Accuracy of liver and spleen stiffness on magnetic resonance elastography for detecting portal hypertension: a systematic review and meta-analysis

Recent Advances in the Pathogenesis and Clinical Evaluation of Portal Hypertension in Chronic Liver Disease

In chronic liver disease, hepatic stellate cell activation and degeneration of liver sinusoidal endothelial cells lead to structural changes, which are secondary to fibrosis and the presence of regenerative nodules in the sinusoids, and to functional changes, which are related to vasoconstriction. The combination of such changes increases intrahepatic vascular resistance and causes portal hypertension. The subsequent increase in splanchnic and systemic hyperdynamic circulation further increases the portal blood flow, thereby exacerbating portal hypertension. In clinical practice, the hepatic venous pressure gradient is the gold-standard measure of portal hypertension; a value of ≥10 mm Hg is defined as clinically significant portal hypertension, which is severe and is associated with the risk of liver-related events. Hepatic venous pressure gradient measurement is somewhat invasive, so evidence on the utility of risk stratification by elastography and serum biomarkers is needed. The various stages of cirrhosis are associated with different outcomes. In viral hepatitis-related cirrhosis, viral suppression or elimination by nucleos(t)ide analog or direct-acting antivirals results in recompensation of liver function and portal pressure. However, careful follow-up should be continued, because some cases have residual clinically significant portal hypertension even after achieving sustained virologic response. In this study, we reviewed the current and future prospects for portal hypertension.

Diagnostic accuracy of CT and MR features for detecting atypical lipomatous tumors and malignant liposarcomas: a systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis evaluated the diagnostic accuracy of CT and MRI for differentiating atypical lipomatous tumors and malignant liposarcomas from benign lipomatous lesions.

METHODS

MEDLINE, EMBASE, Scopus, the Cochrane Library, and the gray literature from inception to January 2022 were systematically evaluated. Original studies with > 5 patients evaluating the accuracy of CT and/or MRI for detecting liposarcomas with a histopathological reference standard were included. Meta-analysis was performed using a bivariate mixed-effects regression model. Risk of bias was evaluated using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). This study is registered on PROSPERO, number CRD42022306479.

RESULTS

Twenty-six studies with a total of 2613 patients were included. Mean/median reported patient ages ranged between 50 and 63 years. The summary sensitivity and specificity of radiologist gestalt for detecting liposarcomas was 85% (79-90% 95% CI) and 63% (52-72%), respectively. Deep depth to fascia, thickened septations, enhancing components, and lesion size (≥ 10 cm) all demonstrated sensitivities ≥ 85%. Other imaging characteristics including heterogenous/amorphous signal intensity, irregular tumor margin, and nodules present demonstrated lower sensitivities ranging from 43 to 65%. Inter-reader reliability for radiologist gestalt within studies ranged from fair to substantial (k = 0.23-0.7). Risk of bias was predominantly mixed for patient selection, low for index test and reference standard, and unclear for flow and timing.

CONCLUSION

Higher sensitivities for detecting liposarcomas were achieved with radiologist gestalt, deep depth to fascia, thickened septations, enhancing components, and large size. Combined clinical and imaging scoring and/or radiomics both show promise for optimal performance, though require further analysis with prospective study designs.

CLINICAL RELEVANCE

This pooled analysis evaluates the accuracy of CT and MRI for detecting atypical lipomatous tumors and malignant liposarcomas. Radiologist gestalt, deep depth to fascia, thickened septations, enhancing components, and large size demonstrate the highest overall sensitivities.

KEY POINTS

• The summary sensitivity and specificity of radiologist gestalt for detecting liposarcomas was 85% (79-90% 95% CI) and 63% (52-72%), respectively. • Radiologist gestalt, deep depth to fascia, thickened septations, enhancing components, and large tumor size (≥ 10 cm) showed the highest sensitivities for detecting atypical lipomatous tumors/well-differentiated liposarcomas and malignant liposarcomas. • A combined clinical and imaging scoring system and/or radiomics is likely to provide the best overall diagnostic accuracy, although currently proposed scoring systems and radiomic feature analysis require further study with prospective study designs.

Transient elastography and von Willebrand factor as predictors of portal hypertension and decompensation in children

Background & Aims

Von Willebrand factor antigen (vWFAg), a protein measured to test the level of vWF released from the vascular endothelium has gained much attention as a marker for portal hypertension (PHT) severity. The objectives of this study were to investigate the use of vWFAg as a biomarker along with liver and spleen stiffness measurements by transient elastography as potential predictors of clinically significant varices (CSV), variceal bleeding (VB) and decompensation in children with PHT.

