Influence of liver stiffness heterogeneity on staging fibrosis in patients with nonalcoholic fatty liver disease

Free-breathing hepatic 2D magnetic resonance elastography

PURPOSE

To evaluate the test-retest repeatability of a rapid, free-breathing two-dimensional (2D) MR elastography (MRE) technique and to assess the reliability of the liver-stiffness measurements compared with conventional breath-hold MREs.

METHODS

Fifteen and 115 participants were enrolled in the technical repeatability and measurement equivalence assessment cohorts, respectively. All participants underwent rapid free-breathing and conventional breath-hold 2D MRE (twice in repeatability cohort) on 1.5T scanners. Both methods have four phase offsets over one harmonic motion cycle at 60 Hz; one and 10 cycles were collected and processed in breath-hold and free-breathing MREs, respectively. The liver stiffness measurements of free-breathing (LSF) and breath-hold MRE (LSB) were calculated from manually drawn regions of interest. The repeatability coefficients and Spearman correlation were used to assess technical repeatability and measurement agreement between LSF and LSB. Univariable and multivariable linear regressions were performed to identify potential influencing factors, including age, sex, body mass index, and fat fraction, in the measurement agreement between LSB and LSF.

RESULTS

The repeatability coefficient of free-breathing 2D MRE is comparable to breath-hold MRE (LSF: 20.8%, LSB: 20.4%). LSF showed a strong agreement and significant correlation with LSB (LSF = 1.01 × LSB, ρ = 0.94, p < 0.001). The measurement agreement between LSF and LSB was only significantly affected by sex (p = 0.047) after adjusting for confounding factors of age, body mass index, and fat fraction.

CONCLUSIONS

The nongated, free-breathing, multislice 2D MRE technique can provide reliable liver stiffness measurements compared with conventional breath-hold 2D MRE. It could provide a comfortable alternative method with reliable liver stiffness measurements for patients who have difficulty in suspending respiration.

Advances in imaging-Elastography

Chronic liver disease affects over a billion people worldwide. Liver fibrosis is the key driver of liver-related complications and mortality. Elastography has been a transformative tool in hepatology, allowing for the diagnosis and staging of liver fibrosis noninvasively, and is evolving beyond these purposes into a prognostication tool. By measuring tissue stiffness, elastography techniques such as shear-wave and magnetic resonance elastography offer critical insights into liver fibrosis, portal hypertension, and the progression of disease. Magnetic resonance elastography stands out for its reliability across fibrosis stages and robustness in obese patients affected by metabolic liver disease. Spleen stiffness measurement complements liver assessments, enhancing the identification of portal hypertension and refining patient risk stratification. This review covers current clinical applications but also anticipates future innovations such as artificial intelligence-based algorithms that could expand elastography's clinical impact, thereby improving patient outcomes.

Three-Dimensional Vector MR Elastography for Evaluating Tissue Mechanical Heterogeneity to Assess Liver Disease Progression

Background Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing global health challenge, with evidence indicating that hepatic inflammation and fibrosis are heterogeneous processes. Purpose To measure liver mechanical property heterogeneity using MR elastography (MRE) and evaluate its potential as a biomarker for tissue inflammation and fibrosis in patients with MASLD. Materials and Methods Mechanical tissue heterogeneity in MASLD was assessed at three-dimensional vector MRE pixel-wise histogram analysis of shear stiffness and loss modulus in preclinical and clinical studies. The preclinical study involved 25 rats that were examined monthly, whereas the clinical study analyzed data from 179 participants across two prospective studies (September 2015 to November 2022), including some who underwent bariatric surgery at pretreatment and posttreatment MRE examinations. Mean and coefficient of variation (CV) of shear stiffness and loss modulus were calculated for each examination. Nonparametric tests and Spearman correlation coefficient were used to compare MRE-derived tissue mechanics with biopsy-confirmed fibrosis and inflammation and assess correlations with portal pressure and histopathologic hepatic fibrosis. Results The preclinical study showed that, in cirrhotic livers, CV of loss modulus positively correlated with portal pressure and fibrosis area ratio variation (ρ = 0.52 [P = .008] and 0.55 [P = .005], respectively). The clinical study showed that, in 10 healthy volunteers (median age, 36.5 years; IQR, 34.0-38.8 years; five females) and 169 participants with MASLD (median age, 50.1 years; IQR, 41.0-58.2 years; 118 females), CV of sheer stiffness (from 0.12 to 0.30 in healthy participants to participants with stage 4 fibrosis) and loss modulus (from 0.31 to 0.51 in healthy participants to participants with grade 3 inflammation) increased with increasing severity of fibrosis and inflammation, respectively. In 36 participants who underwent bariatric surgery, the CV of sheer stiffness decreased at the 1-year follow-up, from 0.16 (IQR, 0.14-0.18) to 0.14 (IQR, 0.12-0.16) (P = .009). Conclusion Tissue mechanical heterogeneity assessed at MRE positively correlated with progression of MASLD, demonstrating potential as a biomarker for liver disease severity and therapeutic intervention. ClinicalTrials.gov Identifier: NCT02565446 Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Moura Cunha in this issue.

