Improving Vessel Segmentation with Multi-Task Learning and Auxiliary Data Available Only During Model Training

Liver vessel segmentation in magnetic resonance imaging data is important for the computational analysis of vascular remodeling, associated with a wide spectrum of diffuse liver diseases. Existing approaches rely on contrast enhanced imaging data, but the necessary dedicated imaging sequences are not uniformly acquired. Images without contrast enhancement are acquired more frequently, but vessel segmentation is challenging, and requires large-scale annotated data. We propose a multi-task learning framework to segment vessels in liver MRI without contrast. It exploits auxiliary contrast enhanced MRI data available only during training to reduce the need for annotated training examples. Our approach draws on paired native and contrast enhanced data with and without vessel annotations for model training. Results show that auxiliary data improves the accuracy of vessel segmentation, even if they are not available during inference. The advantage is most pronounced if only few annotations are available for training, since the feature representation benefits from the shared task structure. A validation of this approach to augment a model for brain tumor segmentation confirms its benefits across different domains. An auxiliary informative imaging modality can augment expert annotations even if it is only available during training.

Comparison of the efficacy of the gadoxetic acid MRI-derived relative enhancement index (REI) and functional liver imaging score (FLIS) in predicting liver function: validation with Albumin-Bilirubin (ALBI) grade

PURPOSE

This study compared the predictive performance of the relative enhancement index (REI) derived from gadoxetic acid (GA)-enhanced MRI with that of the functional liver imaging score (FLIS) in estimating liver function among patients with chronic liver disease (CLD) or liver cirrhosis (LC) by validating them with the albumin-bilirubin (ALBI) grade.

MATERIALS AND METHODS

We retrospectively examined 166 patients (79 women, 87 men; 57.4 years) who were diagnosed with LC or CLD and underwent GA-enhanced MRI between August 2020 and September 2023. The enhancement ratio (ER) is calculated using the formula: ER = [hepatobiliary phase liver signal (SI HBP20)-precontrast liver signal (SI pre)]/SI pre. The REI is calculated using the formula: REI = Liver Volume (LV) × ER. FLIS was assigned from the sum of three HBP image features, each scored between 0 and 2: liver parenchymal enhancement, biliary contrast excretion, and portal vein sign. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal cutoff values of ER, REI, and FLIS in differentiating between ALBI grades. The area under the curve (AUC), accuracy, sensitivity, and specificity were calculated for REI and FLIS to distinguish the ALBI grades. Spearman's rank correlation was used to evaluate the ER, REI, and FLIS correlations between the ALBI grades. To evaluate inter-reader reliability for LV, ER, REI, and FLIS, intraclass correlation coefficient (ICC) was used.

RESULTS

ROC curve analysis showed that the optimal cutoff value of REI for predicting ALBI Grade 1 was 899-905 for readers 1 and 2 and 461-477 for ALBI Grade 3, respectively. REI performed best in predicting ALBI Grade 1, achieving an accuracy range of 94%-92.2%, sensitivity of 94.9%-94.1%, and specificity of 91.7%-87.5% for readers 1 and 2, respectively. All parameters showed high accuracy in distinguishing ALBI Grade 3 from other grades. However, REI outperformed the others, showing an accuracy range of 98.8%-97.6%, sensitivity of 94.4%-94.4%, and specificity of 99.3%-98% for readers 1 and 2, respectively. REI showed the best and very strong correlation with ALBI for both readers.

CONCLUSION

REI showed a very strong correlation with the ALBI grades for assessing liver function. It outperformed FLIS in predicting the ALBI grades, indicating its potential as a radiologic tool comparable to or better than FLIS in predicting liver function, especially given its dependence on liver volume.

Hepatobiliary phase imaging in cirrhotic patients using compressed sensing and controlled aliasing in parallel imaging results in higher acceleration

OBJECTIVE

We aimed to compare the image quality and focal lesion detection ability of hepatobiliary phase (HBP) images obtained using compressed sensing (CS) and controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) in patients with liver cirrhosis.

MATERIALS AND METHODS

We retrospectively included 244 gadoxetic acid-enhanced liver MRI from 244 patients with cirrhosis obtained by two HBP images using CS and CAIPIRINHA from July 2020 to December 2020. The optimized resolution and scan time for CS-HBP and CAIPIRINHA-HBP were 0.9 × 0.9 × 1.5 mm3 and 15 s and 1.3 × 1.3 × 3 mm3 and 16 s, respectively. We compared the image quality between the two sets of images in 244 patients and focal lesion (n = 294) analyses for 112 patients.

RESULTS

CS-HBP showed comparable overall image quality (3.7 ± 0.9 vs. 3.6 ± 0.8, p = 0.680), superior liver edge sharpness (3.9 ± 0.6 vs. 3.6 ± 0.5, p < 0.001), and fewer respiratory motion artifacts (4.0 ± 0.7 vs. 3.8 ± 0.5, p < 0.001), but higher non-respiratory artifacts (3.4 ± 0.7 vs. 3.6 ± 0.6, p < 0.001) and subjective image noise (3.5 ± 0.8 vs. 3.6 ± 0.7, p = 0.014) than CAIPIRINHA-HBP. CS-HBP showed a higher signal-to-noise ratio in the liver than CAIPIRINHA-HBP (20.9 ± 9.0 vs. 18.9 ± 7.1, p = 0.008). The pooled sensitivity, specificity, and AUC were 90.0%, 77.5%, and 0.84 for CS-HBP and 73.5%, 82.4%, and 0.78 for CAIPIRINHA-HBP, respectively.

CONCLUSIONS

CS-HBP showed better focal lesion detection ability, comparable overall image quality, and fewer respiratory motion artifacts, but higher non-respiratory artifacts and noise compared to CAIPIRINHA-HBP. Thus, CS-HBP could be recommended for liver MRI in patients with cirrhosis to improve diagnostic performance.

CLINICAL RELEVANCE STATEMENT

Thin-slice CS-HBP may be useful for detecting sub-centimeter hepatocellular carcinoma in cirrhotic patients with Child-Pugh classification A while maintaining comparable subjective image quality.

KEY POINTS

• Compared with controlled aliasing in parallel imaging results in higher acceleration, compressed sensing hepatobiliary phase yielded thinner slices and shorter scan time at a higher accelerating factor. • Compressed sensing hepatobiliary phase showed comparable overall image quality, superior liver edge sharpness, and fewer respiratory motion artifacts, but higher non-respiratory artifacts and subjective image noise than controlled aliasing in parallel imaging results in higher acceleration-hepatobiliary phase. • Compressed sensing hepatobiliary phase can detect sub-centimeter hepatocellular carcinoma in cirrhotic patients with Child-Pugh classification A.

Noninvasive diagnosis of liver cirrhosis: qualitative and quantitative imaging biomarkers

A diagnosis of cirrhosis initiates a shift in the management of chronic liver disease and affects the diagnostic workflow and treatment decision of primary liver cancer. Liver biopsy remains the gold standard for cirrhosis diagnosis, but it is invasive and susceptible to sampling bias and observer variability. Various qualitative and quantitative imaging biomarkers based on ultrasound, CT and MRI have been proposed for noninvasive diagnosis of cirrhosis. Qualitative imaging features are easy to apply but have moderate diagnostic sensitivity. Elastography techniques allow quantitative assessment of liver stiffness and are highly accurate for cirrhosis diagnosis. Ultrasound elastography are widely used in clinical practice, while MR elastography has narrower availability. Although not applicable in clinical practice yet, other quantitative imaging features, including liver surface nodularity, linear and volumetric measurement, extracellular volume fraction, liver enhancement on hepatobiliary phase, and parameters derived from diffusion-weighted imaging, can provide additional information of liver morphology, perfusion, and function, thus may increase diagnosis performance. The introduction of radiomics and deep learning has further improved diagnostic accuracy while reducing subjectivity. Several imaging features may also help to assess liver function and outcomes in patients with cirrhosis. In this review, we summarize the qualitative and quantitative imaging biomarkers for noninvasive cirrhosis diagnosis, and the assessment of liver function and outcomes, and discuss the challenges and future directions in this field.

Are dilution, slow injection and care bolus technique the causal solution to mitigating arterial-phase artifacts on gadoxetic acid-enhanced MRI? A large-cohort study

OBJECTIVE

Arterial-phase artifacts are gadoxetic acid (GA)-enhanced MRI's major drawback, ranging from 5 to 39%. We evaluate the effect of dilution and slow injection of GA using automated fluoroscopic triggering on liver MRI arterial-phase (AP) acquisition timing, artifact frequency, and lesion visibility.

METHODS AND MATERIALS

Saline-diluted 1:1 GA was injected at 1 ml/s into 1413 patients for 3 T liver MRI. Initially, one senior abdominal radiologist, i.e., principal investigator (PI), assessed all MR exams and compared them to previous and follow-up images, as well as the radiology report on record, determining the standard of reference for lesion detection and characterization. Then, three other readers independently evaluated the AP images for artifact type (truncation (TA), transient severe motion (TSM) or mixed), artifact severity (on a 5-point scale), acquisition timing (on a 4-point scale) and visibility (on a 5-point scale) of hypervascular lesions ≥ 5 mm, selected by the PI. Artifact score ≥ 4 and artifact score ≤ 3 were considered significant and non-significant artifacts, respectively.

RESULTS

Of the 1413 exams, diagnostic-quality arterial-phase images included 1100 (77.8%) without artifacts, 220 (15.6%) with minimal, and 77 (5.4%) with moderate artifacts. Only 16 exams (1.1%) had significant artifacts, 13 (0.9%) with severe artifacts (score 4), and three (0.2%) non-diagnostic artifacts (score 5). AP acquisition timing was optimal in 1369 (96.8%) exams. Of the 449 AP hypervascular lesions, 432 (96.2%) were detected.

CONCLUSION

Combined dilution and slow injection of GA with MR results in well-timed arterial-phase images in 96.8% and a reduction of exams with significant artifacts to 1.1%.

CLINICAL RELEVANCE STATEMENT

Hypervascular lesions, in particular HCC detection, hinge on arterial-phase hyperenhancement, making well-timed, artifact-free arterial-phase images a prerequisite for accurate diagnosis. Saline dilution 1:1, slow injection (1 ml/s), and automated bolus triggering reduce artifacts and optimize acquisition timing.

