Fat Fraction Measurements Research Articles

Accuracy of Proton Density Fat Fraction Measurement Using Chemical Shift-encoded MRI with Fast Imaging Techniques

To investigate the accuracy of proton density fat fraction (PDFF) measurement using chemical shift-encoded MRI (CSE-MRI) with fast imaging techniques in a phantom. A 1.5T imaging system (Prodiva; Philips Healthcare) and PDFF phantom (Fat Fraction Phantom Model 300; Calimetrix) were used in this study. The acquisitions without fast imaging techniques (conventional acquisition), with parallel imaging in phase-encode direction (SENSE acquisition), with compressed sensing (CS-SENSE acquisition), and with parallel imaging in both phase-encode and slice-encode direction (Dual-SENSE acquisition) were performed. The following acceleration factors in SENSE and CS-SENSE acquisition were used: 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, and 8.0. For Dual-SENSE acquisition, the same acceleration factors (1.5, 2.0, 3.0, 4.0, 5.0) were set in each of the two directions. The relationships between reference PDFF values and PDFF measurements obtained using each acquisition were assessed using linear regression analysis and Bland-Altman analysis. According to the linear regression analysis, the slopes and intercepts of regression lines were from 0.87 to 1.02 and from 0.06% to 3.55%, respectively. According to Bland-Altman analysis, there were fixed bias between reference PDFF values and PDFF measurements obtained using SENSE acquisition with reduction factor 8.0 and Dual-SENSE acquisition with reduction factor 5.0. For CS-SENSE acquisition with reduction factor from 7.0 to 8.0, SENSE acquisition with reduction factor from 3.0 to 8.0, and Dual-SENSE acquisition with reduction factor from 2.0 to 5.0, some vials had ±1.5% or more errors between the reference PDFF values and PDFF measurements in the range of 0% to 50% PDFF. In CS-SENSE acquisition, the accuracy of PDFF measurement was maintained within 1.5% up to a reduction factor 6.0. The accuracy of PDFF measurement was maintained within 1.5% up to a reduction factor 2.0 in SENSE acquisition and a reduction factor 1.5 in Dual-SENSE acquisition.

Multi-parameter quantitative magnetic resonance imaging for early detecting skeletal muscle involvement and predicting functional decline in children with Becker muscular dystrophy.

The extreme clinical heterogeneity of children with Becker muscular dystrophy significantly poses a great challenge to accurately assess their disease status. To detect skeletal muscle involvement in children with Becker muscular dystrophy using multiple-parameter quantitative magnetic resonance imaging (qMRI), and to determine the preferred muscle site and qMRI biomarker. Fat fraction, T1, and T2 measurements were conducted in Becker muscular dystrophy (n=29) and healthy controls (n=23). North Star Ambulatory Assessment (NSAA) was performed in Becker muscular dystrophy. Group differences were compared by using the Mann-Whitney or Kruskal-Wallis test or a linear mixed-effect model. Receiver operating characteristic analysis with area under curve (AUC) was used to compare the diagnostic performance. Logistic regression was used to identify the predictor of functional decline. Both fat fraction and T2 were effective in detecting muscle involvement across different functional stages that were categorized by NSAA, with fat fraction in gluteus maximus demonstrating the most superior diagnostic performance (AUC range, 0.85-0.98). The combination of T2 and T1 enables a good diagnosis of no abnormal fat-infiltrated muscles (AUC=0.82). Overall, fat fraction in gluteus maximus exhibited the strongest negative correlation with the NSAA score (r=-0.69, P<0.01) and emerged as an independent risk factor for functional decline (odds ratio=1.12, P=0.02). Multi-parametric qMRI demonstrate effective capabilities for early detection of muscle involvement, with gluteus maximus being the preferred muscle site. Fat fraction in gluteus maximus may serve as a potential biomarker for predicting functional decline.

Spectrally selective and interleaved water imaging and fat imaging (siWIFI).

