Usefulness of MR elastography for predicting esophageal varices in cirrhotic patients

Porto-mesenteric four-dimensional flow MRI: a novel non-invasive technique for assessment of gastro-oesophageal varices

OBJECTIVES

To assess the role of 4D flow MRI in the assessment of gastro-oesophageal varices and in the prediction of high-risk varices in patients with chronic liver disease.

METHODS

Thirty-eight patients diagnosed with either oesophageal or gastric varices were included in this single-centre prospective study. 4D flow MRI was used to calculate peak flow, average flow and peak velocity at the portal vein confluence (PV1) and hilum (PV2), splenic vein hilum (SV1) and confluence (SV2), and superior mesenteric vein (SMV). PV and SV fractional flow changes were also measured.

RESULTS

ROC analysis revealed that both PV2 average flow and PV fractional average flow change had 100% sensitivity to predict high-risk patients with the PV fractional peak flow change having the widest area under the curve (AUC) and the highest specificity (92.3%). SV1 average flow, SV2 average flow, SV2 peak flow, and SV2 peak velocity increased significantly in patients with oesophageal compared to gastric varices included (p = 0.022, < 0.001, < 0.001 and 0.001, respectively).

CONCLUSION

Based on certain porto-mesenteric blood flow, velocity, and fractional flow change parameters, 4D flow MRI showed excellent performance in identifying high-risk patients and giving an idea about the grade and location of varices.

CRITICAL RELEVANCE STATEMENT

Variceal bleeding is a major consequence of unidentified risky upper GI varices. Thus, by identifying and locating high-risk varices early, either oesophageal or gastric, using a non-invasive method like MRI, adverse events might be avoided.

KEY POINTS

4D flow MRI can be used as a potential alternative for endoscopy to predict patients with high-risk varices. Based on portal vein fractional flow change, splenic flow and velocity, 4D MRI can predict and locate high-risk varices. Earlier identification of high-risk varices can allow for interventions to prevent adverse events.

Magnetic resonance elastography (MRE) outperforms acoustic force radiation impulse (ARFI) in predicting oesophageal varices in obese NAFLD cirrhosis

PURPOSE

Liver stiffness measurement (LSM) by transient elastography has been shown to underperform in high-risk varices (HRVs) prediction in obese non-alcoholic fatty liver disease (NAFLD) compensated cirrhosis (CC). LSM by magnetic resonance elastography (MRE) and acoustic force radiation impulse (ARFI) has been shown to be useful in prediction of oesophageal varices (EVs), but has limited evidence in obese NAFLD-CC.

METHODS

Obese patients with NAFLD-CC who underwent MRE and ARFI for LSM and endoscopy for screening of varices were enrolled. Performance of MRE and ARFI for predicting EVs or HRVs was evaluated using area under receiver operating characteristics (AUROC) curves and regression analyses were performed for predictor variables.

RESULTS

One hundred eight patients [mean age 54.7 ± 9.6 years, median BMI, 28.5 (26.4-30.0) kg/m2. 72.2% diabetics, 45.4% hypertensive] were enrolled. Fifty-two (48.1%) had no varices, while 29 (26.8%) and 27 (25%) had low-risk varices (LRVs) and HRVs, respectively. MRE-LSM was higher in patients with LRVs (p = 0.01) or HRVs (p = 0.001) against those without varices. ARFI-LSM did not differ significantly between those without and with LRVs or HRVs (p > 0.05 for all). There was a low correlation between ARFI-LSM and MRE-LSM in the overall cohort (r = 0.19). Only platelet count (PC) [0.98 (0.97-0.99)] and MRE-LSM [1.8 (1.26-2.79)] were predictors of HRVs. At a cut-off of 4.75, MRE showed a sensitivity of 96.3%. Model combining MRE-LSM with PC had a diagnostic AUROC of 0.77 and 0.76 for EVs and HRVs.

CONCLUSION

In obese NAFLD-CC, MRE-LSM is significantly higher in patients with varices. MRE combined with PC predicts EVs and HRVs with better accuracy than ARFI.