KEY POINTS

• There was substantial agreement among the three readers regarding the presence and type of arterial-phase (AP) artifacts, acquisition timing, and lesion visibility. • Impaired AP hypervascular lesion visibility occurred in 17 (3.8%) cases; in eight lesions due to mistiming and in nine lesions due to significant artifacts. • When AP timing was suboptimal, it was too late in 40 exams (3%) and too early in 4 exams (0.2%) of exams.

Diagnosis of functional strictures in patients with primary sclerosing cholangitis using hepatobiliary contrast-enhanced MRI: a proof-of-concept study

OBJECTIVES

PSC strictures are routinely diagnosed on T2-MRCP as dominant- (DS) or high-grade stricture (HGS). However, high inter-observer variability limits their utility. We introduce the "potential functional stricture" (PFS) on T1-weighted hepatobiliary-phase images of gadoxetic acid-enhanced MR cholangiography (T1-MRC) to assess inter-reader agreement on diagnosis, location, and prognostic value of PFS on T1-MRC vs. DS or HGS on T2-MRCP in PSC patients, using ERCP as the gold standard.

METHODS

Six blinded readers independently reviewed 129 MRIs to diagnose and locate stricture, if present. DS/HGS was determined on T2-MRCP. On T1-MRC, PFS was diagnosed if no GA excretion was seen in the CBD, hilum or distal RHD, or LHD. If excretion was normal, "no functional stricture" (NFS) was diagnosed. T1-MRC diagnoses (NFS = 87; PFS = 42) were correlated with ERCP, clinical scores, labs, splenic volume, and clinical events. Statistical analyses included Kaplan-Meier curves and Cox regression.

RESULTS

Interobserver agreement was almost perfect for NFS vs. PFS diagnosis, but fair to moderate for DS and HGS. Forty-four ERCPs in 129 patients (34.1%) were performed, 39 in PFS (92.9%), and, due to clinical suspicion, five in NFS (5.7%) patients. PFS and NFS diagnoses had 100% PPV and 100% NPV, respectively. Labs and clinical scores were significantly worse for PFS vs. NFS. PFS patients underwent more diagnostic and therapeutic ERCPs, experienced more clinical events, and reached significantly more endpoints (p < 0.001) than those with NFS. Multivariate analysis identified PFS as an independent risk factor for liver-related events.

CONCLUSION

T1-MRC was superior to T2-MRCP for stricture diagnosis, stricture location, and prognostication.

CLINICAL RELEVANCE STATEMENT

Because half of PSC patients will develop clinically-relevant strictures over the course of the disease, earlier more confident diagnosis and correct localization of functional stricture on gadoxetic acid-enhanced MRI may optimize management and improve prognostication.

KEY POINTS

• There is no consensus regarding biliary stricture imaging features in PSC that have clinical relevance. • Twenty-minute T1-weighted MRC images correctly classified PSC patients with potential (PFS) vs with no functional stricture (NFS). • T1-MRC diagnoses may reduce the burden of diagnostic ERCPs.

Current status of preoperative risk assessment for posthepatectomy liver failure in patients with hepatocellular carcinoma

Liver resection is an effective therapeutic option for patients with hepatocellular carcinoma. However, posthepatectomy liver failure (PHLF) remains a major cause of hepatectomy-related mortality, and the accurate prediction of PHLF based on preoperative assessment of liver functional reserve is a critical issue. The definition of PHLF proposed by the International Study Group for Liver Surgery has gained acceptance as a standard grading criterion. Liver function can be estimated using a variety of parameters, including routine blood biochemical examinations, clinical scoring systems, dynamic liver function tests, liver stiffness and fibrosis markers, and imaging studies. The Child-Pugh score and model for end-stage liver disease scores are conventionally used for estimating liver decompensation, although the alternatively developed albumin-bilirubin score shows superior performance for predicting hepatic dysfunction. Indocyanine green clearance, a dynamic liver function test mostly used in Japan and other Asian countries, serves as a quantitative estimation of liver function reserve and helps determine indications for surgical procedures according to the estimated risk of PHLF. In an attempt to improve predictive accuracy, specific evaluation of liver fibrosis and portal hypertension has gained popularity, including liver stiffness measurements using ultrasonography or magnetic resonance elastography, as well as noninvasive fibrosis markers. Imaging modalities, including Tc-99m-labeled galactosyl serum albumin scintigraphy and gadolinium-enhanced magnetic resonance imaging, are used for preoperative evaluation in combination with liver volume. This review aims to provide an overview of the usefulness of current options for the preoperative assessment of liver function in predicting PHLF.

CT and MR imaging of primary biliary cholangitis: a pictorial review

Primary biliary cholangitis (PBC) is a rare chronic autoimmune-mediated cholestatic liver disease involving medium and small bile ducts that can lead to liver fibrosis and cirrhosis. To date, the pathogenesis of PBC remains elusive, and there is currently no curative medical treatment. Computed tomography (CT) and magnetic resonance (MR) imaging, as common technical tools that allow non-invasive monitoring of liver tissue in vivo, play crucial roles in the diagnosis, staging, and prognosis prediction in PBC by enabling assessment of abnormalities in liver morphology and parenchyma, irregular configuration of bile ducts, lymphadenopathy, portal hypertension, and complications of cirrhosis. Moreover, CT and MRI can be used to monitor the disease progression after treatment of PBC (e.g. the onset of cirrhotic decompensation or HCC) to guide the clinical decisions for liver transplantation. With the optimization of imaging technology, magnetic resonance elastography (MRE) offers additional information on liver stiffness, allows for the identification of early cirrhosis in PBC and provides a basis for predicting prognosis. Gadoxetic acid-enhanced MRI enables the assessment of liver function in patients with PBC. The purpose of this review is to detail and illustrate the definition, pathological basis, and clinical importance of CT and MRI features of PBC to help radiologists and clinicians enhance their understanding of PBC.Critical Relevance StatementCharacteristic CT and MR imaging manifestations of primary biliary cholangitis may reflect the course of the disease and provide information associated with histological grading and altered cellular function.Key points• Imaging has become highly useful for differentiating PBC from other diseases.• Key pathological alterations of PBC can be captured by CT and MRI.• Characteristic manifestations provide information associated with histological grade and cellular function.• Despite this, the CT or MRI features of PBC are not specific.

Molecular magnetic resonance imaging of liver inflammation using an oxidatively activated probe

Background & Aims

Many liver diseases are driven by inflammation, but imaging to non-invasively diagnose and quantify liver inflammation has been underdeveloped. The inflammatory liver microenvironment is aberrantly oxidising owing in part to reactive oxygen species generated by myeloid leucocytes. We hypothesised that magnetic resonance imaging using the oxidatively activated probe Fe-PyC3A will provide a non-invasive biomarker of liver inflammation.

Methods

A mouse model of drug-induced liver injury was generated through intraperitoneal injection of a hepatoxic dose of acetaminophen. A mouse model of steatohepatitis was generated via a choline-deficient, l-amino acid defined high-fat diet (CDAHFD). Images were acquired dynamically before and after intravenous injection of Fe-PyC3A. The contrast agent gadoterate meglumine was used as a non-oxidatively activated negative control probe in mice fed CDAHFD. The (post-pre) Fe-PyC3A injection change in liver vs. muscle contrast-to-noise ratio (ΔCNR) recorded 2 min post-injection was correlated with liver function test values, histologic scoring assigned using the NASH Clinical Research Network criteria, and intrahepatic myeloid leucocyte composition determined by flow cytometry.

Results

For mice receiving i.p. injections of acetaminophen, intrahepatic neutrophil composition correlated poorly with liver test values but positively and significantly with ΔCNR (r = 0.64, p <0.0001). For mice fed CDAHFD, ΔCNR generated by Fe-PyC3A in the left lobe was significantly greater in mice meeting histologic criteria strongly associated with a diagnosis NASH compared to mice where histology was consistent with likely non-NASH (p = 0.0001), whereas no differential effect was observed using gadoterate meglumine. In mice fed CDAHFD, ΔCNR did not correlate strongly with fractional composition of any specific myeloid cell subpopulation as determined by flow cytometry.

Conclusions

Magnetic resonance imaging using Fe-PyC3A merits further evaluation as a non-invasive biomarker for liver inflammation.

Impact and implications

Non-invasive tests to diagnose and measure liver inflammation are underdeveloped. Inflammatory cells such as neutrophils release reactive oxygen species which creates an inflammatory liver microenvironment that can drive chemical oxidation. We recently invented a new class of magnetic resonance imaging probe that is made visible to the scanner only after chemical oxidation. Here, we demonstrate how this imaging technology could be applied as a non-invasive biomarker for liver inflammation.

Long-term antibody response to inactivated SARS-CoV-2 vaccination in patients with chronic liver disease: A multicenter study

Patients with chronic liver disease (CLD) are at a greater risk of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection. This study investigated the antibody response to inactivated SARS-CoV-2 vaccination in a long-term prospective cohort of CLD patients. The seropositivity rates and antibody concentrations of anti-SARS-CoV-2 NAbs were similar among patients with different severity of CLD 6 months after the third vaccination. In addition, older CLD patients appeared to have lower antibody responses. These data might be helpful to inform vaccine decisions for patients with chronic liver disease.

A radiomics model based on preoperative gadoxetic acid-enhanced magnetic resonance imaging for predicting post-hepatectomy liver failure in patients with hepatocellular carcinoma

Background

Post-hepatectomy liver failure (PHLF) is a fatal complication after liver resection in patients with hepatocellular carcinoma (HCC). It is of clinical importance to estimate the risk of PHLF preoperatively.

Aims

This study aimed to develop and validate a prediction model based on preoperative gadoxetic acid-enhanced magnetic resonance imaging to estimate the risk of PHLF in patients with HCC.

Methods

A total of 276 patients were retrospectively included and randomly divided into training and test cohorts (194:82). Clinicopathological variables were assessed to identify significant indicators for PHLF prediction. Radiomics features were extracted from the normal liver parenchyma at the hepatobiliary phase and the reproducible, robust and non-redundant ones were filtered for modeling. Prediction models were developed using clinicopathological variables (Clin-model), radiomics features (Rad-model), and their combination.

