Magnetic Resonance Imaging Proton Density Research Articles

Diagnosis and non-invasive assessment of MASLD in type 2 diabetes and obesity.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is currently the most common chronic liver disease and an important cause of cirrhosis and hepatocellular carcinoma. It is strongly associated with type 2 diabetes and obesity. Because of the huge number of patients at risk of MASLD, it is imperative to use non-invasive tests appropriately. To provide a narrative review on the performance and limitations of non-invasive tests, with a special emphasis on the impact of diabetes and obesity. We searched PubMed and Cochrane databases for articles published from 1990 to August 2023. Abdominal ultrasonography remains the primary method to diagnose hepatic steatosis, while magnetic resonance imaging proton density fat fraction is currently the gold standard to quantify steatosis. Simple fibrosis scores such as the Fibrosis-4 index are well suited as initial assessment in primary care and non-hepatology settings to rule out advanced fibrosis and future risk of liver-related complications. However, because of its low positive predictive value, an abnormal test should be followed by specific blood (e.g. Enhanced Liver Fibrosis score) or imaging biomarkers (e.g. vibration-controlled transient elastography and magnetic resonance elastography) of fibrosis. Some non-invasive tests of fibrosis appear to be less accurate in patients with diabetes. Obesity also affects the performance of abdominal ultrasonography and transient elastography, whereas magnetic resonance imaging may not be feasible in some patients with severe obesity. This article highlights issues surrounding the clinical application of non-invasive tests for MASLD in patients with type 2 diabetes and obesity.

Assessment of Hepatic Steatosis Using Ultrasound-Based Techniques: Focus on Fat Quantification

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease worldwide, affecting more than 30% of the global population, and is associated with increased liver-related morbidity and mortality, and extrahepatic complications. With the increasing prevalence of MASLD, there is an urgent need for accessible, non-invasive methods to detect hepatic steatosis. Currently, liver biopsy and magnetic resonance imaging proton density fat fraction are considered reference standards for diagnosing hepatic steatosis; however, their invasiveness and limited accessibility limit their widespread use. Ultrasonography (US) is a promising alternative owing to its cost-effectiveness and widespread accessibility. Recently, quantitative US techniques have been developed and commercialized by several vendors to measure steatosis by detecting changes in various acoustic properties associated with hepatic steatosis, making it readily accessible. Controlled attenuation parameter (CAP), which evaluates hepatic steatosis using the attenuation of the US beam, is the most widely studied algorithm as a non-imaging technique. Several other algorithms are also available on B-mode ultrasound systems, and their diagnostic performance is comparable to or better than that of the CAP. Therefore, we aimed to review current US-based methods for detecting and grading hepatic steatosis, discussing their diagnostic performance and utilization.

Role of Resmetirom, a Liver-Directed, Thyroid Hormone Receptor Beta-Selective Agonist, in Managing Nonalcoholic Steatohepatitis: A Systematic Review and Meta-Analysis

BackgroundResmetirom, a liver-directed, thyroid hormone receptor beta-selective agonist, has recently been approved to treat nonalcoholic steatohepatitis (NASH). This meta-analysis aimed to summarize the efficiency and safety of resmetirom in treating NASH. MethodsElectronic databases were searched for randomized controlled trials (RCTs) of resmetirom vs placebo in patients with NASH. The primary outcomes were the changes from baseline in hepatic fat content, liver histology, including NASH resolution, and noninvasive markers of hepatic fibrosis. ResultsThree randomized controlled trials (n = 2231) met the inclusion criteria. Compared to placebo, resmetirom achieved greater reductions from baseline in hepatic fat content assessed by magnetic resonance imaging proton density fat fraction (for resmetirom 80 mg: MD −27.76% [95%CI: −32.84, −22.69]; for resmetirom 100 mg: MD −36.01% [95%CI: −41.54, −30.48]; P < .00001 for both) and FibroScan controlled attenuation parameter (for resmetirom 80 mg: MD −21.45 dBm [95%CI: −29.37, −13.52]; for resmetirom 100 mg: MD −25.51 dBm [95%CI: −33.53, −17.49]; P < .00001 for both). Resmetirom 80 mg outperformed placebo in NASH resolution and ≥2-point nonalcoholic fatty liver disease activity score reduction. Moreover, resmetirom 80 mg and 100 mg were superior to placebo in cytokeratin-18 (M30) reduction. Greater reductions in liver enzymes, lipids, and reverse triiodothyronine were observed in the resmetirom arms with no impact on triiodothyronine. Nausea and diarrhea were more common with resmetirom than with placebo; other adverse events were comparable. ConclusionResmetirom improves hepatic fat content, liver enzymes, and fibrosis biomarkers in NASH patients. Resmetirom generally does not affect thyroid function and is well-tolerated.

