Search

Muscle hyperemia in exercise is usually the combined result of increased cardiac output and local muscle vasodilation, with the latter reflecting muscle's capacity for increased blood perfusion to support exercise. In this study, we aim to quantify muscle's vasodilation capability with dynamic BOLD imaging. A deoxyhemoglobin-kinetics model is proposed to analyze dynamic BOLD signals acquired during exercise recovery, deriving a hyperemia index (HI) for a muscle group of interest. We demonstrated the method's validity with calf muscles of healthy subjects who performed plantar flexion for muscle stimulation. In a test with exercise load incrementally increasing from 0 to 16 lbs., gastrocnemius HI showed considerable variance among the 4 subjects, but with a consistent trend, i.e. low at light load (e.g. 0-6 lbs) and linearly increasing at heavy load. The high variability among different subjects was confirmed with the other 10 subjects who exercised with a same moderate load of 8 lbs., with coefficient of variance among subjects' medial gastrocnemius 87.8%, lateral gastrocnemius 111.8% and soleus 132.3%. These findings align with the fact that intensive exercise induces high muscle hyperemia, but a comparison among different subjects is hard to make, presumably due to the subjects' different rate of oxygen utilization. For the same 10 subjects who exercised with load of 8 lbs., we also performed dynamic contrast enhanced (DCE) MRI to measure muscle perfusion (F). With a moderate correlation of 0.654, HI and F displayed three distinctive responses of calf muscles: soleus of all the subjects were in the cluster of low F and low HI, and gastrocnemius of most subjects had high F and either low or high HI. This finding suggests that parameter F encapsulates blood flow through vessels of all sizes, but BOLD-derived HI focuses on capillary flow and therefore is a more specific indicator of muscle vasodilation. In conclusion, the proposed hyperemia index has the potential of quantitatively assessing muscle vasodilation induced with exercise., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: To determine whether intravoxel incoherent motion (IVIM) describes the blood perfusion in muscles better, assuming pseudo diffusion (Bihan Model 1) or ballistic motion (Bihan Model 2)., Methods: IVIM parameters were measured in 18 healthy subjects with three different diffusion gradient time profiles (bipolar with two diffusion times and one with velocity compensation) and 17 b-values (0-600 s/mm 2 ) at rest and after muscle activation. The diffusion coefficient, perfusion fraction, and pseudo-diffusion coefficient were estimated with a segmented fit in the gastrocnemius medialis (GM) and tibialis anterior (TA) muscles., Results: Velocity-compensated gradients resulted in a decreased perfusion fraction (6.9% ± 1.4% vs. 4.4% ± 1.3% in the GM after activation) and pseudo-diffusion coefficient (0.069 ± 0.046 mm 2 /s vs. 0.014 ± 0.006 in the GM after activation) compared to the bipolar gradients with the longer diffusion encoding time. Increased diffusion coefficients, perfusion fractions, and pseudo-diffusion coefficients were observed in the GM after activation for all gradient profiles. However, the increase was significantly smaller for the velocity-compensated gradients. A diffusion time dependence was found for the pseudo-diffusion coefficient in the activated muscle., Conclusion: Velocity-compensated diffusion gradients significantly suppress the IVIM effect in the calf muscle, indicating that the ballistic limit is mostly reached, which is supported by the time dependence of the pseudo-diffusion coefficient., (© 2024 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Purpose: Calf muscles play an important role in marathon race, and the incidence of injury is high in this process. This study prospectively quantified diffusion tensor metrics, muscle fat fraction (MFF) and cross-sectional area (CSA) of calf muscles induced by endurance exercise in amateur marathoners, and the potential mechanisms underlying the changes in these parameters were analyzed., Method: In this prospective study, 35 marathoners (27 males, 8 females; mean age (standard deviation, SD), 38.92 (4.83) years) and 26 controls (18 males, 8 females; mean age (SD), 38.35 (6.75) years) underwent magnetic resonance imaging (MRI) from September 2022 to March 2023. The diffusion tensor eigenvalues (λ1, λ2, λ3), radial diffusivity (RD), fractional anisotropy (FA), MFF and CSA of calf muscles were compared between marathoners and controls. A binary logistic regression model with gender correction was performed analyze the relationship between marathon exercise and DTI parameters, CSA and MFF of calf muscles., Results: Interobserver agreement was good (κ = 0.71). The results of binary logistic regression model with gender correction showed that the regression coefficients of FA values in anterior group of calf (AC), soleus (SOL), medial gastrocnemius (MG) and lateral gastrocnemius (LG) were negative, and the odds ratios (OR) were 0.33, 0.45, 0.35, 0.05, respectively (P < 0.05). The OR of RD in SOL and λ2 in external group of calf (EC) were relatively higher, 3.74 and 3.26, respectively (P < 0.05). CSA was greater in SOL of marathoners, with an OR value of 1.00(P < 0.05). The MFF in AC and LG was lower in marathoners and OR of two indexes were -0.69 and -0.59, respectively (P < 0.05)., Conclusions: Diffusion tensor imaging (DTI) combined with chemical shift-encoded sequence can noninvasively detect and quantify the adaptive changes of calf muscle morphology, microstructure and tissue composition induced by long-term running training in amateur marathoners., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: The purpose of this study was to investigate the dependence of Intravoxel Incoherent Motion (IVIM) parameters measured in the human calf on B 0 . Methods: Diffusion-weighted image data of eight healthy volunteers were acquired using five b -values (0-600 s/mm 2 ) at rest and after muscle activation at 0.55 and 7 T. The musculus gastrocnemius mediale (GM, activated) was assessed. The perfusion fraction f and diffusion coefficient D were determined using segmented fits. The dependence on field strength was assessed using Student's t -test for paired samples and the Wilcoxon signed-rank test. A biophysical model built on the three non-exchanging compartments of muscle, venous blood, and arterial blood was used to interpret the data using literature relaxation times. Results: The measured perfusion fraction of the GM was significantly lower at 7 T, both for the baseline measurement and after muscle activation. For 0.55 and 7 T, the mean f values were 7.59% and 3.63% at rest, and 14.03% and 6.92% after activation, respectively. The biophysical model estimations for the mean proton-density-weighted perfusion fraction were 3.37% and 6.50% for the non-activated and activated states, respectively. Conclusions: B 0 may have a significant effect on the measured IVIM parameters. The blood relaxation times suggest that 7 T IVIM may be arterial-weighted whereas 0.55 T IVIM may exhibit an approximately equal weighting of arterial and venous blood.

Background: Large calves are considered unattractive. Botulinum toxin type A (BoNT-A), acting as a neurotoxin that reduces muscle contraction, is widely used in calf contouring. However, there lacks detailed anatomical data to guide clinical injection., Objectives: This study aims to use ultrasonography to provide depth information of the calf muscles and determine the morphological types of the gastrocnemius muscle., Methods: Ultrasound scanning was performed at six sites on 40 Chinese adults. A real-time ultrasound scannerwas used to detect the depth of the gastrocnemius muscle and the soleus muscle., Results: The thickness of the gastrocnemius muscle and the soleus muscle was measured. The depth from the skin to the surface, the middle, and the bottom of the gastrocnemius muscle was measured. The morphology of gastrocnemius muscle was classified into four different types under ultrasound according to the muscle bulge pattern., Conclusion: This study took ultrasonic measurements of Asian calves to guide accurate and effective BoNT-A injection in real clinical practice., (© 2022 Wiley Periodicals LLC.)

Intramuscular injections of Botulinum Toxin Type A (BoNT-A) in children with spastic cerebral palsy (CP) have been introduced in clinical practice with the aim of reducing muscle tone, preventing muscle contractures and, ultimately, improving function. The aim of this study was to evaluate prospectively the MRI changes in the calf muscles, gastrocnemius (GN) and soleus (S) of two children with unilateral spastic CP (US-CP), prior and more than 1-year following BoNT-A injections. Two male patients with US-CP were injected at the level of the GN and S muscles. Patients underwent a first lower extremity MRI prior to the first BoNT-A injection at the level of GN and S muscles of the affected side. A second MRI was perfomed 34 and 22 months after the index procedure, respectively. Both legs were investigated together symmetrically, to allow a precise comparison between muscles and structures. The MRI protocol included three sequences: axial-T2 weighted tse, SPACE and axial-T1 weighted. We found that BoNT-A injected GN and S muscles had increased signal intensity on the MRI performed 22 and 34 months after index procedure, when compared to the contralateral, not placebo injected (NaCl) leg. To the best of our knowledge, no previous studies have investigated the changes induced in muscle structures in ambulatory children with US-CP managed by BoNT-A injections. Level of evidence: II., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Cerebral palsy is a neurological condition that is known to affect muscle growth. Detailed investigations of muscle growth require segmentation of muscles from MRI scans, which is typically done manually. In this study, we evaluated the performance of 2D, 3D, and hybrid deep learning models for automatic segmentation of 11 lower leg muscles and two bones from MRI scans of children with and without cerebral palsy. All six models were trained and evaluated on manually segmented T 1 -weighted MRI scans of the lower legs of 20 children, six of whom had cerebral palsy. The segmentation results were assessed using the median Dice similarity coefficient (DSC), average symmetric surface distance (ASSD), and volume error (VError) of all 13 labels of every scan. The best performance was achieved by H-DenseUNet, a hybrid model (DSC 0.90, ASSD 0.5 mm, and VError 2.6 cm 3 ). The performance was equivalent to the inter-rater performance of manual segmentation (DSC 0.89, ASSD 0.6 mm, and VError 3.3 cm 3 ). Models trained with the Dice loss function outperformed models trained with the cross-entropy loss function. Near-optimal performance could be attained using only 11 scans for training. Segmentation performance was similar for scans of typically developing children (DSC 0.90, ASSD 0.5 mm, and VError 2.8 cm 3 ) and children with cerebral palsy (DSC 0.85, ASSD 0.6 mm, and VError 2.4 cm 3 ). These findings demonstrate the feasibility of fully automatic segmentation of individual muscles and bones from MRI scans of children with and without cerebral palsy., (© 2021 John Wiley & Sons, Ltd.)