Application of a quality threshold to improve liver shear wave elastography measurements in free-breathing pediatric patients

PURPOSE

This study assessed the benefits of quality threshold (QT) implementation for liver shear wave elastography (SWE) in children during free breathing.

METHODS

The QT, which adjusts the SWE map display based on shear wave quality, was set at 55%. Phantom measurements (PMs) were taken with a fixed probe using QT (termed PM-1); a moving probe without QT (PM-2); and a moving probe with QT (PM-3). Each measurement was subjected to random samplings of various sizes. Clinical measurements (CMs) were obtained from children with biliary atresia using following protocols: CM-1, manually defined regions of interest (ROIs); CM-2, default ROIs without QT; and CM-3, default ROIs with QT. Elasticity measurements were compared across fibrosis grades, and color patterns on the SWE maps were analyzed.

RESULTS

In the phantom experiments, the moving probe produced lower elasticity measurements; this difference decreased upon QT application. With the moving probe, random sampling indicated fewer interquartile range-to-median ratios exceeding 30% upon QT application (4% vs. 14% when five values were sampled, P=0.004). In clinical experiments, QT improved the differentiation of fibrosis grade in patients over 5 years old, with a significant difference between moderate and severe fibrosis (P=0.004). Elasticity variability was positively correlated with fibrosis grade (τ=0.376, P<0.001). Certain apparent errors, termed artificial stripe patterns, were not eliminated by QT.

CONCLUSION

Applying QT to exclude low-quality pixels can minimize measurement error and improve differentiation of liver fibrosis grades. The presence of an artificial stripe pattern on the SWE map may indicate images requiring exclusion.

Repeatability of vibration-controlled transient elastography versus magnetic resonance elastography in patients with cirrhosis: A prospective study

BACKGROUND AND AIMS

Magnetic resonance elastography (MRE) and vibration-controlled transient elastography (VCTE) have the potential to assess disease progression; however, repeatability data in people with cirrhosis are lacking. We aimed to assess the effect of disease severity on measurement variability and contribute to the evidentiary basis for the qualification of repeating liver stiffness measurements (LSM) in practice and research.

METHODS

This prospective study included 49 adult participants (58.3% female) with cirrhosis who underwent same-day repeat LSM examinations. The primary outcome was the same-day, same-operator repeatability coefficient% (RC%) and the within-case coefficient of variation (wCV) for each modality. Secondary outcomes include the intra-class correlation coefficient (ICC). The relationship between measurement variability (interquartile for VCTE, standard deviation for MRE) and disease severity (mean liver stiffness) was evaluated by linear regression with the coefficient of determination R2 reported.

RESULTS

Same-day repeat MRE and VCTE exams were prospectively conducted in 33 and 45 participants, respectively. The RC% appeared 82% higher for VCTE versus MRE (38% vs. 21%), with consistent findings in head-to-head analyses. The wCV for VCTE and MRE was 14% and 8% respectively, indicating VCTE has 75% higher within-subject measurement variation than MRE. ICC was excellent for LSM by VCTE (0.92) and MRE (0.96). Measurement variability increased with mean liver stiffness for VCTE (R2 = 0.78) and MRE (R2 = 0.93).

CONCLUSION

Both VCTE and MRE demonstrated increased measurement variability with disease severity. However, MRE outperformed VCTE in terms of technical repeatability in patients with cirrhosis. These repeatability estimates may improve the qualification of NITs in practice.