“Fish head” sign on magnetic resonance imaging in knee synovitis – An observational pilot study

Objectives: Synovitis, characterized by joint inflammation, has various causes, including inflammatory, infectious, degenerative, traumatic, hemorrhagic, and neoplastic origins. Early detection is essential, and magnetic resonance imaging (MRI) plays a vital role in identifying synovial diseases before they lead to irreversible joint damage. It provides characterization and non-invasive monitoring of synovial changes. This study introduces and describes the novel “fish head” sign, a unique identifier of early knee synovitis on MRI. Materials and Methods: We conducted a retrospective analysis of 50 MRI cases of patients with rheumatoid arthritis (RA)-related synovitis who were referred to our clinic due to knee pain. The primary aim was to uncover insights into the “fish head” sign, a unique imaging feature observed on sagittal views of the lateral meniscus using proton density (PD)-weighted fat-suppressed sequences. Results: Within our cohort of 50 patients, 20 displayed the fish head sign on MRI, whereas 30 did not exhibit this sign. 17/20 of these patients had mild synovitis, 1/20 patients had moderate synovitis, and 2/20 patients had severe synovitis. Fourteen patients with synovitis did not demonstrate the sign. Conclusion: Our study introduces the “fish head” sign observed in PD MRI images of early knee synovitis among patients with RA. This unique sign has the potential to serve as a diagnostic tool or adjunct for patients with synovitis of the knee, reducing the need for contrast-enhanced imaging. This discovery offers valuable insights into the field of synovitis assessment, imaging, and diagnosis.

A prospective study on the prevalence of at-risk MASH in patients with type 2 diabetes mellitus in the United States.

There are limited data on the prevalence and treatment of at-risk metabolic dysfunction-associated steatohepatitis (MASH) among patients with type 2 diabetes (T2DM) in the United States. To estimate the prevalence of at-risk MASH in a prospectively recruited cohort of adults with T2DM using new nomenclature endorsed by multiple societies. This prospective study enrolled adults aged ≥50 with T2DM from primary care and endocrinology clinics in southern California from 2016 to 2023. Metabolic dysfunction-associated steatotic liver disease (MASLD) was defined by an magnetic resonance imaging proton density fat fraction ≥5% and at least one metabolic risk factor without any other chronic liver disease or secondary cause for hepatic steatosis. We included 530 adult patients with T2DM. The mean (±SD) age and body mass index (BMI) were 64.4 (±8.1) years and 31.5 (±6.1) kg/m2, respectively. Among patients with T2DM, the prevalence of MASLD, at-risk MASH and cirrhosis was 69.6%, 13.6% and 6.8%, respectively. Among patients with co-existing T2DM and obesity, the prevalence of MASLD, at-risk MASH and cirrhosis was 77.8%, 15.9% and 9.0%, respectively, and was higher than in participants without obesity (p < 0.0001, 0.0543 and 0.0128, respectively). Among adults aged ≥50 years with T2DM, the prevalence of MASLD, at-risk MASH and cirrhosis is high, posing a significant risk for liver-related morbidity and mortality. Approximately 14% of patients with T2DM may be candidates for pharmacologic therapies specific to MASH-related fibrosis.

Automated Liver Volumetry and Hepatic Steatosis Quantification with Magnetic Resonance Imaging Proton Density Fat Fraction

BackgroundPreoperative imaging evaluation of liver volume and hepatic steatosis for the donor affects transplantation outcomes. However, computed tomography (CT) for liver volumetry and magnetic resonance spectroscopy (MRS) for hepatic steatosis are time consuming. Therefore, we investigated the correlation of automated 3D-multi-echo-Dixon sequence magnetic resonance imaging (ME-Dixon MRI) and its derived proton density fat fraction (MRI-PDFF) with CT liver volumetry and MRS hepatic steatosis measurements in living liver donors. MethodsThis retrospective cross-sectional study was conducted from December 2017 to November 2022. We enrolled donors who received a dynamic CT scan and an MRI exam within 2 days. First, the CT volumetry was processed semiautomatically using commercial software, and ME-Dixon MRI volumetry was automatically measured using an embedded sequence. Next, the signal intensity of MRI-PDFF volumetric data was correlated with MRS as the gold standard. ResultsWe included the 165 living donors. The total liver volume of ME-Dixon MRI was significantly correlated with CT (r = 0.913, p < 0.001). The fat percentage measured using MRI-PDFF revealed a strong correlation between automatic segmental volume and MRS (r = 0.705, p < 0.001). Furthermore, the hepatic steatosis group (MRS ≥ 5%) had a strong correlation than the non–hepatic steatosis group (MRS < 5%) in both volumetric (r = 0.906 vs. r = 0.887) and fat fraction analysis (r = 0.779 vs. r = 0.338). ConclusionAutomated ME-Dixon MRI liver volumetry and MRI-PDFF were strongly correlated with CT liver volumetry and MRS hepatic steatosis measurements, especially in donors with hepatic steatosis.