To develop a novel imaging sequence that independently acquires water and fat images while being inherently insensitive to motion. The new sequence, termed spectrally selective and interleaved water imaging and fat imaging (siWIFI), uses a narrow bandwidth RF pulse for selective excitation of water and fat separately. The interleaved acquisition method ensures that the obtained water and fat images are inherently coregistered. A radial sampling strategy further reduces motion-induced artifacts. Phantoms with lipid concentrations ranging from 0% to 50% were scanned to measure fat fraction. Moreover, healthy volunteers were scanned to assess the in vivo feasibility of fat fraction measurement at the hip, knee, and liver. In vivo fat fraction measurements were compared with those from vendor-provided iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) scans. Furthermore, a magnetization transfer (MT) preparation module was incorporated to demonstrate the feasibility of simultaneous measurement of fat fraction and MT ratio utilizing the siWIFI framework. The phantom fat fractions measured by siWIFI showed excellent correlation with lipid concentrations (R2 = 0.9995, p < 0.0001). In vivo studies demonstrated that the fat fractions obtained from siWIFI were comparable to those from IDEAL. Additionally, siWIFI demonstrates reduced motion artifacts from pulsatile flow in knee imaging compared to IDEAL scans and exhibits less sensitivity to respiratory motion in liver imaging compared to IDEAL scans without breath-hold. The knee imaging study demonstrated that MT-prepared siWIFI is capable of generating fat fraction and MT ratio maps simultaneously. The proposed siWIFI sequence allows selective water-fat imaging and quantification with reduced motion artifacts.

Ex Vivo Demonstration of a Novel Dual-Frequency Ultrasound Method for Quantitative Measurements of Liver Fat Content

ObjectiveThe rise in metabolic dysfunction–associated steatotic liver disease prevalence, closely linked with metabolic syndromes and obesity, demands accurate, cost-effective diagnostic methods for early-stage fat quantification in the liver. Here we demonstrate a novel dual-frequency ultrasound method that enables the quantitative measurement of liver fat fraction ex vivo and its correlation with actual fat content. MethodsA total of 24 Wistar rats were divided into four different groups, where three groups were given a high-fat diet for 2, 4, and 6 wk, and the last group was given a control diet for 6 wk. Livers were imaged with ultrasound ex vivo in a water bath with a dual-frequency ultrasound transducer and experimental imaging protocol implemented on the Verasonics Vantage research ultrasound scanner. Ultrasound data were post-processed to estimate the non-linear bulk elasticity parameter and the liver samples were analyzed with respect to fat fraction and triglycerides. ResultsRats given a high-fat diet had increased mean levels of liver fat compared with the control group. More importantly, correlation between the ultrasound-based estimation of the non-linear bulk elasticity parameter and fat fraction and triglycerides on an individual level was found to be strong (R2 = 0.81, p = 5.8 × 10-9 and R2 = 0.72, p = 3.6 × 10-7, respectively). ConclusionThis study demonstrates the potential of the novel dual-frequency ultrasound method for the quantitative measurement of liver fat fraction in excised rat livers, showing great promise for this method to become clinically relevant in the diagnosis and follow-up of patients with fatty liver disease.

Inverse association between lung function and nonalcoholic fatty liver disease: An observational and mendelian randomization study

Background and aimThe association between lung function with non-alcoholic fatty liver disease (NAFLD) in the general population remains unknown. We aimed to examine the association between lung function and NAFLD among the general population in an observational and Mendelian randomization (MR) study. Methods and results340, 253 participants without prior liver diseases were included from the UK Biobank. Of these, 30,397 participants had liver proton density fat fraction (PDFF) measurements by magnetic resonance image (MRI). Lung function parameters included forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC). The primary outcome was the presence of NAFLD, defined as a PDFF greater than 5.5%. The secondary outcome included incident severe NAFLD and severe liver diseases (including liver cirrhosis, liver failure, hepatocellular carcinoma and liver-related death), defined by the International Classification of Disease codes with different data sources. During a media follow-up duration of 9.3 years, 7335 (24.1%) the presence of NAFLD cases were documented. There was an inverse association of FEV1 (% predicted) (Per SD increment, adjusted OR = 0.91, 95%CI: 0.88–0.94) and FVC (% predicted) (Per SD increment, adjusted OR = 0.90, 95%CI: 0.87–0.92) with the presence of NAFLD. Similar results were found for incident severe NAFLD, severe liver disease, liver cirrhosis, liver failure and liver-related death. MR analyses showed that the genetically predicted FEV1 (adjusted OR = 0.63, 95%CI: 0.46–0.87) and FVC (adjusted OR = 0.69, 95%CI: 0.51–0.95) were both inversely associated with the presence of NAFLD. ConclusionsThere was an inverse causal relationship between lung function and NAFLD in the general population.

Test-retest reliability and follow-up of muscle magnetic resonance elastography in adults with and without muscle diseases.

