David B Berry¹, Benjamin M Regner², Vitaly L Galinsky³, Samuel R Ward^1,4,5, and Lawrence R Frank^3
1Bioengineering, UCSD, La Jolla, CA, United States, ²Institute of Engineering in Medicine, UCSD, La Jolla, CA, United States, ³Center for Scientific Computation in Imaging, UCSD, La Jolla, CA, United States,⁴Orthopaedic Surgery, UCSD, La Jolla, CA, United States, ⁵Radiology, UCSD, La Jolla, CA, United States

Diffusion tensor imaging (DTI) has been used to measure changes in restricted diffusion in skeletal muscle after injury, which are thought to track microstructural, and therefore functional changes. However, there are few direct comparisons between muscle microstructure and DTI measurements because it is difficult to precisely control in vivo experiments. Here, we use a computational (in silico) modeling approach to explore changes in DTI measurements as muscle microstructure is systemically changed. Muscle fiber diameter and edema have the largest effects on the DT. Additionally, we have shown multi-echo DTI is required to resolve changes in microstructure when edema is present. 

Chiara Giraudo¹, Stano Motyka¹, Siegfried Trattnig¹, and Wolfgang Bogner^1
1Department of Biomedical Imaging and Image-guided Therapy- MR Centre of Excellence, Medical University Vienna, Vienna, Austria

STEAM-DTI sequence recently provided excellent results for DTI analysis of muscle fibers (e.g., high signal-to-noise ratio, low apparent diffusion coefficient, high fractional anisotropy values) but demonstrated also to be affected by strong artifacts, which can be assumed to be due to involuntary muscle contractions. The hereby proposed automatic post-processing method, based on weighted mean of the averages for each DTI-direction and b-value, demonstrated to successfully detect and correct these artifacts, improving fiber tracking of the calf muscles.

M. Perrins¹, E. Barnhill², P. Kennedy¹, J. Braun², I. Sack², A. Hunter³, C. Brown⁴, E. van Beek¹, and Neil Roberts^1
1University of Edinburgh, Edinburgh, United Kingdom, ²Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany, ³School of Sport, University of Stirling, Stirling, United Kingdom, ⁴The Mentholatum Company Ltd., East Kilbride, United Kingdom

Super-Resolution (SR) Magnetic Resonance Elastography (MRE) was applied to measure thigh muscle viscoelastic properties in 20 subjects in whom Exercise Induced Muscle Damage (EIMD) was produced using a well-established muscle damage protocol. SR-MRE is made possible by analysing Multi-frequency MRE (MMRE) in a manner such that multiple low-resolution images of the same scene are interpolated and fused to create a single, high-resolution image. Muscle tissue is well suited to study using SR-MRE and the sites of muscle damage could be clearly identified suggesting potential useful clinical applications for the technique. SR-MRE also has potential to provide insight regarding the mechanisms underlying tissue damage in EIMD.  

Andreas Max Weng¹, Fabian Gilbert², Johannes Tran-Gia^1,3, Tobias Wech¹, Detlef Klein¹, Thorsten Alexander Bley¹, and Herbert Köstler^1
1Department of Diagnostic and Interventional Radiology, University of Würzburg, Würzburg, Germany, ²Department of Trauma, Hand, Plastic and Reconstructive Surgery, University of Würzburg, Würzburg, Germany, ³Department of Nuclear Medicine, University of Würzburg, Würzburg, Germany

Fatty degeneration of the rotator cuff is often investigated by a visual inspection of T$$$_1$$$-weighted MR images. Since this approach is in debate the aim of this study was to investigate fatty degeneration of the supraspinatus muscle by quantitative techniques: SPLASH, model-based acceleration for parameter mapping (MAP) T$$$_1$$$ measurement and shear wave ultrasound. The obtained values from SPLASH and T$$$_1$$$ mapping are in good accordance (Pearson’s r=0.82). However, shear wave ultrasound does neither correlate well with SPLASH (Spearman’s rho= 0.30) nor with MAP (rho=0.19). Since data acquisition time of the T$$$_1$$$ mapping technique used in our study is very short (4s), this might be the technique of choice for investigation of the fatty degeneration of the supraspinatus after rotator cuff tear.

Valentina Mazzoli^1,2,3, Jos Oudeman¹, Marco A Marra³, Klaas Nicolay², Nico Verdonschot³, Andre M Sprengers³, Martijn Froeling⁴, Aart J Nederveen¹, and Gustav J Strijkers^5
1Department of Radiology, Academic Medical Center, Amsterdam, Netherlands, ²Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands,³Orthopaedic Research Lab, Radboud University Medical Center, Nijmegen, Netherlands, ⁴Department of Radiology, University Medical Center, Utrecht, Netherlands, ⁵Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, Netherlands

The aim of this study is to explore Diffusion Tensor Imaging in the assessment of passive muscle elongation. We investigated two dorsiflexor and two plantarflexor muscles of the lower leg with the foot in dorsiflexion, neutral and plantarflexion position. Significant negative correlation was found between changes in fiberlength caused by passive muscle lengthening and radial diffusivity for all muscles. Furthermore the rate of change in radial diffusivity was compatible with a cylindrical model with constant volume. These findings give more insight into diffusion mechanisms in skeletal muscles and are highly relevant for biomechanical models.