While concurrent training is regularly used in older populations, the inverse relationship between fibre size and oxidative capacity suggests that endurance training in resistance-trained individuals may result in some loss of resistance training-induced gains in muscle mass, which may be more pronounced in older people. We investigated the impact of superimposed endurance training in younger (28.5 ± 4.8 years; n = 8) and older (67.5 ± 5.5 years; n = 7) highly resistance-trained men. Participants underwent a 10-week endurance cycling training programme consisting of five 6-min intervals at 75% max heart rate (HRmax) separated by 4-min intervals at 90% HRmax. The anatomical cross-sectional area (ACSA) of the thigh muscles, as determined with MRI, was 24% smaller in older compared to younger participants (p < 0.001). Although maximal oxygen consumption (VO 2 max) was also lower in the older group (p < 0.001), VO 2 max per kg body mass did not differ significantly between younger and older participants. Histological analyses of biopsies of the m. vastus lateralis showed that endurance training induced an increase in succinate dehydrogenase activity in both younger and older participants (p ≤ 0.043), and an increase in the number of capillaries around type I fibres (p = 0.017). The superimposed endurance training did not induce a significant decrease in thigh ACSA, fibre cross-sectional area, or knee extensor maximum voluntary isometric force. These observations indicate that adding endurance training to resistance training can lead to positive endurance-related adaptations without negative consequences for muscle size and strength in older and younger resistance-trained people., (© 2021. The Author(s).)

Developing an exercise model that resembles a traditional form of aerobic exercise and facilitates a complete simultaneous assessment of multiple parameters within the oxygen cascade is critically for understanding exercise intolerances in diseased populations. Measurement of muscle blood flow is a crucial component of such a model and previous studies have used invasive procedures to determine blood flow kinetics; however, this may not be appropriate in certain populations. Furthermore, current models utilizing Doppler ultrasound use isolated limb exercise and while these studies have provided useful data, the exercise model does not mimic the whole-body physiological response to continuous dynamic exercise. Therefore, we aimed to measure common femoral artery blood flow using Doppler ultrasound during continuous dynamic stepping exercise performed at three independent workloads to assess the within day and between-day reliability for such an exercise modality. We report a within-session coefficient of variation of 5.8% from three combined workloads and a between-day coefficient of variation of 12.7%. These values demonstrate acceptable measurement accuracy and support our intention of utilizing this noninvasive exercise model for an integrative assessment of the whole-body physiological response to exercise in a range of populations., (© 2021 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Objectives . The electrical-tomographic imaging has been achieved for exploring differential tendency of physiological-induced conductive response in calf muscle compartments during voltage intensity change of electrical muscle stimulation ( vic -EMS). Approach . In the experiments, the differential tendency of conductivity distribution images σ during vic -EMS were clearly imaged as three responsive muscle compartments, which are called M 1 compartment composed of gastrocnemius muscle, M 2 compartment composed of tibialis anterior, extensor digitorum longus, and peroneus longus muscles, and M 3 compartment composed of soleus muscle. Main results . The differential tendency of spatial-mean conductivity 〈 σ 〉 M 1 is the same as the differential tendency of venous blood flow velocity v bl and blood lactate concentration C bl during vic -EMS by the increased tendency of spatial-mean conductivity difference Δ〈 σ 〉 M 1 , venous blood flow velocity difference Δ v bl and blood lactate concentration difference Δ C bl . The 〈 σ 〉 M 1 is increased with the increase of voltage intensity from 〈 σ pre 〉 M 1  = 0.142 [-] to 〈 σ l 14  〉  M 1  = 0.442 [-] ( pre : pre-training, l 14: voltage level during vic -EMS l  = 14) by Δ〈 σ l 14- pre 〉 M 1  = 204.2% ( n  = 16, p  < 0.01). Correspondingly, the v bl and C bl are increased with the increase of voltage intensity by Δv bl l 14- pre = 1480.5% ( n  = 16, p  < 0.01) and Δ C bl l 14- pre = 230.1% ( n  = 16, p  < 0.01) respectively. Significance : The reason for the differential tendency of increase in < σ > M 1 suggests an increase in muscle extracellular volumes during vic -EMS due to the co-effect of venous blood flow velocity and blood lactate metabolism. Based on the conductivity second-order difference images∂2σM1φ∂φ2φand spatial-mean conductivity second-order difference∂2σM1φ∂φ2φ,optimum voltage intensity φ OVI is discussed among sixteen volunteer subjects, which increased with a thicker subcutaneous fat layer., (© 2021 Institute of Physics and Engineering in Medicine.)

Background: Diffuse large B cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL), occurring predominantly in older people. Skeletal muscle lymphoma is a rare form of DLBCL, most frequently affecting the thigh, upper extremities, calf, and pelvis., Case Presentation: We report a case of skeletal muscle DLBCL that was diagnosed using ultrasound (US)-guided biopsy. A 70-year-old man presented with progressive swelling and pain in the left lower extremity and an elevated erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP), ferritin, and CA125 levels. US, magnetic resonance imaging (MRI), and computed tomography (CT) showed diffuse lesions in several muscles of the left lower extremity. Positron emission tomography/CT (PET/CT) showed FDG-uptake in the affected muscles. The patient was treated with chemotherapy and achieved a good response. A systematic review of the literature published between 1992 and 2019 was conducted to investigate the role of imaging, including imaging-guided biopsy, in the diagnosis of skeletal muscle lymphoma., Conclusions: Skeletal muscle lymphoma is rare. US and MRI features include enlargement of muscular structures, with preservation of the architecture of the tissue and surrounding anatomical structures. Definitive diagnosis relies on histological and immunohistological analysis of a sample obtained through imaging-guided biopsy., (© 2021. The Author(s).)

The current study aimed to verify whether or not passive static stretching affects balance control capacity. Thirty-eight participants (19 women and 19 men) underwent a passive static stretching session, involving the knee extensor/flexor and dorsi/plantarflexor muscles, and a control session (no stretching, CTRL). Before (PRE), immediately after (POST), after 15 (POST15) and 30 min (POST30) from stretching (or rest in CTRL), balance control was evaluated under static and dynamic conditions, with open/closed eyes, and with/without somatosensory perturbation (foam under the feet). During tests, centre of pressure (CoP) sway area and perimeter and antero-posterior and medio-lateral sway mean speed were computed. Surface electromyography root mean square (sEMG RMS) was calculated from the vastus lateralis, biceps femoris, gastrocnemius medialis, and tibialis anterior muscles during MVC and during the balance tests. Hip flexion/extension and dorsi/plantarflexion range of motion (ROM), maximum voluntary contraction (MVC) and sEMG RMS during MVC were measured at the same time points. After stretching, ROM increased (≈6.5%; P<0.05), while MVC and sEMG RMS decreased (≈9% and ≈7.5%, respectively; P<0.05). Regardless of the testing condition, CoP sway area and the perimeter remained similar, while antero-posterior and medio-lateral sway mean speed decreased by ≈8% and ≈12%, respectively (P<0.05). sEMG RMS during the balance tests increased in all muscles in POST (≈7%, P<0.05). All variables recovered in POST30. No changes occurred in CTRL. Passive static stretching did not affect the overall balance control ability. However, greater muscle activation was required to maintain similar CoP sway, thus suggesting a decrease in muscle efficiency., Competing Interests: The authors have declared that no competing interests exist