The Prediction and Treatment of Bleeding Esophageal Varices in the Artificial Intelligence Era: A Review

Esophageal varices (EVs), a significant complication of cirrhosis, present a considerable challenge in clinical practice due to their high risk of bleeding and associated morbidity and mortality. This manuscript explores the transformative role of artificial intelligence (AI) in the management of EV, particularly in enhancing diagnostic accuracy and predicting bleeding risks. It underscores the potential of AI in offering noninvasive, efficient alternatives to traditional diagnostic methods such as esophagogastroduodenoscopy (EGD). The complexity of EV management is highlighted, necessitating a multidisciplinary approach that includes pharmacological therapy, endoscopic interventions, and, in some cases, surgical options tailored to individual patient profiles. Additionally, the paper emphasizes the importance of integrating AI into medical education and practice, preparing healthcare professionals for the evolving landscape of medical technology. It projects a future where AI significantly influences the management of gastrointestinal bleeding, improving clinical decision-making, patient outcomes, and overall healthcare efficiency. The study advocates for a patient-centered approach in healthcare, balancing the incorporation of innovative technologies with ethical principles and the diverse needs of patients to optimize treatment efficacy and enhance healthcare accessibility.

Liver and spleen stiffness for the diagnosis of oesophageal varices in adults with chronic liver disease

This is a protocol for a Cochrane Review (diagnostic). The objectives are as follows:

To assess the diagnostic accuracy of liver stiffness and spleen stiffness, separately or in combination, as measured by vibration‐controlled transient elastography (VCTE) in detection of any oesophageal varices in adults with chronic liver disease. We will regard a combination of tests as positive when at least one is positive.

To compare the diagnostic accuracy of individual tests (liver stiffness and spleen stiffness measured by VCTE) directly and versus the combination of both tests (considering positive when at least one is positive) in detecting any oesophageal varices.

To assess the diagnostic accuracy of liver stiffness and spleen stiffness, separately or in combination, as measured by other elastography techniques (2D‐shear wave elastography (2D‐SWE), point shear wave elastography (pSWE), magnetic resonance elastography (MRE)) in detection of any oesophageal varices in adults with chronic liver disease. We will regard a combination of tests as positive when at least one is positive.

To compare the diagnostic accuracy of liver stiffness and spleen stiffness measured by VCTE with other techniques (pSWE, 2D‐SWE, MRE) in detection of any oesophageal varices in adults with chronic liver disease.

Liver fibrosis assessment: MR and US elastography

Elastography has emerged as a preferred non-invasive imaging technique for the clinical assessment of liver fibrosis. Elastography methods provide liver stiffness measurement (LSM) as a surrogate quantitative biomarker for fibrosis burden in chronic liver disease (CLD). Elastography can be performed either with ultrasound or MRI. Currently available ultrasound-based methods include strain elastography, two-dimensional shear wave elastography (2D-SWE), point shear wave elastography (pSWE), and vibration-controlled transient elastography (VCTE). MR Elastography (MRE) is widely available as two-dimensional gradient echo MRE (2D-GRE-MRE) technique. US-based methods provide estimated Young's modulus (eYM) and MRE provides magnitude of the complex shear modulus. MRE and ultrasound methods have proven to be accurate methods for detection of advanced liver fibrosis and cirrhosis. Other clinical applications of elastography include liver decompensation prediction, and differentiation of non-alcoholic steatohepatitis (NASH) from simple steatosis (SS). In this review, we briefly describe the different elastography methods, discuss current clinical applications, and provide an overview of advances in the field of liver elastography.

Tomoelastography based on multifrequency MR elastography predicts liver function reserve in patients with hepatocellular carcinoma: a prospective study

BACKGROUND

Estimating liver function reserve is essential for preoperative surgical planning and predicting post-hepatectomy complications in patients with hepatocellular carcinoma (HCC). We investigated hepatic viscoelasticity quantified by tomoelastography, a multifrequency magnetic resonance elastography technique, to predict liver function reserve.

METHODS

One hundred fifty-six patients with suspected HCC (mean age, 60 ± 1 years; 131 men) underwent preoperative tomoelastography examination between July 2020 and August 2021. Sixty-nine were included in the final analysis, and their 15-min indocyanine green retention rates (ICG-R15s) were obtained to determine liver function reserve. Tomoelastography quantified the shear wave speed (c, m/s), which represents stiffness, and loss angle (φ, rad), which represents fluidity. Both were correlated with the ICG-R15. A prediction model based on logistic regression for major hepatectomy tolerance (ICG-R15 ≥ 14%) was established.

RESULTS

Patients were assigned to either the ICG-R15 < 14% (n = 50) or ICG-R15 ≥ 14% (n = 19) group. Liver c (r = 0.617) and φ (r = 0.517) were positively correlated with the ICG-R15 (both p < 0.001). At fibrosis stages F1-2, φ was positively correlated with the ICG-R15 (r = 0.528; p = 0.017), but c was not (p = 0.104). At stages F3-4, c (r = 0.642; p < 0.001) and φ (r = 0.377; p = 0.008) were both positively correlated with the ICG-R15. The optimal cutoffs of c and φ for predicting ICG-R15 ≥ 14% were 2.04 m/s and 0.79 rad, respectively. The area under the receiver operating characteristic curve was higher for c (0.892) than for φ (0.779; p = 0.045).