Results

The PHLF incidence rate was 24% in the whole cohort. The combined model, consisting of albumin-bilirubin (ALBI) score, indocyanine green retention test at 15 min (ICG-R15), and Rad-score (derived from 16 radiomics features) outperformed the Clin-model and the Rad-model. It yielded an area under the receiver operating characteristic curve (AUC) of 0.84 (95% confidence interval (CI): 0.77-0.90) in the training cohort and 0.82 (95% CI: 0.72-0.91) in the test cohort. The model demonstrated a good consistency by the Hosmer-Lemeshow test and the calibration curve. The combined model was visualized as a nomogram for estimating individual risk of PHLF.

Conclusion

A model combining clinicopathological risk factors and radiomics signature can be applied to identify patients with high risk of PHLF and serve as a decision aid when planning surgery treatment in patients with HCC.

Conventional and artificial intelligence-based computed tomography and magnetic resonance imaging quantitative techniques for non-invasive liver fibrosis staging

Chronic liver disease (CLD) ultimately develops into liver fibrosis and cirrhosis and is a major public health problem globally. The assessment of liver fibrosis is important for patients with CLD for prognostication, treatment decisions, and surveillance. Liver biopsies are traditionally performed to determine the stage of liver fibrosis. However, the risks of complications and technical limitations restrict their application to screening and sequential monitoring in clinical practice. CT and MRI are essential for evaluating cirrhosis-associated complications in patients with CLD, and several non-invasive methods based on them have been proposed. Artificial intelligence (AI) techniques have also been applied to stage liver fibrosis. This review aimed to explore the values of conventional and AI-based CT and MRI quantitative techniques for non-invasive liver fibrosis staging and summarized their diagnostic performance, advantages, and limitations.

The value of contrast-enhanced portal vein imaging at the hepatobiliary phase obtained with gadobenate dimeglumine for predicting decompensation and transplant-free survival in chronic liver disease

OBJECTIVES

To investigate the value of contrast-enhanced portal vein imaging at the hepatobiliary phase obtained with gadobenate dimeglumine for predicting clinical outcomes in patients with chronic liver disease (CLD).

METHODS

Three hundred and fourteen CLD patients who underwent gadobenate dimeglumine-enhanced hepatic magnetic resonance imaging were stratified into three groups: nonadvanced CLD (n = 116), compensated advanced CLD (n = 120), and decompensated advanced CLD (n = 78) groups. The liver-to-portal vein contrast ratio (LPC) and liver-spleen contrast ratio (LSC) at the hepatobiliary phase were measured. The value of LPC for predicting hepatic decompensation and transplant-free survival was assessed using Cox regression analysis and Kaplan-Meier analysis.

RESULTS

The diagnostic performance of LPC was significantly better than LSC in evaluating the severity of CLD. During a median follow-up period of 53.0 months, the LPC was a significant predictor for hepatic decompensation (p < 0.001) in patients with compensated advanced CLD. The predictive performance of LPC was higher than that of the model for end-stage liver disease score (p = 0.006). With the optimal cut-off value, patients with LPC ≤ 0.98 had a higher cumulative incidence of hepatic decompensation than patients with LPC > 0.98 (p < 0.001). The LPC was also a significant predictive factor for transplant-free survival in patients with compensated advanced CLD (p = 0.007) and those with decompensated advanced CLD (p = 0.002).

CONCLUSIONS

Contrast-enhanced portal vein imaging at the hepatobiliary phase obtained with gadobenate dimeglumine is a valuable imaging biomarker for predicting hepatic decompensation and transplant-free survival in CLD patients.

KEY POINTS

• The liver-to-portal vein contrast ratio (LPC) significantly outperformed liver-spleen contrast ratio in evaluating the severity of chronic liver disease. • The LPC was a significant predictor for hepatic decompensation in patients with compensated advanced chronic liver disease. • The LPC was a significant predictor for transplant-free survival in patients with compensated and those with decompensated advanced chronic liver disease.

Inter-reader reliability of functional liver imaging score derived from gadoxetic acid-enhanced MRI: a meta-analysis

PURPOSE

This study aimed to systematically determine the inter-reader reliability of the functional liver imaging score (FLIS) and explore the factors affecting it.

METHODS

Original articles reporting the inter-reader reliability of FLIS derived from gadoxetic acid-enhanced magnetic resonance imaging (MRI) were systematically searched in the MEDLINE and EMBASE databases from January 2013 to June 2022. Data synthesis was performed to calculate the meta-analytic pooled estimates of the FLIS and its three subcategories, including enhancement quality score (EnQS), excretion quality score (ExQS), and portal vein sign quality score (PVsQS) using the DerSimonian-Laird random-effects model. To explore any cause of study heterogeneity, we conducted a meta-regression analysis.

RESULTS

Six studies with data from 1419 patients were included. The meta-analytic pooled inter-reader reliability of FLIS was 0.93 (95% confidence interval [CI], 0.88-0.98). That of the three FLIS subcategories were 0.93 (95% CI, 0.85-1.00), 0.95 (95% CI, 0.91-1.00), and 0.90 (95% CI, 0.81-0.99) for EnQS, ExQS, and PVsQS, respectively. The pooled FLIS data was moderately heterogenous, but heterogeneity was not associated with the study methodology, MRI-related factors, and reader experience.

CONCLUSION

The FLIS and its three subcategories showed almost perfect inter-reader reliability. Therefore, FLIS may be a reliable imaging parameter that reflects liver function and outcomes in patients with chronic liver disease. Further studies should be conducted to confirm any factors affecting the inter-reader reliability of FLIS.

Relative enhancement index can be used to quantify liver function in cirrhotic patients that undergo gadoxetic acid-enhanced MRI

OBJECTIVES

To evaluate MRI with gadoxetic acid to quantify liver function in cirrhotic patients using the relative enhancement index (REI) compared with Child-Pugh score (CPS), MELD score, and indocyanine green plasma disappearance rate (ICG-PDR) and to establish cutoffs for REI to stratify cirrhotic patients into good and poor liver function groups.

METHODS

We prospectively evaluated 60 cirrhotic patients and calculated CPS, MELD score, ICG-PDR, and REI for each patient. Spearman's correlation coefficient was used to assess correlation between REI, CPS, MELD, and ICG-PDR. Good and poor liver function groups were created by k-means clustering algorithm using CPS, MELD, and ICG-PDR. ROC curve analysis was performed and optimal cutoff was identified for group differentiation.

RESULTS

Good correlations were found between REI and other liver function biomarkers: REI and CPS (rho =  - 0.816; p < 0.001); REI and MELD score (rho =  - 0.755; p < 0.001); REI and ICG-PDR (rho = 0.745; p < 0.001)]. REI correlation was stronger for patients with Child-Pugh A (rho = 0.642, p = 0.002) and B (rho = 0.798, p < 0.001) than for those with Child-Pugh C (rho = 0.336, p = 0.148). REI is significantly lower in patients with poor liver function (p < 0.001). ROC curve showed an AUC 0.94 to discriminate patients with poor liver function (REI cutoff < 100; 100% sensitivity; 76% specificity).

CONCLUSIONS

REI is a valuable non-invasive index for liver function quantification that has good correlations with other liver function biomarkers. REI can be easily calculated and can be used to estimate liver function in clinical practice in the routine evaluation of cirrhotic patients that undergo MR imaging with gadoxetic acid contrast.

KEY POINTS

• REI is a valuable non-invasive index for liver function quantification that has good correlations with other liver function biomarkers. • REI can be easily calculated in the routine evaluation of cirrhotic patients that undergo gadoxetic acid-enhanced MRI. • The REI enables stratification of cirrhotic patients into good and poor liver function groups and can be used as additional information, together with morphological and focal liver lesion evaluation.

Effect of type 2 diabetes on liver images of GD-EOB-DTPA-enhanced MRI during the hepatobiliary phase

To analyze alterations of the liver appearance during the hepatobiliary phase of individuals with type 2 diabetes who are receiving gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) enhanced magnetic resonance imaging (MRI). Fifty-seven individuals who received Gd-EOB-DTPA-enhanced MRI and had normal liver and renal function but did not have (control group) or have type 2 diabetes (observation group) were retrospectively included in this study. The liver enhancement ratio (LER) and contrast between liver parenchyma and portal vein (LPC) were calculated from hepatobiliary phase images. Utilizing liver to kidney signal intensity, signs of the biliary system, and signs of the portal vein, a functional liver imaging score (FLIS) was calculated. Wilcoxon rank-sum test was used to assess the between-group differences in LER, LPC, and FLIS. FLIS constituent ratios between the two groups were tested using the χ² test. The effectiveness of LER, LPC, and FLIS for identifying type 2 diabetes was assessed by receiver operating characteristic curves (ROCs). The interobserver consistency of FLIS was evaluated using the intraclass correlation coefficients. The observation group's LER and LPC were lower than the control group. The constituent ratio of the FLIS score (liver to kidney signal intensity, p = 0.011) showed a significant between-group difference. According to ROCs, LER and LPC were associated with the identification of type 2 diabetes. LER = 0.54 and LPC = 1.46 were the optimal cutoff for identifying type 2 diabetes, respectively. FLIS demonstrated excellent inter-reader agreement. The relative signal intensity of the liver during the hepatobiliary phase is decreased in patients with type 2 diabetes. This should be considered when individuals with type 2 diabetes undergo Gd-EOB-DTPA-enhanced MRI to avoid misdiagnoses, such as small hepatocellular carcinoma or abnormal liver function.

Imaging features facilitate diagnosis of porto-sinusoidal vascular disorder

OBJECTIVES

Porto-sinusoidal vascular disorder (PSVD) is a recently defined vascular liver disease. Since diagnosis remains challenging, we aimed to evaluate radiological features that are distinct between PSVD and cirrhosis.

METHODS

Clinical, laboratory, and radiological parameters (CT/MRI) of patients with histologically-confirmed PSVD vs. cirrhosis vs. non-cirrhotic parenchymal liver disease were retrospectively evaluated.