Velacur ACE outperforms FibroScan CAP for diagnosis of MASLD.

As the prevalence of metabolic dysfunction-associated steatotic liver disease increases, it is imperative to have noninvasive alternatives to liver biopsy. Velacur offers a non-invasive, point-of-care ultrasound-based method for the assessment of liver stiffness and attenuation. The aim of this study was to perform a head-to-head comparison of liver stiffness and liver fat determined by Velacur and FibroScan using MRI-based measurements as the reference standard. This prospective cross-sectional study included 164 adult participants with well-characterized metabolic dysfunction-associated steatotic liver disease. Patients underwent a research exam including Velacur, FibroScan and contemporaneous magnetic resonance elastography, and magnetic resonance imaging proton density fat fraction (MRI-PDFF) scans. The primary outcome was the presence of advanced fibrosis (>F2) as measured by magnetic resonance elastography and the presence of liver fat (>5%) as measured by MRI-PDFF. The mean age and body mass index were 57±12 years and 30.6±4.8kg/m2, respectively. The mean liver stiffness on magnetic resonance elastography was 3.22±1.39kPa and the mean liver fat on MRI-PDFF was 14.2±8%. The liver stiffness assessments by Velacur and FibroScan were similar for the detection of advanced fibrosis (AUC 0.95 vs. 0.97) and were not statistically different (p=0.43). Velacur was significantly better than FibroScan (AUC 0.94 vs. 0.79, p=0.01), for the detection of MRI-PDFF >5% (diagnosis of metabolic dysfunction-associated liver disease). Velacur was superior to FibroScan for liver fat detection with MRI-PDFF as the reference. Velacur and FibroScan were not statistically different for liver stiffness assessment as defined by magnetic resonance elastography.

Correlation between magnetic resonance imaging proton density fat fraction (MRI-PDFF) and liver biopsy to assess hepatic steatosis in obesity

Obesity is highly associated with Non-alcoholic fatty liver disease (NAFLD) and increased risk of liver cirrhosis and liver cancer-related death. We determined the diagnostic performance of the complex-based chemical shift technique MRI-PDFF for quantifying liver fat and its correlation with histopathologic findings in an obese population within 24 h before bariatric surgery. This was a prospective, cross-sectional, Institutional Review Board-approved study of PDFF-MRI of the liver and MRI-DIXON image volume before bariatric surgery. Liver tissues were obtained during bariatric surgery. The prevalence of NAFLD in the investigated cohort was as high as 94%. Histologic hepatic steatosis grades 0, 1, 2, and 3 were observed in 3 (6%), 25 (50%), 14 (28%), and 8 (16%) of 50 obese patients, respectively. The mean percentages of MRI-PDFF from the anterior and posterior right hepatic lobe and left lobe vs. isolate left hepatic lobe were 15.6% (standard deviation [SD], 9.28%) vs. 16.29% (SD, 9.25%). There was a strong correlation between the percentage of steatotic hepatocytes and MRI-PDFF in the left hepatic lobe (r = 0.82, p < 0.001) and the mean value (r = 0.78, p < 0.001). There was a strong correlation between MRI-derived subcutaneous adipose tissue volume and total body fat mass by dual-energy X-ray absorptiometry, especially at the L2–3 and L4 level (r = 0.85, p < 0.001). MRI-PDFF showed good performance in assessing hepatic steatosis and was an excellent noninvasive technique for monitoring hepatic steatosis in an obese population.

Aspirin for Metabolic Dysfunction–Associated Steatotic Liver Disease Without Cirrhosis

