Improved Ultrasound Attenuation Measurement Method for the Non-invasive Evaluation of Hepatic Steatosis Using FibroScan

Controlled attenuation parameter (CAP) is a measurement of ultrasound attenuation used to assess liver steatosis non-invasively. However, the standard method has some limitations. This study assessed the performance of a new CAP method by ex vivo and in vivo assessments. The major difference with the new method is that it uses ultrasound data continuously acquired during the imaging phase of the FibroScan examination. Seven reference tissue-mimicking phantoms were used to test the performance. In vivo performance was assessed in two cohorts (in total 195 patients) of patients using magnetic resonance imaging proton density fat fraction (MRI-PDFF) as a reference. The precision of CAP was improved by more than 50% on tissue-mimicking phantoms and 22%-41% in the in vivo cohort studies. The agreement between both methods was excellent, and the correlation between CAP and MRI-PDFF improved in both studies (0.71 to 0.74; 0.70 to 0.76). Using MRI-PDFF as a reference, the diagnostic performance of the new method was at least equal or superior (area under the receiver operating curve 0.889-0.900, 0.835-0.873). This study suggests that the new continuous CAP method can significantly improve the precision of CAP measurements ex vivo and in vivo.

Emerging New Diagnostic Modalities and Therapies of Nonalcoholic Fatty Liver Disease

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease (NAFLD) has emerged as the leading cause of chronic liver disease in both adults and children. In this article, we review recent developments in the screening, diagnosis, and treatment of pediatric NAFLD.

RECENT FINDINGS

Although alanine aminotransferase (ALT) remains the best screening test for NAFLD in children, and liver biopsy is still required for the diagnosis of nonalcoholic steatohepatitis (NASH), other noninvasive biomarker/imaging studies (MRI-PDFF and VCTE) have emerged as diagnostic methods for pediatric NAFLD. Two large clinical therapeutic trials testing vitamin E, metformin, and cysteamine in pediatric NAFLD yielded mostly inconclusive results. Bariatric surgery has begun to be used in adolescents with severe obesity. An adult phase 2 study using obeticholic acid (OCA) to treat NASH patients with fibrosis showed some positive results. As we continue to await the first FDA-approved therapeutic agent for NASH, lifestyle change remains the main modality of treatment. Newer diagnostic and treatment modalities for pediatric NAFLD continue to be in development under FDA guidance.

Diagnostic accuracy of combined biomarker measurements and vibration-controlled transient elastography (VCTE) for predicting fibrosis stage of non-alcoholic fatty liver disease

BACKGROUND

Numerous biomarkers have been developed for assessing the presence and severity of liver fibrosis associated with non-alcoholic fatty liver disease (NAFLD). Fibrosis can be assessed by liver stiffness measurement (LSM) using vibration-controlled transient elastography (VCTE). Here we examined whether diagnostic accuracy and applicability can be further improved by combining various biomarker measurements with LSM.

METHODS

A total of 278 patients with biopsy-confirmed Japanese NAFLD patients were enrolled. Area under the receiver operator characteristic curve (AUROC) was evaluated for obtaining the optimum interpretation criteria for LSM by VCTE and comparing various biomarkers alone and in combination with LSM.

RESULTS

Liver stiffness measurements including cases with interquartile range (IQR)/median (M) < 30% or LSM ≤ 7.1 kPa demonstrated high applicability (90% of patients with NAFLD) and accuracy (AUROC: 0.891) for predicting stage ≥ 3 fibrosis. For all biomarkers tested, the AUROC values for predicting stage ≥ 3 fibrosis were increased when combined with LSM [platelet count, 0.734 vs. 0.912; type-4 collagen 7s (T4C7s), 0.894 vs. 0.921; aspartate aminotransferase to alanine aminotransferase ratio (AST/ALT), 0.774 vs. 0.906; AST to platelet ratio index, 0.789 vs. 0.902; FIB-4 index, 0.828 vs. 0.922; NAFLD fibrosis score, 0.800 vs. 0.906; CA index-fibrosis, 0.884 vs. 0.913; FM-fibro index, 0.920 vs. 0.943; FIB-4 index + T4C7s, 0.901 vs. 0.930], demonstrating the advantage of concurrent LSM.

CONCLUSIONS

While VCTE has slightly limited applicability (90%) for patients with NAFLD, concurrent measurement with certain biomarkers (especially FM-fibro, T4C7s, and FIB-4) greatly improves the diagnostic accuracy.

A Novel FibroScan Examination Dedicated to Spleen Stiffness Measurement

Esophageal varices (EVs) are among the most severe complications of cirrhosis, with a prevalence of 50% to 60% among cirrhotic patients. International guidelines therefore recommend that cirrhotic patients should be screened for the presence of EVs. The main objective of this study was to introduce a new spleen-dedicated FibroScan (Echosens, Paris, France) examination and to assess its performance in detecting large EVs (grade 2 and 3). This novel examination has been validated in simulation and phantom studies and has been used in a population of patients with chronic liver disease. The study described here suggests that the novel spleen-dedicated FibroScan examination performs better than the standard FibroScan for the detection of large EVs (area under the curve = 0.70 for the standard examination and 0.79 [p <0.01] for the spleen examination), but further clinical studies are needed to investigate the role of spleen stiffness in the management of cirrhotic patients.

Liver Steatosis Assessed by Controlled Attenuation Parameter (CAP) Measured with the XL Probe of the FibroScan: A Pilot Study Assessing Diagnostic Accuracy

To assess liver steatosis, the controlled attenuation parameter (CAP; giving an estimate of ultrasound attenuation ∼3.5 MHz) is available with the M probe of the FibroScan. We report on the adaptation of the CAP for the FibroScan XL probe (center frequency 2.5 MHz) without modifying the range of values (100-400 dB/m). CAP validation was successfully performed on Field II simulations and on tissue-mimicking phantoms. In vivo performance was assessed in a cohort of 59 patients spanning the range of steatosis. In vivo reproducibility was good and similar with both probes. The area under receiver operative characteristic curve was equal to 0.83/0.84 and 0.92/0.91 for the M/XL probes to detect >2% and >16% liver fat, respectively, as assessed by magnetic resonance imaging. Patients can now be assessed simultaneously for steatosis and fibrosis using the FibroScan, regardless of their morphology.