RESULTS

Sixty-three PSVD, 155 cirrhosis, and 41 non-cirrhotic patients were included. As compared to cirrhosis, PSVD patients were younger and had lower HVPG, liver stiffness, and MELD. Routine clinical and imaging findings indicative of portal hypertension were similarly common. Intrahepatic portal tract abnormalities (49% vs. 15%; p < 0.001), FNH-like lesions (30% vs. 1%; p < 0.001), and abnormal liver morphology defined as peripheral parenchymal atrophy and compensatory hypertrophy of central segments (32% vs. 7%; p < 0.001) were significantly more common in PSVD patients. Hypertrophy of segment I (70% vs. 84%; p = 0.019), atrophy of segment IV (24% vs. 47%; p = 0.001), and nodular liver surface (22% vs. 89%; p < 0.001) were more common in patients with cirrhosis. In patients with gadoxetic acid-enhanced MRI, we identified the distinct imaging feature of "periportal hyperintensity" in the hepatobiliary phase (HBP) in 42% of patients with PSVD (14/33) vs. 1% in cirrhosis (1/95) vs. 0% in non-cirrhotic controls (0/41); p < 0.001).

CONCLUSIONS

Diagnosis of PSVD must be considered in younger patients presenting with clinical features of portal hypertension, portal tract abnormalities, and FNH-like lesions on CT/MRI. 'Periportal hyperintensity' in the HBP of gadoxetic acid-enhanced MRI was identified as a specific radiological feature of PSVD.

KEY POINTS

• Cross-sectional imaging can provide essential information to identify patients with porto-sinusoidal vascular disorder (PSVD). • Intrahepatic portal tract abnormalities, FNH-like lesions, and abnormal liver morphology are common in PSVD patients. • Periportal hyperintensity on the hepatobiliary phase of gadoxetic acid-enhanced MRI seems to be specific for patients with PSVD.

Updates on Quantitative MRI of Diffuse Liver Disease: A Narrative Review

Diffuse liver diseases are highly prevalent conditions around the world, including pathological liver changes that occur when hepatocytes are damaged and liver function declines, often leading to a chronic condition. In the last years, Magnetic Resonance Imaging (MRI) is reaching an important role in the study of diffuse liver diseases moving from qualitative to quantitative assessment of liver parenchyma. In fact, this can allow noninvasive accurate and standardized assessment of diffuse liver diseases and can represent a concrete alternative to biopsy which represents the current reference standard. MRI approach already tested for other pathologies include diffusion-weighted imaging (DWI) and radiomics, able to quantify different aspects of diffuse liver disease. New emerging MRI quantitative methods include MR elastography (MRE) for the quantification of the hepatic stiffness in cirrhotic patients, dedicated gradient multiecho sequences for the assessment of hepatic fat storage, and iron overload. Thus, the aim of this review is to give an overview of the technical principles and clinical application of new quantitative MRI techniques for the evaluation of diffuse liver disease.

Evaluation of liver function in patients with liver cirrhosis and chronic liver disease using functional liver imaging scores at different acquisition time points

Purpose: This paper aims to explore whether functional liver imaging score (FLIS) based on Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) images at 5, 10, and 15 min can predict liver function in patients with liver cirrhosis or chronic liver disease and its association with indocyanine green 15-min retention rate (ICG-R₁₅), Child-Pugh (CP) score, albumin-bilirubin (ALBI) score, and model for end-stage liver disease (MELD) score. In addition, it also examines the inter- and intra-observer consistency of FLIS and three FLIS parameters at three different time points. Methods: This study included 110 patients with chronic liver disease (CLD) or liver cirrhosis (LC) (93 men, 17 women; mean ± standard deviation = 56.96 ± 10.16) between July 2019 and May 2022. FLIS was assigned in accordance with the sum of the three hepatobiliary phase characteristics, all of which were scored on the 0-2 ordinal scale, including the biliary excretion, hepatic enhancement and portal vein signal intensity. FLIS was calculated independently by two radiologists using transitional and hepatobiliary phase images at 5, 10, and 15 min after enhancement. The relationship between FLIS and three FLIS quality scores and the degree of liver function were evaluated using Spearman's rank correlation coefficient. The ability of FLIS to predict hepatic function was investigated using receiver operating characteristic (ROC) curves. Results: Intra- and inter-observer intraclass correlation coefficients (ICCs) (ICC = 0.937-0.978, 95% CI = 0.909-0.985) for FLIS at each time point indicated excellent agreement. At each time point, FLIS had a moderate negative association with liver function classification (r = [-0.641]-[-0.428], p < 0.001), and weak to moderate correlation with some other clinical parameters except for creatinine (p > 0.05). FLIS showed moderate discriminatory ability between different liver function levels. The area under the ROC curves (AUCs) of FLIS at 5, 10, and 15 min after enhancement to predict ICG-R₁₅ of 10% or less were 0.838, 0.802, and 0.723, respectively; those for predicting ICG-R₁₅ greater than 20% were 0.793, 0.824, and 0.756, respectively; those for predicting ICG-R₁₅ greater than 40% were 0.728, 0.755, and 0.741, respectively; those for predicting ALBI grade 1 were 0.734, 0.761, and 0.691, respectively; those for predicting CP class A cirrhosis were 0.806, 0.821, and 0.829, respectively; those for predicting MELD score of 10 or less were 0.837, 0.877, and 0.837, respectively. No significant difference was found in the AUC of FLIS at 5, 10 and 15 min (p > 0.05). Conclusion: FLIS presented a moderate negative correlation with the classification system of hepatic function at a delay of 5, 10, and 15 min, and patients with LC or CLD were appropriately stratified based on ICG-R₁₅, ALBI grade, MELD score, and CP classification. In addition, the use of FLIS to evaluate liver function can reduce the observation time of the hepatobiliary period.

Prediction of Decompensation and Death in Advanced Chronic Liver Disease Using Deep Learning Analysis of Gadoxetic Acid-Enhanced MRI

OBJECTIVE

This study aimed to evaluate the usefulness of quantitative indices obtained from deep learning analysis of gadoxetic acid-enhanced hepatobiliary phase (HBP) MRI and their longitudinal changes in predicting decompensation and death in patients with advanced chronic liver disease (ACLD).

MATERIALS AND METHODS

We included patients who underwent baseline and 1-year follow-up MRI from a prospective cohort that underwent gadoxetic acid-enhanced MRI for hepatocellular carcinoma surveillance between November 2011 and August 2012 at a tertiary medical center. Baseline liver condition was categorized as non-ACLD, compensated ACLD, and decompensated ACLD. The liver-to-spleen signal intensity ratio (LS-SIR) and liver-to-spleen volume ratio (LS-VR) were automatically measured on the HBP images using a deep learning algorithm, and their percentage changes at the 1-year follow-up (ΔLS-SIR and ΔLS-VR) were calculated. The associations of the MRI indices with hepatic decompensation and a composite endpoint of liver-related death or transplantation were evaluated using a competing risk analysis with multivariable Fine and Gray regression models, including baseline parameters alone and both baseline and follow-up parameters.

RESULTS

Our study included 280 patients (153 male; mean age ± standard deviation, 57 ± 7.95 years) with non-ACLD, compensated ACLD, and decompensated ACLD in 32, 186, and 62 patients, respectively. Patients were followed for 11-117 months (median, 104 months). In patients with compensated ACLD, baseline LS-SIR (sub-distribution hazard ratio [sHR], 0.81; p = 0.034) and LS-VR (sHR, 0.71; p = 0.01) were independently associated with hepatic decompensation. The ΔLS-VR (sHR, 0.54; p = 0.002) was predictive of hepatic decompensation after adjusting for baseline variables. ΔLS-VR was an independent predictor of liver-related death or transplantation in patients with compensated ACLD (sHR, 0.46; p = 0.026) and decompensated ACLD (sHR, 0.61; p = 0.023).

CONCLUSION

MRI indices automatically derived from the deep learning analysis of gadoxetic acid-enhanced HBP MRI can be used as prognostic markers in patients with ACLD.

Current management of liver diseases and the role of multidisciplinary approach

Liver is an organ having extremely diversified functions, ranging from metabolic and synthetic to detoxification of harmful chemicals. The multifunctionality of the liver in principle requires the multidisciplinary and pluralistic interventions for its management. Several studies have investigated liver function, dysfunction and clinic. This editorial work discusses new ideas, challenges and perspectives of current research regarding multidisciplinary and pluralistic management of liver diseases. In one hand the discussions have carried out on the involvement of extracellular vesicles, Na⁺/H⁺ exchangers, severe acute respiratory syndrome coronavirus 2 and Epstein–Barr virus infections, Drug-induced liver injury, sepsis, pregnancy, and food supplements in hepatic disorders. In the other hand this study has discussed hepatocellular carcinoma algorithms and new biochemical and imaging experiments pertaining to liver diseases. Relevant articles with an impact index value "> 0" from reference citation analysis, which is an open multidisciplinary citation analysis database based on artificial intelligence technology, have served for the study’s argumentation. This work may be a useful tool for the clinical practice and research in managing and investigating liver disorders.

Gadoxetic acid-enhanced MRI-derived functional liver imaging score (FLIS) and spleen diameter predict outcomes in ACLD

BACKGROUND & AIMS

Functional liver imaging score (FLIS) - derived from gadoxetic acid-enhanced MRI - correlates with liver function and independently predicts liver-related mortality in patients with chronic liver disease (CLD), while splenic craniocaudal diameter (SCCD) is a marker of portal hypertension. The aim of this study was to investigate the accuracy of a combination of FLIS and SCCD for predicting hepatic decompensation, acute-on-chronic liver failure (ACLF), and mortality in patients with advanced CLD (ACLD).

METHODS

We included 397 patients with CLD who underwent gadoxetic acid-enhanced liver MRI. The FLIS was calculated by summing the points (0-2) of 3 hepatobiliary-phase features: hepatic enhancement, biliary excretion, and portal vein signal intensity. Patients were stratified into 3 groups according to liver fibrosis severity and presence/history of hepatic decompensation: non-ACLD, compensated ACLD (cACLD), and decompensated ACLD (dACLD).

