Three-dimensional dental microwear texture analysis and diet in extant Suidae (Mammalia: Cetartiodactyla)

International audienceWe investigated the dietary differences among four extant suid genera using 3D dental microwear texture analysis on the enamel surfaces of molar shearing facets. We tested the differences among four taxa for four variables: complexity, anisotropy, and heterogeneity at two scales. This enabled us to distinguish omnivorous taxa (Sus scrofa and Potamochoerus sp.) from herbivorous ones (Phacochoerus africanus and Hylochoerus meinertzhageni) in terms of complexity. Heterogeneity likely distinguishes the suids displaying specialized diets (homogenous surfaces in the grazer Ph. africanus) from the more generalized suids (heterogeneous surfaces in the omnivorous S. scrofa and Potamochoerus sp., and mixed feeder herbivorous H. meinertzhageni). This study represents the first step toward a better comprehension of the diet and ecology of extant and fossil suids and also puts forward new hypotheses to be tested, especially on the effects of rootling behavior

Lean regional muscle volume estimates using explanatory bioelectrical models in healthy subjects and patients with muscle wasting

International audienceBackground: The availability of non-invasive, accessible, and reliable methods for estimating regional skeletal muscle volume is paramount in conditions involving primary and/or secondary muscle wasting. This work aimed at (i) optimizing serial bioelectrical impedance analysis (SBIA ) by computing a conductivity constant based on quantitative magnetic resonance imaging (MRI) data and (ii) investigating the potential of SBIA for estimating lean regional thigh muscle volume in patients with severe muscle disorders.Methods: Twenty healthy participants with variable body mass index and 20 patients with idiopathic inflammatory myopathies underwent quantitative MRI. Anatomical images and fat fraction maps were acquired in thighs. After manual muscle segmentation, lean thigh muscle volume (lVMRI ) was computed. Subsequently, multifrequency (50 to 350 kHz) serial resistance profiles were acquired between current skin electrodes (i.e. ankle and hand) and voltage electrodes placed on the anterior thigh. In vivo values of the muscle electrical conductivity constant were computed using data from SBIA and MRI gathered in the right thigh of 10 healthy participants. Lean muscle volume (lVBIA ) was derived from SBIA measurements using this newly computed constant. Between-day reproducibility of lVBIA was studied in six healthy participants.Results: Electrical conductivity constant values ranged from 0.82 S/m at 50 kHz to 1.16 S/m at 350 kHz. The absolute percentage difference between lVBIA and lVMRI was greater at frequencies >270 kHz (P < 0.0001). The standard error of measurement and the intra-class correlation coefficient for lVBIA computed from measurements performed at 155 kHz (i.e. frequency with minimal difference) against lVMRI were 6.1% and 0.95 in healthy participants and 9.4% and 0.93 in patients, respectively. Between-day reproducibility of lVBIA was as follows: standard error of measurement = 4.6% (95% confidence interval [3.2, 7.8] %), intra-class correlation coefficient = 0.98 (95% confidence interval [0.95, 0.99]).Conclusions: These findings demonstrate a strong agreement of lean muscle volume estimated using SBIA against quantitative MRI in humans, including in patients with severe muscle wasting and fatty degeneration. SBIA shows promises for non-invasive, fast, and accessible estimation and follow-up of lean regional skeletal muscle volume for transversal and longitudinal studies

Lean regional muscle volume estimates using explanatory bioelectrical models in healthy subjects and patients with muscle wasting

