Linda Heskamp¹, Matthew G. Birkbeck^1,2,3, Julie Hall^1,4, Ian S. Schofield¹, Hugo de Oliveira⁵, Timothy L. Williams⁵, Roger G. Whittaker¹, and Andrew M. Blamire^1
1Newcastle University Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom, ²Newcastle Biomedical Research Centre, Newcastle University, Newcastle upon Tyne, United Kingdom, ³Northern Medical Physics and Clinical Engineering, Freeman Hospital, Freeman Hospital, Newcastle upon Tyne NHS Foundation Trust, Newcastle upon Tune, United Kingdom, ⁴Department of Neuroradiology, Royal Victoria Infirmary, Newcastle upon Tyne, United Kingdom, ⁵Directorate of Clinical Neurosciences, Royal Victoria Infirmary, Newcastle upon Tyne, United Kingdom

The spontaneous contraction of motor units in muscle, i.e. fasciculation, has been recognised as an important diagnostic marker in amyotrophic lateral sclerosis (ALS). Fasciculation can be imaged with a novel MRI technique called motor unit MRI. This technique uses a diffusion weighted sequence on which fasciculation presents as short-living signal voids. We demonstrated an increased fasciculation rate in ALS patients compared to healthy controls by assessing the four body regions relevant in the diagnosis of ALS. The affected body regions differed between patients. This is in line with the heterogeneous disease onset and supports our proposed whole-body approach. 

Donnie Cameron^1,2, David A. Reiter³, Fatemeh Adelnia⁴, Ceereena Ubaida-Mohien⁵, Christopher M. Bergeron⁶, Seongjin Choi⁷, Kenneth W. Fishbein⁶, Richard G. Spencer⁶, and Luigi Ferrucci^5
1Norwich Medical School, University of East Anglia, Norwich, United Kingdom, ²Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, ³Emory University School of Medicine, Atlanta, GA, United States, ⁴Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, ⁵Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States, ⁶Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States, ⁷Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, United States

Here we apply diffusion-tensor-(DT)-MRI to study muscle microstructural and architectural changes with healthy ageing in 94 participants (median age=56, range=22-89yrs). Fractional anisotropy (FA) and mean diffusivity (MD), were calculated for 12 thigh muscles, as were pennation angle, fascicle length, fibre curvature, and physiological cross-sectional area (PCSA) for the rectus femoris and biceps femoris longus. Knee extension/flexion torques were also measured. FA and MD were significantly associated with age (β=0.34 and −0.34, p<0.05), as were architecture parameters. Pennation angle and PCSA were positively associated with strength. This may prove useful for studying muscle response to interventions designed to delay sarcopenia.  

Valentina Mazzoli¹, Elka Rubin ¹, Marco Barbieri¹, Andrew Schmidt¹, Lauren Watkins¹, Akshay Chaudhary¹, Feliks Kogan¹, and Garry Gold^1
1Department of Radiology, Stanford University, Stanford, CA, United States

5 healthy subjects consistently performed a declined squad training routine for 3 months. Every subject received an MRI scan before undergoing the training and subsequently every month until the end of the training. We observed a decrease in AD, MD and FA over the course of training, with a significant change after 1 month. Muscle volume increased, with changes only apparent at 3 months. Changes in diffusion parameters were predictive of changes in global volume. Our study shows that DTI can be a sensitive tool to study muscle hypertrophy and could be used for early monitoring of training and rehabilitation.

Kevin R. Keene^1,2, Jan J.G.M. Verschuuren¹, Irene C. Notting³, Martijn R. Tannemaat¹, Jan-Willem M. Beenakker^2,3, and Hermien E. Kan^2
1Department of Neurology, Leiden University Medical Center, Leiden, Netherlands, ²C.J. Gorter Center of High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, ³Department of Opthalmology, Leiden University Medical Center, Leiden, Netherlands

Quantitative MRI of the extra-ocular muscles might have diagnostic value and play a role in therapeutic monitoring in myasthenia gravis (MG). Our data show a slight increase in volume, fat fraction and T2_water in extra-ocular muscles of MG patients compared to controls. Volume and fat fraction changes were most pronounced in chronic MG patients, T2_water changes were most pronounced in recently diagnosed and untreated MG patients. The absence of gross structural changes implies that eye muscle weakness might be reversible, even in chronic patients with residual ophthalmoplegia.