RESULTS

SCCD showed excellent intra- and inter-reader agreement. Importantly, SCCD was an independent risk factor for hepatic decompensation in patients with cACLD (per cm; adjusted hazard ratio [aHR] 1.13; 95% CI 1.04-1.23; p = 0.004). Patients with cACLD and a FLIS of 0-3 points and/or a SCCD of >13 cm were at increased risk of hepatic decompensation (aHR 3.07; 95% CI 1.43-6.59; p = 0.004). In patients with dACLD, a FLIS of 0-3 was independently associated with an increased risk of ACLF (aHR 2.81; 95% CI 1.16-6.84; p = 0.02), even after adjusting for other prognostic factors. Finally, a FLIS and SCCD-based algorithm was independently predictive of transplant-free mortality and stratified the probability of transplant-free survival (TFS) in ACLD (p <0.001): FLIS 4-6 and SCCD ≤13 cm (5-year TFS of 84%) vs. FLIS 4-6 and SCCD >13 cm (5-year TFS of 70%) vs. FLIS 0-3 (5-year TFS of 24%).

CONCLUSION

The FLIS and SCCD are simple imaging markers that provide complementary information for risk stratification in patients with compensated and decompensated ACLD.

LAY SUMMARY

Magnetic resonance imaging (MRI) can be used to assess the state of the liver. Previously the functional liver imaging score, which is based on MRI criteria, was developed as a measure of liver function and to predict the risk of liver-related complications or death. By combining this score with a measurement of spleen diameter, also using MRI, we generated an algorithm that could predict the risk of adverse liver-related outcomes in patients with advanced chronic liver disease.

Determining the efficacy of functional liver imaging score (FLIS) obtained from gadoxetic acid-enhanced MRI in patients with chronic liver disease and liver cirrhosis: the relationship between Albumin-Bilirubin (ALBI) grade and FLIS

PURPOSE

(1) To evaluate the efficacy of functional liver imaging score (FLIS) in predicting liver function on gadoxetic acid-enhanced MRI in patients with chronic liver disease (CLD) or liver cirrhosis (LC) and its relationship with ALBI grade. (2) To assess the intra-reader reliability and interreader agreement of readers with different levels of experience in abdominal imaging of FLIS.

METHODS

We retrospectively included 131 patients (70 men, 61 women; mean ± SD, 53.7 ± 14.6 years) with CLD and LC who underwent GA-enhanced MRI between November 2019 and March 2022. FLIS was assigned as a result of the sum of three hepatobiliary phase (HBP) images features, each scored 0-2: liver parenchymal enhancement, biliary contrast excretion, and portal vein sign. FLIS was calculated using HPB images independently by three radiologists with different experience. In addition, 50 randomly selected patients were reviewed a second time by a reader to assess intra-reader reliability. Patients were divided into the following three groups according to the albumin-bilirubin (ALBI) grade: ALBI grade 1, 2, and 3. We evaluated the correlation between ALBI grade and both FLIS and its parameters using Spearman's rank correlation for each reader. Receiver operating characteristic (ROC) curve analysis was performed to show the optimal cut-off value of FLIS to distinguish between ALBI grades. Intra-reader reliability and inter-reader agreement were evaluated by intraclass correlation coefficient (ICC).

RESULTS

FLIS and three FLIS parameters showed very strong correlation with ALBI grade for each readers (r =  - 0.843 to 0.976, - 0.831 to 0.962, and - 0.819 to 0.902, respectively). ROC curve analysis showed that FLIS ≥ 5 was the optimal cutoff for prediction of ALBI grade 1 for each readers (sensitivity, 83.7% to 95.4%; specificity, 82.6% to 87%; accuracy, 88.6% to 93.6% and area under the curve (AUC), 0.882 to 0.917), and FLIS ≤ 3 was the optimal cutoff for distinguish ALBI grade 3 from other grades for each readers (sensitivity, 100%; specificity, 95.2% to 96%; accuracy, 95.4% to 96.2% and AUC, 0.974 to 0.994). Intra-reader reliability (ICC = 0.95; 95% CI 0.93-0.96) and inter-reader agreement (ICC = 0.85 to 0.90; 95% CI 0.82-0.97) for FLIS were excellent.

CONCLUSION

FLIS showed a very correlation with hepatic function level and can stratify the ALBI grades. This feature has demonstrated the potential of FLIS to be excellent radiological tools for predicting of liver function of CLD and LC patients in clinical practice. Also, the excellent agreement of FLIS among readers with different levels of experience indicates that it can be used with high accuracy and reproducibility regardless of experience.

The value of gadobenate dimeglumine-enhanced biliary imaging from the hepatobiliary phase for predicting post-hepatectomy liver failure in HCC patients

OBJECTIVES

To determine the value of gadobenate dimeglumine-enhanced biliary imaging from the hepatobiliary phase for predicting post-hepatectomy liver failure (PHLF) in patients with hepatocellular carcinoma (HCC).

METHODS

Patients with HCC who underwent gadobenate dimeglumine-enhanced hepatobiliary magnetic resonance imaging prior to hepatectomy were collected in two centers. The relative enhancement ratio of the biliary system (REB) and the liver to muscle ratio (LMR) were measured at the hepatobiliary phase. Potential risk factors for PHLF were analyzed by logistic regression. The capacity of the REB and LMR to predict PHLF was analyzed via receiver operating characteristic curve.

RESULTS

Of the 221 patients, post-hepatectomy liver failure occurred in 60 patients (27.1%). The REB was an independent risk factor for PHLF (odds ratio [OR] = 0.127 [0.047-0.348], p < 0.001). Although the LMR tended to be associated with PHLF (p = 0.063), it was not an independent risk factor in the multivariable analysis (OR = 0.624 [0.023-16.709], p = 0.779). Moreover, the area under the receiver operating characteristic curve of the REB and LMR was 0.87 and 0.60. The most appropriate cutoff value for the REB was 2.21. The HCC patients with the REB ≤ 2.21 had a higher incidence of post-hepatectomy liver failure than those with the REB > 2.21 (60.0% versus 8.5%, p < 0.001).

CONCLUSIONS

Gadobenate dimeglumine-enhanced biliary imaging from the hepatobiliary phase was valuable in predicting post-hepatectomy liver failure in HCC patients.

KEY POINTS

• The relative enhancement ratio of the biliary system (REB) was an independent risk factor for post-hepatectomy liver failure in HCC patients. • HCC patients with the REB ≤ 2.21 had significantly higher incidence of post-hepatectomy liver failure than those with the REB > 2.21 (60.0% versus 8.5%).

Gadoxetate-Enhanced MRI as a Diagnostic Tool in the Management of Hepatocellular Carcinoma: Report from a 2020 Asia-Pacific Multidisciplinary Expert Meeting

Gadoxetate magnetic resonance imaging (MRI) is widely used in clinical practice for liver imaging. For optimal use, we must understand both its advantages and limitations. This article is the outcome of an online advisory board meeting and subsequent discussions by a multidisciplinary group of experts on liver diseases across the Asia-Pacific region, first held on September 28, 2020. Here, we review the technical considerations for the use of gadoxetate, its current role in the management of patients with hepatocellular carcinoma (HCC), and its relevance in consensus guidelines for HCC imaging diagnosis. In the latter part of this review, we examine recent evidence evaluating the impact of gadoxetate on clinical outcomes on a continuum from diagnosis to treatment decision-making and follow-up. In conclusion, we outline the potential future roles of gadoxetate MRI based on an evolving understanding of the clinical utility of this contrast agent in the management of patients at risk of, or with, HCC.

Gd-BOPTA-enhanced hepatobiliary phase MR imaging can predict the prognosis of patients with acute-on-chronic liver failure

OBJECTIVES

To determine the value of gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance imaging (MRI) from the hepatobiliary phase for predicting poor outcome in acute-on-chronic liver failure (ACLF) patients.

METHODS

In this single-center retrospective study, 74 patients diagnosed as ACLF who underwent Gd-BOPTA-enhanced hepatobiliary magnetic resonance imaging were collected. The quantitative liver-spleen contrast ratio (Q-LSC) and the relative enhancement ratio of the biliary system (REB) at the hepatobiliary phase were measured. Cox proportional hazards regression models were used to evaluate prognostic factors. The capacity of the Q-LSC and REB to predict the 90-day outcome was evaluated via receiver operating characteristic (ROC) curve.

RESULTS

During the follow-up period, twenty-eight of 74 ACLF patients (38%) had a poor outcome. The Q-LSC and REB were significant predictive factors (hazard ratio [HR] = 0.03 [0.002-0.54], p < 0.05; HR = 0.07 [0.01-0.88], p < 0.05) for prognosis in patients with ACLF. Moreover, the areas under the ROC curves of Q-LSC and REB for predicting poor outcome in patients with ACLF were 0.81 and 0.80, respectively. The most appropriate cutoff values for the Q-LSC and REB were 1.09 and 0.57, respectively. The ACLF patients with the Q-LSC ≤ 1.09 or REB ≤ 0.57 had a low cumulative survival.

CONCLUSIONS

Gd-BOPTA-enhanced hepatobiliary phase MR imaging can predict poor outcome in patients with acute-on-chronic liver failure.

KEY POINTS

• The quantitative liver-spleen contrast ratio at the hepatobiliary phase was a significant predictive prognostic factor in patients with acute-on-chronic liver failure. • The relative enhancement ratio of the biliary system at the hepatobiliary phase was a significant prognostic factor in patients with acute-on-chronic liver failure. • Gadobenate dimeglumine contrast-enhanced MR imaging from the hepatobiliary phase can predict poor outcome in patients with acute-on-chronic liver failure.

Assessment of Liver Function With MRI: Where Do We Stand?

Liver disease and hepatocellular carcinoma (HCC) have become a global health burden. For this reason, the determination of liver function plays a central role in the monitoring of patients with chronic liver disease or HCC. Furthermore, assessment of liver function is important, e.g., before surgery to prevent liver failure after hepatectomy or to monitor the course of treatment. Liver function and disease severity are usually assessed clinically based on clinical symptoms, biopsy, and blood parameters. These are rather static tests that reflect the current state of the liver without considering changes in liver function. With the development of liver-specific contrast agents for MRI, noninvasive dynamic determination of liver function based on signal intensity or using T1 relaxometry has become possible. The advantage of this imaging modality is that it provides additional information about the vascular structure, anatomy, and heterogeneous distribution of liver function. In this review, we summarized and discussed the results published in recent years on this technique. Indeed, recent data show that the T1 reduction rate seems to be the most appropriate value for determining liver function by MRI. Furthermore, attention has been paid to the development of automated tools for image analysis in order to uncover the steps necessary to obtain a complete process flow from image segmentation to image registration to image analysis. In conclusion, the published data show that liver function values obtained from contrast-enhanced MRI images correlate significantly with the global liver function parameters, making it possible to obtain both functional and anatomic information with a single modality.