CONCLUSIONS

Liver stiffness and fluidity, quantified by tomoelastography, were correlated with liver function and may be used clinically to noninvasively assess liver function reserve and stratify treatments.

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.

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

INTRODUCTION

The purpose of this systematic review and meta-analysis was to evaluate the diagnostic accuracy of liver and spleen stiffness on magnetic resonance elastography (MRE) for detecting clinically significant portal hypertension.

METHODS

A systematic review of MEDLINE, EMBASE, Scopus, the Cochrane Library, and the Grey Literature through to 15 August 2019 was performed. Original articles with >10 patients evaluating liver and/or spleen stiffness on MRE using a reference standard of portal hypertension defined as intractable ascites, esophageal varices, encephalopathy and/or death were included in analysis. Patient, clinical, MRI, and diagnostic performance was independently acquired by two reviewers. Meta-analysis was performed using a bivariate mixed-effects regression model.

RESULTS

Fourteen studies were included with 12 studies evaluating liver stiffness and eight studies evaluating spleen stiffness. The pooled and weighted sensitivity, specificity, and area under the curve (AUC) values for liver stiffness on MRE were 83% [95% confidence interval (CI) 72-90%], 80% (95% CI 70-88%), and 88% (95% CI 85-91%), respectively. The pooled and weighted sensitivity, specificity, and AUC values for spleen stiffness on MRE were 79% (95% CI 61-90%), 90% (95% CI 80-95%), and 92% (95% CI 89-94%), respectively. The liver and spleen stiffness sensitivity and specificity values were comparable when evaluating for esophageal varices only at of 80% (95% CI 66-89%) and 76% (95% CI 62-86%) for liver stiffness, and 75% (95% CI 52-90%) and 89% (95% CI 70-96%) for spleen stiffness.

DISCUSSION

Liver and spleen stiffness on MRE can serve as a supplemental noninvasive assessment tools for detecting clinically significant portal hypertension. Spleen stiffness may be more specific and accurate than liver stiffness for detecting portal hypertension.

Liver and spleen elastography as predictor of portal hypertension and esophageal varices

Liver stiffness is related to the degree of hepatic fibrosis which ultimately causes portal hypertension and gastroesophageal varices. Variceal bleeding is a worrisome and potentially fatal complication of cirrhosis, primary prophylaxis has demonstrated a reduction in decompensation and mortality. Portal hypertension and esophageal varices needing treatment could be predicted through noninvasive methods, including elastography, that evaluates the mechanical properties of liver or spleen tissue in concordance to the propagation of mechanical waves. The accurate prediction of the risk of gastroesophageal varices could spare unnecessary endoscopies in patients with low probability of finding varices needing treatment. In the current review, we discuss the elastography modalities available and the current evidence for its implementation in daily clinical practice.

MR elastography of liver: current status and future perspectives

Non-invasive evaluation of liver fibrosis has evolved over the last couple of decades. Currently, elastography techniques are the most widely used non-invasive methods for clinical evaluation of chronic liver disease (CLD). MR elastography (MRE) of the liver has been used in the clinical practice for nearly a decade and continues to be widely accepted for detection and staging of liver fibrosis. With MRE, one can directly visualize propagating shear waves through the liver and an inversion algorithm in the scanner automatically converts the shear wave properties into an elastogram (stiffness map) on which liver stiffness can be calculated. The commonly used MRE method, two-dimensional gradient recalled echo (2D-GRE) sequence has produced excellent results in the evaluation of liver fibrosis in CLD from various etiologies and newer clinical indications continue to emerge. Advances in MRE technique, including 3D MRE, automated liver elasticity calculation, improvements in shear wave delivery and patient experience, are promising to provide a faster and more reliable MRE of liver. Innovations, including evaluation of mechanical parameters, such as loss modulus, displacement, and volumetric strain, are promising for comprehensive evaluation of CLD as well as understanding pathophysiology, and in differentiating various etiologies of CLD. In this review, the current status of the MRE of liver in CLD are outlined and followed by a brief description of advanced techniques and innovations in MRE of liver.

