Keywords: Tendon/Ligament, Quantitative Imaging, T2*, Bi-exponential, UTE, CONES

Motivation: Tendon laxity, which may cause skeletal maltracking, can lead to pain and increased injury risk. Non-invasive measurement of tendon laxity remains a challenge but Ultrashort echo time (UTE)-T2* mapping may serve as a potential evaluation method.

Goal(s): This study aims to evaluate the sensitivity and repeatability of UTE-T2* mapping to tendon laxity.

Approach: We scanned the Achilles tendons of human subjects under tension and relaxation using UTE sequences.

Results: T2* relaxation times seemed to decrease as tendon load increased, from plantar flexion to dorsiflexion. However, the changes observed were small and intra-subject variability with position did not show any specific trends.

Impact: As the changes in T2* relaxation times were small and showed poor reproducibility, UTE-T2* mapping may not be sensitive enough to changes in tendon tensile loading and laxity.

Keywords: Muscle, Muscle

Motivation: Understanding the visual representation of spontaneous activities in DWI.

Goal(s): Automatically identifying visual differences in patterns of spontaneous muscular activities.

Approach: Deep-learning based detection and segmentation with subsequent feature analysis.

Results: Feasibility of feature-based clustering in individual subjects was shown.

Impact: Investigation of a pipeline for automated image processing for exploring differences in spontaneous muscular activities visible in DWI.

Keywords: Muscle, Motion Correction

Motivation: Respiratory muscles are often altered in subjects with neuromuscular diseases. Characterizing their structure using quantitative MRI is then crucial but challenging due to respiratory motion.

Goal(s): We developed a 3D free-breathing Magnetic Resonance Fingerprinting sequence for quantifying fat fraction (FF) and water T1 (T1_H2O) of upper body muscles at 3T.

Approach: We estimated the free-form respiration motion deformation on a 3D pre-scan using VoxelMorph and subsequently applied it in an iterative reconstruction framework to retrieve the MRF image series.

Results: This method allows a significant reduction of motion artefacts on parametric FF and  T1_H2O maps.

Impact: Free-breathing MRF T1-FF on 3T scanners paves the way for high resolution quantification of FF and T1_H2O in the upper body muscles for monitoring their structural alterations in subjects with neuromuscular diseases with high precision.

Keywords: Tendon/Ligament, Tendon/Ligament, Knee, Tendinopathy, Joint, Patient Reported Outcomes, Sports Injury

Motivation: Patellar tendinopathy (PT) is a common athletic overuse injury affecting either or both knees that can lead to pain and early sport retirement. However, athlete reported differences between bilateral and unilateral PT remains unknown.

Goal(s): We tested the hypothesis that athletes with MRI signs of bilateral PT have more self-reported knee problems compared to athletes with no or unilateral PT.

Approach: 53 pre-season elite college athletes were bilaterally imaged and completed knee surveys. Statistical tests were conducted to determine differences between no, unilateral, or bilateral PT.

Results: Significant differences in pain and quality of life in athletes with bilateral PT exist.

Impact: Elite athletes with bilateral patellar tendinopathy (PT) have more pain and a reduced quality of life, problems that may keep athletes from optimal sport performance. MR may help identify at-risk athletes for preventive care, potentially keeping athletes from further injury.

Keywords: Muscle, Bone, lumbar,paravertebral muscle,mDixon-Quant, T2 mapping

Motivation: Ankylosing spondylitis (AS) may cause changes in the patient's lumbar region, so it’s worth investigating whether AS affects the paraspinal muscles.

Goal(s):   To examine the changes in both the lumbar region and paraspinal muscles in AS patients, as well as any correlations between them.

Approach:  In this study, we utilized mDixon-Quant and T2 mapping to assess the FF and T2 values of the lumbar region and paraspinal muscles.

Results:  The AS group showed significantly higher FF and T2 values in the lumbar region and psoas major compared to the healthy controls, and there was a positive correlation between them.

Impact: This investigation has revealed a notable correlation between changes in the paravertebral muscles and the vertebral body. Clinicians will be able to perform thorough assessments of patients with AS and develop effective treatment plans.

Keywords: Muscle, Diabetes

Motivation: Fat deposition in skeletal muscle plays a vital role in type 2 diabetes mellitus (T2DM) but it lacks assessment of muscle fat infiltration in various stages of progression. 

Goal(s):  Quantitatively detect skeletal muscle fat content in T2DM patients with different courses and severity.

Approach: We measured thigh and paravertebral muscle fat fraction (FF) in T2DM patients using the mDixon-quant sequence and analyzed its association with other ectopic fat and clinical markers. 

Results: The FF value of skeletal muscle in T2DM patients was significantly higher than in the healthy group and was correlated with visceral adipose tissue and the course of T2DM.