A functional liver imaging score for preoperative prediction of liver failure after hepatocellular carcinoma resection

OBJECTIVES

Posthepatectomy liver failure (PHLF) is a challenging complication after resection to treat hepatocellular carcinoma (HCC), and it is associated with high mortality. Preoperative prediction of PHLF may improve patient subsequent and reduce such mortality. This study examined whether a functional liver imaging score (FLIS) based on preoperative gadoxetic acid-enhanced magnetic resonance imaging (MRI) could predict PHLF.

MATERIALS AND METHODS

The study included 502 patients who underwent preoperative gadoxetic acid-enhanced MRI, followed by HCC resection. Significant preoperative predictors of PHLF were identified using logistic regression analysis. The ability of FLIS to predict PHLF was evaluated using receiver operating characteristic curves, and its predictive power was compared to that of the model for end-stage liver disease (MELD) score, albumin-bilirubin (ALBI) score, and indocyanine green 15-min retention rate (ICG-R15).

RESULTS

In multivariate analysis, PHLF was independently associated with FLIS (OR 0.452, 95% CI 0.361 to 0.568, p < 0.001) and major resection (OR 1.898, 95% CI 1.057 to 3.408, p = 0.032). FLIS was associated with a higher area under the receiver operating characteristic curve (0.752) than the MELD score (0.557), ALBI score (0.609), or ICG-R15 (0.605) (all p < 0.05). Patients with FLIS ≤ 4 who underwent major resection were at 9.4-fold higher risk of PHLF than patients with lower FLIS who underwent minor resection.

CONCLUSION

FLIS is an independent predictor of PHLF, and it may perform better than the MELD score, ALBI score, and ICG-R15 clearance. We propose treating elevated FLIS and major resection as risk factors for PHLF.

KEY POINTS

• A functional liver imaging score can independently predict posthepatectomy liver failure in patients with HCC. • The score may predict such failure better than MELD and ALBI scores and ICG-R15. • Patients with scores ≤ 4 who undergo major hepatic resection may be at nearly tenfold higher risk of posthepatectomy liver failure.

Manganese(II) EOB-Pyclen Diacetate for Liver-Specific MRI

MRI is increasingly utilized for the diagnosis of liver disease and focal liver lesions. Although liver-targeted gadolinium-based contrast agents (GBCAs) have high efficacy, there continue to be safety concerns regarding release of toxic Gd(III) ions. Herein, Mn(EOB-PC2A) is synthesized as a nongadolinium alternative for liver-specific MRI. Mn(EOB-PC2A) has an r₁ relaxivity of 2.8 mM^-1 s^-1 in Dulbecco's phosphate-buffered saline (DPBS) and 5.9 mM^-1 s^-1 in saline containing human serum albumin at 1.5 T. It has a strong uptake in hepatocytes with minimal toxicity and demonstrated robust liver-specific enhancement at a dose of 60 μmol/kg. Mn(EOB-PC2A) is a promising liver-specific contrast agent for liver MRI.

Total Bilirubin Level as a Predictor of Suboptimal Image Quality of the Hepatobiliary Phase of Gadoxetic Acid-Enhanced MRI in Patients with Extrahepatic Bile Duct Cancer

Objective

This study aimed to determine a factor for predicting suboptimal image quality of the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI in patients with extrahepatic bile duct (EHD) cancer before MRI examination.

Materials and Methods

We retrospectively evaluated 259 patients (mean age ± standard deviation: 68.0 ± 8.3 years; 162 male and 97 female) with EHD cancer who underwent gadoxetic acid-enhanced MRI between 2011 and 2017. Patients were divided into a primary analysis set (n = 184) and a validation set (n = 75) based on the diagnosis date of January 2014. Two reviewers assigned the functional liver imaging score (FLIS) to reflect the HBP image quality. The FLIS consists of the sum of three HBP features, each scored on a 0–2 scale: liver parenchymal enhancement, biliary excretion, and signal intensity of the portal vein. Patients were classified into low-FLIS (0–3) or high-FLIS (4–6) groups. Multivariable analysis was performed to determine a predictor of low FLIS using serum biochemical and imaging parameters of cholestasis severity. The optimal cutoff value for predicting low FLIS was obtained using receiver operating characteristic analysis, and validation was performed.

Results

Of the 259 patients, 140 (54.0%) and 119 (46.0%) were classified into the low-FLIS and high-FLIS groups, respectively. In the primary analysis set, total bilirubin was an independent factor associated with low FLIS (adjusted odds ratio per 1-mg/dL increase, 1.62; 95% confidence interval [CI], 1.32–1.98). The optimal cutoff value of total bilirubin for predicting low FLIS was 2.1 mg/dL with a sensitivity of 95.1% (95% CI: 88.9–98.4) and a specificity of 89.0% (95% CI: 80.2–94.9). In the validation set, the total bilirubin cutoff showed a sensitivity of 92.1% (95% CI: 78.6–98.3) and a specificity of 83.8% (95% CI: 68.0–93.8).

Conclusion

Serum total bilirubin before acquisition of gadoxetic acid-enhanced MRI may help predict suboptimal HBP image quality in patients with EHD cancer.

Distinct prognostic value of different portal hypertension-associated features in patients with primary biliary cholangitis

BACKGROUND

Primary biliary cholangitis (PBC) may progress to cirrhosis and clinically significant portal hypertension (CSPH). This study assesses different features of CSPH and their distinct prognostic impact regarding decompensation and survival in patients with PBC.

METHODS

Patients with PBC were identified during a database query of our digital patient reporting system.

RESULTS

A total of 333 PBC patients (mean age 54.3 years, 86.8% females, median follow-up 5.8 years) were retrospectively assessed and 127 (38.1%) showed features of CSPH: 63 (18.9%) developed varices, 98 (29.4%) splenomegaly, 62 (18.6%) ascites and 20 (15.7%) experienced acute variceal bleeding. Splenomegaly, portosystemic collaterals and esophageal varices were associated with an increased 5-year (5Y) risk of decompensation (15.0%, 17.8% and 20.9%, respectively). Patients without advanced chronic liver disease (ACLD) had a similar 5Y-transplant free survival (TFS) (96.6%) compared to patients with compensated ACLD (cACLD) but without CSPH (96.9%). On the contrary, PBC patients with cACLD and CSPH (57.4%) or decompensated ACLD (dACLD) (36.4%) had significantly decreased 5Y survival rates. The combination of LSM < 15 kPa and platelets ≥ 150G/L indicated a negligible risk for decompensation (5Y 0.0%) and for mortality (5Y 0.0%). Overall, 44 (13.2%) patients died, with 18 (40.9%) deaths attributed to CSPH-related complications.

CONCLUSION

In PBC, features of CSPH may occur early and indicate an increased risk for subsequent decompensation and mortality. Hence, regular screening and on-time treatment for CSPH is crucial. Combining LSM and platelets serves as a valuable preliminary assessment, as LSM < 15 kPa and platelets ≥ 150G/L indicate an excellent long-term outcome.

Advances in liver US, CT, and MRI: moving toward the future

Over the past two decades, the epidemiology of chronic liver disease has changed with an increase in the prevalence of nonalcoholic fatty liver disease in parallel to the advent of curative treatments for hepatitis C. Recent developments provided new tools for diagnosis and monitoring of liver diseases based on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), as applied for assessing steatosis, fibrosis, and focal lesions. This narrative review aims to discuss the emerging approaches for qualitative and quantitative liver imaging, focusing on those expected to become adopted in clinical practice in the next 5 to 10 years. While radiomics is an emerging tool for many of these applications, dedicated techniques have been investigated for US (controlled attenuation parameter, backscatter coefficient, elastography methods such as point shear wave elastography [pSWE] and transient elastography [TE], novel Doppler techniques, and three-dimensional contrast-enhanced ultrasound [3D-CEUS]), CT (dual-energy, spectral photon counting, extracellular volume fraction, perfusion, and surface nodularity), and MRI (proton density fat fraction [PDFF], elastography [MRE], contrast enhancement index, relative enhancement, T1 mapping on the hepatobiliary phase, perfusion). Concurrently, the advent of abbreviated MRI protocols will help fulfill an increasing number of examination requests in an era of healthcare resource constraints.

Concentrations and pharmacokinetic parameters of MRI and SPECT hepatobiliary agents in rat liver compartments

Background

In hepatobiliary imaging, systems detect the total amount of agents originating from extracellular space, bile canaliculi, and hepatocytes. They add in situ concentration of each compartment corrected by its respective volume ratio to provide liver concentrations. In vivo contribution of each compartment to liver concentration is inaccessible. Our aim was to quantify the compartmental distribution of two hepatobiliary agents in an ex vivo model and determine how their liver extraction ratios and cholestasis (livers lacking canalicular transporters) might modify it.

Methods

We perfused labelled gadobenate dimeglumine (Bopta, 200 μM, 7% liver extraction ratio) and mebrofenin (Meb, 64 μM, 94% liver extraction ratio) in normal (n = 18) and cholestatic (n = 6) rat livers. We quantified liver concentrations with a gamma counter placed over livers. Concentrations in hepatocytes and bile canaliculi were calculated. Mann-Whitney and Kruskal-Wallis tests were used.

Results

Hepatocyte concentrations were 2,043 ± 333 μM (Meb) versus 360 ± 69 μM (Bopta, p < 0.001). Meb extracellular concentrations did not contribute to liver concentrations (1.3 ± 0.3%). The contribution of Bopta extracellular concentration was 12.4 ± 1.9% (p < 0.001 versus Meb). Contribution of canaliculi was similar for both agents (16%). Cholestatic livers had no Bopta in canaliculi but their hepatocyte concentrations increased in comparison to normal livers.

Conclusion

Hepatocyte concentrations are correlated to liver extraction ratios of hepatobiliary agents. When Bopta is not present in canaliculi of cholestatic livers, hepatocyte concentrations increase in comparison to normal livers. This new understanding extends the interpretation of clinical liver images.