Objective: To identify the best quantitative fat-water MRI biomarker for disease progression of leg muscles in Becker muscular dystrophy (BMD) by applying a stepwise approach based on standardized response mean (SRM) over 24 months, correlations with baseline ambulatory tests, and reproducibility., Methods: Dixon fat-water imaging was performed at baseline (n = 24) and 24 months (n = 20). Fat fractions (FF) were calculated for 3 center slices and the whole muscles for 19 muscles and 6 muscle groups. Contractile cross-sectional area (cCSA) was obtained from the center slice. Functional assessments included knee extension and flexion force and 3 ambulatory tests (North Star Ambulatory Assessment [NSAA], 10-meter run, 6-minute walking test). MRI measures were selected using SRM (≥0.8) and correlation with all ambulatory tests (ρ ≤ -0.8). Measures were evaluated based on intraclass correlation coefficient (ICC) and SD of the difference. Sample sizes were calculated assuming 50% reduction in disease progression over 24 months in a clinical trial with 1:1 randomization., Results: Median whole muscle FF increased between 0.2% and 2.6% without consistent cCSA changes. High SRMs and strong functional correlations were found for 8 FF but no cCSA measures. All measures showed excellent ICC (≥0.999) and similar SD of the interrater difference. Whole thigh 3 center slices FF was the best biomarker (SRM 1.04, correlations ρ ≤ -0.81, ICC 1.00, SD 0.23%, sample size 59) based on low SD and acquisition and analysis time., Conclusion: In BMD, median FF of all muscles increased over 24 months. Whole thigh 3 center slices FF reduced the sample size by approximately 40% compared to NSAA., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Purpose: To evaluate the repeatability of multinuclear interleaved 1 H/ 31 P NMR dynamic acquisitions in skeletal muscle and the impact of nuclear Overhauser enhancement (nOe) on the 31 P results at 3T in exercise-recovery and ischemia-hyperemia paradigms., Methods: A 1 H/ 31 P interleaved pulse sequence was used to measure every 2.5 s a perfusion-weighted image, a T 2 ∗ map, a 31 P spectrum and 32 1 H spectra sensitive to deoxymyoglobin. 21 subjects performed a plantar flexion exercise and after recovery underwent an 8-min lower leg ischemia. The procedure was repeated in visit 2 with 12 subjects. An additional exercise bout without 1 H excitation was appended to visit 1. Individual 1 H RF pulse nOe was measured at rest in every visit., Results: Repeatability scores (coefficient of variation, Bland-Altman analysis) were similar to those found in the literature using similar mono-nuclear acquisitions. |Pi]/[PCr], pH drop, creatine rephosphorylation rate (τ PCr ), maximum perfusion, time to peak perfusion, and blood flow post-exercise showed high reliability (intraclass correlation coefficient > 0.7), whereas hemodynamic results from reactive hyperemia showed higher repeatability. After accounting for nOe, which increased Pi and PCr signal-to-noise ratio by 30%, no differences in 31 P results were observed between interleaved and 31 P MRS-only acquisitions. τ PCr was unaffected by nOe., Conclusion: The method shows good repeatability for both paradigms while simultaneously providing multiple dynamic data sets on a clinical scanner. The nOe effects were accounted for on a per-subject and per-visit basis using a short 31 P reference scan. This multiparametric approach has a multitude of applications for the study of oxygen utilization and ATP turnover in the muscle., (© 2021 International Society for Magnetic Resonance in Medicine.)

Abstract: To compare the speed of propagation of ultrasound (US) waves (SoS) of the lower leg with the clinical reference standard computed tomography (CT) at the level of lumbar vertebra 3 (L3) for muscle loss assessment. Both calf muscles of 50 patients scheduled for an abdominal CT were prospectively examined with ultrasound. A plexiglas-reflector located on the opposite side of the probe with the calf in between was used as a timing reference for SoS (m/s). CT measurements were performed at the level of L3 and included area (cm2) and attenuation (HU) of the psoas muscle, abdominal muscles, subcutaneous fat, visceral fat and abdominal area. Correlations between SoS, body mass index (BMI) and CT were determined using Pearson's correlation coefficient. Based on reported CT sarcopenia threshold values, receiver operating characteristic (ROC) analysis was performed for SoS. Inter-examiner agreement was assessed with the median difference, inter-quartile range (IQR) and intraclass correlation coefficients. SoS of the calf correlated moderately with abdominal muscle attenuation (r = 0.48; P < .001), psoas muscle attenuation (r = 0.40; P < .01), abdominal area (r = -0.44; P < .01) and weakly with subcutaneous fat area (r = -0.37; P < .01). BMI correlated weakly with psoas attenuation (r = -0.28; P < .05) and non-significantly with abdominal muscle attenuation. Normalization with abdominal area resulted in moderate correlations with abdominal muscle area for SoS (r = 0.43; P < .01) and BMI (r = -0.46; P < .001). Based on sarcopenia threshold values for skeletal muscle attenuation (SMRA), area under curve (AUC) for SoS was 0.724. Median difference between both examiners was -3.4 m/s with IQR = 15.1 m/s and intraclass correlation coefficient = 0.794. SoS measurements of the calf are moderately accurate based on CT sarcopenia threshold values, thus showing potential for muscle loss quantification., Competing Interests: The authors have no conflicts of interests to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Abstract: Short-term immobilization leads to fatty muscular degeneration, which is associated with various negative health effects. Based on literature showing very high correlations between MRI Dixon fat fraction and Speed-of-Sound (SoS), we hypothesized that we can detect short-term-immobilization-induced differences in SoS.Both calves of 10 patients with a calf cast on one side for a mean duration of 41 ± 26 days were examined in relaxed position using a standard ultrasound machine. Calf perimeters were measured for both sides. A flat Plexiglas-reflector, placed vertically on the opposite side of the probe with the calf in-between, was used as a timing reference for SoS. SoS was both manually annotated by two readers and assessed by an automatic annotation algorithm. The thickness values of the subcutaneous fat and muscle layers were manually read from the B-mode images. Differences between the cast and non-cast calves were calculated with a paired t test. Correlation analysis of SoS and calf perimeter was performed using Pearson's correlation coefficient.Paired t test showed significant differences between the cast and non-cast side for both SoS (P < .01) and leg perimeter (P < .001). SoS was reduced with the number of days after cast installment (r = -0.553, P = .097). No significant differences were found for muscle layer thickness, subcutaneous fat layer thickness, mean fat echo intensity, or mean muscle echo intensity.Short-term-immobilization led to a significant reduction in SoS in the cast calf compared to the healthy calf, indicating a potential role of SoS as a biomarker in detecting immobilization-induced fatty muscular degeneration not visible on B-mode ultrasound., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: Skeletal muscle involvement in Wilson disease is rare. Calf muscle pain might be attributed as growing pain in children. We report calf muscle involvement in Wilson disease and describe the magnetic resonance imaging (MRI) findings of leg, differential diagnosis with literature review., Patients and Methods: Our observations describe calf muscle MRI abnormality in 5 cases of Wilson disease from 2 families. The clinical presentations were neurologic in 3, hepatic in 1, and asymptomatic in 1 patient. We systematically describe the clinical characteristics and their calf muscle MRI findings., Results: Three patients had bilateral calf pain and intermittent cramps. The pain was of mild to moderate intensity and managed symptomatically. Serum alkaline phosphatase, creatinine phosphokinase, and needle electromyography were normal. Turbo inversion recovery magnitude sequence MRI of calf muscle revealed hyperintensity in bilateral gastrocnemii muscles. These muscles appear hyperintense in diffusion-weighted imaging., Conclusion: The calf muscle involvement could be attributed to muscle edema due to copper-induced muscle toxicity mediated by inhibition of Na + /K + -ATPase on cellular membranes of fast-twitch gastrocnemii muscles which contain predominant type II myofiber. In Wilson disease patients with calf pain or cramps, muscle MRI may show nonspecific gastrocnemius hyperintensity. Further evaluation may give insight into its pathophysiology.

Background: The leg muscles are important for balance, posture, and movement during static and dynamic activity. Obtaining cross-sectional area measurements (CSA) of the leg muscles helps researchers understand the health and force production capability of individual leg muscles. Therefore, having an easy to use and readily available method to assess leg muscle CSA is needed. Thus, the purpose of this study was to compare the magnitude, repeatability, and validity of CSA measurements of select leg muscles from ultrasound (US) and the current gold standard, magnetic resonance imaging (MRI)., Methods: 20 healthy volunteers participated in this study. Each participant was imaged via US and MRI. The muscles of interest obtained on each participant consisted of the tibialis anterior at both 30 and 50% of the shank length, tibialis posterior at both 30 and 50% of the shank length, the flexor digitorum longus, the fibularis (peroneus) longus, and the fibularis (peroneus) brevis., Results: Strong Pearson correlations were seen for all of the muscles when comparing US to MRI with a range from .7840 to .9676. For all measurements, standard error of the measurement ranged from .003 to 0.260 cm 2 . Minimum detectable difference for muscle measurements ranged from .008 cm 2 for MRI fibularis longus and fibularis brevis to .693 cm 2 for MRI of tibialis anterior at 30%. US minimum detectable difference ranged from .125 cm 2 for the tibialis posterior muscle at 30% to .449 cm 2 for the tibialis anterior muscle at 50%., Conclusions: Based on these results ultrasound is a valid method to obtain CSA of muscles of the leg when compared with MRI.

Background: Muscle MRI protocols have been developed to assess muscle involvement in a wide variety of muscular dystrophies. Different muscular dystrophies can involve muscle groups in characteristic patterns. These patterns can be identified in muscle MRI in the form of fatty infiltration., Objective: This study was conducted to add the existing knowledge of muscle MRI in GNE myopathy and evaluate the correlation of muscular involvement with different gene mutations., Methods: The MRI scans of the 18 GNE patients were analyzed retrospectively. Cluster analysis was done for grouping the muscles and patients., Results: The four muscles with the highest fat infiltration were adductor magnus, tibialis anterior, semitendinosus, and semimembranosus. Furthermore, three clusters of muscle involvement were found, including cluster 1, typical muscle involvement indicating muscles with the highest infiltration: extensor digitorum longus, gracilis, biceps femoris, soleus, gastrocnemius medial, adductor longus, tibialis anterior, adductor magnus, semimembranosus, semitendinosus; cluster 2, less typical muscle involvement indicating muscles with intermediate fat infiltration, peroneus longus, gastrocnemius lateral, and minimal fat infiltration in most of the patients, i.e., tibialis posterior; and cluster 3, atypical muscle involvement with low-fat infiltration: rectus femoris, sartorius, vastus intermedius, vastus medialis, and vastus lateralis., Conclusions: This study found three clusters of muscle involvement and three groups of patients among GNE patients. Hamstring muscles and the anterior compartment of the lower leg were the muscles with the highest fat infiltration. Moreover, a weak genotype-muscle MRI association was found in which tibialis posterior was more involved in patients with the most frequent mutation, i.e., C.2228T > C (p.M743T) mutation; however, this finding may be related to longer disease duration.