Impact: Analyzing the variation in muscle fat deposition in diabetes may provide a more accurate assessment of insulin resistance, which can be utilized to guide clinical medication.

Keywords: Muscle, Diffusion/other diffusion imaging techniques, Magnetic Resonance Spectroscopic Imaging, Radial trajectories

Motivation: To investigate the diffusion of calf muscle intra-myocellular droplets in diabetes and obesity.

Goal(s): To validate  diffusion-weighted radial echo-planar spectroscopic imaging (DW-REPSI) in calf muscle. 

Approach: We acquired DW-REPSI spectra using 2 different b-values  in 3 young healthy subjects and one type2 diabetic patient; regional variations of intra- and extra- myocellular lipids (IMCL and EMCL), creatine and trimethylamines (TMA) and their diffusivities were quantified. 
 

Results: Decreased TMA was recorded in the tibialis anterior muscle compared to that of soleus and gastronomic muscles. ADCs of IMCL and EMCL and metabolites were quantified. Lower ADCs of IMCL indicated restricted motion. Shifts in EMCL was observed.
 

Impact: A  diffusion-weighted spectroscopic imaging sequence was evaluated to investigate the diffusion characteristics and regional variations of IMCL, EMCL and metabolites in calf muscle. The outcome may provide new biophysical insights in the investigation of lipid metabolism in diabetes.
 

Keywords: Muscle, Quantitative Imaging, Neuropathy, Follow-up

Motivation: Intramuscular fat fraction (FF) quantified using MRI has emerged as one of the few responsive outcome measures in neuropathic patients.

Goal(s): In the present one-year follow-up study we tracked changes in multiple qMRI biomarkers for CMT1A patients.

Approach: We assessed correlations between MRI and clinical parameters and compared 2D vs 3D segmentation analysis.

Results: As expected, we quantified a significant FF rise in both thigh and leg muscles and a length-dependent gradient in leg muscles. Given the varied FF distribution, the existence of a length-dependent gradient, and the differential fatty involution across muscles, 3D volume analysis appeared more faithful than single slice analysis.

Impact: Our longitudinal study further supports FF as a outcome of interest in neuropathic patients. The complexity of fat infiltration in terms of distribution among muscles and heterogeneity along the proximo-distal axis can be identified using a 3D volume analysis.

Keywords: CEST / APT / NOE, CEST & MT

Motivation: CrCEST measurements are sensitive to the changes in muscle pH, which confound the measurement and interpretation of τCr. Our motivation was to develop a technique that removed acidic bias from CrCEST measurements to ensure OXPHOS measurement. 

Goal(s): Develop a personalized mild exercise technique that limits acidosis in the calf to ensure measurement of OXPHOS using CrCEST.

Approach: To test the dependence of CrCEST recovery time on pH with different exercise regimes. 

Results: Carnosine ¹HMRS can be used to quickly measure pH change induced by a prescribed exercise regime and can facilitate an unbiased measurement of personalized muscle group specific OXPHOS capacity with CrCEST. 

Impact: Carnosine ¹HMRS can be used to quickly measure pH change induced by a prescribed exercise regime and can facilitate an unbiased measurement of personalized muscle group specific OXPHOS capacity with CrCEST. 

Keywords: Muscle, Muscle, Data Analysis, MSK

Motivation: Estimating physical performance including muscle function is conventionally done by having a subject complete physical tasks. MRI-based estimates leveraging deep learning could complement such measures.

Goal(s): To investigate the feasibility of predicting measures physical performance including muscle strength from MRI scans of the leg using deep learning.

Approach: We used large MRI databases (OAI and SOMMA) to train a neural network for classification into high or low physical performance. We also tried the method on a small prospective cohort.

Results: We obtained over 70% accuracy for estimating high or low muscle function, indicating high predictive power.

Impact: We demonstrate the feasibility of predicting muscle function from anatomical MRI scans using deep learning, leveraging advances in deep learning and musculoskeletal MRI databases that include functional measures. Such MRI-based predictions could complement conventional methods for estimating muscle function.

Keywords: Muscle, Diffusion Tensor Imaging, Hamstring muscle, diffusion tensor imaging, axial diffusivity, mean diffusivity, radial diffusivity, nordic hamsrting exercise, eccentric training

Motivation: To unveil the mechanism of preventative action offered by eccentric exercise regimes towards hamstring strain injuries, understanding muscle adaptations at microstructural level is crucial.

Goal(s): To investigate microstructural adaptations in hamstring muscles post 9-weeks of eccentric NHE using diffusion tensor imaging (DTI) metrics like axial (AD), mean (MD), and radial (RD) diffusivities.

Approach: Ten participants underwent Dixon and DTI scans pre and post 9-weeks of supervised eccentric NHE training.