Shear wave trajectory detection in ultra-fast M-mode images for liver fibrosis assessment: A deep learning-based line detection approach

Stiffness measurement using shear wave propagation velocity has been the most common non-invasive method for liver fibrosis assessment. The velocity is captured through a trace recorded by transient ultrasonographic elastography, with the slope indicating the velocity of the wave. However, due to various factors such as noise and shear wave attenuation, detecting shear wave trajectory on wave propagation maps is a challenging task. In this work, we made the first attempt to use deep learning methods for shear wave trajectory detection on wave propagation maps. Specifically, we adopted five deep learning models in this task and evaluated them by using a well-acknowledged metric based on EA-Angular-Score (EAA) and task-specific metric based on Young s-Score (Ys) in the line-detection field. Furthermore, we proposed an end-to-end framework based on a Transformer and Hough transform, named Transformer-enhanced Hough Transform (TEHT). It took a wave propagation map as input image and directly output the slope of the shear wave trajectory. The framework extracts multi-scale local features from wave propagation maps, employs a deformable attention mechanism for feature fusion, identifies the target line using the Hough transform's voting mechanism, and calculates the contribution of each scale through channel attention. Wave propagation maps from 68 patients were utilized in this study, with manual annotation performed by a rater who was trained as a radiologist, serving as the reference value. The evaluation revealed that the SLNet model exhibited F-measure of EA and Ys values as 40.33 % and 40.72 %, respectively, while the TEHT model showed F-measure of EA and Ys values as 80.96 % and 98.00 %, respectively. TEHT yielded significantly better performance than other deep learning models. Moreover, TEHT demonstrated strong concordance with the gold standard, yielding R2 values of 0.967 and 0.968 for velocity and liver stiffness, respectively. The present study therefore suggests the application of the TEHT model for assessing liver fibrosis owing to its superiority among the five deep learning models.

A Simple and Reliable 2D-Shear Wave Elastography and UltraSound Coefficient Attenuation Parameter Technique in Chronic Liver Diseases

BACKGROUND

The performance and reliability criteria for Aixplorer MACH30 (SS) in chronic liver diseases (CLD) have not been validated.

AIMS

The objectives were to define the optimal procedure, the accuracy for fibrosis and steatosis diagnosis, and the reliability criteria using SS.

METHODS

Patients had 2D-shear wave elastography (SWE) and ultraSound-guided controlled attenuation parameter (SCAP) performed in triplicate at the mid-axillary line (MAL), posterior axillary line (PAL), and anterior axillary line (AAL). Performances of SWE and SCAP were defined using transient elastography (TE ≥ 9.5 kPa) and CAP (≥ 275 dB/m) using Fibroscan (FS) as reference and validated with liver biopsy (LB).

RESULTS

FS and SS data from 203 CLD patients were analyzed (55 ± 14 years; 59% male; MASLD 58%). Median TE and CAP were 6.4 kPa (2.5-66.9) and 270 dB/m (141-400). The best technique for the diagnosis of advanced fibrosis and significant steatosis was the median of three SWE values and three SCAP values at MAL, PAL, and AAL with an AUROC of 0.96 [95% CI 0.93-0.98] and 0.91 [95% CI 0.86-0.95]. Only skin-to-liver distance ≥ 2.4 cm (p = 0.012, 95% CI 1.37-13.38) was independently associated with discordance. The accuracy of SWE (≥ 8.5 kPa) and SCAP (≥ 0.44) was analyzed in 58 patients with LB. The PPV and NPV were 50% and 94%, and 71% and 88% for fibrosis and steatosis, respectively.

CONCLUSION

A reliable diagnosis of advanced fibrosis and significant steatosis can be obtained with the median of three measurements in different liver portions using SS. The only non-reliable criterion is skin-to-liver distance ≥ 2.4 cm.

Prediction of outcomes in patients with metabolic dysfunction-associated steatotic liver disease based on initial measurements and subsequent changes in magnetic resonance elastography

BACKGROUND

The prognosis of metabolic dysfunction-associated steatotic liver disease (MASLD) is strongly associated with liver fibrosis. We aimed to investigate whether liver stiffness measurement (LSM) and changes in LSM (ΔLSM) on magnetic resonance elastography (MRE) can predict clinical events in patients with MASLD.

METHODS

We included 405 patients with MASLD who underwent at least two MREs. The patients were divided into five groups corresponding to fibrosis stages (0-4) based on initial LSM and classified as progressors (ΔLSM ≥ 19%) or non-progressors (ΔLSM < 19%) based on the difference between the first and last LSM.