Methods

This observational prospective cohort study included 117 children (median age 10 [IQR 6-14] years) who underwent oesophagogastroduodenoscopy between January'2012 to November'2021 and a validation group of 33 children who underwent the same procedure between December'2021 to March'2023. Measurements of vWFAg and glycoprotein Ib binding activity of VWF (GPIbR) were available in 97 patients in the study group and in all patients in the validation group.Results: vWFAg and GPIbR were significantly higher in children with CSV (223 IU/dl and 166 IU/dl; p = 0.015 and p = 0.04, respectively) and VB (218 IU/dl and 174 IU/dl; p = 0.077 and p = 0.03, respectively) than in those without CSV or VB, respectively. Ninety-six patients had liver and spleen stiffness measurements. Spleen stiffness was significantly higher in patients with CSV compared to those without CSV (p = 0.003). In a chronic liver disease subgroup, a predictive scoring tool based on vWFAg, GPIbR, platelet count, and spleen/liver stiffness measurements could predict CSV with an AUROC of 0.76 (p = 0.04).

Conclusions

This study suggests the predictive value of vWF for CSV and VB increases when combined with spleen stiffness, with AUROCs of 0.88 and 0.82, respectively. Hence, a combination of biomarkers could assist clinicians in diagnosing CSV, preventing unnecessary invasive procedures.

Impacts and implications

Surveillance endoscopies in children with portal hypertension (PHT) have their own risks and non-invasive markers, such as von Willebrand factor antigen, glycoprotein Ib binding activity of VWF (GPIbR), and transient elastography could be used to predict clinically significant varices, variceal bleeding and disease compensation in children with PHT. Such non-invasive markers for PHT and varices are lacking in the paediatric population. The results show that von Willebrand factor and GPIbR along with transient elastography can be used to formulate a scoring system which can be used as a clinical tool by paediatric hepatologists to monitor the progression of PHT and risk of bleeding, and hence to stratify the performance of invasive endoscopic procedures under general anaesthesia. However, there is a need to validate the scoring system in children with portal vein thrombosis and for hepatic decompensation in a multi-centre registry in the future.

Accuracy of spleen stiffness measurement for the diagnosis of clinically significant portal hypertension in patients with compensated advanced chronic liver disease: a systematic review and individual patient data meta-analysis

BACKGROUND

The diagnosis of clinically significant portal hypertension is crucial for prognosis and treatment guidance in patients with compensated advanced chronic liver disease (ACLD). Spleen stiffness measurement (SSM) might improve the non-invasive diagnosis of clinically significant portal hypertension, but previous studies have reported heterogeneous SSM cutoffs. We aimed to evaluate the accuracy of SSM and SSM-based algorithms in this setting.

METHODS

In this systematic review and individual patient data meta-analysis, we searched PubMed, Embase, Scopus, Web of Science, and the Cochrane Library from database inception to Dec 31, 2022, for articles, abstracts, and letters, with no restrictions on language. Cross-sectional studies reporting hepatic venous pressure gradient and SSM by different techniques (transient elastography; two-dimensional shear-wave elastography [2D-SWE]; point shear-wave elastography [p-SWE]) in adults (≥18 years) with compensated ACLD were eligible for inclusion. The main outcome was the diagnostic performance of two SSM-based algorithms, with the Baveno VII model as a reference, evaluating sensitivity and specificity, as well as summary negative predictive values (NPVs) and positive predictive values (PPVs). In the Baveno VII model, clinically significant portal hypertension was ruled out if patients had a liver stiffness measurement (LSM) of 15 kPa or less and a platelet count of 150 × 109 platelets per L or higher and ruled in if they had an LSM of greater than 25 kPa. The two SSM-based models combined these same cutoffs with additional criteria. In the Baveno VII-SSM single cutoff model, clinically significant portal hypertension was ruled out if at least two of the following were present: LSM of 15 kPa or less, platelet count of 150 × 109 platelets per L or higher, and SSM of 40 kPa or less; and ruled in if at least two were present: LSM of greater than 25 kPa, platelet count of less than 150 × 109 platelets per L, and SSM of greater than 40 kPa. The Baveno VII-SSM dual cutoff model used the same criteria, but with a cutoff of SSM of less than 21 kPa to rule out, and greater than 50 kPa to rule in, clinically significant portal hypertension. This study is registered with PROSPERO, CRD42019127164.