Results: Post intervention, significant increases in AD, MD, and RD were observed, suggesting muscle hypertrophy, exercise-induced microtrauma, structural remodelling and potential Type II muscle fiber adaptations.

Impact: This study explored the ability of DTI to provide novel insights into microstructural adaptations of hamstring muscle to eccentric training. The findings highlight hypertrophy, structural remodelling, and fiber type shifts, advancing injury prevention and rehabilitation strategies through a fiber-level perspective.

Keywords: Neurography, Nerves, Muscle

Motivation: To evaluate the feasibility and reliability of an accelerated T2 mapping technique (GRAPPATINI) for MR neurography and muscle evaluation.

Goal(s): The study aims to qualitatively and quantitatively evaluate GRAPPATINI for MR neurography in patients with foot drop.

Approach: To compare the image quality from GRAPPATINI T2-weighted images against conventional T2-weighted images, and to compare T2 values between abnormal and normal muscles.

Results: No significant qualitative differences were observed between GRAPPATINI and conventional images diagnostically; there was complete agreement in assessment of nerve signal hyperintensity and size, and muscle edema. Significant differences in GRAPPATINI T2 values were observed between abnormal and normal muscles.

Impact: In one acquisition, GRAPPATINI can simultaneously provide clinically equivalent qualitative information and quantitative T2 maps for MR neurography evaluation of foot drop.

Keywords: Muscle, MSK

Motivation: Conservative treatment can lead to lumbar disc herniation (LDH) regression. However, the relationship between LDH regression and paraspinal muscle (PSM) fat content remains unclear.

Goal(s): To assess radiological changes in LDH with conservative treatment and investigate the connection between LDH regression and PSM fat content.

Approach: 80 LDH patients underwent MRI before and after conservative treatments. They were divided into resorption and non-resorption groups. PSM fat content and age were analyzed.

Results: 64% experienced LDH regression, mainly those with lower PSM fat content. Age-related muscle atrophy played a role. We highlights PSM fat content as a predictor of LDH regression during conservative treatment.

Impact: The fat content of paraspinal muscles serves as an important predictor of the conservative treatment outcomes for LDH patients. Patients with lower fat content in their paraspinal muscles are more likely to experience lumbar disc reabsorption.

Keywords: Muscle, Nervous system, Mitochondrial function, energy metabolism

Motivation: Parkinson’s disease (PD) is a leading neurodegenerative disorder. Currently there are no medical interventions or medications to slow the progression of PD. Rehabilitation for aerobics, strength and motor control is critical to consider as it ameliorates symptoms, decrease falls, and improves quality of life. However, the metabolic mechanism of rehab is not fully understood.

Goal(s): Report evidence that, upon targeted muscle exercise training, the muscle energetics is improved at cellular and molecular level.

Approach: PD patients were scanned by 31P MRS before and after a 4-week progressive strengthening program. 

Results: Upon rehabilitation, PCr decline with exercise is slowed in parallel to delayed fatigue.

Impact: The metabolic findings in the present study support the note and practice that strength-focused rehab programs can benefit patients with PD in the management of their weakness and improving quality of life.

Keywords: fMRI Analysis, fMRI

Motivation: Understanding the link between paraspinal muscle changes and common causes is crucial for improving treatment approaches for chronic lower back pain (CLBP), which has diverse underlying factors.

Goal(s): Assessing the relationship between MRI findings and paraspinal muscle changes in patients with CLBP.

Approach: We prospectively collected lumbar spine MRI images from CLBP patients. Analyses assessed correlations and regressions between MRI findings and paraspinal muscle cross-sectional area (CSA) and proton density fat fraction (PDFF).

Results: Degenerative lumbar spondylolisthesis (DLS) and intervertebral disc degeneration (IVDD) have a significant impact on the increase in the PDFF of paraspinal muscles.

Impact: This study provides valuable insights for clinicians, enabling them to implement targeted interventions for CLBP patients based on specific MRI findings and key characteristics of muscle remodeling. By improving prevention and treatment approaches.

Keywords: Muscle, Aging, Dixon, fat fraction, texture analysis

Motivation: Pathological changes in the masseter muscle have been associated with head and neck cancer (HNC). Nevertheless, investigations on the quantification of fatty infiltration in the masseter muscle and its correlation with HNC is limited.

Goal(s): We aim to assess fatty infiltration, morphological characteristics, and texture features of the masseter muscle in HNC.

Approach: This study sought to employ the Dixon method for fat fraction estimation conjugated with a machine learning-based auto-segmentation of the masseter muscle.

Results: Our analysis revealed an elevated level of fatty infiltration in the masseter muscle among patients with head and neck cancer.

Impact: Dixon method conjugated with machine learning-based auto-segmentation should facilitate in reliably assessing masseter fat alteration in head and neck cancer (HNC), this may be beneficial in response prediction in HNC treatment.