Modern imaging of cholangitis

Cholangitis refers to inflammation of the bile ducts with or without accompanying infection. When intermittent or persistent inflammation lasts 6 months or more, the condition is classified as chronic cholangitis. Otherwise, it is considered an acute cholangitis. Cholangitis can also be classified according to the inciting agent, e.g. complete mechanical obstruction, which is the leading cause of acute cholangitis, longstanding partial mechanical blockage, or immune-mediated bile duct damage that results in chronic cholangitis.The work-up for cholangitis is based upon medical history, clinical presentation, and initial laboratory tests. Whereas ultrasound is the first-line imaging modality used to identify bile duct dilatation in patients with colicky abdominal pain, cross-sectional imaging is preferable when symptoms cannot be primarily localised to the hepatobiliary system. CT is very useful in oncologic, trauma, or postoperative patients. Otherwise, magnetic resonance cholangiopancreatography is the method of choice to diagnose acute and chronic biliary disorders, providing an excellent anatomic overview and, if gadoxetic acid is injected, simultaneously delivering morphological and functional information about the hepatobiliary system. If brush cytology, biopsy, assessment of the prepapillary common bile duct, stricture dilatation, or stenting is necessary, then endoscopic ultrasound and/or retrograde cholangiography are performed. Finally, when the pathologic duct is inaccessible from the duodenum or stomach, percutaneous transhepatic cholangiography is an option. The pace of the work-up depends upon the severity of cholestasis on presentation. Whereas sepsis, hypotension, and/or Charcot's triad warrant immediate investigation and management, chronic cholestasis can be electively evaluated.This overview article will cover the common cholangitides, emphasising our clinical experience with the chronic cholestatic liver diseases.

Validation of functional liver imaging scores (FLIS) derived from gadoxetic acid-enhanced MRI in patients with chronic liver disease and liver cirrhosis: the relationship between Child-Pugh score and FLIS

OBJECTIVES

To validate the functional liver imaging score (FLIS) for prediction of hepatic function in gadoxetic acid-enhanced MRI.

METHODS

We retrospectively identified 134 patients (88 men, 46 women; mean age, 58.8 years) between January 2015 and December 2018 with the following inclusion criteria: patients diagnosed with liver cirrhosis or chronic liver disease (CLD) who underwent gadoxetic acid-enhanced MRI. Three parameters on hepatobiliary phase images were evaluated for FLIS: liver parenchymal enhancement, biliary excretion, and signal intensity of the portal vein. Patients were classified as CLD (n = 11), Child-Pugh (CP) class A (n = 87), CP B (n = 22), or CP C (n = 14). We assessed the correlation between CP score and both FLIS and its components using Spearman rank correlation. Receiver operating characteristic (ROC) curve analysis was performed to demonstrate the cutoff value of FLIS for differentiating between CP classes. The associations between patient characteristics, serum markers, FLIS, and hepatic decompensation were evaluated with Cox proportional hazard models.

RESULTS

FLIS and three FLIS parameters showed strong to very strong correlation with CP score (r = -0.60 to 0.82). ROC curve analysis showed that FLIS ≥ 5 was the optimal cutoff for prediction of CP class A or CLD (sensitivity, 83.7%; specificity, 94.4%; area under the curve [AUC], 0.93). FLIS < 5 was independently associated with the development of first hepatic decompensation in patients with CP A (HR, 50.0; 95% confidence interval, 6.2, 400.4).

CONCLUSION

FLIS showed a strong correlation with hepatic function and can stratify the CP class. In addition, FLIS can help prediction for the development of first decompensation.

KEY POINTS

• Functional liver imaging scores (FLIS) and its three parameters, derived from hepatobiliary phase image, have strong to very strong correlations with Child-Pugh (CP) scores. • FLIS can stratify patients with chronic liver disease or liver cirrhosis according to CP classification. • Low FLIS is an independent predictor for first hepatic decompensation in patients with CP class A.

Gadoxetic acid-enhanced MRI in primary sclerosing cholangitis: added value in assessing liver function and monitoring disease progression

PURPOSE

To investigate the added value of gadoxetic acid-enhanced MRI in monitoring liver function and disease progression in patients with primary sclerosing cholangitis (PSC).

METHODS

We retrospectively identified 104 consecutive patients (75 males; mean age 41.98 ± 12.5 years) with confirmed diagnosis of PSC who underwent 227 gadoxetic acid-enhanced MRI examinations between January 2008 and May 2019. Relative enhancement (RE) of the liver was correlated with the results of liver function tests (LFTs), scoring models (Model for End-Stage Liver Disease (MELD) score, Mayo Risk Score (MRS), Amsterdam-Oxford model (AOM)), and qualitative MRI findings. In addition, results were analyzed separately for excretory MRI examinations (n = 164) and nonexcretory examinations (n = 63) depending on excretion of gadoxetic acid into the common bile duct in the hepatobiliary phase (HBP).

RESULTS

There was a significant correlation of RE with MRS (r = - 0.652), MELD score (r = - 0.474), AOM (r = - 0.468), and LFTs (P < 0.001). RE and albumin were significantly higher in the excretory group whereas scoring models, bilirubin, aspartate aminotransferase, alkaline phosphatase, and international normalized ratio were lower (P < 0.001). RE was lower in segments with absent HBP gadoxetic acid excretion into dilated bile ducts, reduced HBP parenchymal enhancement, atrophy, T2 hyperintensity, and bile duct abnormalities (P < 0.001).

CONCLUSION

Relative enhancement of the liver in gadoxetic acid-enhanced MRI can be used to evaluate global and regional liver function and monitor disease progression in patients with PSC. Hepatobiliary phase gadoxetic acid biliary excretion appears to be a reproducible qualitative parameter for evaluating disease severity that can be easily integrated into routine clinical practice.

Consensus report from the 9th International Forum for Liver Magnetic Resonance Imaging: applications of gadoxetic acid-enhanced imaging

Objectives

The 9th International Forum for Liver Magnetic Resonance Imaging (MRI) was held in Singapore in September 2019, bringing together radiologists and allied specialists to discuss the latest developments in and formulate consensus statements for liver MRI, including the applications of gadoxetic acid–enhanced imaging.

Methods

As at previous Liver Forums, the meeting was held over 2 days. Presentations by the faculty on days 1 and 2 and breakout group discussions on day 1 were followed by delegate voting on consensus statements presented on day 2. Presentations and discussions centered on two main meeting themes relating to the use of gadoxetic acid–enhanced MRI in primary liver cancer and metastatic liver disease.

Results and conclusions

Gadoxetic acid–enhanced MRI offers the ability to monitor response to systemic therapy and to assist in pre-surgical/pre-interventional planning in liver metastases. In hepatocellular carcinoma, gadoxetic acid–enhanced MRI provides precise staging information for accurate treatment decision-making and follow-up post therapy. Gadoxetic acid–enhanced MRI also has potential, currently investigational, indications for the functional assessment of the liver and the biliary system. Additional voting sessions at the Liver Forum debated the role of multidisciplinary care in the management of patients with liver disease, evidence to support the use of abbreviated imaging protocols, and the importance of standardizing nomenclature in international guidelines in order to increase the sharing of scientific data and improve the communication between centers.

Key Points

• Gadoxetic acid–enhanced MRI is the preferred imaging method for pre-surgical or pre-interventional planning for liver metastases after systemic therapy.

• Gadoxetic acid–enhanced MRI provides accurate staging of HCC before and after treatment with locoregional/biologic therapies.

• Abbreviated protocols for gadoxetic acid–enhanced MRI offer potential time and cost savings, but more evidence is necessary. The use of gadoxetic acid–enhanced MRI for the assessment of liver and biliary function is under active investigation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-020-07637-4.

Imaging biomarkers of diffuse liver disease: current status

We are happy to introduce this special issue of Abdominal Radiology on "diffuse liver disease". We have invited imaging experts to discuss various topics pertaining to diffuse liver disease, covering a vast array of imaging techniques including ultrasound (US), CT, MRI and new molecular imaging agents. Below, we briefly discussed the current status, limitations, and future directions of imaging biomarkers of diffuse liver disease.

Quantification of liver function using gadoxetic acid-enhanced MRI

The introduction of hepatobiliary contrast agents, most notably gadoxetic acid (GA), has expanded the role of MRI, allowing not only a morphologic but also a functional evaluation of the hepatobiliary system. The mechanism of uptake and excretion of gadoxetic acid via transporters, such as organic anion transporting polypeptides (OATP1,3), multidrug resistance-associated protein 2 (MRP2) and MRP3, has been elucidated in the literature. Furthermore, GA uptake can be estimated on either static images or on dynamic imaging, for example, the hepatic extraction fraction (HEF) and liver perfusion. GA-enhanced MRI has achieved an important role in evaluating morphology and function in chronic liver diseases (CLD), allowing to distinguish between the two subgroups of nonalcoholic fatty liver diseases (NAFLD), simple steatosis and nonalcoholic steatohepatitis (NASH), and help to stage fibrosis and cirrhosis, predict liver transplant graft survival, and preoperatively evaluate the risk of liver failure if major resection is planned. Finally, because of its noninvasive nature, GA-enhanced MRI can be used for long-term follow-up and post-treatment monitoring. This review article aims to describe the current role of GA-enhanced MRI in quantifying liver function in a variety of hepatobiliary disorders.

MRI-defined sarcopenia predicts mortality in patients with chronic liver disease

BACKGROUND & AIMS

To explore whether sarcopenia, diagnosed by an abbreviated magnetic resonance imaging (MRI) protocol is a risk factor for hepatic decompensation and mortality in patients with chronic liver disease (CLD).

METHODS

In this retrospective single-centre study we included 265 patients (164 men, mean age 54 ± 16 years) with CLD who had undergone MRI of the liver between 2010 and 2015. Transverse psoas muscle thickness (TPMT) was measured on unenhanced and contrast-enhanced T1-weighted and T2-weighted axial images. Sarcopenia was defined by height-adjusted and gender-specific cut-offs in women as TPMT < 8 mm/m and in men as TPMT < 12 mm/m respectively. Patients were further stratified into three prognostic stages according to the absence of advanced fibrosis (FIB-4 < 1.45, non-advanced CLD), compensated-advanced CLD (cACLD) and decompensated-advanced CLD (dACLD).