FINDINGS

Of the 44 records assessed for eligibility, 17 studies (with 1245 patients) were included in the meta-analysis. In the transient elastography cohort (n=600), the Baveno VII algorithm was validated for both ruling out (NPV 100%, 95% CI 64-100; sensitivity 100%, 95% CI 70-100) and ruling in (PPV 95%, 85-98; specificity 94%, 95% CI 87-97) clinically significant portal hypertension, but the proportion of patients with indeterminate results (grey zone) was 48% (95% CI 44-52); 57% (95% CI 52-62) of patients with clinically significant portal hypertension were included in the rule-in zone. The Baveno VII-SSM dual cutoff model had adequate NPV (98%, 95% CI 58-100; sensitivity 100%, 95% CI 91-100) and PPV (93%, 95% CI 84-97; specificity 89%, 95% CI 84-93), with 32% (95% CI 28-36) of patients in the grey zone; 76% (95% CI 72-80) of the patients with clinically significant portal hypertension were in the rule-in zone. The Baveno VII-SSM single cutoff model had a sensitivity of 93% (95% CI 85-97) and a NPV of 85% (95% CI 60-96) for ruling out, and a specificity of 86% (95% CI 80-91) and a PPV of 92% (95% CI 83-95) for ruling in, clinically significant portal hypertension. 88% (95% CI 84-91) of patients with clinically significant portal hypertension were included in the rule-in zone and 9% (95% CI 7-12) of patients were in the grey zone. In the 2D-SWE cohort (n=225), all three algorithms could safely rule in clinically significant portal hypertension with adequate PPV (≥90%), but NPV was inadequate for ruling out clinically significant portal hypertension. Insufficient data were available to evaluate the performance of SSM assessed by p-SWE. Heterogeneity was low (I2<25%) for most estimates.

INTERPRETATION

Algorithms combining Baveno VII criteria with SSM showed good performance and reduced the diagnostic grey zone for clinically significant portal hypertension compared with Baveno VII criteria alone. Future studies should evaluate whether SSM-based diagnosis allows for the identification of patients who would benefit from non-selective β-blocker treatment.

FUNDING

None.

Abdominal MR elastography with multiple driver arrays: performance and repeatability

PURPOSE

To evaluate the performance and repeatability assessing liver, spleen, and kidney stiffness with magnetic resonance elastography (MRE), using arrays of pneumatic passive drivers.

METHODS

An array of four flexible, pneumatically activated passive drivers for abdominal MRE were developed and tested in this study. Multiple MRE acquisitions were performed prospectively in a series of eleven volunteers, with activation of all combinations of the four drivers, individually and simultaneously. MRE exams were repeated three times to study within-day and between-day test-retest repeatability. Semi-quantitative evaluation of wave propagation and penetration, and quantitative assessment of tissue stiffness was conducted for liver, spleen, and kidneys.

RESULTS

When driver location and amplitude were sufficient to achieve necessary shear wave illumination in any given region of interest, the results showed excellent test-retest repeatability in abdominal organ stiffness with both single and multiple driver configurations. The results confirmed that multiple driver arrays provided suitable shear wave illumination over a larger region of the abdomen, allowing more reliable stiffness measurements in multiple organs. MRE assessment of the spleen was found to be prone to effects of excessive shear wave amplitude, however.

CONCLUSION

A multiple driver array provides shear wave illumination over a larger region of the abdomen than obtained with a single driver, for MRE assessment of multiple abdominal organs, providing excellent test-retest repeatability in stiffness measurements. However, careful tuning of the location and amplitude of each driver is essential to achieve consistent results.

Clinical application of Magnetic resonance elastography in hepatocellular carcinoma: from diagnosis to prognosis

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and a major public health problem worldwide. Liver fibrosis is closely correlated with liver functional reserve and the risk of HCC development. Meanwhile, malignant tumors generally have high cellularity compared to benign tumors, which results in increased stiffness. Magnetic resonance elastography (MRE) has emerged as a new non-invasive technique for assessing tissue stiffness with excellent diagnostic accuracy, not only for assessing liver fibrosis but also for measuring tumor stiffness. Recent studies provide new evidence that MRE may play an important role in the management of patients with HCC and show several novel clinical applications, such as predicting the development of HCC, differentiating between benign/malignant liver lesions (FLL) and HCC pathological grades, assessing treatment response, and predicting recurrence after treatment, although some findings are controversial. Therefore, we conducted this review to summarize these novel applications of MRE in HCC patients and also discuss their limitations and future advancement.