ImportanceAspirin may reduce severity of metabolic dysfunction–associated steatotic liver disease (MASLD) and lower the incidence of end-stage liver disease and hepatocellular carcinoma, in patients with MASLD. However, the effect of aspirin on MASLD is unknown.ObjectiveTo test whether low-dose aspirin reduces liver fat content, compared with placebo, in adults with MASLD.Design, Setting, and ParticipantsThis 6-month, phase 2, randomized, double-blind, placebo-controlled clinical trial was conducted at a single hospital in Boston, Massachusetts. Participants were aged 18 to 70 years with established MASLD without cirrhosis. Enrollment occurred between August 20, 2019, and July 19, 2022, with final follow-up on February 23, 2023.InterventionsParticipants were randomized (1:1) to receive either once-daily aspirin, 81 mg (n = 40) or identical placebo pills (n = 40) for 6 months.Main Outcomes and MeasuresThe primary end point was mean absolute change in hepatic fat content, measured by proton magnetic resonance spectroscopy (MRS) at 6-month follow-up. The 4 key secondary outcomes included mean percentage change in hepatic fat content by MRS, the proportion achieving at least 30% reduction in hepatic fat, and the mean absolute and relative reductions in hepatic fat content, measured by magnetic resonance imaging proton density fat fraction (MRI-PDFF). Analyses adjusted for the baseline value of the corresponding outcome. Minimal clinically important differences for study outcomes were not prespecified.ResultsAmong 80 randomized participants (mean age, 48 years; 44 [55%] women; mean hepatic fat content, 35% [indicating moderate steatosis]), 71 (89%) completed 6-month follow-up. The mean absolute change in hepatic fat content by MRS was −6.6% with aspirin vs 3.6% with placebo (difference, −10.2% [95% CI, −27.7% to −2.6%]; P = .009). Compared with placebo, aspirin treatment significantly reduced relative hepatic fat content (−8.8 vs 30.0 percentage points; mean difference, −38.8 percentage points [95% CI, −66.7 to −10.8]; P = .007), increased the proportion of patients with 30% or greater relative reduction in hepatic fat (42.5% vs 12.5%; mean difference, 30.0% [95% CI, 11.6% to 48.4%]; P = .006), reduced absolute hepatic fat content by MRI-PDFF (−2.7% vs 0.9%; mean difference, −3.7% [95% CI, −6.1% to −1.2%]; P = .004]), and reduced relative hepatic fat content by MRI-PDFF (−11.7 vs 15.7 percentage points; mean difference, −27.3 percentage points [95% CI, −45.2 to −9.4]; P = .003). Thirteen participants (32.5%) in each group experienced an adverse event, most commonly upper respiratory tract infections (10.0% in each group) or arthralgias (5.0% for aspirin vs 7.5% for placebo). One participant randomized to aspirin (2.5%) experienced drug-related heartburn.Conclusions and RelevanceIn this preliminary randomized clinical trial of patients with MASLD, 6 months of daily low-dose aspirin significantly reduced hepatic fat quantity compared with placebo. Further study in a larger sample size is necessary to confirm these findings.Trial RegistrationClinicalTrials.gov Identifier: NCT04031729

Protocol of quantitative ultrasound techniques for noninvasive assessing of hepatic steatosis after bariatric surgery.

Roux-en-Y gastric bypass surgery can effectively improve steatosis, necroinflammatory activity, and hepatic fibrosis in individuals diagnosed with morbid obesity or nonalcoholic steatohepatitis (NASH). Common methods such as body mass index (BMI) to evaluate the postoperative effect of clinical bariatric surgery cannot differentiate subcutaneous fats from visceral fats and muscles. Several Quantitative ultrasound (QUS)-based approaches have been developed to quantify hepatic steatosis. QUS techniques (tissue attenuation imaging (TAI), tissue scatter distribution imaging (TSI)) from radio frequency (RF) data analysis as a means for the detection and grading of hepatic steatosis has been posited as an objective and noninvasive approach. The implementation and standardization of QUS techniques (TAI, TSI) in assessing hepatic steatosis quantitatively after bariatric surgery is of high-priority. Our study is aimed to assess hepatic steatosis with QUS techniques (TAI, TSI) in morbidly obese individuals before and after bariatric surgery, and to compare with anthropometric measurements, laboratory assessments and other imaging methods. The present investigation, a self-discipline examination of navigational capacity devoid of visual cues, is designed as a single-site, forward-looking evaluation of efficacy with the imprimatur of the institutional review board. The duration of the study has been provisionally determined to span from 1 January 2023 through 31 December 2025. Our cohort shall encompass one hundred participants, who was scheduled to undergo Roux-en-Y gastric bypass (RYGB) at Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine. All patients will undergo anthropometric measurements, blood-based biochemical analyses, ultrasonic examination and magnetic resonance imaging proton density fat fraction (MRI-PDFF). The primary endpoint is the analysis of evaluating the efficacy of QUS techniques assessing hepatic steatosis compared to other methods before and after bariatric surgery. Prior to the fomal study, we recruited 21 obese Chinese participants who received ultrasonic examination (TAI, TSI) and MRI-PDFF. AC-TAI showed moderate correlations with MRI-PDFF (adjusted r = 0.632; P < 0.05). For MRI-PDFF ≥10%, SC-TSI showed moderate correlations with MRI-PDFF (adjusted r = 0.677; P < 0.05). Our pre-experiment results signified that using QUS techniques for postoperative evaluation of bariatric surgery is promising. QUS techniques will be signed a widespread availability, real-time functionality, and low-cost approach for assessing hepatic steatosis before and after bariatric surgery in obese individuals, thus is capable for subsequent scale-up liver fat quantification. The present research endeavor has been bestowed with the imprimatur of the Ethics Committee of the Hospital, as indicated by its Approval Number: 2023-KY-015. In due course, upon completion of the study, we intend to disseminate our findings by publishing them in a suitable academic journal, thereby facilitating their widespread utilization. The trial is duly registered with the Chinese Clinical Trial Registry, and with a unique Trial Registration Number, ChiCTR2300069892, approved on March 28, 2023.