Abstract Background The availability of non‐invasive, accessible, and reliable methods for estimating regional skeletal muscle volume is paramount in conditions involving primary and/or secondary muscle wasting. This work aimed at (i) optimizing serial bioelectrical impedance analysis (SBIA) by computing a conductivity constant based on quantitative magnetic resonance imaging (MRI) data and (ii) investigating the potential of SBIA for estimating lean regional thigh muscle volume in patients with severe muscle disorders. Methods Twenty healthy participants with variable body mass index and 20 patients with idiopathic inflammatory myopathies underwent quantitative MRI. Anatomical images and fat fraction maps were acquired in thighs. After manual muscle segmentation, lean thigh muscle volume (lVMRI) was computed. Subsequently, multifrequency (50 to 350 kHz) serial resistance profiles were acquired between current skin electrodes (i.e. ankle and hand) and voltage electrodes placed on the anterior thigh. In vivo values of the muscle electrical conductivity constant were computed using data from SBIA and MRI gathered in the right thigh of 10 healthy participants. Lean muscle volume (lVBIA) was derived from SBIA measurements using this newly computed constant. Between‐day reproducibility of lVBIA was studied in six healthy participants. Results Electrical conductivity constant values ranged from 0.82 S/m at 50 kHz to 1.16 S/m at 350 kHz. The absolute percentage difference between lVBIA and lVMRI was greater at frequencies >270 kHz (P < 0.0001). The standard error of measurement and the intra‐class correlation coefficient for lVBIA computed from measurements performed at 155 kHz (i.e. frequency with minimal difference) against lVMRI were 6.1% and 0.95 in healthy participants and 9.4% and 0.93 in patients, respectively. Between‐day reproducibility of lVBIA was as follows: standard error of measurement = 4.6% (95% confidence interval [3.2, 7.8] %), intra‐class correlation coefficient = 0.98 (95% confidence interval [0.95, 0.99]). Conclusions These findings demonstrate a strong agreement of lean muscle volume estimated using SBIA against quantitative MRI in humans, including in patients with severe muscle wasting and fatty degeneration. SBIA shows promises for non‐invasive, fast, and accessible estimation and follow‐up of lean regional skeletal muscle volume for transversal and longitudinal studies

Effect of sirolimus on muscle in inclusion body myositis observed with magnetic resonance imaging and spectroscopy

Abstract Background Finding sensitive clinical outcome measures has become crucial in natural history studies and therapeutic trials of neuromuscular disorders. Here, we focus on 1‐year longitudinal data from quantitative magnetic resonance imaging (MRI) and phosphorus magnetic resonance spectroscopy (31P MRS) in a placebo‐controlled study of sirolimus for inclusion body myositis (IBM), also examining their links to functional, strength, and clinical parameters in lower limb muscles. Methods Quantitative MRI and 31P MRS data were collected at 3 T from a single site, involving 44 patients (22 on placebo, 22 on sirolimus) at baseline and year‐1, and 21 healthy controls. Assessments included fat fraction (FF), contractile cross‐sectional area (cCSA), and water T2 in global leg and thigh segments, muscle groups, individual muscles, as well as 31P MRS indices in quadriceps or triceps surae. Analyses covered patient‐control comparisons, annual change assessments via standard t‐tests and linear mixed models, calculation of standardized response means (SRM), and exploration of correlations between MRI, 31P MRS, functional, strength, and clinical parameters. Results The quadriceps and gastrocnemius medialis muscles had the highest FF values, displaying notable heterogeneity and asymmetry, particularly in the quadriceps. In the placebo group, the median 1‐year FF increase in the quadriceps was 3.2% (P < 0.001), whereas in the sirolimus group, it was 0.7% (P = 0.033). Both groups experienced a significant decrease in cCSA in the quadriceps after 1 year (P < 0.001), with median changes of 12.6% for the placebo group and 5.5% for the sirolimus group. Differences in FF and cCSA changes between the two groups were significant (P < 0.001). SRM values for FF and cCSA were 1.3 and 1.4 in the placebo group and 0.5 and 0.8 in the sirolimus group, respectively. Water T2 values were highest in the quadriceps muscles of both groups, significantly exceeding control values in both groups (P < 0.001) and were higher in the placebo group than in the sirolimus group. After treatment, water T2 increased significantly only in the sirolimus group's quadriceps (P < 0.01). Multiple 31P MRS indices were abnormal in patients compared to controls and remained unchanged after treatment. Significant correlations were identified between baseline water T2 and FF at baseline and the change in FF (P < 0.001). Additionally, significant correlations were observed between FF, cCSA, water T2, and functional and strength outcome measures. Conclusions This study has demonstrated that quantitative MRI/31P MRS can discern measurable differences between placebo and sirolimus‐treated IBM patients, offering promise for future therapeutic trials in idiopathic inflammatory myopathies such as IBM

Relationship between markers of disease activity and progression in skeletal muscle of GNE myopathy patients using quantitative nuclear magnetic resonance imaging and (31)P nuclear magnetic resonance spectroscopy.