Background: Ryanodine receptor 1-related myopathy (RYR1-RM) can present with a selective pattern and gradient of intramuscular fatty infiltration (IMFI) on magnetic resonance imaging (MRI)., Objective: To demonstrate an automated protocol for quantification of IMFI in the lower extremity muscles of individuals with RYR1-RM using T1-weighted MRI and to examine the relationships of IMFI with motor function and clinical severity., Methods: Axial images of the lower extremity muscles were acquired by T1-weighted fast spin-echo and short tau inversion recovery (STIR) sequences. A modified ImageJ-based program was used for quantification. IMFI data was analyzed by mode of inheritance, motor function, and clinical severity., Results: Upper and lower leg IMFI from 36 genetically confirmed and ambulatory RYR1-RM affected individuals (26 dominant and 10 recessive) were analyzed using Grey-scale quantification. There was no statistically significant difference in IMFI between dominant and recessive cases in upper or lower legs. IMFI in both upper and lower legs was inversely correlated with participant performance on the motor function measure (MFM-32) total score (upper leg: p < 0.001; lower leg: p = 0.003) and the six-minute walk test (6MWT) distance (upper leg: p < 0.001; lower leg: p = 0.010). There was no significant difference in mean IMFI between participants with mild versus severe clinical phenotypes (p = 0.257)., Conclusion: A modified ImageJ-based algorithm was able to select and quantify fatty infiltration in a cohort of heterogeneously affected individuals with RYR1-RM. IMFI was not predictive of mode of inheritance but showed strong correlation with motor function and capacity tests including MFM-32 and 6MWT, respectively.

MRI is a helpful tool for monitoring disease progression in late-onset Pompe disease (LOPD). Our study aimed to evaluate if muscle diffusion tensor imaging (mDTI) shows alterations in muscles of LOPD patients with <10% fat-fraction. We evaluated 6 thigh and 7 calf muscles (both legs) of 18 LOPD and 29 healthy controls (HC) with muscle diffusion tensor imaging (mDTI), T1w, and mDixonquant sequences in a 3T MRI scanner. The quantitative mDTI-values axial diffusivity (λ 1 ), mean diffusivity (MD), radial diffusivity (RD), and fractional anisotropy (FA) as well as fat-fraction were analyzed. 6-Minute Walk Test (6-MWT) data were correlated to diffusion metrics. We found that mDTI showed significant differences between LOPD and HC in diffusion parameters (P < .05). Thigh muscles with <10% fat-fraction showed significant differences in MD, RD, and λ 1-3 . MD positively correlated with 6-MWT (P = .06). To conclude, mDTI reveals diffusion restrictions in muscles of LOPD with and without fat-infiltration and reflects structural changes prior to fatty degeneration., (© 2020 The Authors. Muscle & Nerve published by Wiley Periodicals LLC.)

Purpose: The purpose of this study was to investigate differences in the associations between passive ankle dorsiflexion range of motion (ROM) and stiffness of the triceps surae, sciatic nerve, and deep fascia located in the posterior leg between young and older people., Methods: Twenty young and twenty older males were recruited and were placed in a prone position with their hip and knee fully extended. Passive ankle dorsiflexion ROM was determined based on the onset of pain during passive dorsiflexion at 1°·s using an isokinetic dynamometer. Shear wave speeds (as a stiffness index) of the triceps surae, the sciatic nerve, and the deep fascia in the posterior leg were evaluated by ultrasound shear wave elastography., Results: The shear wave speeds of the medial and lateral gastrocnemius measured at 15° dorsiflexion correlated negatively with passive ROM in young but not in older participants. The shear wave speed of the sciatic nerve measured at 15° dorsiflexion correlated negatively with passive ROM only in older participants. No association was observed between passive ROM and shear wave speed of the deep fascia in the posterior leg. For data measured at maximal dorsiflexion angle (as an index of stretch tolerance), shear wave speeds of the triceps surae and passive joint torque correlated positively with passive ROM in both groups., Conclusion: These results suggest that the tissues limiting passive ankle dorsiflexion ROM are muscle and nerve for young and older people, respectively, whereas stretch tolerance influences passive ROM for both groups. This implies that the relative contribution of nonmuscular tissues to joint flexibility become stronger than that of muscles with age.

Purpose: MR offers the unique possibility to noninvasively investigate cellular energy metabolism via 31P MRS, while blood perfusion, which provides oxygen and substrates to the tissue, is accessible by arterial spin labeling (ASL) 1H MRI. Because metabolic and hemodynamic parameters are linked, it would be desirable to study them simultaneously. A 3D-resolved method is presented that allows such measurements with high spatiotemporal resolution and has the potential to discern differences along an exercising muscle., Methods: Multi-voxel localized 31 P MRS was temporally interleaved with multi-slice pASL 1H MRI. Phosphorus spectra were collected from two adjacent positions in gastrocnemius medialis (GM) during rest, submaximal plantar flexion exercise and recovery, while perfusion and T 2 * -weighted axial images were acquired at the same time. Seventeen healthy volunteers (9 f / 8 m) were studied at 7 T., Results: An increase of postexercise perfusion and T 2 * -weighted signal in GM positively correlated with end-exercise PCr depletion and pH drop. At proximal positions functional and metabolic activity was higher than distally, that is, perfusion increase and peak T 2 * -weighted signal, end-exercise PCr depletion, end-exercise pH, and PCr recovery time constant were significantly different. An NOE-induced SNR increase of approximately 20 % (P < .001), at rest, was found in interleaved 31 P spectra, when comparing to 31 P-only acquisitions., Conclusions: A technique for fast, simultaneous imaging of muscle functional heterogeneity in ASL, T 2 * and acquisition of time-resolved 31 P  MRS data is presented. These single exercise recovery experiments can be used to investigate local variations during disease progression in patients suffering from vascular or muscular diseases., (© 2019 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.)

Background Upper extremity MRI and proton MR spectroscopy are increasingly considered to be outcome measures in Duchenne muscular dystrophy (DMD) clinical trials. Purpose To demonstrate the feasibility of acquiring upper extremity MRI and proton ( 1 H) MR spectroscopy measures of T2 and fat fraction in a large, multicenter cohort (ImagingDMD) of ambulatory and nonambulatory individuals with DMD; compare upper and lower extremity muscles by using MRI and 1 H MR spectroscopy; and correlate upper extremity MRI and 1 H MR spectroscopy measures to function. Materials and Methods In this prospective cross-sectional study, MRI and 1 H MR spectroscopy and functional assessment data were acquired from participants with DMD and unaffected control participants at three centers (from January 28, 2016, to April 24, 2018). T2 maps of the shoulder, upper arm, forearm, thigh, and calf were generated from a spin-echo sequence (repetition time msec/echo time msec, 3000/20-320). Fat fraction maps were generated from chemical shift-encoded imaging (eight echo times). Fat fraction and 1 H 2 O T2 in the deltoid and biceps brachii were measured from single-voxel 1 H MR spectroscopy (9000/11-243). Groups were compared by using Mann-Whitney test, and relationships between MRI and 1 H MR spectroscopy and arm function were assessed by using Spearman correlation. Results This study evaluated 119 male participants with DMD (mean age, 12 years ± 3 [standard deviation]) and 38 unaffected male control participants (mean age, 12 years ± 3). Deltoid and biceps brachii muscles were different in participants with DMD versus control participants in all age groups by using quantitative T2 MRI ( P < .001) and 1 H MR spectroscopy fat fraction ( P < .05). The deltoid, biceps brachii, and triceps brachii were affected to the same extent ( P > .05) as the soleus and medial gastrocnemius. Negative correlations were observed between arm function and MRI (T2: range among muscles, ρ = -0.53 to -0.73 [ P < .01]; fat fraction, ρ = -0.49 to -0.70 [ P < .01]) and 1 H MR spectroscopy fat fraction (ρ = -0.64 to -0.71; P < .01). Conclusion This multicenter study demonstrated early and progressive involvement of upper extremity muscles in Duchenne muscular dystrophy (DMD) and showed the feasibility of MRI and 1 H MR spectroscopy to track disease progression over a wide range of ages in participants with DMD. © RSNA, 2020 Online supplemental material is available for this article.

Purpose: The purpose of this study was to evaluate the change in capillary blood volume in the muscles of the lower limbs, before and after exercise, using intravoxel incoherent motion (IVIM)., Materials and Methods: Diffusion-weighted images were obtained (with 16 b values) from the thigh and leg muscles of 11 subjects. The imaging was obtained before and immediately exercise; additionally, imaging was performed at 3 h, 6 h, and 24 h after exercise, and an IVIM index was calculated. The exercise involved walking up and down a flight of stairs (140 steps) ten times. The IVIM of each time course-before and after the exercise-was compared. In addition, we examined the correlation of IVIM measurements with the degree of the muscle ache that occurred at 24 h following the exercise., Results: The IVIM index significantly increased after exercise compared with that before exercise (P < 0.01). IVIM decreased at 3 h following exercise, but increased again at 24 h. A correlation was found between the IVIM index at 24 h after exercise and the degree of the muscle ache (r = 0.80) CONCLUSIONS: The capillary blood volume significantly increased after exercise when compared to before exercise. The capillary blood volume decreased after exercise at 3 h and 6 h following exercise, but it increased again at 24 h. There was a correlation between the degree of muscle ache and the amount of capillary blood volume measured from the femoral muscle at 24 h after exercise.

