in terms of methodology and imaging technique. Of the thirteen studies reporting on postoperative mortality, most were descriptive without detailed diagnostic data. A few with detailed data found that nuclear imaging had better predictive value than volumetric imaging. Nineteen studies investigated the prediction of postoperative LF of which seven papers investigated the predictive value of both modalities in multivariable regression analysis. Two papers found that only nuclear imaging parameters were predictive of LF, one paper found that the CT parameter was predictive, and four papers found that combined nuclear and CT/MR imaging parameters were predictive of LF.

Conclusion

Both methodologies were useful in the preoperative assessment of patients scheduled for liver interventions, especially in combination, but nuclear imaging demonstrated better predictive value for postoperative mortality and LF in a few trials. The overall technical and methodological heterogeneity of the included studies complicates the ability to directly compare the clinical utility of the two imaging techniques.

Safe standard remnant liver volume after hepatectomy in HCC patients in different stages of hepatic fibrosis

Background

To determine the standard remnant liver volume (SRLV) threshold to avoid postoperative hepatic insufficiency inpatients in different stages of hepatic fibrosis who undergo right hemi-hepatectomy.

Methods

Data for 85 patients at our single medical center were analysed prospectively to examine whether the following factors differed significantly between those who experienced postoperative hepatic insufficiency and those who did not: height, prothrombin time, remnant liver volume, SRLV or hepatic fibrosis stage.

Results

Logistic regression showed SRLV and hepatic fibrosis stage to be independent risk factors for postoperative hepatic insufficiency. The threshold SRLV for predicting insufficiency was 203.2 ml/m² across all patients [area under receiver operating characteristic curve (AUC) 0.778, sensitivity 66.67%, specificity 83.64%, p<0.0001), 193.8 ml/m² for patients with severe hepatic fibrosis (AUC 0.938, sensitivity 91.30%, specificity 85.71%, p<0.0001), and 224.3 ml/m² for patients with cirrhosis (AUC 0.888, sensitivity 100%, specificity 64.29%, p<0.0001).

Conclusions

Right hemi-hepatectomy may be safer in Chinese patients when the standard remnant liver volume is more than 203.2 ml/m² in the absence of hepatic fibrosis or cirrhosis, 193.8 ml/m² in the presence of severe hepatic fibrosis or 224.3 ml/m² in the presence of cirrhosis.

Nuclear imaging methods for the prediction of postoperative morbidity and mortality in patients undergoing localized, liver-directed treatments: a systematic review

Background

Several nuclear imaging methods may predict postoperative liver function and outcome, but none has achieved recommendations in clinical guidelines. The purpose of this systematic review was to summarize the existing knowledge on this topic.

Methods

MEDLINE and Web of Science were searched for studies investigating nuclear medicine imaging methods for the prediction of postoperative liver function in patients undergoing localized, liver-directed treatments. The postoperative endpoints were clinical outcome (morbidity and mortality) as well as measures of postoperative liver function, e.g., liver function assessed by biochemical tests or nuclear imaging.

Results

A total of 1352 references were identified, of which 82 fulfilled the eligibility criteria and were included in the review. Most studies (n = 63) were retrospective studies. The vast majority of studies assessed [^99mTc]Tc-galactosyl serum albumin (GSA) (n = 57) and [^99mTc]Tc-mebrofenin (n = 19). Liver resection was entirely or partly major (involved at least three segments) in 78 reports. There were notable variations in the research methodology, e.g., image acquisition, imaging variables, and endpoints. Thirty-seven studies reported on postoperative mortality, of which most reported descriptive data at the patient level. Of the four reports that performed multivariate analyses, two showed significant predictive results of isotope-based preoperative tests. Fifty-two papers presented data on postoperative liver failure. Multivariate predictive analyses were performed in eighteen trials, of which fifteen showed the significant value of nuclear medicine tests.

Conclusion

There is sparse evidence supporting the significant value of nuclear medicine imaging methods in predicting postoperative mortality. In contrast, a notable number of trials showed a significant prediction of liver failure in multivariate analyses. The research methodology was heterogeneous and exploratory in most trials. Documentation of nuclear medicine tests in this setting awaits the results of properly designed, prospective trials with the standardization of both the nuclear medicine test and endpoints.

Systematic review and meta-analysis of thrombocytopenia as a predictor of post-hepatectomy liver failure

BACKGROUND

We performed a systematic review and meta-analysis to assess whether thrombocytopenia constituted a risk factor for post-hepatectomy liver failure (PHLF).

METHODS

We searched MEDLINE and EMBASE from inception until February the 17th, 2018 for studies reporting cases of PHLF in patients with and without thrombocytopenia (defined as a platelet count below 100 or 150 (G/l)) and/or platelet counts in patients with and without PHLF. Pooled odd ratios for PHLF, as well as mean difference in platelet counts between patients with and without PHLF, were obtained by random effects models. Robustness was tested by subgroups and leave-one out sensitivity analyses. Heterogeneity was assessed using the Q-test and quantified based on I2 value.