Magnetic resonance imaging for the assessment of pathological hepatic findings in nonalcoholic fatty liver disease

The prevalence of nonalcoholic fatty liver disease (NAFLD) is expected to increase because of the current epidemics of obesity and diabetes, and NAFLD has become a major cause of chronic liver disease worldwide. Liver fibrosis is associated with poor long-term outcomes in patients with NAFLD. Additionally, increased mortality and liver-related complications are primarily seen in patients with nonalcoholic steatohepatitis (NASH); however, nonalcoholic fatty liver (NAFL) is believed to be benign and non-progressive. Therefore, distinguishing between NASH and NAFL is clinically important. Liver biopsy is the gold standard method for the staging of liver fibrosis and distinguishing between NASH and NAFL. Unfortunately, liver biopsy is an invasive and expensive procedure. Therefore, noninvasive methods, to replace biopsy, are urgently needed for the staging of liver fibrosis and diagnosing NASH. In this review, we discuss the recent studies on magnetic resonance imaging (MRI), including magnetic resonance elastography, proton density fat fraction measurement, and multiparametric MRI (mpMRI) that can be used in the assessment of NASH components such as liver fibrosis, steatosis, and liver injury including inflammation and ballooning.

MR elastography, T1 and T2 relaxometry of liver: role in noninvasive assessment of liver function and portal hypertension

PURPOSE

To evaluate the correlation between liver stiffness as measured on MR elastography and T1 and T2 relaxation times from T1 and T2 mapping with clinical parameters of liver disease, including the MELD score, MELD-Na and ALBI grade, and endoscopically visible esophageal varices.

MATERIALS AND METHODS

223 patients with known or suspected liver disease underwent MRI of the liver with T1 mapping (Look-Locker sequence) and 2D SE-EPI MR elastography (MRE) sequences. 139 of these patients also underwent T2 mapping with radial T2 FS sequence. Two readers measured liver stiffness, T1 relaxation times and T2 relaxation times, and assessed qualitative features such as presence or absence of cirrhosis, ascites, spleen length, and varices on conventional MRI images. A third reader collected the clinical data (MELD score, MELD-Na Score, ALBI grade, and results of endoscopy in 78 patients).

RESULTS

Significant moderate correlation was found between MELD score and all three imaging techniques for both readers (MRE, r = 0.35 and 0.28; T1 relaxometry, r = 0.30 and 0.29; T2 relaxometry, r = 0.45, and 0.37 for reader 1 and reader 2 respectively). Correlation with MELD-Na score was even higher (MRE, r = 0.49 and 0.40; T1, r = 0.45 and 0.41; T2, r = 0.47 and 0.35 for reader 1 and reader 2 respectively). Correlations between MRE and ALBI grade was significant and moderate for both readers: r = 0.39 and 0.37, higher than T1 relaxometry (r = 0.22 and 0.20) and T2 relaxometry (r = 0.17, and r = 0.24). Significant moderate correlations were found for both readers between MRE and the presence of varices on endoscopy (r = 0.28 and 0.30). MRE and T1 relaxometry were significant predictors of varices at endoscopy for both readers (MRE AUC 0.923 and 0.873; T1 relaxometry AUC = 0.711 and 0.675 for reader 1 and reader 2 respectively). Cirrhotic morphology (AUC = 0.654), spleen length (AUC = 0.610) and presence of varices in the upper abdomen on MRI (AUC of 0.693 and 0.595) were all significant predictors of endoscopic varices. Multivariable logistic regression model identified that spleen length and liver MRE were significant independent predictors of endoscopic varices for both readers.

CONCLUSION

MR elastography, T1 and T2 relaxometry demonstrated moderate positive correlation with the MELD score and MELD-Na Score. Correlation between MRE and ALBI grade was superior to T1 and T2 relaxometry methods. MRE performed better than T1 and T2 relaxometry to predict the presence of varices at endoscopy. On multivariate analyses, spleen length and MRE were the only two significant independent predictors of endoscopic varices.

Assessment of liver fibrosis with liver and spleen magnetic resonance elastography, serum markers in chronic liver disease

Background

The accurate assessment of liver fibrosis is essential for patients with chronic liver disease. A liver biopsy is an invasive procedure that has many potential defects and complications. Therefore, noninvasive assessment techniques are of considerable value for clinical diagnosis. Liver and spleen magnetic resonance elastography (MRE) and serum markers have been proposed for quantitative and noninvasive assessment of liver fibrosis. This study aims to compare the diagnostic performance of liver and spleen stiffness measured by MRE, fibrosis index based on the 4 factors (FIB-4), aspartate aminotransferase-to-platelet ratio index (APRI), and their combined models for staging hepatic fibrosis.