Objective: To quantitatively describe the MRI fat infiltration pattern of muscle degeneration in Charcot-Marie-Tooth (CMT) type 1A (CMT1A) disease and to look for correlations with clinical variables., Methods: MRI fat fraction was assessed in lower-limb musculature of patients with CMT1A and healthy controls. More particularly, 14 muscle compartments were selected at leg and thigh levels and for proximal, distal, and medial slices. Muscle fat infiltration profile was determined quantitatively in each muscle compartment and along the entire volume of acquisition to determine a length-dependent gradient of fat infiltration. Clinical impairment was evaluated with muscle strength measurements and CMT Examination Scores (CMTESs)., Results: A total of 16 patients with CMT1A were enrolled and compared to 11 healthy controls. Patients with CMT1A showed a larger muscle fat fraction at leg and thigh levels with a proximal-to-distal gradient. At the leg level, the largest fat infiltration was quantified in the anterior and lateral compartments. CMTES was correlated with fat fraction, especially in the anterior compartment of leg muscles. Strength of plantar flexion was also correlated with fat fraction of the posterior compartments of leg muscles., Conclusion: On the basis of quantitative MRI measurements combined with a dedicated segmentation method, muscle fat infiltration quantified in patients with CMT1A disclosed a length-dependent peroneal-type pattern of fat infiltration and was correlated to main clinical variables. Quantification of fat fraction at different levels of the leg anterior compartment might be of interest in future clinical trials., (© 2020 American Academy of Neurology.)

Aim: This study aimed to examine changes in lean mass during hospitalization in geriatric patients and the effect of muscle activation by neuromuscular electrical stimulation., Methods: Thirteen patients (69-94 yr) at a geriatric ward completed tests at hospital admission (days 2-3) and discharge (days 8-10). One leg received daily stimulation of the knee extensors, whereas the other leg served as a control leg. Lean mass was evaluated by dual-energy x-ray absorptiometry scans and muscle thickness by ultrasound scans. Muscle biopsies were collected from both legs at admission and discharge in nine patients and analyzed for fiber size, satellite cell number, and activation and expression of genes associated with muscle protein synthesis and breakdown, connective tissue, and cellular stress., Results: The relative decline in leg lean mass and midthigh region lean mass was larger in the control (-2.8% ± 1.5%) versus the stimulated leg (-0.5% ± 1.4%, P < 0.05). Although there were no changes in fiber size or satellite cell number, the mRNA data revealed that, compared with control, the stimulation resulted in a downregulation of myostatin (P < 0.05) and a similar trend for MAFbx (P = 0.099), together with an upregulation of Collagen I (P < 0.001), TenascinC (P < 0.001), CD68 (P < 0.01), and Ki67 (P < 0.05) mRNA., Conclusion: These findings demonstrate a moderate decline in leg lean mass during a hospital stay in geriatric patients, whereas leg lean mass was preserved with daily neuromuscular electrical muscle activation. At the cellular level, the stimulation had a clear influence on suppression of atrophy signaling pathways in parallel with a stimulation of connective tissue and cellular remodeling processes.

Background: Reduced push-off intensity during walking is thought to play an important role in age-related mobility impairment. We posit that an age-related shift toward shorter plantarflexor operating lengths during walking functionally limits force generation, and thereby the ability of those muscles to respond to increased propulsive demands during walking., Research Question: To determine whether gastrocnemius muscle fascicle lengths during normal walking: (1) are shorter in older than young adults, and (2) correlate with one's capacity to increase the propulsive demands of walking to their maximum., Methods: We used in vivo cine B-mode ultrasound to measure gastrocnemius fascicle lengths in 9 older and 9 young adults walking at their preferred speed, their maximum speed, and with horizontal impeding forces that increased in a ramped design at 1%BW/s to their maximum. A repeated measures ANOVA tested for effects of age and walking condition, and Pearson correlations assessed the relation between fascicle outcomes and condition performance., Results: A tendency toward shorter medial gastrocnemius muscle fascicle lengths in older versus young adults was not statistically significant. However, older adults walked with reduced peak fascicle shortening during all conditions compared to young adults - an outcome not explained by reduced muscle-tendon unit shortening and exacerbated during tasks with greater than normal propulsive demand. As hypothesized, we found a strong and significant positive correlation in older subjects between gastrocnemius fascicle lengths during normal walking and performance on the ramped impeding force condition (p = 0.005, r² = 0.704), even after controlling for isometric strength (p = 0.011, r² = 0.792) and subject stature (p = 0.010, r² = 0.700)., Significance: Our findings provide muscle-level insight to develop more effective rehabilitation techniques to improve push-off intensity in older adults and assistive technologies designed to steer plantarflexor muscle fascicle operating behavior during functional tasks., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to disclose., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Objectives: Assessment of the repeatability of diffusion parameter estimations in the upper leg muscles of healthy adults over the time course of 2 weeks, from a simultaneous bilateral upper leg DTI measurement., Methods: SE-EPI DTI datasets were acquired at 3 T in the upper legs of 15 active adults at a time interval of 2 weeks. ROIs were manually drawn for four quadriceps and three hamstring muscles of both legs. The following DTI parameters were analyzed: 1st, 2nd, and 3rd eigenvalue (λ 1 , λ 2 , and λ 3 ), mean diffusivity (MD), and fractional anisotropy (FA). DTI parameters per muscle were calculated with and without intravoxel incoherent motion (IVIM) correction together with SNR levels per muscle. Bland-Altman plots and within-subject coefficient of variation (wsCV) were calculated. Left-right differences between muscles were assessed., Results: The Bland-Altman analysis showed good repeatability of all DTI parameters except FA for both the IVIM-corrected and standard data. wsCV values show that MD has the highest repeatability (4.5% IVIM; 5.6% standard), followed by λ 2 (4.9% IVIM; 5.5% standard), λ 1 (5.3% IVIM; 7.5% standard), and λ 3 (5.7% IVIM; 5.7% standard). wsCV values of FA were 15.2% for the IVIM-corrected data and 13.9% for the standard analysis. The SNR (41.8 ± 16.0 right leg, 41.7 ± 17.1 left leg) and wsCV values were similar for the left and right leg and no left-right bias was detected., Conclusions: Repeatability was good for standard DTI data and slightly better for IVIM-corrected DTI data. Our protocol is suitable for DTI of the upper legs with overall good SNR., Key Points: • The presented DTI protocol is repeatable and therefore suitable for bilateral DT imaging of the upper legs. • Additional B1 + calibrations improve SNR and repeatability. • Correcting for perfusion effects improves repeatability.

Objective: Hereditary neuropathy with liability to pressure palsies (HNPP) is caused by heterozygous deletion of the peripheral myelin protein 22 (PMP22) gene. Patients with HNPP present multifocal, reversible sensory/motor deficits due to increased susceptibility to mechanical pressure. Additionally, age-dependent axonal degeneration is reported. We hypothesize that length-dependent axonal loss can be revealed by MRI, irrespective of the multifocal phenotype in HNPP., Methods: Nerve and muscle MRI data were acquired in the proximal and distal leg of patients with HNPP (n = 10) and matched controls (n = 7). More specifically, nerve magnetization transfer ratios (MTR) were evaluated to assay proximal-to-distal gradients in nerve degeneration, while intramuscular fat percentages (F per ) were evaluated to assay muscle fat replacement following denervation. Neurological disabilities were assessed via the Charcot-Marie-Tooth neuropathy score (CMTNS) for correlation with MRI., Results: F per values were elevated in HNPP proximal muscle (9.8 ± 2.2%, P = 0.01) compared to controls (6.9 ± 1.0%). We observed this same elevation of HNPP distal muscles (10.5 ± 2.5%, P < 0.01) relative to controls (6.3 ± 1.1%). Additionally, the amplitude of the proximal-to-distal gradient in F per was more significant in HNPP patients than controls (P < 0.01), suggesting length-dependent axonal loss. In contrast, nerve MTR values were similar between HNPP subjects (sciatic/tibial nerves = 39.4 ± 2.0/34.2 ± 2.5%) and controls (sciatic/tibial nerves = 37.6 ± 3.8/35.5 ± 1.2%). Proximal muscle F per values were related to CMTNS (r = 0.69, P = 0.03), while distal muscle F per and sciatic/tibial nerve MTR values were not related to disability., Interpretation: Despite the multifocal nature of the HNPP phenotype, muscle F per measurements relate to disability and exhibit a proximal-to-distal gradient consistent with length-dependent axonal loss, suggesting that F per may be a viable biomarker of disease progression in HNPP., (© 2019 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals, Inc on behalf of American Neurological Association.)

Objectives: This study aimed to evaluate the relationship of leg muscle symmetry to the prevalence, radiographic grade, and symptoms of knee osteoarthritis (OA)., Method: We conducted a cross-sectional study using data from the Korean National Health and Nutrition Examination Survey (KNHANES), collected in 2010 and 2011. Men and women aged 60 years or older were included. Leg muscle mass was measured using dual-energy X-ray absorptiometry, and the muscle asymmetry index was defined as ∣(left leg muscle mass)/(left and right leg muscle mass) × 100 - 50∣. Statistical analyses were performed to examine the relationships between the muscle asymmetry index and the radiographic grade and knee symptoms., Results: A total of 2548 subjects were included in the analysis. The muscle asymmetry index was positively associated with radiographic knee OA grade and knee pain, especially in men. Men with knee OA and the highest quartile of muscle asymmetry index were 3.3 times more likely to have knee pain compared with those in the lowest quartile. When subjects were divided into four groups by body mass index (BMI) and muscle asymmetry index, subjects with asymmetric obese and men with asymmetric normal BMI had worse grade of radiographic knee OA., Conclusions: Leg muscle asymmetry in men, irrespective of obesity, was associated with significantly higher grade of radiographic knee OA and prevalent knee pain. Longitudinal studies will be needed to determine the cause-and-effect relationship and to determine whether the higher or lower mass, beyond the asymmetry, is associated with radiographic severity or symptomatic knee OA.Key Points•Leg muscle asymmetry was related to prevalence and radiographic severity of knee OA, especially in men.•Leg muscle asymmetry was associated with knee pain.•Those with both leg muscle asymmetry and obesity showed higher prevalence of knee pain and worse radiographic knee OA.