Diagnostic accuracy of liver stiffness on two-dimensional shear wave elastography for detecting clinically significant portal hypertension: a meta-analysis

PURPOSE

Two-dimensional shear wave elastography (2D-SWE) has recently been proposed to detect clinically significant portal hypertension (CSPH), we aimed to perform a meta-analysis based on the published data to assess the diagnostic accuracy of 2D-SWE for detecting CSPH.

METHOD

Literature databases were searched up until 1 August 2021. The summary area under receiver operating characteristics curve (AUROC), the summary diagnostic odds ratio (DOR), and the summary sensitivity and specificity were used to examine the accuracy of 2D-SWE for evaluating CSPH. Heterogeneity was explored using meta-regression.

RESULTS

Finally 9 studies with 956 patients were included in this study for evaluation and meta-analysis. 2D-SWE showed good diagnostic performance for detecting CSPH with a summary sensitivity of 83% (95% confidence interval [CI]: 76%-88%) and summary specificity of 78% (95% CI: 65%-87%); the summary AUROC was 0.88 (95% CI: 0.84-0.90). Summary positive likelihood ratio (LR), negative LR, and DOR of 2D-SWE for detecting CSPH were 3.7 (95% CI: 2.4-5.9), 0.22 (95% CI: 0.16-0.30), and 17 (95% CI: 10-29), respectively.

CONCLUSIONS

2D-SWE showed good performance in diagnosing CSPH and can be considered as an important and noninvasive adjunctive approach in the management of patients with CSPH.

Indications and methods for measuring portal hypertension in cirrhosis

Background and objectives: Over the last decade our understanding of the pathophysiology of portal hypertension has increased. Novel diagnostic technologies have facilitated and improved the diagnosis and treatment of hepatic fibrosis and cirrhosis. With this review we aim to provide an overview of contemporary diagnostic principles of portal hypertension and indications for measuring portal pressure in cirrhosis.Methods: By review of current literature, we assessed new and old principles of measuring portal hypertension and the diagnostic values of the methods.Results: Invasive measurement of the portal pressure is still the gold standard to quantitate portal hypertension and to assess response to vasoactive treatment. The size of the portal pressure is important to assess since it contains information on the course of the disease and risk of developing hepatic decompensation, hepatocellular carcinoma, and mortality. Reliable non-invasive Elastography techniques are emerging that adequately assess portal pressure, but the available methods are not yet sufficiently accurate.Conclusion: Although elastography techniques provide valuable information and are good monitoring tools, liver vein catheterization remains valuable in diagnosing and monitoring portal hypertension, especially in combination with a trans-jugular liver biopsy.

Predictive Value of Liver Stiffness Measurement by Magnetic Resonance Elastography for Complications after Liver Resection: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

Liver fibrosis has been recognized as a significant risk factor for short-term outcomes after hepatectomy. Magnetic resonance elastography (MRE) showed higher diagnostic performance in staging liver fibrosis than other elastography modalities. This study aimed to assess the accuracy of predicting postoperative complications in patients with malignant liver tumors using liver stiffness measurement (LSM) by MRE.

METHODS

After a systematic review of the relevant studies, the sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratio, and area under the curve (AUC) for the diagnosis of postoperative complications were pooled using bivariate meta-analysis. Meanwhile, the pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the effect. Heterogeneity was explored by sensitivity analysis, univariate meta-regression, and subgroup analysis. The potential publication bias was evaluated by the Deek's funnel plot test.

RESULTS

Eight studies comprising a total of 1,154 patients that predicted postoperative outcomes as their purpose were ultimately included in the quantitative analysis. The pooled results of the meta-analysis revealed that the pooled sensitivity, specificity, and AUC were 78% (95% CI: 69-85%, Higgins's inconsistency index [I2] = 43.00), 75% (95% CI: 70-80%, Higgins's inconsistency index [I2] = 72.53), and 0.83 (95% CI: 0.80-0.86), respectively. Preoperative LSM by MRE was significantly associated with the development of overall postoperative outcomes (OR 1.78, 95% CI: 1.49-2.08). Univariate meta-regression showed that advanced fibrosis stage (≥F3), HCC patient proportion and cut-off value significantly influenced the heterogeneity of the included studies. The AUC of several novel prediction models based on LSM by MRE ranged from 0.818 to 0.911.