RESULTS

The inter-observer agreement for the TPMT measurements (κ = 0.98; 95% confidence interval [95% CI]:0.96-0.98), as well as the intra-observer agreement between the three image sequences (κ = 0.99; 95% CI: 0.99-1.00) were excellent. Sarcopenia was not predictive of first or further hepatic decompensation. In patients with cACLD and dACLD, sarcopenia was a risk factor for mortality (cACLD: hazard ratio (HR):3.13, 95% CI: 1.33-7.41, P = .009; dACLD:HR:2.45, 95% CI: 1.32-4.57, P = .005) on univariate analysis. After adjusting for the model of end-stage liver disease (MELD) score, albumin and evidence of clinical significant portal hypertension, sarcopenia (adjusted HR: 2.76, 95% CI: 1.02-7.42, P = .045) remained an independent risk factor for mortality in patients with cACLD.

CONCLUSION

Sarcopenia can be easily evaluated by a short MRI exam without the need for contrast injection. Sarcopenia is a risk factor for mortality, especially in patients with cACLD.

Other types of diffuse liver disease: is there a way to do it?

There are a variety of less common diffuse liver diseases that can be asymptomatic or cause severe liver dysfunction. For the majority of them, the association of clinical, laboratory, and imaging findings are needed to narrow the differential diagnosis. In this article, we will review and describe the rarer diffuse liver diseases including drug-related liver disease, inflammatory and infectious diseases, and deposition disorders such as amyloidosis, glycogen storage disease, Wilson's disease, and alpha-1 antitrypsin deficiency. Abdominal radiologists should be familiar with the imaging features of different types of diffuse liver diseases to help the multidisciplinary team involved in the treatment of these patients. The data related to some of these conditions are scarce and sometimes experimental, but we want to demonstrate to the reader the value of imaging techniques in their analysis and introduce the potential of new imaging methods.

Advances in functional and molecular MRI technologies in chronic liver diseases

MRI has emerged as the most comprehensive non-invasive diagnostic tool for liver diseases. In recent years, the value of MRI in hepatology has been significantly enhanced by a wide range of contrast agents, both clinically available and under development, that add functional information to anatomically detailed morphological images, or increase the distinction between normal and pathological tissues by targeting molecular and cellular events. Several classes of contrast agents are available for contrast-enhanced hepatic MRI, including i) conventional non-specific extracellular fluid contrast agents for assessing tissue perfusion; ii) hepatobiliary-specific contrast agents that are taken up by functioning hepatocytes and excreted through the biliary system for evaluating hepatobiliary function; iii) superparamagnetic iron oxide particles that accumulate in Kupffer cells; and iv) novel molecular contrast agents that are biochemically targeted to specific molecular/cellular processes for staging liver diseases or detecting treatment responses. The use of different functional and molecular MRI methods enables the non-invasive assessment of disease burden, progression, and treatment response in a variety of liver diseases. A high diagnostic performance can be achieved with MRI by combining imaging biomarkers.

Intracellular accumulation capacity of gadoxetate: initial results for a novel biomarker of liver function

Previous studies have shown gadoxetate disodium’s potential to represent liver function by its retention in the hepatobiliary phase. Additionally, in cardiac imaging, quantitative characterization of altered parenchyma is established by extracellular volume (ECV) calculation with extracellular contrast agents. Therefore, the purpose of our study was to evaluate whether intracellular accumulation capacity (IAC) of gadoxetate disodium derived from ECV calculation provides added scientific value in terms of liver function compared to the established parameter reduction rate (RR). After local review board approval, 105 patients undergoing standard MR examination with gadoxetate disodium were included. Modified Look-Locker sequences were obtained before and 20 min after contrast agent administration. RR and IAC were calculated and correlated with serum albumin, as a marker of synthetic liver function. Correlation was higher between IAC and albumin, than between RR and albumin. Additionally, capacity of both RR and IAC to distinguish between patients with or without liver cirrhosis was investigated, and differed significantly in their respective means between patients with cirrhosis and those without. We concluded, that the formula to calculate ECV can be transferred to calculate IAC of gadoxetate disodium in hepatocytes, and, thereby, IAC may possibly qualify as an imaging-based parameter to estimate synthetic liver function.

Gadoxetate disodium-enhanced MRI: Assessment of arterial phase artifacts and hepatobiliary uptake in a large series

PURPOSE

To report the quality of gadoxetate disodium MRI in a large series by assessing the prevalence of: 1) arterial phase (AP) artifacts and its predictive factors, 2) decreased hepatic contrast uptake during the hepatobiliary phase (HBP).

METHODS

This retrospective single center study included 851 patients (M/F:537/314, mean age: 63y) with gadoxetate disodium MRI. The MRI protocol included unenhanced, dual arterial [early and late arterial phases (AP)], portal venous, transitional and hepatobiliary phases. Three radiologists graded dynamic images using a 5-scale score (1: no motion, 5: severe, nondiagnostic) for assessment of transient severe motion (TSM, defined as a score ≥4 during at least one AP with a score ≤3 during other phases). HBP uptake was assessed using a 3-scale score (based on portal vein/hepatic signal). The association between demographic, clinical and acquisition parameters with TSM was tested in uni- and multivariate logistic regression.

RESULTS

TSM was observed in 103/851 patients (12.1 %): 83 (9.8 %) in one AP and 20 (2.3 %) in both APs. A score of 5 (nondiagnostic) was assigned in 7 patients in one AP (0.8 %) and none in both. Presence of TSM was significantly associated with age (p = 0.002) and liver disease (p = 0.033) in univariate but not in multivariate analysis (p > 0.05). No association was found between acquisition parameters and TSM occurrence. Limited or severely limited HBP contrast uptake was observed in 87 patients (10.2 %), and TSM was never associated with severely limited HBP contrast uptake.

CONCLUSION

TSM was present in approximately 12 % of gadoxetate disodium MRIs, rarely on both APs (2.3 %), and was poorly predicted. TSM was never associated with severely limited HBP contrast uptake.

Magnetic resonance-based biomarkers in nonalcoholic fatty liver disease and nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease is a growing epidemic affecting 30% of the adult population in the Western world. Its progressive form, nonalcoholic steatohepatitis (NASH), is associated with an increased risk of advanced fibrosis, cirrhosis and liver-related mortality. Therefore, the detection of NAFLD and risk stratification according to the severity of the disease is crucial for the management of patients with NAFLD. Liver biopsy for such risk stratification strategies is limited by its cost and risks; therefore, noninvasive alternatives have been developed. Among noninvasive biomarkers developed in NAFLD, magnetic resonance (MR)-based biomarkers have emerged as key noninvasive biomarkers in NAFLD with the ability to accurately detect hepatic steatosis and liver fibrosis. The potential utility of MRI for the detection of NASH and functional liver assessment has also recently emerged. In the current review, we will discuss the data supporting the utility of MR-based biomarker for the detection of features of NAFLD and its potential use in clinical practice and clinical research in NAFLD.

Noninvasive Diagnostics for Portal Hypertension: A Comprehensive Review

Noninvasive diagnostics for portal hypertension include imaging and functional tests, as well as blood-based biomarkers, and capture different features of the portal hypertensive syndrome. Definitive conclusions regarding their clinical utility require assessment of their diagnostic value in specific clinical settings (i.e., diagnosing a particular hemodynamic condition within a well-defined target population). Several noninvasive methods are predictive of clinically significant portal hypertension (CSPH; hepatic venous pressure gradient [HVPG] ≥ 10 mm Hg; the threshold for complications of portal hypertension); however, only a minority of them have been evaluated in compensated advanced chronic liver disease (i.e., the target population). Importantly, most methods correlate only weakly with HVPG at high values (i.e., in patients with CSPH). Nevertheless, selected methods show promise for diagnosing HVPG ≥ 16 mm Hg (the cut-off for increased risks of hepatic decompensation and mortality) and monitoring HVPG changes in response to nonselective beta-blockers or etiological treatments. Finally, we review established and potential future clinical applications of noninvasive methods.

Diffusion tensor imaging quantifying the severity of chronic hepatitis in rats

BACKGROUND

Diffusion tensor imaging (DTI) is mainly used for detecting white matter fiber in the brain. DTI was applied to assess fiber in liver disorders in previous studies. However, the data obtained have been insufficient in determining if DTI can be used to exactly stage chronic hepatitis. This study assessed the value of DTI for staging of liver fibrosis (F), necroinflammatory activity (A) and steatosis (S) with chronic hepatitis in rats.

METHODS

Seventy male Sprague-Dawley rats were divided into a control group(n = 10) and an experimental group(n = 60). The rat models of chronic hepatitis were established by abdominal subcutaneous injections of 40% CCl₄. All of the rats underwent 3.0 T MRI. Regions of interest (ROIs) were subjected to DTI to estimate the MR parameters (rADC value and FA value). Histopathology was used as the reference standard. Multiple linear regression was used to analyze the associations between the MR parameters and pathology. The differences in the MR parameters among the pathological stages were evaluated by MANOVA or ANOVA. The LSD test was used to test for differences between each pair of groups. ROC analysis was also performed.

RESULTS

The count of each pathology was as follows: F0(n = 15), F1(n = 11), F2(n = 6), F3(n = 9), F4(n = 6); A0(n = 8), A1(n = 16), A2(n = 16), A3(n = 7); S0(n = 10), S1(n = 7), S2(n = 3), S3(n = 11), S4(n = 16). The rADC value had a negative correlation with liver fibrosis (r = - 0.392, P = 0.008) and inflammation (r = - 0.359, P = 0.015). The FA value had a positive correlation with fibrosis (r = 0.409, P = 0.005). Significant differences were found in the FA values between F4 and F0 ~ F3 (P = 0.03), while no significant differences among F0 ~ F3 were found (P > 0.05). The AUC of the FA value differentiating F4 from F0 ~ F3 was 0.909 (p < 0.001) with an 83.3% sensitivity and an 85.4% specificity when the FA value was at the cut-off of 588.089 (× 10^- 6 mm²/s).

CONCLUSION

The FA value for DTI can distinguish early cirrhosis from normal, mild and moderate liver fibrosis, but the rADC value lacked the ability to differentiate among the fibrotic grades. Both the FA and rADC values were unable to discriminate the stages of necroinflammatory activity and steatosis.