Donnie Cameron¹, David A. Reiter¹, Kenneth W. Fishbein¹, Christopher M. Bergeron¹, Richard G. Spencer¹, and Luigi Ferrucci^1
1National Institute on Aging, National Institutes of Health, Baltimore, MD, United States

This work investigates how ageing influences diffusion tensor imaging (DTI) measures through application of a robust protocol to the human thigh. Fifteen participants, from 27-73 years old, were recruited, and mean diffusivity (MD) and fractional anisotropy (FA) were calculated in their quadriceps and plotted against age. Fibre tractography was also calculated. Rectus femoris FA showed a significant correlation with age (R²=0.27, p=0.04), while FA approached significant correlations in other muscle heads. MD had a more complicated relationship with age, if any, in contrast to previous work where lipid influence was neglected. This highlights the need for high-quality fat-suppression in DTI.

Melissa Tamara Hooijmans¹, Melissa Tamara Hooijmans¹, Nathalie Doorenweerd¹, Jedrek Burakiewicz¹, Andrew Webb¹, Jan Vershuuren², Erik Niks², and Hermien Kan^1
1Radiology, Leiden University Medical Center, Leiden, Netherlands, ²Neurology, Leiden University Medical Center, Leiden, Netherlands

Quantitative MRI and MRS are increasingly important as non-invasive and objective outcome measures in therapy development for DMD. Several MR indices, have been shown to correlate individually with age and functional measures. However, much less attention has been given to how these indices relate to each other. Our work combined quantitative MRI and spatially resolved 31P MRS in the lower leg muscles of DMD patients and showed that combining multimodal MR measures is very important to objectively assess muscle degeneration processes and potentially the effect of therapeutic interventions in DMD.

Kerryanne V. Winters^1,2, Olivier Reynaud^1,2, Dmitry S. Novikov^1,2, Els Fieremans^1,2, and Sungheon G. Kim^1,2
1Center of Biomedical Imaging, Department of Radiology, NYU School of Medicine, New York, NY, United States, ²Center for Advanced Imaging Innovation and Research, NYU Langone Medical Center, New York, NY, United States

The random permeable barrier membrane (RPBM) model for diffusion tensor imaging (DTI) provides a non-invasive modality potentially useful for early and accurate diagnosis for the wide range of myopathies. We have utilized the DTI-RPBM method to assess myofiber changes in the Surface-to-Volume ratio S/V and sarcolemma permeability κ as markers in growing and wasting skeletal muscle. Preliminary results show that S/V and κ decrease in both wild-type and mdx mice, with a more pronounced change between weeks 3 and 4 in mdx mice. The conventional IDEAL-Dixon and T2 mapping measures were not sensitive enough to observe the same change.

Prodromos Parasoglou¹, Ryan Brown^1,2, and Guillaume Madelin^1
1Department of Radiology, New York University School of Medicine, New York, NY, United States, ²NYU WIRELESS, Polytechnic Institute of New York University, Brooklyn, NY, United States

We developed a spectrally selective 3D non-Cartesian FLORET pulse sequence to map phosphorus-containing metabolites in the human tissue. In particular, through this highly efficient pulse sequence we mapped phosphocreatine and γ-adenosine triphosphate at 1.4 cm isotropic nominal voxel size in the human brain. In addition, we were able to map phosphocreatine in the skeletal muscle during exercise and recovery with 6 s temporal resolution. We showed that spectrally selective 3D-FLORET is an efficient pulse sequence that can be used to image ³¹P-containing metabolites in the human tissue when high spatiotemporal resolution is needed.

Thomas Baum¹, Stephanie Inhuber², Michael Dieckmeyer¹, Christian Cordes¹, Stefan Ruschke¹, Elisabeth Klupp³, Holger Eggers⁴, Hendrik Kooijman⁵, Ernst J Rummeny¹, Ansgar Schwirtz², Jan S Kirschke³, and Dimitrios C Karampinos^1
1Department of Radiology, TU Munich, Munich, Germany, ²Department of Sports and Health Sciences, TU Munich, Munich, Germany, ³Section of Neuroradiology, TU Munich, Munich, Germany, ⁴Philips Research Laboratory, Hamburg, Germany, ⁵Philips Healthcare, Hamburg, Germany

MR-based assessment of quadriceps muscle fat has been proposed as surrogate marker in sarcopenia, osteoarthritis, and neuromuscular disorders. The present study demonstrated strong associations between chemical shift encoding-based water-fat MRI quadriceps inter- and intramuscular fat parameters and corresponding physical strength measurements in healthy males. Thus, chemical shift encoding-based water-fat MRI can provide clinically important information beyond quadriceps muscle morphology and T1-weighted muscle fat quantifications and may potentially track early changes in muscles that are not severely atrophied or fatty infiltrated in the beginning of a disease process.