CONCLUSIONS

In conclusion, liver stiffness measured by MRE was a significant predictor of postoperative outcomes in patients undergoing liver resection. Future studies could focus on setting a prognostic model integrated with LSM by MRE in distinguishing patients at high risk of posthepatectomy complications.

MR elastography outperforms shear wave elastography for the diagnosis of clinically significant portal hypertension

OBJECTIVES

Portal hypertension (PH) is associated with complications such as ascites and esophageal varices and is typically diagnosed through invasive hepatic venous pressure gradient (HVPG) measurement, which is not widely available. In this study, we aim to assess the diagnostic performance of 2D/3D MR elastography (MRE) and shear wave elastography (SWE) measures of liver and spleen stiffness (LS and SS) and spleen volume, to noninvasively diagnose clinically significant portal hypertension (CSPH) using HVPG measurement as the reference.

METHODS

In this prospective study, patients with liver disease underwent 2D/3D MRE and SWE of the liver and spleen, as well as HVPG measurement. The correlation between MRE/SWE measures of LS/SS and spleen volume with HVPG was assessed. ROC analysis was used to determine the utility of MRE, SWE, and spleen volume for diagnosing CSPH.

RESULTS

Thirty-six patients (M/F 22/14, mean age 55 ± 14 years) were included. Of the evaluated parameters, 3D MRE SS had the strongest correlation with HVPG (r = 0.686, p < 0.001), followed by 2D MRE SS (r = 0.476, p = 0.004). 3D MRE SS displayed the best performance for diagnosis of CSPH (AUC = 0.911) followed by 2D MRE SS (AUC = 0.845) and 3D MRE LS (AUC = 0.804). SWE SS showed poor performance for diagnosis of CSPH (AUC = 0.583) while spleen volume was a fair predictor (AUC = 0.738). 3D MRE SS was significantly superior to SWE LS/SS (p ≤ 0.021) for the diagnosis of CSPH.

CONCLUSION

SS measured with 3D MRE outperforms SWE for the diagnosis of CSPH. SS appears to be a useful biomarker for assessing PH severity. These results need further validation.

KEY POINTS

• Spleen stiffness measured with 2D and 3D MR elastography correlates significantly with hepatic venous pressure gradient measurement. • Spleen stiffness measured with 3D MR elastography demonstrates excellent performance for the diagnosis of clinically significant portal hypertension (AUC 0.911). • Spleen stiffness measured with 3D MR elastography outperforms liver and spleen stiffness measured with shear wave elastography for diagnosis of clinically significant portal hypertension.

Noninvasive imaging of hepatic dysfunction: A state-of-the-art review

Hepatic dysfunction represents a wide spectrum of pathological changes, which can be frequently found in hepatitis, cholestasis, metabolic diseases, and focal liver lesions. As hepatic dysfunction is often clinically silent until advanced stages, there remains an unmet need to identify affected patients at early stages to enable individualized intervention which can improve prognosis. Passive liver function tests include biochemical parameters and clinical grading systems (e.g., the Child-Pugh score and Model for End-Stage Liver Disease score). Despite widely used and readily available, these approaches provide indirect and limited information regarding hepatic function. Dynamic quantitative tests of liver function are based on clearance capacity tests such as the indocyanine green (ICG) clearance test. However, controversial results have been reported for the ICG clearance test in relation with clinical outcome and the accuracy is easily affected by various factors. Imaging techniques, including ultrasound, computed tomography, and magnetic resonance imaging, allow morphological and functional assessment of the entire hepatobiliary system, hence demonstrating great potential in evaluating hepatic dysfunction noninvasively. In this article, we provide a state-of-the-art summary of noninvasive imaging modalities for hepatic dysfunction assessment along the pathophysiological track, with special emphasis on the imaging modality comparison and selection for each clinical scenario.