Kidney and liver fat accumulation: from imaging to clinical consequences.

Recent studies indicate that accumulation of adipose tissue in various organs such as liver and kidney may contribute to the pathophysiology of metabolic syndrome. We aim to investigate the association between kidney and liver adipose tissue accumulation, assessed by the magnetic resonance imaging (MRI) proton density fat fraction technique, along with its relation to clinical and biochemical parameters. We included 51 volunteers with phenotypical features of metabolic syndrome (mean age = 34years, mean body-mass index = 26.4kg/m2) in our study in which liver and kidney adipose tissue accumulation was assessed via MRI-proton density fat fraction along with multiple other clinical and biochemical parameters such as estimated glomerular filtration rate (eGFR), urine albumin-to-creatinine ratio, serum lipid profile, liver function tests and body-mass index (BMI). Our results from the univariate linear regression analysis indicate that both the kidney and liver scores were positively correlated with markers such as BMI, urine albumin-to-creatinine ratio, triglycerides (p < 0.001) and negatively correlated with eGFR (p < 0.05). In multivariate analysis, urine albumin-to-creatinine ratio (p < 0.05), triglycerides (p < 0.01), eGFR (p < 0.05) and BMI (p < 0.001) were found to be independently associated with kidney and liver fat accumulation, respectively (R2 = 0.64; R2 = 0.89). There was also a positive correlation between kidney and liver fat accumulation. We have found a significant association between adipose tissue accumulation in liver and kidney and the parameters of metabolic syndrome. Moreover, the presence of a strong association between kidney and liver fat accumulation and kidney function parameters such as urine albumin-to-creatinine ratio and eGFR may be an indicator of the clinical significance of parenchymalfat accumulation.

Prospective Comparison of Attenuation Imaging and Controlled Attenuation Parameter for Liver Steatosis Diagnosis in Patients With Nonalcoholic Fatty Liver Disease and Type 2 Diabetes

Background and aimsSimilarly to the controlled attenuation parameter (CAP), the ultrasound-based attenuation imaging (ATI) can quantify hepatic steatosis. We prospectively compared the performance of ATI and CAP for the diagnosis of hepatic steatosis in patients with type 2 diabetes (T2D) and nonalcoholic fatty liver disease (NAFLD) using histology and magnetic resonance imaging proton density fat fraction (MRI-PDFF) as references. MethodsPatients underwent ATI and CAP measurement, MRI, and biopsy on the same day. Steatosis was classified as S0, S1, S2, and S3 on histology (<5%, 5-33%, 33-66%, and >66%, respectively) while the thresholds of 6.4%, 17.4%, and 22.1%, respectively, were used for MRI-PDFF. The area under the curve (AUC) of ATI and CAP was compared using a DeLong test. ResultsSteatosis could be evaluated in 191 and 187 patients with liver biopsy and MRI-PDFF, respectively.For MRI–PDFF steatosis the AUC of ATI and CAP were 0.86 (95%C.I. 0.81–0.91) vs 0.69 (95%C.I. 0.62-0.75) for S0 vs S1-S3 (p=0.02) and 0.71 (95%C.I. 0.64–0.77) vs 0.69 (95%C.I. 0.61-0.75) for S0-S1 vs S2-S3 (p=0.60), respectively.For histological steatosis the AUC of ATI and CAP were 0.92 (95%C.I. 0.87-0.95) vs. 0.95 (95%C.I. 0.91-0.98) for S0 vs S1-S3 (p=0.64) and 0.79 (95%C.I. 0.72-0.84) vs. 0.76 (95%C.I. 0.69–0.82) for S0-S1 vs S2-S3 (p=0.61), respectively. ConclusionATI may be used as an alternative to CAP for the diagnosis and quantification of steatosis, in patients with T2D and NAFLD.

Diagnostic value of FibroTouch in identifying hepatic steatosis in NAFLD with MRI-PDFF as the reference standard.