Methods

One hundred and twenty patients with chronic liver disease underwent MRE scans. Liver and spleen stiffness were measured by the MRE stiffness maps. Serum markers were collected to calculate FIB-4 and APRI. Liver biopsies were used to identify pathologic grading. Spearman's rank correlation analysis evaluated the correlation between the parameters and fibrosis stages. Receiver operating characteristic (ROC) analysis evaluated the performance of the four individual parameters, a liver and spleen stiffness combined model, and an all-parameters combined model in assessing liver fibrosis.

Results

Liver stiffness, spleen stiffness, FIB-4, and APRI were all correlated with fibrosis stage (r=0.87, 0.64, 0.65, and 0.51, respectively, all P<0.001). Among the 4 individual diagnostic markers, liver stiffness showed the highest values in staging F1-4, F2-4, F3-4 and F4 (AUC =0.89, 0. 97, 0.95, and 0.95, all P<0.001). The AUCs of the liver and spleen stiffness combined model in the F1-4, F2-4, F3-4, and F4 staging groups were 0.89, 0.97, 0.95, and 0.96, respectively (all P<0.001). The corresponding AUCs of the all-parameters combined model were 0.90, 0.97, 0.95, and 0.96 (all P<0.001). The AUCs of the liver and spleen stiffness combined model were significantly higher than those of APRI, FIB-4 in the F2-4, F3-4, and F4 staging groups (all P<0.05). Both combined models were not significantly different from liver stiffness in staging liver fibrosis (all P>0.05).

Conclusions

Liver stiffness measured with MRE had better diagnostic performance than spleen stiffness, APRI, and FIB-4 for fibrosis staging. The combined models did not significantly improve the diagnostic value compared with liver stiffness in staging fibrosis.

Computed tomography vs liver stiffness measurement and magnetic resonance imaging in evaluating esophageal varices in cirrhotic patients: A systematic review and meta-analysis

BACKGROUND

Computed tomography (CT), liver stiffness measurement (LSM), and magnetic resonance imaging (MRI) are non-invasive diagnostic methods for esophageal varices (EV) and for the prediction of high-bleeding-risk EV (HREV) in cirrhotic patients. However, the clinical use of these methods is controversial.

AIM

To evaluate the accuracy of LSM, CT, and MRI in diagnosing EV and predicting HREV in cirrhotic patients.

METHODS

We performed literature searches in multiple databases, including PubMed, Embase, Cochrane, CNKI, and Wanfang databases, for articles that evaluated the accuracy of LSM, CT, and MRI as candidates for the diagnosis of EV and prediction of HREV in cirrhotic patients. Summary sensitivity and specificity, positive likelihood ratio and negative likelihood ratio, diagnostic odds ratio, and the areas under the summary receiver operating characteristic curves were analyzed. The quality of the articles was assessed using the quality assessment of diagnostic accuracy studies-2 tool. Heterogeneity was examined by Q-statistic test and I² index, and sources of heterogeneity were explored using meta-regression and subgroup analysis. Publication bias was evaluated using Deek’s funnel plot. All statistical analyses were conducted using Stata12.0, MetaDisc1.4, and RevMan5.3.

RESULTS

Overall, 18, 17, and 7 relevant articles on the accuracy of LSM, CT, and MRI in evaluating EV and HREV were retrieved. A significant heterogeneity was observed in all analyses (P < 0.05). The areas under the summary receiver operating characteristic curves of LSM, CT, and MRI in diagnosing EV and predicting HREV were 0.86 (95% confidence interval [CI]: 0.83-0.89), 0.91 (95%CI: 0.88-0.93), and 0.86 (95%CI: 0.83-0.89), and 0.85 (95%CI: 0.81-0.88), 0.94 (95%CI: 0.91-0.96), and 0.83 (95%CI: 0.79-0.86), respectively, with sensitivities of 0.84 (95%CI: 0.78-0.89), 0.91 (95%CI: 0.87-0.94), and 0.81 (95%CI: 0.76-0.86), and 0.81 (95%CI: 0.75-0.86), 0.88 (95%CI: 0.82-0.92), and 0.80 (95%CI: 0.72-0.86), and specificities of 0.71 (95%CI: 0.60-0.80), 0.75 (95%CI: 0.68-0.82), and 0.82 (95%CI: 0.70-0.89), and 0.73 (95%CI: 0.66-0.80), 0.87 (95%CI: 0.81-0.92), and 0.72 (95%CI: 0.62-0.80), respectively. The corresponding positive likelihood ratios were 2.91, 3.67, and 4.44, and 3.04, 6.90, and2.83; the negative likelihood ratios were 0.22, 0.12, and 0.23, and 0.26, 0.14, and 0.28; the diagnostic odds ratios were 13.01, 30.98, and 19.58, and 11.93, 49.99, and 10.00. CT scanner is the source of heterogeneity. There was no significant difference in diagnostic threshold effects (P > 0.05) or publication bias (P > 0.05).