We investigated the potential of magnetic resonance elastography (MRE) stiffness measurements in skeletal muscles as an outcome measure, by determining its test-retest reliability, as well as its sensitivity to change in a longitudinal follow-up study. We assessed test-retest reliability of muscle MRE in 20 subjects with (n=5) and without (n=15) muscle diseases and compared this to Dixon proton density fat fraction (PDFF) and volume measurements. Next, we measured MRE muscle stiffness in 21 adults with Becker muscular dystrophy (BMD) and 21 age-matched healthy controls at baseline, and after 9 and 18months. We compared two different methods of analysing MRE data in this study: 'Method A' used the stiffness maps generated by the Philips MRE software, and 'Method B' applied a custom-made procedure based on wavelength measurements on the MRE images. Intraclass correlation coefficients (ICC) of muscle stiffness ranged from good (0.83 for left vastus medialis, P<0.001) to poor (0.19 for right rectus femoris, P=0.212) for the examined thigh muscles with Method A, but we did not find a significant test-retest reliability with Method B (P>0.050 for all). The ICC of muscle PDFF and volume measurements was excellent (>0.90; P<0.001) for all muscles. At baseline, the average stiffness of all thigh muscles was significantly lower in adults with BMD than in controls for both Method A (-0.2kPa, P=0.025) and Method B (-0.6kPa, P<0.001). Regardless of which method was used, there was no significant difference in the evolution of muscle stiffness in patients and controls over 18months. Test-retest reliability of muscle MRE using a simple 2D technique was suboptimal, and did not reliably measure muscle stiffness changes in adults with BMD as compared with controls over 18months. While the results provide motivation for testing more advanced 3D MRE methods, we conclude that the simple 2D MRE implementation used in this study is not suitable as an outcome measure for characterizing thigh muscle in clinical trials.

Ultrasound-Derived Fat Fraction for Hepatic Steatosis Assessment: Prospective Study of Agreement With MRI PDFF and Sources of Variability in a Heterogeneous Population.

BACKGROUND. Metabolic dysfunction-associated steatotic liver disease is a growing global public health concern. Quantitative ultrasound measurements, such as ultrasound-derived fat fraction (UDFF), could provide noninvasive, cost-effective, and portable steatosis evaluation. OBJECTIVE. The purpose of this article was to evaluate utility of UDFF for steatosis assessment using proton density fat fraction (PDFF) as reference in patients undergoing liver MRI for heterogeneous indications and to assess UDFF variability. METHODS. This prospective study included a primary analysis of 187 patients (mean age, 53.8 years; 112 men, 75 women) who underwent 3-T liver MRI for any clinical indication from December 2020 to July 2021. Patients underwent investigational PDFF measurement, including determination of PDFFwhole-liver (mean PDFF of entire liver), and PDFFvoxel (PDFF in single voxel within right lobe, measured by MR spectroscopy), as well as investigational ultrasound with UDFF calculation (mean of five inter-costal measurements) within 1 hour after MRI. In a subanalysis, 21 of these patients underwent additional UDFF measurements 1, 3, and 5 hours after meal consumption. The study also included repeatability and reproducibility analysis of 30 patients (mean age, 26.3 years; 10 men, 20 women) who underwent clinical abdominal ultrasound between November 2022 and January 2023; in these patients, three operators sequentially performed UDFF measurements. RESULTS. In primary analysis, UDFF and PDFFwhole-liver measurements showed intra-class correlation coefficient (ICC) of 0.79. In Bland-Altman analysis, UDFF and PDFFvoxel measurements showed mean difference of 1.5% (95% CI, 0.6-2.4%), with 95% limits of agreement from -11.0% to 14.0%. UDFF measurements exhibited AUC for detecting PDFFvoxel at historic thresholds of 6.5% and greater, 17.4% and greater, and 22.1% and greater of 0.90, 0.95, and 0.95, respectively. In subanalysis, mean UDFF was not significantly different across time points with respect to meal consumption (p = .21). In repeatability and reproducibility analysis, ICC for intraoperator repeatability ranged from 0.98 to 0.99 and for interoperator reproducibility from 0.90 to 0.96. Visual assessment of patient-level data plots indicated increasing variability of mean UDFF measurements across operators and of intercostal measurements within individual patients with increasing steatosis. CONCLUSION. UDFF showed robust agreement with PDFF, diagnostic performance for steatosis grades, and intraoperator repeatability and interoperator reproducibility. Nonetheless, UDFF exhibited bias toward slightly larger values versus PDFF; intraoperator and interoperator variation increased with increasing steatosis. CLINICAL IMPACT. UDFF shows promise for steatosis assessment across diverse populations, although continued optimization remains warranted.