To estimate the performance of the FibroTouch-based ultrasound attenuation parameter (UAP) for assessing hepatic steatosis in nonalcoholic fatty liver disease (NAFLD), with magnetic resonance imaging proton density fat fraction (MRI-PDFF) as the reference standard. This prospective, cross-sectional study included 275 individuals in the training group and 110 individuals in the validation group, all of whom completed a standardized research visit, laboratory tests, MRI-PDFF, and UAP measurements over 1 month. Pearson correlation coefficient and Bland-Altman analysis were used to assess the agreement between UAP and MRI-PDFF for the detection of hepatic steatosis. The diagnostic value of UAP was evaluated by the area under the receiver operating characteristic (ROC) curve (AUROC). Confounding factors to UAP performance were identified by ROC curves and regression analyses. The AUROC of UAP for detecting MRI-PDFF at ≥5%, ≥10%, and ≥20% were 0.95 (95% confidence interval [CI] 0.92-0.97), 0.86 (95% CI 0.81-0.90), and 0.90 (95% CI 0.86-0.93), respectively, and their optimal thresholds were 259, 274, and 295 dB/m, respectively. The UAP measurements had higher diagnostic accuracy in participants with lower waist circumference (≤90 cm for men and ≤80 cm for women) compared to those with higher waist circumference (AUROC values: 0.97 vs 0.84, P < 0.05). Bland-Altman analysis showed good agreement between UAP and MRI-PDFF (bias 0.00021). According to established regression analyses, hepatic steatosis could be accurately diagnosed using UAP estimation. FibroTouch-UAP has a high diagnostic potential for hepatic steatosis in NAFLD patients and helps clinical assessment and monitoring.

Potential of MRI (Magnetic Resonance Imaging) Proton Density Fat Fraction for the Assessment of Liver Disorders

Proton density fat fraction MRI is a special MRI method used to evaluate liver disorders, especially in terms of assessing fat accumulation in the liver. PDFF MRI is based on the principle of magnetic resonance of hydrogen nuclei in the human body. Our bodies contain many hydrogen atoms, mainly in the form of water and fat. These hydrogen atoms will give different signals in response to magnetic fields and radiofrequency waves. Liver disorders, such as steatosis or fatty liver, are characterized by the accumulation of fat in liver cells. The literature search process was carried out on various databases (PubMed, Web of Sciences, EMBASE, Cochrane Libraries, and Google Scholar) regarding the Potential of MRI (magnetic resonance imaging) proton density fat fraction for the assessment of liver disorders. This study follows the preferred reporting items for systematic reviews and meta-analysis (PRISMA) recommendations. Proton Density Fat Fraction (PDFF) MRI is a medical imaging technique that focuses on the magnetic resonance of hydrogen nuclei in the human body. This is a very effective method in the assessment of liver disorders related to fat accumulation, such as steatosis or fatty liver. PDFF MRI has very high accuracy in measuring the amount of fat in the liver, even in small amounts, thus providing very precise information about the level of fat accumulation.

Plasma ceramides are associated with MRI-based liver fat content but not with noninvasive scores of liver fibrosis in patients with type 2 diabetes

BackgroundThere is growing evidence that ceramides play a significant role in the onset and progression of non-alcoholic fatty liver disease (NAFLD), a highly prevalent condition in patients with type 2 diabetes associated with hepatic and cardiovascular events. However, the relationship between plasma ceramide levels and NAFLD severity in type 2 diabetes remains unclear. The main purpose of the present study was to investigate whether circulating levels of ceramides in patients with type 2 diabetes are associated with liver steatosis assessed by the highly accurate magnetic resonance imaging proton density fat fraction (MRI-PDFF). The secondary objective was to assess the relationship between plasma ceramides and noninvasive scores of liver fibrosis.MethodsIn this cross-sectional single-center study, plasma concentrations of 7 ceramides were measured by liquid chromatography-mass spectrometry in 255 patients with type 2 diabetes (GEPSAD cohort). Liver fat content was assessed by MRI-PDFF, and noninvasive scores of liver fibrosis (i.e. Fibrosis-4 index, NAFLD Fibrosis Score, FibroTest® and Fibrotic NASH Index) were calculated. A validation cohort of 80 patients with type 2 diabetes was also studied (LIRA-NAFLD cohort).ResultsLiver steatosis, defined as a liver fat content > 5.56%, was found in 62.4 and 82.5% of individuals with type 2 diabetes in the GEPSAD and LIRA-NAFLD cohorts, respectively. In GEPSAD, MRI-PDFF-measured liver fat content was positively associated with plasma levels of total ceramides (r = 0.232, p = 0.0002), and 18:0, 20:0, 22:0 and 24:0 ceramides in univariate analysis (p ≤ 0.0003 for all). In multivariate analysis, liver fat content remained significantly associated with total ceramides (p = 0.001), 18:0 (p = 0.006), 22:0 (p = 0.0009) and 24:0 ceramides (p = 0.0001) in GEPSAD, independently of age, diabetes duration, body mass index and dyslipidemia. Overall, similar relationship between plasma ceramides and liver fat content was observed in the LIRA-NAFLD validation cohort. No significant association was found between plasma ceramides and noninvasive scores of fibrosis after adjustment for age in both cohorts.ConclusionsPlasma ceramide levels are associated with liver steatosis in patients with type 2 diabetes, independently of traditional risk factors for NAFLD. The independent association between plasma ceramides and liver steatosis adds new insights regarding the relationship between ceramides and NAFLD in type 2 diabetes.