CONCLUSION

Based on the meta-analysis of observational studies, it is suggested that CT imaging, a non-invasive diagnostic method, is the best choice for the diagnosis of EV and prediction of HREV in cirrhotic patients compared with LSM and MRI.

Feasibility of measuring spleen stiffness with MR elastography and splenic volume to predict hepatic fibrosis stage

AIM

The aim of this study was to investigate the relationship between spleen stiffness value, splenic volume and the liver fibrosis stages.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board of our institute. We enrolled 109 patients that had undergone abdominal MR imaging and histopathological examination. The preoperative MR imaging, MR elastography and laboratory data were reviewed. Liver stiffness and spleen stiffness were determined with MR elastography, and splenic volume was calculated. Liver fibrosis stage was determined using surgical pathology.

RESULTS

The correlation coefficient between the liver stiffness and the fibrosis stage was r = 0.72 and r = 0.62 when the passive driver was on right chest wall and the left chest wall, respectively. The correlation coefficient between the spleen stiffness and the fibrosis stage was r = 0.63 and r = 0.18 when the passive driver was on the left chest wall and the right chest wall, respectively. The correlation coefficient between the splenic volume and the fibrosis stage was r = 0.31. The diagnostic performance of spleen stiffness was similar to liver stiffness in prediction of advanced liver fibrosis. The combination of spleen stiffness and liver stiffness provided greater sensitivity in prediction of advanced fibrosis than spleen or liver stiffness alone, but no significant difference was found.

CONCLUSION

According to our study, the spleen stiffness value was useful in staging liver fibrosis. The combination of spleen stiffness and liver stiffness could provide higher diagnostic sensitivity than liver stiffness alone in prediction of advanced fibrosis.

Prediction of esophageal varices by liver and spleen MR elastography

OBJECTIVES

We aimed to assess the diagnostic performance of MR elastography (MRE) in predicting esophageal varices (EVs) in patients with chronic liver disease.

METHODS

We prospectively performed liver (LSM) and spleen stiffness measurements (SSM) using MRE and endoscopic screening for EVs to determine if patients with hepatocellular carcinoma were eligible for resection. We investigated whether LSM, SSM, and other non-invasive preoperative parameters were associated with the presence of EVs. In order to predict EVs, 211 patients were divided into training (n = 140) and test (n = 71) groups. A nomogram was built using independent factors based on logistic regression analysis in the training group and its accuracy was validated using an independent cohort.

RESULTS

Forty-six patients (21.8%) were diagnosed as having EVs (mild, n = 36; severe, n = 10). According to multiple regression analysis, LSM (odds ratio, 2.362; 95% confidence interval [CI], 1.341-4.923; p = 0.001) and SSM (1.489; 1.095-2.235; p = 0.010) were independent predictors of EVs in the training group. The nomogram showed good discrimination, with a C-index of 0.942 (95% CI, 0.892-0.974) through internal validation, and good calibration. Application of the nomogram in the test group still gave good discrimination (C-index, 0.948; 95% CI, 0.868-0.995).

CONCLUSIONS

The combination of LSM and SSM using MRE is an accurate tool to identify patients at risk for EVs.

KEY POINTS

• Performance of MR elastography can estimate the presence of esophageal varices non-invasively. • Liver and spleen stiffness measurements are independent predictors for esophageal varices. • The nomogram using a combination of liver and spleen stiffness measurements allows for the risk of esophageal varices.

Elastography-based screening for esophageal varices in patients with advanced chronic liver disease

Elastography-based liver stiffness measurement (LSM) is a non-invasive tool for estimating liver fibrosis but also provides an estimate for the severity of portal hypertension in patients with advanced chronic liver disease (ACLD). The presence of varices and especially of varices needing treatment (VNT) indicates distinct prognostic stages in patients with compensated ACLD (cACLD). The Baveno VI guidelines suggested a simple algorithm based on LSM < 20 kPa (by transient elastography, TE) and platelet count > 150 G/L for ruling-out VNT in patients with cACLD. These (and other) TE-based LSM cut-offs have been evaluated for VNT screening in different liver disease etiologies. Novel point shear-wave elastography (pSWE) and two-dimensional shear wave elastography (2D-SWE) methodologies for LSM have also been evaluated for their ability to screen for “any” varices and for VNT. Finally, the measurement of spleen stiffness (SSM) by elastography (mainly by pSWE and 2D-SWE) may represent another valuable screening tool for varices. Here, we summarize the current literature on elastography-based prediction of “any” varices and VNT. Finally, we have summarized the published LSM and SSM cut-offs in clinically useful scale cards.