Quantitative Assessment of Portal Hypertension by Two-Dimensional Shear Wave Elastography in Rat Models of Nonalcoholic Fatty Liver Disease: Comparison With Four Composite Scores

Background

Measurement of hepatic venous pressure gradients is the gold standard for assessing portal hypertension (PH) but is invasive with potential complications. We aimed to assess the performance in liver and spleen stiffness measurement (LSM and SSM, respectively) by two-dimensional shear wave elastography (2D-SWE) and composite scores including liver stiffness-spleen diameter to platelet ratio score (LSPS), platelet (PLT) count/spleen diameter ratio (PSR), aspartate aminotransferase (AST)/alanine aminotransferase ratio (AAR), and AST-to-PLT ratio index (APRI) for diagnosing PH in nonalcoholic fatty liver disease (NAFLD) rat models.

Methods

Animal models with PH in NAFLD were established in 65 rats, which then underwent 2D-SWE measurements. Morphological and biological parameters were collected for calculation of four composite scores. Correlations of noninvasive methods with portal venous pressure were evaluated by Spearman correlation analysis. The area under the receiver operating characteristic curve (AUC) was used to assess the performance of noninvasive methods in predicting PH.

Results

LSM and SSM were significantly associated with portal venous pressure (r = 0.636 and 0.602, respectively; all P < 0.001). The AUCs of LSM and SSM in the diagnosis of PH were 0.906 (95% confidence interval [CI]:0.841–0.97) and 0.87 (95% CI:0.776–0.964), respectively, and were significantly higher than those in composite scores. The AUCs for LSPS, PSR, AAR, and APRI were 0.793, 0.52, 0.668, and 0.533, respectively, for diagnosing PH. The AUCs of the combined models of LSM and SSM, LSM and PLT, SSM and PLT, and LSM, SSM and PLT were 0.923, 0.913, 0.872, and 0.923, respectively. The four combined models showed no statistical differences compared to LSM and SSM in evaluating PH (all P > 0.05).

Conclusions

LSM and SSM by 2D-SWE can be used as promising noninvasive parameters for diagnosing PH in NAFLD and have higher accuracy than composite scores. The combined models, compared to LSM and SSM, did not significantly improve the performance in diagnosing PH.

Magnetic Resonance Elastography for the Clinical Risk Assessment of Fibrosis, Cirrhosis, and Portal Hypertension in Patients With NAFLD

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming one of the most common causes of liver disease. The progressive subtype of NAFLD, nonalcoholic steatohepatitis (NASH), leads to cirrhosis, hepatocellular carcinoma, and mortality. Fibrosis is the strongest predictor for complications. Due to the invasive nature of liver biopsy, noninvasive testing methods have emerged to detect fibrosis and predict outcomes. Of these modalities, magnetic resonance elastography (MRE) has demonstrated the highest accuracy to detect fibrosis. In this review, we will focus on the emerging data regarding MRE and liver fibrosis, cirrhosis, and portal hypertension in NAFLD.

Dipeptidyl peptidase-3 is associated with severity of liver disease and circulatory complications in patients with cirrhosis

BACKGROUND

Patients with cirrhosis suffer from a complex multiorgan disturbance and their prognosis is influenced by the development of portal hypertension and systemic circulatory dysfunction. Although non-invasive techniques such as transient elastography aid in early detection, there is an unmet need for reliable markers of these clinically significant complications.

METHODS

We conducted an exploratory single-center study investigating dipeptidyl peptidase-3 (DPP3) concentrations in various vascular beds in a cohort of 48 patients with cirrhosis and 16 healthy controls. Liver vein catheterization with sampling from femoral artery and femoral, renal and hepatic veins as well as measurement of hepatic pressure and liver function via indocyanine green and galactose elimination tests were performed.

RESULTS

DPP3 concentrations were higher in cirrhotic patients compared to controls (12.6 vs. 7.4 ng/mL, p = 0.006) and increased according to the severity of cirrhosis. DPP3 associated with MELD-Na score, Child class, indocyanine green clearance, increased DPP3 with the increased hepatic venous pressure gradient (p = 0.015) as well as increased heart rate and reduced systemic vascular resistance. DPP3 concentrations predicted the presence of clinically significant portal hypertension in cirrhotic patients (AUROC 0.78, 95% CI 0.65 - 0.9).

CONCLUSION

DPP3 is a promising marker for portal hypertension and systemic hemodynamic changes in cirrhosis.