WED-343 Transducer reproducibility in liver ultrasound-derived fat fraction measurements

WED-343 Transducer reproducibility in liver ultrasound-derived fat fraction measurements

Dual-Energy CT muscle fat fraction as a new imaging biomarker of body composition and survival predictor in critically ill patients

ObjectiveTo analyze changes in the muscular fat fraction (FF) during immobilization at the intensive care unit (ICU) using dual-energy CT (DECT) and evaluate the predictive value of the DECT FF as a new imaging biomarker for morbidity and survival.MethodsImmobilized ICU patients (n = 81, 43.2% female, 60.3 ± 12.7 years) were included, who received two dual-source DECT scans (CT1, CT2) within a minimum interval of 10 days between 11/2019 and 09/2022. The DECT FF was quantified for the posterior paraspinal muscle by two radiologists using material decomposition. The skeletal muscle index (SMI), muscle radiodensity attenuation (MRA), subcutaneous-/ visceral adipose tissue area (SAT, VAT), and waist circumference (WC) were assessed. Reasons for ICU admission, clinical scoring systems, therapeutic regimes, and in-hospital mortality were noted. Linear mixed models, Cox regression, and intraclass correlation coefficients were employed.ResultsBetween CT1 and CT2 (median 21 days), the DECT FF increased (from 20.9% ± 12.0 to 27.0% ± 12.0, p = 0.001). The SMI decreased (35.7 cm2/m2 ± 8.8 to 31.1 cm2/m2 ± 7.6, p < 0.001) as did the MRA (29 HU ± 10 to 26 HU ± 11, p = 0.009). WC, SAT, and VAT did not change. In-hospital mortality was 61.5%. In multivariable analyses, only the change in DECT FF was associated with in-hospital mortality (hazard ratio (HR) 9.20 [1.78–47.71], p = 0.008), renal replacement therapy (HR 48.67 [9.18–258.09], p < 0.001), and tracheotomy at ICU (HR 37.22 [5.66–245.02], p < 0.001). Inter-observer reproducibility of DECT FF measurements was excellent (CT1: 0.98 [0.97; 0.99], CT2: 0.99 [0.96–0.99]).ConclusionThe DECT FF appears to be suitable for detecting increasing myosteatosis. It seems to have predictive value as a new imaging biomarker for ICU patients.Clinical relevance statementThe dual-energy CT muscular fat fraction appears to be a robust imaging biomarker to detect and monitor myosteatosis. It has potential for prognosticating, risk stratifying, and thereby guiding therapeutic nutritional regimes and physiotherapy in critically ill patients.Key PointsThe dual-energy CT muscular fat fraction detects increasing myosteatosis caused by immobilization.Change in dual-energy CT muscular fat fraction was a predictor of in-hospital morbidity and mortality.Dual-energy CT muscular fat fraction had a predictive value superior to established CT body composition parameters.

Assessing hepatic steatosis by magnetic resonance in potential living liver donors

To determine the accuracy of magnetic resonance imaging-proton density fat fraction (MRI-PDFF) measurements for detecting liver fat content in potential living liver donors and to compare these results using liver biopsy findings. A total of 139 living liver donors (men/women: 83/56) who underwent MRI between January 2017 and September 2021 were included in this analysis retrospectively. The PDFFs were measured using both MR spectroscopy (MRS) and chemical shift-based MRI (CS-MRI) for each donor in a blinded manner. Significant positive correlations were found between liver biopsy and MRS-PDFF and CS-MRI PDFF in terms of hepatic steatosis detection [r = 0.701, 95% confidence interval (CI): 0.604–0.798, r = 0.654, 95% CI: 0.544–0.765, P < 0.001, respectively). A weak level correlation was observed between liver biopsy, MRI methods, and vibration-controlled transient elastography attenuation parameters in 42 available donors. Based on receiver operating characteristic (ROC) analysis, MRS-PDFF and CS-MRI PDFF significantly distinguished >5% of histopathologically detected hepatic steatosis with an area under the ROC curve (AUC) of 0.837 ± 0.036 (P < 0.001, 95% CI: 0.766–0.907) and 0.810 ± 0.036 (P < 0.001, 95% CI: 0.739–0.881), respectively. The negative predictive values (NPVs) of MRS-PDFF and CS-MRI PDFF were 88.3% and 81.3%, respectively. In terms of distinguishing between clinically significant hepatic steatosis (≥10% on histopathology), the AUC of MRS-PDFF and CS-MRI were 0.871 ± 0.034 (P < 0.001 95% CI: 0.804–0.937) and 0.855 ± 0.036 (P < 0.001, 95% CI: 0.784–0.925), respectively. The NPVs of MRS-PDFF and CS-MRI were 99% and 92%, respectively. The methods of MRS-PDFF and CS-MRI PDFF provide a non-invasive and accurate approach for assessing hepatic steatosis in potential living liver donor candidates. These MRI PDFF techniques present a promising clinical advantage in the preoperative evaluation of living liver donors by eliminating the requirement for invasive procedures like liver biopsy.