Four-dimensional Flow MRI as a Marker for Risk Stratification of Gastroesophageal Varices in Patients with Liver Cirrhosis

Purpose To assess the feasibility of four-dimensional (4D) flow MRI as a noninvasive imaging marker for stratifying the risk of variceal bleeding in patients with liver cirrhosis. Materials and Methods This study recruited participants scheduled for both liver MRI and gastroesophageal endoscopy. Risk of variceal bleeding was assessed at endoscopy by using a three-point scale: no varices, low risk, and high risk requiring treatment. Four-dimensional flow MRI was used to create angiograms for evaluating visibility of varices and to measure flow volumes in main portal vein (PV), superior mesenteric vein, splenic vein (SV), and azygos vein. Fractional flow changes in PV and SV were calculated to quantify shunting (outflow) from PV and SV into varices. Logistic analysis was used to identify the independent indicator of high-risk varices. Results There were 23 participants (mean age, 52.3 years; age range, 25-75 years), including 14 men (mean age, 51.7 years; age range, 25-75 years) and nine women (mean age, 53.2 years; age range, 31-72 years) with no varices (n = 8), low-risk varices (n = 8), and high-risk varices (n = 7) determined at endoscopy. Four-dimensional flow MRI-based angiography helped radiologists to view varices in four of 15 participants with varices. Independent indicators of high-risk varices were flow volume in the azygos vein greater than 0.1 L/min (P = .034; 100% sensitivity [seven of seven] and 62% specificity [10 of 16]) and fractional flow change in PV of less than 0 (P < .001; 100% sensitivity [seven of seven] and 94% specificity [15 of 16]). Conclusion Azygos flow greater than 0.1 L/min and portal venous flow less than the sum of splenic and superior mesenteric vein flow are useful markers to stratify the risk of gastroesophageal varices bleeding in patients with liver cirrhosis. © RSNA, 2018 Online supplemental material is available for this article.

Magnetic resonance elastography of liver and spleen: Methods and applications

The viscoelastic properties of the liver and spleen can be assessed with magnetic resonance elastography (MRE). Several actuators, MRI acquisition sequences and reconstruction algorithms have been proposed for this purpose. Reproducible results are obtained, especially when the examination is performed in standard conditions with the patient fasting. Accurate staging of liver fibrosis can be obtained by measuring liver stiffness or elasticity with MRE. Moreover, emerging evidence shows that assessing the tissue viscous parameters with MRE is useful for characterizing liver inflammation, non-alcoholic steatohepatitis, hepatic congestion, portal hypertension, and hepatic tumors. Further advances such as multifrequency acquisitions and compression-sensitive MRE may provide novel quantitative markers of hepatic and splenic mechanical properties that may improve the diagnosis of hepatic and splenic diseases.

Νon-invasive screening for esophageal varices in patients with liver cirrhosis

Esophageal varices are one of the main complications of liver cirrhosis. Upper gastrointestinal endoscopy is the gold standard for the detection of esophageal varices. Many less invasive methods for screening of varices have been investigated and the most recent Baveno VI guidelines suggest that endoscopy is not necessary in patients with liver stiffness <20 kPa and platelets >150,000/μL. A critical review of the literature was performed concerning non-invasive or minimally invasive methods of screening for esophageal varices. Liver and spleen elastography, imaging methods including computed tomography, magnetic resonance imaging and ultrasound, laboratory tests and capsule endoscopy are discussed. The accuracy of each method, and its advantages and limitations compared to endoscopy are analyzed. There are data to support the Baveno VI guidelines, but there is still a lack of large prospective studies and low specificity has been reported for the liver stiffness and platelet count combination. Spleen elastography has shown promising results, as there are data to support its superiority to liver elastography, but it needs further assessment. Computed tomography has shown high diagnostic accuracy and can be part of the diagnostic work up of cirrhotic patients in the future, including screening for varices.