Diagnostic Accuracy of MRI for the Detection of Malignant Peripheral Nerve Sheath Tumors: A Systematic Review and Meta-Analysis

OBJECTIVE. This systematic review and meta-analysis evaluates the diagnostic accuracy of MRI for differentiating malignant (MPNSTs) from benign peripheral nerve sheath tumors (BPNSTs). MATERIALS AND METHODS. A systematic review of MEDLINE, Embase, Scopus, the Cochrane Library, and the gray literature from inception to December 2019 was performed. Original articles that involved at least 10 patients and that evaluated the accuracy of MRI for detecting MPNSTs were included. Two reviewers independently extracted clinical and radiologic data from included articles to calculate sensitivity, specificity, PPV, NPV, and accuracy. A meta-analysis was performed using a bivariate mixed-effects regression model. Risk of bias was evaluated using QUADAS-2. RESULTS. Fifteen studies involving 798 lesions (252 MPNSTs and 546 BPNSTs) were included in the analysis. Pooled and weighted sensitivity, specificity, and AUC values for MRI in detecting MPNSTs were 68% (95% CI, 52-80%), 93% (95% CI, 85-97%), and 0.89 (95% CI, 0.86-0.92) when using feature combination and 88% (95% CI, 74-95%), 94% (95% CI, 89-96%), and 0.97 (95% CI, 0.95-0.98) using diffusion restriction with or without feature combination. Subgroup analysis, such as patients with neurofibromatosis type 1 (NF1) versus those without NF1, could not be performed because of insufficient data. Risk of bias was predominantly high or unclear for patient selection, mixed for index test, low for reference standard, and unclear for flow and timing. CONCLUSION. Combining features such as diffusion restriction optimizes the diagnostic accuracy of MRI for detecting MPNSTs. However, limitations in the literature, including variability and risk of bias, necessitate additional methodologically rigorous studies to allow subgroup analysis and further evaluate the combination of clinical and MRI features for MPNST diagnosis.

Noninvasive imaging assessment of portal hypertension

Portal hypertension (PH) is a spectrum of complications of chronic liver disease (CLD) and cirrhosis, with manifestations including ascites, gastroesophageal varices, splenomegaly, hypersplenism, hepatic hydrothorax, hepatorenal syndrome, hepatopulmonary syndrome and portopulmonary hypertension. PH can vary in severity and is diagnosed via invasive hepatic venous pressure gradient measurement (HVPG), which is considered the reference standard. Accurate diagnosis of PH and assessment of severity are highly relevant as patients with clinically significant portal hypertension (CSPH) are at higher risk for developing acute variceal bleeding and mortality. In this review, we discuss current and upcoming noninvasive imaging methods for diagnosis and assessment of severity of PH.

Nonalcoholic fatty liver disease and portal hypertension

Nonalcoholic fatty liver disease (NAFLD) is a substantial and growing problem worldwide and has become the second most common indication for liver transplantation as it may progress to cirrhosis and develop complications from portal hypertension primarily caused by advanced fibrosis and erratic tissue remodeling. However, elevated portal venous pressure has also been detected in experimental models of fatty liver and in human NAFLD when fibrosis is far less advanced and cirrhosis is absent. Early increases in intrahepatic vascular resistance may contribute to the progression of liver disease. Specific pathophenotypes linked to the development of portal hypertension in NAFLD include hepatocellular lipid accumulation and ballooning injury, capillarization of liver sinusoidal endothelial cells, enhanced contractility of hepatic stellate cells, activation of Kupffer cells and pro-inflammatory pathways, adhesion and entrapment of recruited leukocytes, microthrombosis, angiogenesis and perisinusoidal fibrosis. These pathological events are amplified in NAFLD by concomitant visceral obesity, insulin resistance, type 2 diabetes and dysbiosis, promoting aberrant interactions with adipose tissue, skeletal muscle and gut microbiota. Measurement of the hepatic venous pressure gradient by retrograde insertion of a balloon-tipped central vein catheter is the current reference method for predicting outcomes of cirrhosis associated with clinically significant portal hypertension and guiding interventions. This invasive technique is rarely considered in the absence of cirrhosis where currently available clinical, imaging and laboratory correlates of portal hypertension may not reflect early changes in liver hemodynamics. Availability of less invasive but sufficiently sensitive methods for the assessment of portal venous pressure in NAFLD remains therefore an unmet need. Recent efforts to develop new biomarkers and endoscopy-based approaches such as endoscopic ultrasound-guided measurement of portal pressure gradient may help achieve this goal. In addition, cellular and molecular targets are being identified to guide emerging therapies in the prevention and management of portal hypertension.