Lara Schlaffke¹, Marlena Rohm¹, Robert Rehmann^1,2, Anne-Katrin Güttsches¹, Martijn Froeling³, Matthias Vorgerd¹, and Johannes Forsting^1
1Neurology, University Clinic Bergmannsheil Bochum gGmbH, Bochum, Germany, ²Neurology, Klinikum Dortmund, University Witten-Herdecke, Dortmund, Germany, ³Radiology, UMC Utrecht, Utrecht, Netherlands

Quantitative MRI (qMRI) techniques like Dixon fat-fraction (FF) and quantitative water-T2 relaxation time (T2) are promising non-invasive tools in the evaluation of neuromuscular diseases like LGMD2A. In this study, we were able to show moderate to strong correlations between quantitative MRI values, especially FF, with clinical outcome measures and daily life activities. Analysis of T2 relaxation time in non-fat-infiltrated leg muscles of LGMD2A patients showed a significantly higher water T2 values compared to healthy controls. Therefore, T2 relaxation times may offer an earlier detection of disease-related change of muscular tissue in limb girdle muscular dystrophy  compared to irreversible fat-fractions.

Tim Yiran Li¹, Erin Argentieri², Emily Pedrick², Darryl B. Sneag², and Ek T. Tan^2
1Weill Cornell Medical College, New York, NY, United States, ²Hospital for Special Surgery, New York, NY, United States

Macroscopic muscle volume evaluation and quantitative MRI of diffusion microstructure may provide objective, longitudinal assessment of muscle denervation. Analysis of subjects with Parsonage-Turner syndrome (neuralgic amyotrophy) showed both reduced muscle volume and reduced muscle diameter. Macroscopic muscle volume demonstrated a strong positive correlation with microscopic diffusion-based muscle diameter, and a strong negative correlation with T₂-mapping. Denervated muscles exhibited longitudinal changes in quantitative MRI metrics, whereas non-denervated (control) muscles showed minimal quantitative changes.

Melissa Tamara Hooijmans¹, Thom T.J. Veeger², Valentina Mazzoli³, Hans C. van Assen⁴, Lukas M. Gottwald¹, Aart J. Nederveen¹, Jurriaan H. de Groot⁵, Gustav J. Strijkers⁶, and Hermien E. Kan^2,7
1Radiology and Nuclear Medicine, Amsterdam University Medical Centers, Amsterdam Movement Sciences, Amsterdam, Netherlands, ²C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, ³Department of Radiology, Stanford University, Stanford, CA, United States, ⁴Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, ⁵Department of Rehabilitation Medicine, Leiden University Medical Center, Leiden, Netherlands, ⁶Department of Biomedical Engineering and Physics, Amsterdam Movement Sciences, Amsterdam University Medical Center, Amsterdam, Netherlands, ⁷Duchenne Center Netherlands, Leiden, Netherlands

In this study we assessed strain rates along and close to perpendicular to the fiber in the lower-leg muscles, by combining 3D phase contrast with DTI-derived fiber orientations, during dynamic exercise with and without load. Our data revealed spatially heterogeneous strain rate patterns along the fiber within lower-leg muscles, with smallest and largest strain rates in the most proximal and distal segments of the Gastrocnemii muscles, respectively, and opposed (expansion and contraction) strain rate patterns between some of the Tibialis Anterior (TA) muscle compartments. Additional loading resulted in higher strain rates in TA compartments but lower in the Gastrocnemii muscles.

Fabian Balsiger¹, Noah Locher², Benedikt Wagner¹, and Olivier Scheidegger^1,2
1Support Center for Advanced Neuroimaging (SCAN), Institute for Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland, ²Centre for Neuromuscular Diseases, Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland

The diagnostic ability of quantitative water T2 mapping using multi-slice multi-echo sequences for the early detection of neuromuscular diseases (NMDs) was compared to fat-suppressed T2-weighted turbo inversion recovery magnitude (TIRM) MRI. Water T2 mapping had a significantly higher sensitivity and diagnostic ability in detecting muscle abnormalities than the subjective grading of TIRM MRI, prior to late-stage fatty infiltration signal alternations in T1-weighted MRI. Normal appearing TIRM MRI does not rule out disease activity in muscles in NMDs. Our findings suggest considering water T2 mapping over TIRM MRI for early detection of NMDs in clinical practice.