RESULTS

We included 15 studies representing 3966 patients. Pooled odds ratio for PHLF in thrombocytopenic patients was 3.71 (95% CI: 2.51 to 5.48; I2 = 0%). Pooled odds ratio was 5.53 (95% CI: 2.85 to 10.48) when pooling only studies based on preoperative platelet count, and 3.13 (95% CI: 1.75 to 5.58) when pooling studies including only patients without liver cirrhosis. The pooled mean difference in platelet counts between patients with and without PHLF was -21.2 (G/l) (95% CI: -36.1 to 6.4) in disfavor of patients with PHLF. When pooling only patients with various qualities of liver tissue, the pooled mean difference was 0.6 (G/l) (95% CI: -21.1 to 22.2).

CONCLUSION

Preoperative and/or postoperative thrombocytopenia constitute significant risk factors for PHLF in cirrhotic and non-cirrhotic patients.

Liver fibrosis: stretched exponential model outperforms mono-exponential and bi-exponential models of diffusion-weighted MRI

OBJECTIVES

To compare the ability of diffusion-weighted imaging (DWI) parameters acquired from three different models for the diagnosis of hepatic fibrosis (HF).

METHODS

Ninety-five patients underwent DWI using nine b values at 3 T magnetic resonance. The hepatic apparent diffusion coefficient (ADC) from a mono-exponential model, the true diffusion coefficient (D _t ), pseudo-diffusion coefficient (D _p ) and perfusion fraction (f) from a biexponential model, and the distributed diffusion coefficient (DDC) and intravoxel heterogeneity index (α) from a stretched exponential model were compared with the pathological HF stage. For the stretched exponential model, parameters were also obtained using a dataset of six b values (DDC^#, α^#). The diagnostic performances of the parameters for HF staging were evaluated with Obuchowski measures and receiver operating characteristics (ROC) analysis. The measurement variability of DWI parameters was evaluated using the coefficient of variation (CoV).

RESULTS

Diagnostic accuracy for HF staging was highest for DDC^# (Obuchowski measures, 0.770 ± 0.03), and it was significantly higher than that of ADC (0.597 ± 0.05, p < 0.001), D _t (0.575 ± 0.05, p < 0.001) and f (0.669 ± 0.04, p = 0.035). The parameters from stretched exponential DWI and D _p showed higher areas under the ROC curve (AUCs) for determining significant fibrosis (≥F2) and cirrhosis (F = 4) than other parameters. However, D _p showed significantly higher measurement variability (CoV, 74.6%) than DDC^# (16.1%, p < 0.001) and α^# (15.1%, p < 0.001).

CONCLUSIONS

Stretched exponential DWI is a promising method for HF staging with good diagnostic performance and fewer b-value acquisitions, allowing shorter acquisition time.

KEY POINTS

• Stretched exponential DWI provides a precise and accurate model for HF staging. • Stretched exponential DWI parameters are more reliable than D _p from bi-exponential DWI model • Acquisition of six b values is sufficient to obtain accurate DDC and α.

Predictability of 99mTc-Galactosyl Human Serum Albumin Scintigraphy for Posthepatectomy Liver Failure

OBJECTIVE

Posthepatectomy liver failure (PHLF) is one of the most serious complications after hepatectomy. The objective of the present study is to assess the potential diagnostic ability of ^99mTc-galactosyl human serum albumin (GSA) scintigraphy to predict PHLF as defined by the International Study Group of Liver Surgery (ISGLS).

MATERIALS AND METHODS

Data from 100 patients who underwent ^99mTc-GSA scintigraphy and subsequent hepatectomy were retrospectively analyzed. The blood clearance ratio (HH15), hepatic uptake ratio (LHL15), and maximal removal rate (Rmax) of ^99mTc-GSA (GSA-Rmax) were calculated as scintigraphic parameters for the total liver. In addition to the ratio of preoperatively estimated remnant liver (ERL) counts to total liver counts (rERL-GSA), the ratio of actual remnant liver (ARL) counts to total liver counts (rARL-GSA), determined by applying a more accurate resection line with reference to both pre- and postoperative CT, was obtained from SPECT images. Functional remnant liver parameters of ERL-LHL15 (LHL15 of the estimated remnant liver), ERL-Rmax (maximal removal rate of estimated remnant liver counts), ARL-LHL15 (LHL15 of the actual remnant liver), and ARL-Rmax (maximal removal rate of actual remnant liver counts) were calculated using these values. ROC analysis was performed to evaluate the ability of these parameters to predict PHLF. Multivariate analysis was performed to identify independent predictors of PHLF.

RESULTS

PHLF occurred in 33 patients. Each of the ARL parameters had a significantly higher diagnostic performance compared with the corresponding ERL parameter (AUC values: for rARL-GSA vs rERL-GSA, 0.77 vs 0.62 [p = 0.0004]; for ARL-LHL15 vs ERL-LHL15, 0.79 vs 0.64 [p = 0.0005]; and for ARL-Rmax vs ERL-Rmax, 0.78 vs 0.66 [p = 0.0003]). According to multivariate analysis, each of three ARL parameters was identified as an independent predictor of PHLF (p < 0.0001 for all).

CONCLUSION

Technetium-99m-labeled GSA scintigraphy is useful for predicting PHLF, particularly for applying an accurate resection line on GSA-SPECT images.