Influence of Gd-EOB-DTPA on proton-density fat fraction in the liver using chemical shift-encoded magnetic resonance imaging at 3-T.

Non-alcoholic fatty liver disease (NAFLD) and its advanced stage, non-alcoholic steatohepatitis (NASH), have become increasingly prevalent owing to the rise in metabolic syndromes. Accurate assessment of hepatic fat deposition and inflammation is crucial for diagnosing and managing NAFLD/NASH. We investigated the influence of Gd-EOB-DTPA, (EOB) on proton-density fat fraction (PDFF) measurements using chemical shift-encoded magnetic resonance imaging (CSE-MRI) at 3-T. In total, 431 patients who underwent EOB contrast-enhanced MRI were included. PDFF measurements were obtained from pre- and post-contrast CSE-MRI. Linear regression and Bland-Altman analyses were performed to assess the correlation and agreement between pre- and post-EOB PDFF measurements. Relative enhancement (RE) of the liver was calculated as an EOB uptake index. There was a significant decrease in PDFF following EOB administration compared with the pre-contrast values (P < 0.0001), which was observed across all PDFF ranges (< 10% and ≥ 10%). Linear regression analysis revealed high correlation between pre- and post-EOB PDFF measurements. Bland-Altman analysis indicated a small bias between pre- and post-EOB PDFF values. Subgroup analysis based on RE showed a significant difference in ΔPDFF between patients with high RE (> 120%) and those with lower RE levels. EOB administration resulted in a slight decrease in PDFF measurements obtained using CSE-MRI at 3-T. We were able to generalize and clarify that the PDFF of the liver on 3D CSE-MRI at 3-T was slightly decreased after EOB administration as we used a larger group of patients compared to previous studies.

Multiparametric quantification and visualization of liver fat using ultrasound

ObjectivesSeveral ultrasound measures have shown promise for assessment of steatosis compared to traditional B-scan, however clinicians may be required to integrate information across the parameters. Here, we propose an integrated multiparametric approach, enabling simple clinical assessment of key information from combined ultrasound parameters. MethodsWe have measured 13 parameters related to ultrasound and shear wave elastography. These were measured in 30 human subjects under a study of liver fat. The 13 individual measures are assessed for their predictive value using independent magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF) measurements as a reference standard. In addition, a comprehensive and fine-grain analysis is made of all possible combinations of sub-sets of these parameters to determine if any subset can be efficiently combined to predict fat fraction. ResultsWe found that as few as four key parameters related to ultrasound propagation are sufficient to generate a linear multiparametric parameter with a correlation against MRI-PDFF values of greater than 0.93. This optimal combination was found to have a classification area under the curve (AUC) approaching 1.0 when applying a threshold for separating steatosis grade zero from higher classes. Furthermore, a strategy is developed for applying local estimates of fat content as a color overlay to produce a visual impression of the extent and distribution of fat within the liver. ConclusionIn principle, this approach can be applied to most clinical ultrasound systems to provide the clinician and patient with a rapid and inexpensive estimate of liver fat content.

Chemical shift-encoded MRI with compressed sensing combined with parallel imaging for proton density fat fraction measurement of the lumbar vertebral bone marrow.

We aimed to investigate the accuracy of proton density fat fraction (PDFF) measurement of the lumbar vertebral bone marrow using chemical shift-encoded magnetic resonance imaging (CSE-MRI) with compressed sensing combined with parallel imaging (CSPI). This study recruited a commercially available phantom, and 43 patients. Fully sampled data without CSPI and under-sampled data with CSPI acceleration factors of 2.4, 3.6, and 4.8 were acquired using a 1.5T imaging system. The relationships between PDFF measurements obtained with the no-CSPI acquisition and those obtained with each CSPI acquisition were assessed using Pearson correlation coefficient (r), linear regression analyses, and Bland-Altman analysis. The intra- and inter-observer variabilities of the PDFF measurements were evaluated using the intraclass correlation coefficient. PDFF measurements obtained with all acquisitions showed a significant correlation and strong agreement with the reference PDFF measurement of the phantom. PDFF measurements obtained using CSE-MRI with and without CSPI were positively correlated (all acquisitions: r = 0.99; P < .001). The mean bias was -0.31% to -0.17% with 95% limits of agreement within ±2.02%. The intra- and inter-observer agreements were excellent (intraclass correlation coefficient: 0.988 and 0.981, respectively). A strong agreement and positive correlation were observed between the PDFF measurements obtained using CSE-MRI with and without CSPI. PDFF measurement of the lumbar vertebral bone marrow using CSE-MRI with CSPI can be acquired with a maximum reduction of approximately 75% in the acquisition time compared with a fully sampled acquisition.