Comparison of the efficacy of Gd-EOB-DTPA-enhanced magnetic resonance imaging and magnetic resonance elastography in the detection and staging of hepatic fibrosis

The present study compared the efficacy of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and magnetic resonance elastography (MRE) in the estimation of hepatic fibrosis stages with histopathologic correlation.This retrospective study included 104 patients (87 men and 17 women; mean age, 60.6 ± 10.6 years) with chronic liver disease who underwent both Gd-EOB-DTPA-enhanced MRI and MRE. The relative enhancement (RE) ratio of the liver parenchyma and the contrast enhancement index (CEI) were calculated as (SIpostliver - SIpreliver)/SIpreliver and SIpost/SIpre, respectively, where SIpost and SIpre were the liver-to-muscle signal intensity ratios on the hepatobiliary phase images and noncontrast-enhanced images, respectively. The liver stiffness values were measured using MRE stiffness maps. The diagnostic performance of MRE, RE ratios, and CEI values for hepatic fibrosis staging were compared.The distribution of fibrosis stages was as follows: F0, n = 3 (2.9%); F1, n = 12 (11.5%); F2, n = 17 (16.3%); F3, n = 26 (25.0%); and F4, n = 46 (44.2%). MRE, RE ratios, and CEI values correlated significantly with hepatic fibrosis (rs = .79, -.35, -.25, respectively, P < .05). MRE showed a significantly higher diagnostic performance than did RE ratios and CEI values for each fibrosis stage, except while distinguishing the F1 fibrosis stage (CEI, P = .15). A cutoff value of RE ratio = 0.89 can be used to identify patients with significant hepatic fibrosis, with positive predictive value, sensitivity, specificity, and negative predictive value of 93.2%, 61.8%, 73.3%, and 24.4%, respectively.Gd-EOB-DTPA-enhanced MRI can potentially predict significant hepatic fibrosis. However, the diagnostic performance of MRE for hepatic fibrosis staging was superior to that of Gd-EOB-DTPA-enhanced MRI.

Management of gastroesophageal varices in cirrhotic patients: current status and future directions

Bleeding from gastroesophageal varices (GEV) is a serious event in cirrhotic patients and can cause death. According to the explosion theory, progressive portal hypertension is the primary mechanism underlying variceal bleeding. There are two approaches for treating GEV: primary prophylaxis to manage bleeding or emergency treatment for bleeding followed by secondary prophylaxis. Treatment methods can be classified into two categories: 1) Those used to decrease portal pressure, such as medication (i.e., nonselective β-blockers), radiological intervention [transjugular intrahepatic portosystemic shunt (TIPS)] or a surgical approach (i.e., portacaval shunt), and 2) Those used to obstruct GEV, such as endoscopy [endoscopic variceal ligation (EVL), endoscopic injection sclerotherapy (EIS), and tissue adhesive injection] or radiological intervention [balloon-occluded retrograde transvenous obliteration (BRTO)]. Clinicians should choose a treatment method based on an understanding of its efficacy and limitations. Furthermore, elastography techniques and serum biomarkers are noninvasive methods for estimating portal pressure and may be helpful in managing GEV. The impact of these advances in cirrhosis therapy should be evaluated for their effectiveness in treating GEV.

Clinical applications, limitations and future role of transient elastography in the management of liver disease

Transient elastography (TE) is a reliable tool for the non-invasive assessment of liver fibrosis in routine clinical practice. TE is currently approved for use in Europe, Asia and the United States. The widespread adoption of this technology is certain to increase the use of TE worldwide. Although TE has been well validated in chronic viral hepatitis, its clinical role in other liver diseases remains less clear. The advent of new treatment for chronic hepatitis C and emerging prevalence of non-alcoholic steatohepatitis raises new questions on the role of TE in current clinical practice. This review aims to examine the clinical applications, limitations and future role of TE in current clinical practice in light of the changing epidemiology of liver diseases and new clinical management paradigms. In current clinical practice, TE is the most accurate non-invasive method for diagnosis of liver cirrhosis. TE is useful to rule out fibrosis and cirrhosis but does not have sufficient accuracy to discern between various stages of fibrosis. The clinical role of TE has evolved from cross-sectional point-in-time assessment of fibrosis and cirrhosis to the more relevant role of prediction of vital clinical end-points. This provides clinicians with the ability to modify treatment strategies based on the information provided by TE. TE has evolved over the past decade to become an essential tool to assist the clinician in the management of chronic liver disease.

Magnetic resonance elastography of abdomen

Many diseases cause substantial changes in the mechanical properties of tissue, and this provides motivation for developing methods to noninvasively assess the stiffness of tissue using imaging technology. Magnetic resonance elastography (MRE) has emerged as a versatile MRI-based technique, based on direct visualization of propagating shear waves in the tissues. The most established clinical application of MRE in the abdomen is in chronic liver disease. MRE is currently regarded as the most accurate noninvasive technique for detection and staging of liver fibrosis. Increasing experience and ongoing research is leading to exploration of applications in other abdominal organs. In this review article, the current use of MRE in liver disease and the potential future applications of this technology in other parts of the abdomen are surveyed.