Prevalence, distribution, and hepatic fibrosis burden of the different subtypes of steatotic liver disease in primary care settings.

In relation to the new umbrella terminology for steatotic liver disease (SLD), we aimed to elucidate the prevalence, distribution, and clinical characteristics of the SLD subgroups in the primary care setting. We retrospectively collected data from 2535 individuals who underwent magnetic resonance elastography and MRI proton density fat fraction during health checkups in 5 primary care health promotion clinics. We evaluated the presence of cardiometabolic risk factors according to predefined criteria and divided all the participants according to the new SLD classification. The prevalence of SLD was 39.13% in the total cohort, and 95.77% of the SLD cases had metabolic dysfunction (one or more cardiometabolic risk factors). The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) was 29.51%, with those of metabolic dysfunction and alcohol associated steatotic liver disease (MetALD) and alcohol-associated liver disease (ALD) at 7.89% and 0.39%, respectively. According to the old criteria, the prevalence of NAFLD was 29.11%, and 95.80% of the NAFLD cases fulfilled the new criteria for MASLD. The distribution of SLD subtypes was highest for MASLD, at 75.40%, followed by MetALD at 20.06%, cryptogenic SLD at 3.33%, and ALD at 1.01%. The MetALD group had a significantly higher mean magnetic resonance elastography than the MASLD or ALD group. Almost all the patients with NAFLD met the new criteria for MASLD. The fibrosis burden of the MetALD group was higher than those of the MASLD and ALD groups.

The Calculation and Evaluation of an Ultrasound-Estimated Fat Fraction in Non-Alcoholic Fatty Liver Disease and Metabolic-Associated Fatty Liver Disease

We aimed to develop a non-linear regression model that could predict the fat fraction of the liver (UEFF), similar to magnetic resonance imaging proton density fat fraction (MRI-PDFF), based on quantitative ultrasound (QUS) parameters. We measured and retrospectively collected the ultrasound attenuation coefficient (AC), backscatter-distribution coefficient (BSC-D), and liver stiffness (LS) using shear wave elastography (SWE) in 90 patients with clinically suspected non-alcoholic fatty liver disease (NAFLD), and 51 patients with clinically suspected metabolic-associated fatty liver disease (MAFLD). The MRI-PDFF was also measured in all patients within a month of the ultrasound scan. In the linear regression analysis, only AC and BSC-D showed a significant association with MRI-PDFF. Therefore, we developed prediction models using non-linear least squares analysis to estimate MRI-PDFF based on the AC and BSC-D parameters. We fitted the models on the NAFLD dataset and evaluated their performance in three-fold cross-validation repeated five times. We decided to use the model based on both parameters to calculate UEFF. The correlation between UEFF and MRI-PDFF was strong in NAFLD and very strong in MAFLD. According to a receiver operating characteristics (ROC) analysis, UEFF could differentiate between &lt;5% vs. ≥5% and &lt;10% vs. ≥10% MRI-PDFF steatosis with excellent, 0.97 and 0.91 area under the curve (AUC), accuracy in the NAFLD and with AUCs of 0.99 and 0.96 in the MAFLD groups. In conclusion, UEFF calculated from QUS parameters is an accurate method to quantify liver fat fraction and to diagnose ≥5% and ≥10% steatosis in both NAFLD and MAFLD. Therefore, UEFF can be an ideal non-invasive screening tool for patients with NAFLD and MAFLD risk factors.

The metabolic influence of duodenal mucosal resurfacing for nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD) or nonalcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease worldwide with decreased life expectancy. Duodenal mucosal resurfacing (DMR) has been associated with metabolic improvement in glycemic and hepatic parameters of type 2 diabetes, but the metabolic impact of DMR for NAFLD/NASH remains inconclusive. We conducted a meta-analysis to investigate metabolic effects of DMR in patients with NAFLD/NASH. Three major bibliographic databases were reviewed for enrollment of trials prior to January 28, 2022. We included adults with biopsy-proven NAFLD/NASH or liver magnetic resonance imaging proton density fat fraction (MRI-PDFF) >5% at baseline and focused on the metabolic difference of MRI-PDFF at 12 weeks, and HbA1c or homeostatic model assessment index for insulin resistance (HOMA-IR) at 24 weeks. Two studies involved a total of 67 participants for analysis. When compared with pre-intervention status, mean difference of MRI-PDFF, HbA1c, and HOMA-IR after DMR were -2.22 (95% CI: -12.79~8.34), -0.32% (95% CI: -0.80~0.16), and 0.15 (95% CI: -5.11~5.41) without statistical significance. For patients with NAFLD/NASH, DMR has the trend to improve liver fat at 12 weeks, and glycemic control in terms of HbA1c level at 24 weeks based on a very low quality of evidence.