Hepatic steatosis using ultrasound-derived fat fraction: First technical and clinical evaluation.

To explore the technical and clinical evaluation of ultrasound-derived fat fraction (UDFF) measurement in adult patients in whom fatty liver was suspected. In this prospective study, 41 participants were initially enrolled in our hospital between October 2022 and December 2022 and received UDFF assessment using Siemens ACUSON Sequoia system equipped with DAX transducer. UDFF measurement was performed three times to obtain UDFF values from each imaging location (V hepatic segment and VIII hepatic segment) per participant, and the depth (skin-to-capsule distance) was automatically measured. The echogenicity of liver tissue in B mode ultrasound (BMUS) was compared to the normal kidney tissue, and fatty liver was graded as mild (Grade 1), moderate (Grade 2), and severe (Grade 3). The median of the acquired overall median UDFF values was used for statistical analysis. All ultrasound examinations were performed by one of two radiologists (with 20 and 10 years of liver ultrasound imaging experience). Finally, UDFF measurement was successfully performed on 38 participants to obtain valid values, including 21 men with a median age of 40.0 years (interquartile range [IQR]: 23.0 - 58.5) and 17 women with a median age of 60.0 years (IQR: 29.5 - 67.0). Fatty liver was diagnosed by BMUS features in 47.4% (18/38) participants. Among all participants, the median UDFF value was 7.0% (IQR: 4.0 - 15.6). A significant difference in UDFF values was found between participants with fatty liver and without fatty liver (U = 7.0, P < 0.001), and UDFF values elevated as the grade of the fatty liver increased (P < 0.001). The median UDFF values from the three UDFF measurements obtained during each ultrasound examination showed excellent agreement (ICC = 0.882 [95% confidence interval: 0.833 - 0.919]). The Spearman correlation of UDFF values in different depths was moderate, with a rs value of 0.546 (P < 0.001). No significant differences in UDFF values were found between V hepatic segment and VIII hepatic segment (U = 684.5, P = 0.697). UDFF provides a novel non-invasive imaging tool for hepatic steatosis assessment with excellent feasibility.

Evaluation of masticatory muscles in temporomandibular joint disorder patients using quantitative MRI fat fraction analysis-Could it be a biomarker?

Temporomandibular joint disorders (TMDs) are closely related to the masticatory muscles, but objective and quantitative methods to evaluate muscle are lacking. IDEAL-IQ, a type of chemical shift-encoded magnetic resonance imaging (CSE-MRI), can quantify the fat fraction (FF). The purpose of this study was to develop an MR IDEAL-IQ-based method for quantitative muscle diagnosis in TMD patients. A total of 65 patients who underwent 3 T MRI scans, including CSE-MRI sequences, were retrospectively included. MRI diagnoses and clinical data were reviewed. There were 19 patients in the normal group and 46 patients in the TMD group with unilateral disc displacement. The TMD group was subdivided into those with and without clenching. The right and left FF values of the masseter, medial, and lateral pterygoid muscles were measured twice by two oral radiologists on CSE-MRI, and the average value was used. FF measurements using CSE-MRI showed excellent intra- and inter-observer agreement (ICC > 0.889 for both). There were no statistically significant differences between the right and left FF values in the masseter, medial pterygoid, and lateral pterygoid of the normal group (p > 0.05). A statistically significant difference was found in the TMD group without clenching, in which the masseter muscle had a statistically significantly lower FF value on the disc displacement side (3.94 ± 1.61) than on the normal side (4.52 ± 2.24) (p < 0.05). CSE-MRI, which can reproducibly quantify muscle FF values, is expected to be a biomarker for objective muscle evaluation in TMD patients. The masseter muscle is expected to be particularly useful compared to other masticatory muscles, but further research is needed.