Background: sufficient research has not been conducted to determine the role of core and lower limb muscles in providing balance in older people., Objective: to investigate the relationships between the thickness of core/lower limb muscles and static/dynamic balance in older people., Methods: the study included a total of 68 older people (≥ 65 years) and 68 gender-matched young subjects, aged 20-40 years. Balance, knee proprioception sense, regional and total muscle measurements and grip strength were assessed using a force platform system, isokinetic dynamometer, ultrasound imaging, bioelectrical impedance analysis and Jamar dynamometer, respectively., Results: all the static (postural sway) parameters were higher and all the dynamic (limits of stability) parameters were lower in the older adults compared to the young adults (all P<0.05). The diaphragm was thicker and all the other muscles (except for multifidus and tibialis anterior) were thinner in the older group (all P<0.05). A higher error of knee proprioception sense was determined at 45 and 70 degrees in the older subjects (both P<0.001). According to the multivariate analyses, significant predictors for balance were age, gender, height, and rectus femoris, vastus intermedius and diaphragm muscle thicknesses in the older group, and age, gender, height, grip strength, and rectus abdominis, internal oblique, longissimus, tibialis anterior and soleus muscle thicknesses in the young group (all P<0.05)., Conclusions: the thickness of core/lower limb muscles are important determinants of balance in both older and young adults. These findings could provide a strong rationale for strengthening specific (abdominal and quadriceps) muscles to prevent falls and regional sarcopenia, and to improve posture/balance in the older population., Clinical Trial Registration Number: NCT03791047., Ethics Committee Approval: Hacettepe University Non-interventional Clinical Research Ethics Board. Decision number:GO 18/506-39., (© The Author(s) 2019. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Duchenne muscular dystrophy (DMD) is a hereditary neuromuscular disease leading to progressive muscle wasting. Since there is a need for MRI variables that serve as early sensitive indicators of response to treatment, several quantitative MRI methods have been suggested for disease monitoring., Purpose: To evaluate the potential of sodium ( 23 Na) and proton ( 1 H) MRI methods to assess early pathological changes in skeletal muscle of DMD., Study Type: Prospective clinical study., Population: 23 Na and 1 H MRI of the right leg were performed in 13 patients with DMD (age 7.8 ± 2.4) and 14 healthy boys (age 9.5 ± 2.2)., Field Strength/sequence: 3 T including a multiecho-spin-echo sequence, diffusion-weighted sequences, 1 H spectroscopy, 3-pt Dixon, and 23 Na ultrashort echo time sequences., Assessment: We obtained water T 2 maps, fat fraction (FF), pH, and diffusion properties of the skeletal muscle tissue. Moreover, total tissue sodium concentration (TSC) was calculated from the 23 Na sequence. Intracellular-weighted 23 Na signal (ICwS) was derived from 23 Na inversion-recovery imaging., Statistical Tests: Results from DMD patients and controls were compared using Wilcoxon rank-sum tests and repeated analysis of variance (ANOVA). Spearman-rank correlations and area under the curve (AUC) were calculated to assess the performance of the different MRI methods to distinguish dystrophic from healthy muscle tissue., Results: FF, water T 2 , and pH were higher in DMD patients (0.07 ± 0.03, 39.4 ± 0.8 msec, 7.06 ± 0.03, all P < 0.05) than in controls (0.02 ± 0.01, 36.0 ± 0.4 msec, 7.03 ± 0.02). No difference was observed in diffusion properties. TSC (26.0 ± 1.3 mM, P < 0.05) and ICwS (0.69 ± 0.05 a.u., P < 0.05) were elevated in DMD (controls: 16.5 ± 1.3 mM and 0.47 ± 0.04 a.u.). The ICwS was frequently abnormal in DMD even when water T 2 , FF, and pH were in the normal range. 23 Na MRI showed higher AUC values in comparison to the 1 H methods., Data Conclusion: Sodium anomalies were regularly observed in patients with DMD compared with controls, and were present even in absence of fatty degenerative changes and water T 2 increases., Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1103-1113., (© 2019 International Society for Magnetic Resonance in Medicine.)

Calcific myonecrosis is a rare disease that has been shown to be a late sequela of trauma. This article presents a 68-year-old man with calcific myonecrosis of the leg 40 years after a tibial fracture complicated with peroneal nerve palsy. The soft tissue mass increased in size after another injury to the leg that occurred two years before his presentation. Physical examination at presentation showed a palpable extra-osseous mass at the anterior aspect of the left leg; the mass was not adherent to adjacent soft-tissues and bone, and it was painless but tender to palpation. Radiographs of the left leg showed extensive calcification at the soft-tissue of the anterior and posterior leg. An ultrasonography-guided trocar biopsy was done; histological findings were indicative of calcific myonecrosis. Given the benign entity of the lesion and known high rate of complications, he was recommended for no further treatment except for clinical and imaging observation. Located at the site of the biopsy, he experienced infection with drainage that eventually healed after six months with antibiotics and wound dressing changes. During the last follow-up examination, two years after diagnosis, the patient was asymptomatic without progression of the mass.

Cerebral palsy (CP) is a movement disorder associated with small and weak muscles. Methods that accurately assess muscle mass in children with CP are scarce. The purpose of this study was to determine whether dual-energy X-ray absorptiometry (DXA) accurately estimates midleg muscle mass in ambulatory children with spastic CP. Ambulatory children with spastic CP and typically developing children 5-11 y were studied (n = 15/group). Fat-free soft tissue mass (FFST) and fat mass at the middle third of the tibia (i.e., midleg) were estimated using DXA. Muscle mass (muscle MRI ) and muscle mass corrected for intramuscular fat (muscle MRIfc ) in the midleg were estimated using magnetic resonance imaging (MRI). Statistical models were created to predict muscle MRI and muscle MRIfc using DXA. Children with CP compared to typically developing children had lower FFST (38%), muscle MRI (40%) and muscle MRIfc (47%) (all p < 0.05) and a lower ratio of muscle MRIfc to FFST (17%, p < 0.05). DXA-based models developed using data from typically developing children overestimated muscle MRI (13%) and muscle MRIfc (22%) (both p < 0.05) in children with CP. DXA-based models developed using data from children with CP explained 91% of the variance in muscle MRI and 90% of the variance in muscle MRIfc in children with CP (both p < 0.05). Moreover, the estimates were not different from muscle MRI and muscle MRIfc (both p > 0.99). We conclude that DXA-based statistical models accurately estimate midleg muscle mass in children with CP when the models are composed using data from children with CP rather than typically developing children., (Copyright © 2018 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.)

Context : Patients with chronic ankle instability (CAI) have demonstrated atrophy of foot and ankle musculature and deficits in ankle strength. The effect of rehabilitation on muscle morphology and ankle strength has not previously been investigated in patients with CAI. Objective : Our objective was to analyze the effect of impairment-based rehabilitation on intrinsic and extrinsic foot and ankle muscle volumes and strength in patients with CAI. Design : Controlled laboratory study. Setting : Laboratory. Patients : Five young adults with CAI. Intervention : Twelve sessions of supervised impairment-based rehabilitation that included range of motion, strength, balance, and functional exercises. Main Outcome Measures : Measures of extrinsic and intrinsic foot muscle volume and ankle strength measured before and after 4 weeks of supervised rehabilitation. Novel fast-acquisition magnetic resonance imaging was used to scan from above the femoral condyles through the entire foot. The perimeter of each muscle was outlined on each axial slice and then the 2-dimensional area was multiplied by the slice thickness (5 mm) to calculate muscle volume. Plantar flexion, dorsiflexion, inversion, and eversion isometric strength were measured using a hand-held dynamometer. Results : Rehabilitation resulted in hypertrophy of all extrinsic foot muscles except for the flexor hallucis longus and peroneals. Large improvements were seen in inversion, eversion, and plantar flexion strength following rehabilitation. Effect sizes for significant differences following rehabilitation were all large and ranged from 1.54 to 3.35. No significant differences were identified for intrinsic foot muscle volumes. Conclusion : Preliminary results suggest that impairment-based rehabilitation for CAI can induce hypertrophy of extrinsic foot and ankle musculature with corresponding increases in ankle strength.