RESULTS

The mean follow-up period was 72.6 months, and the mean interval between MREs was 23.5 months. There were 52 (12.8%) progressors and 353 (87.2%) non-progressors. The initial LSM was significantly associated with the cumulative probabilities of decompensated cirrhosis, hepatocellular carcinoma (HCC), liver-related events, extrahepatic malignancies, and overall mortality but not with cardiovascular disease. Progressors had significantly higher hazard ratios (HRs) for decompensated cirrhosis, HCC, and liver-related events but not for extrahepatic malignancies, cardiovascular disease, or overall mortality. Among patients without cirrhosis, the HR for developing cirrhosis among progressors was 60.15. Progressors had a significantly higher risk of liver-related events, even in the low initial LSM (fibrosis stage 0-2) subgroups.

CONCLUSIONS

Both initial LSM and ΔLSM can predict liver-related events in patients with MASLD, even for low initial LSM. This integrated assessment can allow more detailed risk stratification compared with single LSM assessments and identify high-risk patients with MASLD among those previously considered as low risk.

Diagnosis and Treatment of Liver Disease: Current Trends and Future Directions

This narrative review delves into the intricate landscape of liver diseases, providing a comprehensive background of the diverse conditions that afflict this vital organ. Liver diseases, ranging from viral hepatitis and non-alcoholic fatty liver disease (NAFLD) to cirrhosis and hepatocellular carcinoma (HCC), pose significant global health challenges. Understanding these diseases' multifaceted origins and progression is pivotal for developing effective diagnostic and therapeutic strategies. The epidemiology and etiology of liver diseases emphasize the global impact of viral hepatitis, with hepatitis B and C as significant contributors. Concurrently, the rising prevalence of NAFLD, linked to lifestyle factors and metabolic syndrome, underscores the intricate relationship between modern living and liver health. Chronic liver diseases often evolve insidiously, progressing from inflammation to fibrosis and, ultimately, to cirrhosis - a stage characterized by irreversible scarring and compromised function. The heightened risk of HCC in advanced liver disease stages further underscores the urgency of effective diagnostic and therapeutic interventions. The evolving landscape of non-invasive diagnostic tools is explored for their role in enabling early detection and accurate staging of liver diseases. In the realm of treatment, there is a continuous transition toward personalized medicine, customized to suit the unique profiles of individual patients. This shift encompasses a broad spectrum, ranging from personalized pharmacological interventions to lifestyle modifications and surgical options. Delving into innovative therapies, such as gene editing and immunomodulation, offers a glimpse into the promising future directions that have the potential to redefine the landscape of liver disease diagnosis and treatment.

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.

SWOT analysis of noninvasive tests for diagnosing NAFLD with severe fibrosis: an expert review by the JANIT Forum

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. Nonalcoholic steatohepatitis (NASH) is an advanced form of NAFLD can progress to liver cirrhosis and hepatocellular carcinoma (HCC). Recently, the prognosis of NAFLD/NASH has been reported to be dependent on liver fibrosis degree. Liver biopsy remains the gold standard, but it has several issues that must be addressed, including its invasiveness, cost, and inter-observer diagnosis variability. To solve these issues, a variety of noninvasive tests (NITs) have been in development for the assessment of NAFLD progression, including blood biomarkers and imaging methods, although the use of NITs varies around the world. The aim of the Japan NASH NIT (JANIT) Forum organized in 2020 is to advance the development of various NITs to assess disease severity and/or response to treatment in NAFLD patients from a scientific perspective through multi-stakeholder dialogue with open innovation, including clinicians with expertise in NAFLD/NASH, companies that develop medical devices and biomarkers, and professionals in the pharmaceutical industry. In addition to conventional NITs, artificial intelligence will soon be deployed in many areas of the NAFLD landscape. To discuss the characteristics of each NIT, we conducted a SWOT (strengths, weaknesses, opportunities, and threats) analysis in this study with the 36 JANIT Forum members (16 physicians and 20 company representatives). Based on this SWOT analysis, the JANIT Forum identified currently available NITs able to accurately select NAFLD patients at high risk of NASH for HCC surveillance/therapeutic intervention and evaluate the effectiveness of therapeutic interventions.

Letter: association of laboratory indexes and magnetic resonance elastography-associated liver stiffness with complications and mortality

This article is linked to Higuchi et al papers. To view these articles, visit https://doi.org/10.1111/apt.16745 and https://doi.org/10.1111/apt.16792