Comparative Evaluation of Imaging Techniques for Paraspinal Muscle Fat Quantification

Introduction: Low back pain (LBP) is a prevalent health issue associated with morphological changes in paravertebral muscles. Magnetic resonance imaging (MRI) is effective in identifying muscle steatosis, with MR spectroscopy (MRS) considered the gold standard. However, MRS is limited by technical challenges, prompting interest in Dixon sequences for fat quantification. Materials and Methods: We conducted a study comparing Multi Echo VIBE Dixon with single-voxel MR spectroscopy in quantifying fat fractions in lumbar multifidus muscles of chronic LBP patients. Ninety-eight measurements from 49 patients were analysed. Qualitative and quantitative image analyses were performed, and statistical analysis was conducted using SPSS 27. Results: Significant positive correlation (correlation coefficient: 0.992, p &lt; 0.001) was found between Dixon and MRS fat fraction measurements. Intra-class correlation coefficient was 0.991 (p &lt; 0.001), indicating strong agreement. No proportion bias was observed. Factors such as age, sex, and spinal degeneration correlated positively with multifidus fat atrophy. Conclusion: T2*-corrected Dixon imaging aligns well with spectroscopic measurements, offering an accurate alternative for estimating paraspinal muscle fat content in chronic LBP patients. Further studies are needed to establish threshold values for Dixon imaging. Chronic LBP is associated with multifidus muscle atrophy and fat infiltration, highlighting the need for effective management strategies.

Hyperpolarized [1-13 C] pyruvate MRSI to detect metabolic changes in liver in a methionine and choline-deficient diet rat model of fatty liver disease.

Nonalcoholic fatty liver disease is an important cause of chronic liver disease. There are limited methods for monitoring metabolic changes during progression to steatohepatitis. Hyperpolarized 13 C MRSI (HP 13 C MRSI) was used to measure metabolic changes in a rodent model of fatty liver disease. Fifteen Wistar rats were placed on a methionine- and choline-deficient (MCD) diet for 1-18 weeks. HP 13 C MRSI, T2 -weighted imaging, and fat-fraction measurements were obtained at 3 T. Serum aspartate aminotransaminase, alanine aminotransaminase, and triglycerides were measured. Animals were sacrificed for histology and measurement of tissue lactate dehydrogenase (LDH) activity. Animals lost significant weight (13.6% ± 2.34%), an expected characteristic of the MCD diet. Steatosis, inflammation, and mild fibrosis were observed. Liver fat fraction was 31.7% ± 4.5% after 4 weeks and 22.2% ± 4.3% after 9 weeks. Lactate-to-pyruvate and alanine-to-pyruvate ratios decreased significantly over the study course; were negatively correlated with aspartate aminotransaminase and alanine aminotransaminase (r = -[0.39-0.61]); and were positively correlated with triglycerides (r = 0.59-0.60). Despite observed decreases in hyperpolarized lactate signal, LDH activity increased by a factor of 3 in MCD diet-fed animals. Observed decreases in lactate and alanine hyperpolarized signals on the MCD diet stand in contrast to other studies of liver injury, where lactate and alanine increased. Observed hyperpolarized metabolite changes were not explained by alterations in LDH activity, suggesting that changes may reflect co-factor depletion known to occur as a result of oxidative stress in the MCD diet. HP 13 C MRSI can noninvasively measure metabolic changes in the MCD model of chronic liver disease.

Correlation between Vertebral Marrow Fat Fraction in MRI Using DIXON Technique and BMD in DXA in Patients of Suspected Osteoporosis.

Aim Osteoporosis is a common metabolic bone disease accounting for low back pain (LBP). It is diagnosed by dual-energy X-ray absorptiometry (DXA). Magnetic resonance imaging (MRI), a routine investigation for LBP, is also sensitive to detect fat fraction (FF) of the vertebral body that increases with increasing age. This study aimed to correlate vertebral marrow FF using MRI and bone mineral density (BMD). Material and Methods Patients presenting with low backache and suspected osteoporosis were included. All patients underwent an MRI of lumbosacral spine and DXA. Patients were categorized into an osteoporotic and a nonosteoporotic group based on the T-score obtained from DXA. "T-scores" of < -2.5 on BMD were considered as osteoporotic spine. T-score of > -2.5 was considered as nonosteoporotic. The FF obtained from the DIXON sequence of MRI was correlated between the two groups. Result Thirty-one patients were included with a mean age of 54.26 ± 11.6 years. Sixteen patients were osteoporotic based on the defined criteria in the methods. The mean vertebral marrow FF was significantly higher in the osteoporotic patients (64.98 ± 8.8%) compared with the nonosteoporotic (45.18 ± 13.2%) ( p = 0.001). The mean FF of the vertebra having fracture (69.19 ± 7.73%) was significantly higher than that of patients without fracture (57.96 ± 5.75%) ( p = 0.03). Taking a cutoff value of vertebral marrow FF of 54.85, the sensitivity and specificity of diagnosing osteoporosis were 93 and 80%, respectively, with a confidence interval of 95%. The area under the curve was 0.925. Conclusion Increased vertebral marrow FF is noted in the osteoporotic spine. FF has an inverse correlation with the T-score obtained from BMD. MRI with FF measurement can provide indirect evidence of osteoporosis, which can be done under one roof, especially in young patients where we need to avoid ionizing radiation.