Background: In patients with arm or leg lymphedema, more fat has been found in the epifascial compartment of the edematous limb compared to the healthy limb. However, not much is known about subfascial fat accumulation in these patients. This study aims to investigate the intramuscular and intermuscular fat and muscle/water volume in lymphedema patients. The excess of intramuscular and intermuscular fat volume was also compared to the excess epifascial fat volume, the excess limb volume, and the duration of lymphedema. Methods and Results: Data from 13 patients (seven arm and six leg lymphedemas) were acquired using a 1.5 T magnetic resonance imaging (MRI) scanner before liposuction and at five time points (4 days, 4 weeks, 3 months, 6 months, and 1 year) after liposuction. From water-fat imaging, fat and muscle/water volumes within the intramuscular and intermuscular compartments were calculated. The relative excess volume was defined as (volume of edematous limb-volume of healthy limb)/volume of healthy limb. Elevated relative excess volumes of intramuscular and intermuscular fat were found at all time points. A decrease in the relative excess volume of muscle/water over time was found. This decrease was not correlated to the relative excess of epifascial fat volume, the relative excess of limb volume, or the duration of lymphedema. Conclusions: An excess fat volume was found in the intramuscular and intermuscular compartments in lymphedema patients. The results suggest that the subfascial compartment needs to be studied separately as no correlation between intramuscular/intermuscular fat accumulation and other measured parameters was found.

Muscle performance is closely related to the structure and function of tendons and aponeuroses, the sheet-like, intramuscular parts of tendons. The architecture of aponeuroses has been difficult to study with magnetic resonance imaging (MRI) because these thin, collagen-rich connective tissues have very short transverse relaxation (T2) times and therefore provide a weak signal with conventional MRI sequences. Here, we validated measurements of aponeurosis dimensions from two MRI sequences commonly used in muscle-tendon research (mDixon and T1-weighted images), and an ultrashort echo time (UTE) sequence designed for imaging tissues with short T2 times. MRI-based measurements of aponeurosis width, length, and area of 20 sheep leg muscles were compared to direct measurements made with three-dimensional (3D) quantitative microdissection. The errors in measurement of aponeurosis width relative to the mean width were 1.8% for UTE, 3.7% for T1, and 18.8% for mDixon. For aponeurosis length, the errors were 7.6% for UTE, 1.9% for T1, and 21.0% for mDixon. Measurements from T1 and UTE scans were unbiased, but mDixon scans systematically underestimated widths, lengths, and areas of the aponeuroses. Using the same methods, we then found high inter-rater reliability (intraclass correlation coefficients >0.92 for all measures) of measurements of the dimensions of the central aponeurosis of the human tibialis anterior muscle from T1-weighted scans. We conclude that valid and reliable measurements of aponeurosis dimensions can be obtained from UTE and from T1-weighted scans. When the goal is to study the macroscopic architecture of aponeuroses, UTE does not hold an advantage over T1-weighted imaging., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Diffusion tensor imaging (DTI) has been used to characterize calf skeletal muscle architecture., Purpose: To assess the diffusional properties of the calf muscles of subjects with and without diabetes, at rest and during isometric plantarflexion exercise., Study Type: Prospective., Subjects: Twenty-six subjects in two groups: 13 healthy and 13 subjects with type 2 diabetes (DM); each group consisted of seven females and six males., Field Strength/sequence: 3T/2D single-shot spin echo planar imaging., Assessment: Fractional anisotropy (FA), mean diffusivity (MD), diffusion eigenvalues, and fiber tracking indices were obtained from the medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus (SOL) muscles of the calf at rest and during isometric plantarflexion exercise., Statistical Tests: We used a combination of nonparametric (Wilcoxon) and parametric (t-test) statistical assessments., Results: The medial gastrocnemius muscle had more indices with significant differences between the two groups (six indices with P < 0.05) than did the lateral gastrocnemius (three indices with P < 0.05) and soleus muscles (only one index with P < 0.05). While the healthy group showed elevated MD values from rest to exercise (MG = 5.83%, LG = 13.45%, and SOL = 11.68%), the diabetic MD showed higher increases (MG = 19.74%, LG = 29.31%, and SOL = 20.84%) that were different between groups (MG: P = 0.009, LG: P = 0.037, and SOL: P = 0.049)., Data Conclusion: Our results indicate considerable diffusional changes between healthy subjects and subjects with diabetes at rest and during isometric plantarflexion exercise in the calf muscles. The medial gastrocnemius muscle displayed the most diffusion sensitivity to diabetes-related microstructural changes., Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1285-1295., (© 2018 International Society for Magnetic Resonance in Medicine.)

Introduction: Acute compartment syndrome (ACS) is a limb-threatening condition often associated with leg injury. The only treatment of ACS is fasciotomy with the purpose of reducing muscle compartment pressures (MCP). Patient discomfort and low reliability of invasive MCP measurements, has led to the search for alternative methods. Our goal was to test the feasibility of using ultrasound to diagnose elevated MCP., Methods: A cadaver model of elevated MCPs was used in 6 cadaver legs. An ultrasound transducer was combined with a pressure sensing transducer to obtain a B-mode image of the anterior compartment, while controlling the amount of pressure applied to the skin. MCP was increased from 0 to 75 mmHg. The width of the anterior compartment (CW) and the pressure needed to flatten the bulging superficial compartment fascia (CFFP) were measured., Results: Both the CW and CFFP showed high correlations to MCP in the individual cadavers. Average CW and CFFP significantly increased between baseline and the first elevated MCP states. Both Inter-observer and intra-observer agreements for the ultrasound measurements were good to excellent., Discussion: Ultrasound indexes showed excellent correlations in compartment pressures, suggesting that there is a potential for the clinical use of this modality in the future., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Introduction: The extensor hallucis longus (EHL) muscle is important for diagnosis of neurologic lesions. It is also a target muscle for treatment. We investigated EHL with ultrasonography to determine optimal needle placement for safety and accuracy., Methods: A total of 96 legs of 48 healthy volunteers were examined through ultrasonography. Four published electromyographic methods for finding the EHL were assessed. We identified the midpoint of EHL (MD) using landmarks to determine optimal needle placement., Results: Mean values of bimalleolar line-MD on skin (MD-S) and tibial crest-MD-S were 10.5 ± 1.2 cm and 3.6 ± 0.4 cm, respectively. The depth of MD was 1.6 ± 0.2 cm. According to 4 EMG methods, the probability of needle penetrating EHL was 13% to 79% and that of needle penetrating the neurovascular bundle was 50% to 89%., Conclusions: Using ultrasonography, we could determine optimal needle placement in the EHL. Muscle Nerve 59:331-336, 2019., (© 2018 Wiley Periodicals, Inc.)

Objectives: The mechanism by which compression therapy works is still discussed, especially at calf level. Whether lower limb deep vein diameters change under compression stockings is a matter of debate: no change versus great change. New study material helps to address this question., Methods: This was an experimental single centre controlled study on nine selected patients with mild to moderate superficial venous disease. A total of 34 deep vein segments were examined. A new hybrid (elastic + non-elastic materials) cuff pressure device enabled the deep vein diameter changes from baseline to occlusion similar to that which could be observed under stockings. The deep vein diameters were measured through the device with the patients in a standing position and their body weight distributed equally on both legs. This was compared to a 20-35 mm Hg medical compression stocking. The diameter change when patients put their whole body weight on the tested leg was also measured., Results: A pressure of 25.3 ± 6.4 mm Hg (mean, SD) was required to ovalise lower leg deep veins and a pressure of 43.1 ± 16.2 mm Hg (mean, SD) to occlude them. Both pressures were significantly different from baseline: p = .003 and p < .0001, respectively. No diameter reduction was achieved when the stockings were worn, and occlusion of deep veins occurred when the patients transferred their body weight onto the examined leg., Conclusion: In the standing position, deep vein diameter reduction is not caused by compression stockings but may be due to the isometric muscle contractions required to support the patient's body weight., (Copyright © 2018 European Society for Vascular Surgery. Published by Elsevier B.V. All rights reserved.)

Background: Measures of skeletal muscle function decline at a faster rate with ageing than do indices of skeletal muscle mass. These observations have been attributed to age-related changes in muscle quality, another functional determinant separate from skeletal muscle mass. This study tested the hypothesis that improved predictions of skeletal muscle strength can be accomplished by combining clinically available measures of skeletal muscle mass and quality., Methods: The participants included 146 healthy adult (age ≥ 18 years, range 18-77 years; X ± SD 47 ± 17 years and body mass index 16.5-51.8 kg/m 2 ; 27.7 ± 6.2 kg/m 2 ) men (n = 60) and women (n = 86) in whom skeletal muscle mass was estimated as appendicular lean soft tissue (LST) measured by dual-energy X-ray absorptiometry and skeletal muscle quality as bioimpedance analysis-derived phase angle and B-mode-evaluated echogenicity of mid-thigh skeletal muscle. Strength of the right leg and both arms was quantified as knee isokinetic extension and handgrip strength using dynamometers. The statistical significance of adding phase angle or echogenicity to strength prediction multiple regression models that included extremity-specific LST and other covariates (e.g. age and sex) was evaluated to test the study hypothesis., Results: Right leg LST mass alone was significantly (P < 0.0001) correlated with isokinetic right leg strength (R 2  = 0.57). The addition of segmental phase angle measured in the right leg at 50 kHz increased the R 2 of this model to 0.66 (P < 0.0001); other phase angle frequencies (5 and 250 kHz) did not contribute significantly to these models. Results were similar for both right and left arm handgrip strength prediction models. Adding age and sex as model covariates increased the R 2 values of these models further (e.g. right leg strength model R 2 increased to 0.71), but phase angle continued to remain a significant (all P < 0.01) predictor of extremity strength. Similarly, when predicting isokinetic right leg strength, mid-thigh skeletal muscle echogenicity added significantly (P < 0.0001) to right leg LST, increasing R 2 from 0.57 to 0.64; age was a significant (P < 0.0001) covariate in this model, increasing R 2 further to 0.68., Conclusions: The hypothesis of the current study was confirmed, strongly supporting and extending earlier reports by quantifying the combined independent effects of skeletal muscle mass and quality on lower-body and upper-body measures of strength. These observations provide a clinically available method for future research aimed at optimizing sarcopenia and frailty risk prediction models., (© 2018 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.)