Artifact Reduction Proton Density Magnetic Resonance Imaging Can Better Visualize Unicompartmental Knee Arthroplasty Components but Does Not Improve Measurement Accuracy at 3T: An In Vitro Phantom Study.

Background There are no studies of the efficacy of slice encoding for metal artifact correction (SEMAC) magnetic resonance imaging (MRI) at 3T for patients following unicompartmental knee arthroplasty (UKA), although the artifact is expected to increase compared with 1.5T. Purpose To clarify whether SEMAC MRI can better visualize UKA components and improve measurement accuracy at 3T MRI. Materials and methods The phantom consisted of femoral and tibial standard UKA components embedded in agarose gel. The MR images were scanned on a 3T MR system including proton density (PD) MR images. Six orthopedic surgeons blinded to the size and details of the components independently scored the diagnostic value for measurement and measured the lengths of the femoral posterior condyle, femoral peg, anterior-posterior (AP) tibial component, medial-lateral (ML) tibial component, and tibial keel, with and without SEMAC. Visualization scores were stratified as 0 = definitely nondiagnostic, 1 = probably nondiagnostic, 2 = possibly diagnostic, 3 = probably diagnostic, and 4 = definitely diagnostic. In addition, the differences between actual length and 95% confidence intervals of five measurement points were analyzed. Results The diagnostic values of the posterior condyle (2.0; 1.5 vs. 0; 0) and femoral peg (1.5; 1.0 vs. 0; 0) were significantly better in SEMAC-PD MRI than in non-SEMAC-PD MRI (P<0.05). On the other hand, there were no significant differences in the visualizations of AP, ML, and keel of the tibial components. Measurements of the femoral posterior condyle and tibial keel approached the actual length, but were not involved within the 95% confidence interval(actual length, 19.4 mm vs. 95% CI, 15.7-19.1 mm). Conclusion A significant reduction of metal artifacts was observed only around the femoral component in SEMAC-PD MRI. Despite artifact reduction, this sequence did not result in better visualization for measurement.

Ultrasound Shear Wave Attenuation Imaging for Grading Liver Steatosis in Volunteers and Patients With Non-alcoholic Fatty Liver Disease: A Pilot Study.

The aims of the work described here were to assess shear wave attenuation (SWA) in volunteers and patients with non-alcoholic fatty liver disease (NAFLD) and compare its diagnostic performance with that of shear wave dispersion (SWD), magnetic resonance imaging (MRI) proton density fat fraction (PDFF) and biopsy. Forty-nine participants (13 volunteers and 36 NAFLD patients) were enrolled. Ultrasound and MRI examinations were performed in all participants. Biopsy was also performed in patients. SWA was used to assess histopathology grades as potential confounders. The areas under curves (AUCs) of SWA, SWD and MRI-PDFF were assessed in different steatosis grades by biopsy. Youden's thresholds of SWA were obtained for steatosis grading while using biopsy or MRI-PDFF as the reference standard. Spearman's correlations of SWA with histopathology (steatosis, inflammation, ballooning and fibrosis) were 0.89, 0.73, 0.62 and 0.31, respectively. Multiple linear regressions of SWA confirmed the correlation with steatosis grades (adjusted R2 = 0.77, p < 0.001). The AUCs of MRI-PDFF, SWA and SWD were respectively 0.97, 0.99 and 0.94 for S0 versus ≥S1 (p > 0.05); 0.94, 0.98 and 0.78 for ≤S1 versus ≥S2 (both MRI-PDFF and SWA were higher than SWD, p < 0.05); and 0.90, 0.93 and 0.68 for ≤S2 versus S3 (both SWA and MRI-PDFF were higher than SWD, p < 0.05). SWA's Youden thresholds (Np/m/Hz) (sensitivity, specificity) for S0 versus ≥S1, ≤S1 versus ≥S2 and ≤S2 versus S3 were 1.05 (1.00, 0.92), 1.37 (0.96, 0.96) and 1.51 (0.83, 0.87), respectively. These values were 1.16 (1.00, 0.81), 1.49 (0.91, 0.82) and 1.67 (0.87, 0.92) when considering MRI-PDFF as the reference standard. In this pilot study, SWA increased with increasing steatosis grades, and its diagnostic performance was higher than that of SWD but equivalent to that of MRI-PDFF.