BACKGROUND: Quantitative nuclear magnetic resonance imaging (NMRI) is an objective and precise outcome measure for evaluating disease progression in neuromuscular disorders. We aimed to investigate predictive 'disease activity' NMR indices, including water T(2) and (31)P NMR spectroscopy (NMRS), and its relation to NMR markers of 'disease progression', such as the changes in fat fraction (ΔFat%) and contractile cross-sectional area (ΔcCSA), in GNE myopathy (GNEM) patients. METHODS: NMR was performed on a 3T clinical scanner, at baseline and at a 1-year interval, in 10 GNEM patients and 29 age-matched controls. Dixon-based fat-water imaging and water T(2) mapping were acquired in legs and thighs, and in the dominant forearm. (31)P NMRS was performed at the level of quadriceps and hamstring. Water T(2) and (31)P NMRS indices were determined for all muscle groups and visits. Correlations were performed with 'disease progression' indices ΔFat%, ΔcCSA and the muscle fat transformation rate (R(muscle_transf)). RESULTS: In quadriceps, known to be relatively preserved in GNEM, water T(2) at baseline was significantly higher compared to controls, and correlated strongly with the one-year evolution of Fat% and cCSA and R(muscle_transf). Various (31)P NMRS indices showed significant differences in quadriceps and hamstring compared to controls and correlations existed between these indices and ΔFat%, ΔcCSA and R(muscle_transf). CONCLUSIONS: This study demonstrates that disease activity indices such as water T(2) and (31)P NMRS may predict disease progression in skeletal muscles of GNEM patients, and suggests that these measures may be considered to be valuable surrogate endpoints in the assessment of GNEM disease progression

Global versus individual muscle segmentation to assess quantitative MRI-based fat fraction changes in neuromuscular diseases

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Can global muscle segmentation detect changes in neuromuscular disorders using quantitative nuclear magnetic resonance imaging?

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Severe axial and pelvifemoral muscle damage in immune-mediated necrotizing myopathy evaluated by whole-body MRI

International audienceBackground: Our objective was to define the pattern and severity of muscle damage in immune-mediated necrotizing myopathy (IMNM) and its relationship with clinical and serological features.Methods: IMNM patients with a whole-body MRI (n=42) were included and compared to sporadic inclusion-body myositis (s-IBM) patients (n=60). Fat replacement was estimated using the Mercuri score in 55 muscles. Overall lesion load was defined as the sum of all abnormal Mercuri scores (reported in % maximal score) and lesion load quotient was defined as the overall lesion load divided by disease duration. Linear relationships between variables were assessed and multidimensional analysis was performed to define homogenous groups of patients.Results: IMNM patients were aged 48.1±15.8 years and had a disease duration of 9.8±8.1 years. Most severely affected muscle groups were located in the pelvifemoral and lumbar region. Unsupervised analysis showed two subgroups of patients: one with mild lesion load (15±10%, n=32/42) and another with severe lesion load (60±10%, n=10/42: p<0.001) associated with a mean disease duration of 6.8±6.0 years and 19.5±5.7 years, respectively (p<0.0001). Correlational studies confirmed that disease duration was the most important predictor of muscle damage. Multivariate analyses demonstrated a more severe involvement in select muscle groups in females and seropositive patients. No difference was found in overall lesion load quotient of IMNM compared to IBM (p=0.07) but with a distinct muscle pattern.Conclusion: IMNM is associated with severe axial and pelvifemoral muscle damage. Disease duration is an important predictor of muscle damage. IMNM and s-IBM patients have a comparable damage burden