Shear wave elastography (SWE) is emerging as an innovative tool to evaluate muscle properties and function. It has been shown to correlate with both passive and active muscle forces, and is sensitive to physiological processes and pathological conditions. Similarly, intramuscular pressure (IMP) is an important parameter that changes with passive and active muscle contraction, body position, exercise, blood pressure, and several pathologies. Therefore, the objective of this study was to quantify the dependency of shear modulus within the lower-leg muscles on IMP in healthy individuals. Nineteen healthy individuals (age: Mean age ± SD, 23.84 ± 6.64 years) were recruited. Shear modulus was measured using ultrasound SWE on the tibialis anterior (TA) and peroneus longus (PL) muscles using pressure cuff inflation around the thigh at 40 mmHg, 80 mmHg, and 120 mmHg. Changes in IMP were verified using a catheter connected to a blood pressure monitor. It was found that IMP was correlated to TA and PL shear modulus (spearman's rank correlation = 0.99 and 0.99, respectively). Applying a gradual increase of cuff pressure from 0 to 120 mmHg increased the shear modulus of the TA and PL muscles from 15.83 (2.46) kPa to 21.88 (4.33) kPa and from 9.64 (1.97) kPa to 12.88 (5.99) kPa, respectively. These results demonstrate that changes of muscle mechanical properties are dependent on IMP. This observation is important to improve interpretation of ultrasound elastograms and to potentially use it as a biomarker for more accurate diagnosis of pathologies related to increased IMP., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objective: The aim of this study was to assess and compare the overall performance, reliability, variability, as well as the accuracy of diffusion tensor imaging (DTI) and fiber tracking metrics, for the muscles of the calf at 3 T and 7 T., Materials and Methods: Ten volunteers (5 males; mean age, 29.1 ± 4.7 years), with no history of muscle disease, were examined twice at 3 T and 7 T, using a stimulated-echo acquisition mode DTI sequence. Signal-to-noise ratio (SNR) and DTI metrics (track numbers [trn], length [trl], volume [trv], fractional anisotropy [FA], mean [MD], axial [AD], and radial diffusivity [RD]) of the whole-calf muscles, the tibialis anterior, the gastrocnemius medialis, the gastrocnemius lateralis, and the soleus were collected. The Student t test was used to compare SNR and DTI metrics obtained at 3 T and 7 T. The coefficients of variation and the intraclass correlation coefficients were derived to assess the variability and the reliability of the DTI measurements at 3 T and 7 T. To further assess the accuracy of the measurements, the absolute difference was computed for each DTI metric at 3 T and 7 T and then compared (Student t test). The applied level of significance for all the statistical analyses was P < 0.05., Results: As expected, the SNR was higher at 7 T than at 3 T (+111%; P < 0.001). At 7 T, the tracked fibers of the whole calf muscles, the gastrocnemii, and the soleus were more numerous (trn +5.5%, +3.1%, +8.5%, and +15.1%, respectively), longer (trl +13.1%, +18.8%, +19.3%, and +33.3%, respectively), and showed a greater volume (trv +12.1%, +12.2%, +14.7%, and +15.7%, respectively) than at 3 T (P < 0.05 each). The soleus demonstrated higher FA (+14.3%), lower MD (-1.7%), AD (-1.9%), and RD (-2%) at 7 T than at 3 T (P < 0.05 each), whereas the other muscles showed more heterogeneous results. The coefficients of variation were good (ie, <10%) for all DTI metrics at both 3 T and 7 T. The intraclass correlation coefficient was excellent (>0.750) at 7 T and 3 T for several DTI metrics, such as the trn of the gastrocnemii and the soleus, the trv of the gastrocnemii, the FA of the whole-calf muscles, gastrocnemius medialis, tibialis anterior, and soleus, and the RD of all investigated muscles (ie, whole-calf muscles, gastrocnemii, tibialis anterior, and soleus). There were no significant differences between the 2 consecutive measurements with each device, except for the trn of the whole-calf muscles and the FA of the gastrocnemius lateralis (higher mean absolute difference at 3 T and 7 T, respectively; P < 0.05 each)., Conclusions: Despite the numerous challenges associated with DTI of the muscles, both 3 T and 7 T demonstrated reliable and precise results.

Objective: This paper presents magnetic resonance images of the dorsi- and plantar flexor muscles for individual young and older healthy adults. Also included are measurements of the volume, proportion, and longitudinal distribution of contractile and non-contractile tissue. This dataset was previously used to quantify age-related differences in these measures, constrain subject- and muscle-specific estimates of dorsi- and plantar flexor maximal isometric force capability, and quantify the degree to which maximal isometric force capability explains the age-related variance in postural control., Data Description: The data include contiguous axial magnetic resonance images of the lower leg for 12 young (21-31 years) and 12 older (66-79 years) healthy adults. The data are in the form of MATLAB binary files with a freely distributable custom MATLAB analysis program that allows image viewing and navigation in two and three dimensions, muscle outlining, tissue segmentation, and cross-sectional area calculation. The latter measurements are contained in a set of companion MATLAB binary files, which are included with the image data files. If desired, the magnetic resonance images could be used to identify other anatomical structures, or the MATLAB programs could be used to analyze other image sets.

Renal cell carcinoma (RCC) is a tumor that usually metastasizes to lung, liver, bone and brain, but rarely to skeletal muscles. We report a case of an elderly man with a history of bilateral metachronous RCC for which he underwent curative bilateral nephrectomies and renal transplantation, was in remission, and presented with a large solitary skeletal muscle metastasis from the initial RCC, 3 years later.

Background: Delayed-onset muscle soreness (DOMS) is one of the most common reasons for impaired muscle performance in sports. However, little consensus exists regarding which treatments may be most effective, and the underlying mechanisms are poorly understood., Objectives: To investigate the influence of compression garments on the development of DOMS, focusing on changes in muscle perfusion and muscle stiffness., Methods: In this controlled laboratory study with repeated measures, muscle perfusion and stiffness, calf circumference, muscle soreness, passive ankle dorsiflexion, and creatine kinase levels were assessed in participants before (baseline) a DOMS-inducing eccentric calf exercise intervention and 60 hours later (follow-up). After DOMS induction, a sports compression garment (18-21 mmHg) was worn on 1 randomly selected calf until follow-up, while the contralateral calf served as an internal control. Muscle perfusion was assessed using contrast-enhanced ultrasound (peak enhancement and wash-in area under the curve), while muscle stiffness was assessed using acoustic radiation force impulse (shear-wave velocities). A magnetic resonance imaging scan of both lower legs was also performed during the follow-up testing session to characterize the extent of exercise-induced muscle damage. Comparisons were made between limbs and over time., Results: Shear-wave velocity values of the medial gastrocnemius showed a significant interaction between time and treatment (P = .006), with the noncompressed muscle demonstrating lower muscle stiffness values at follow-up compared to baseline or to the compressed muscle. No significant differences in soleus muscle stiffness were noted between limbs or over time, as was the case for muscle perfusion metrics (peak enhancement and wash-in area under the curve) for the medial gastrocnemius and soleus muscles. Further, compression had no significant effect on passive ankle dorsiflexion, muscle soreness, calf circumference, or injury severity, per magnetic resonance imaging., Conclusion: Continuous wearing of compression garments during the inflammation phase of DOMS may play an important role in regulating muscle stiffness; however, compression garments have no significant effects on intramuscular perfusion or other common clinical assessments. J Orthop Sports Phys Ther 2018;48(11):887-894. Epub12 Jun 2018. doi:10.2519/jospt.2018.8038.

Purpose: 3D time-resolved (4D) phase contrast MRI can be used to study muscle contraction. However, 3D coverage with sufficient spatiotemporal resolution can only be achieved by interleaved acquisitions during many repetitions of the motion task, resulting in long scan times. The aim of this study was to develop a compressed sensing accelerated 4D phase contrast MRI technique for quantification of velocities and strain rate of the muscles in the lower leg during active plantarflexion/dorsiflexion., Methods: Nine healthy volunteers were scanned during active dorsiflexion/plantarflexion task. For each volunteer, we acquired a reference scan, as well as 4 different accelerated scans (k-space undersampling factors: 3.14X, 4.09X, 4.89X, and 6.41X) obtained using Cartesian Poisson disk undersampling schemes. The data was reconstructed using a compressed sensing pipeline. For each scan, velocity and strain rate values were quantified in the gastrocnemius lateralis, gastrocnemius medialis, tibialis anterior, and soleus., Results: No significant differences in velocity values were observed as a function acceleration factor in the investigated muscles. The strain rate calculation resulted in one positive (s + ) and one negative (s - ) eigenvalue, whereas the third eigenvalue (s 3 ) was consistently 0 for all the acquisitions. No significant differences were observed for the strain rate eigenvalues as a function of acceleration factor., Conclusions: Data undersampling combined with compressed sensing reconstruction allowed obtainment of time-resolved phase contrast acquisitions with 3D coverage and quantitative information comparable to the reference scan. The 3D sensitivity of the method can help in understanding the connection between muscle architecture and muscle function in future studies., (© 2018 International Society for Magnetic Resonance in Medicine.)