Thresholding approaches for estimating paraspinal muscle fat infiltration using T1- and T2-weighted MRI: Comparative analysis using water-fat MRI.

Paraspinal muscle fat infiltration is associated with spinal degeneration and low back pain, however, quantifying muscle fat using clinical magnetic resonance imaging (MRI) techniques continues to be a challenge. Advanced MRI techniques, including chemical-shift encoding (CSE) based water-fat MRI, enable accurate measurement of muscle fat, but such techniques are not widely available in routine clinical practice. To facilitate assessment of paraspinal muscle fat using clinical imaging, we compared four thresholding approaches for estimating muscle fat fraction (FF) using T1- and T2-weighted images, with measurements from water-fat MRI as the ground truth: Gaussian thresholding, Otsu's method, K-mean clustering, and quadratic discriminant analysis. Pearson's correlation coefficients (r), mean absolute errors, and mean bias errors were calculated for FF estimates from T1- and T2-weighted MRI with water-fat MRI for the lumbar multifidus (MF), erector spinae (ES), quadratus lumborum (QL), and psoas (PS), and for all muscles combined. We found that for all muscles combined, FF measurements from T1- and T2-weighted images were strongly positively correlated with measurements from the water-fat images for all thresholding techniques (r = 0.70-0.86, p < 0.0001) and that variations in inter-muscle correlation strength were much greater than variations in inter-method correlation strength. We conclude that muscle FF can be quantified using thresholded T1- and T2-weighted MRI images with relatively low bias and absolute error in relation to water-fat MRI, particularly in the MF and ES, and the choice of thresholding technique should depend on the muscle and clinical MRI sequence of interest.

СОВРЕМЕННЫЕ ВОЗМОЖНОСТИ МЕТОДОВ ЛУЧЕВОЙ ДИАГНОСТИКИ В ОЦЕНКЕ ТЯЖЕСТИ ЖИРОВОГО ГЕПАТОЗА ПРИ НЕАЛКОГОЛЬНОЙ ЖИРОВОЙ БОЛЕЗНИ ПЕЧЕНИ (КЛИНИЧЕСКИЙ СЛУЧАЙ)

Purpose: To estimate the potential of imaging methods in the diagnosis of non-alcoholic fatty liver disease (NAFLD) based on the example of a clinical case. Material and methods: A 42 years-old man with suspected of NAFLD, by the clinical and laboratory tests results, underwent a quantitative assessment of fatty hepatosis using radiodiagnosis imaging methods. We used US “liver protocol” with attenuation imaging technique (ATI), shear wave elastography (SWE), shear wave dispersion imaging (SWD), computed tomography (CT) with quantitative and qualitative assessment using the liver-spleen index (CTL-S); MRI with application that provides volumetric whole-liver fat fraction (FF) measurements by proton density (PDFF), on the basis of IDEAL IQ program. The morphological verification of liver biopsy was also performed. Results: All imaging method used in this clinical case showed severe degree of fatty hepathosis, that correlated with biopsy of liver. In repeated studies, on the background of treatment, the quantitative indicators of all imaging methods had a similar dynamics of reduction of the degree of fatty hepatosis. Conclusion: The clinical case of verified acute steatohepatitis shows the possibilities of its diagnostics by means of the radiation modalities. We used US with ATI, SWE и SWD, CT with CTL-S, MRI with FF that demonstrated high diagnostic efficiency for determination fatty hepatosis and the possibility of its quantification. These technologies are suitable for widespread implementation into clinical practice providing good diagnostic accuracy. CT associated with higher doses of radiation is not considered to be the basic method of choice for diagnosing NAFLD, but still may provide a physician with necessary information to determine further treatment strategy.