Marc-Adrien Hostin^1,2, Augustin C. Ogier², Constance P. Michel¹, Yann Le Fur¹, Maxime Guye^1,3, Shahram Attarian⁴, Marc-Emmanuel Bellemare², and David Bendahan^1
1Aix Marseille Univ, CNRS, CRMBM, UMR 7339, Marseille, France, ²Aix Marseille Univ, Université de Toulon, CNRS, LIS, Marseille, France, ³APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France, ⁴Centre de référence des maladies neuromusculaires et de la SLA, Marseille, France

Quantification of Fat Fraction (FF) in individual lower limb muscles of patients with neuromuscular disorders relies on segmentation. Few studies have indicated that Fully Convolutional Networks (FCNs) can provide reliable automatic segmentations to replace manual tasks. However, their sensitivity to fat infiltration has never been accurately assessed. Four FCN were benchmarked for the segmentation of 114 thigh and 108 calf images (1788 muscles) with FF up to 60%. HRNet was the only network that didn't show any segmentation failures. DSC obtained was comparable to other networks. The FF values calculated from the automatic (FF_a) and manual (FF_m) segmentations were consistent.

Yajun Ma¹, Michael Carl², Alan Bao¹, Hyungseok Jang ¹, Saeed Jerban¹, Alecio F Lombardi ¹, Christine B Chung ¹, Eric Y Chang^1,3, and Jiang Du^1
1Radiology, University of California, San Diego, San Diego, CA, United States, ²GE Healthcare, San Diego, CA, United States, ³Radiology Service, Veterans Affairs San Diego Healthcare System, San Diego, CA, United States

Adiabatic T1rho (AdiabT1rho) is much less sensitive to the magic angle effect compared to the regular continuous wave T1rho (CW-T1rho). In this study we developed a novel phase modulated ultrashort echo time adiabatic T1rho (PM-UTE-AdiabT1rho) sequence for quantitative assessment of both short and long T2 tissue components in the knee joint, including cartilage, meniscus, ligaments, tendons, and muscle, on a clinical 3T scanner. Our results showed excellent single exponential fitting for all the major tissue components in both ex vivo and in vivo normal knee joints. 

Susanne Rauh¹, Jithsa Monte², Melissa Hooijmans², Joep Suskens³, Oliver Gurney-Champion², Johannes Tol³, Mario Maas², Aart Nederveen², and Gustav Strijkers^1
1Department of Biomedical Engineering and Physics, Amsterdam UMC, Amsterdam, Netherlands, ²Department of Radiology and Nuclear Medicine, Amsterdam UMC, Amsterdam, Netherlands, ³Department of Orthopedic Surgery, Amsterdam UMC, Amsterdam, Netherlands

DTI and IVIM are sensitive to hamstring injuries, but suffer from long scan times. Using b-values above a certain threshold only (high-b DTI) or a simplified IVIM approach (sIVIM-DTI), which estimates the perfusion fraction and diffusion tensor, can reduce the scan time while inherently correcting DTI-indices for IVIM effects. We showed in this work that those methods provide similar sensitivity to hamstring injuries in comparison to a full IVIM-DTI fit while reducing acquisition time up to 42%. Since no difference in perfusion fraction was found between injury states, we suggest high-b DTI is the method of choice in this application.

Robert Lloyd^1,2, Iain Ball³, and Lynne Bilston^1,2
1Neuroscience Research Australia, Sydney, Australia, ²University of New South Wales, Sydney, Australia, ³Philips Australia & New Zealand, Sydney, Australia

Simulations of obstructive sleep apnoea (OSA) require detailed models of the muscle fibres within the tongue, to correctly capture the motion of the tongue. Diffusion weighted images (DWI) of the oral cavity were collected for 5 healthy controls. Fibre-orientation distributions (FOD) estimated from subject DWI, can resolve intersecting muscles in the tongue. The group averaged FOD reduced the influence of spurious peaks, which gave clearer boundaries between the intrinsic muscles of the tongue. These results may help fully automate the segmentation of the muscles within the tongue.

Azadeh Sharafi¹, Marcelo V. W. Zibetti¹, Gregory Chang¹, Martijn Cloos ², and Ravinder Regatte^1
1Radiology, NYU Langone Health, New York, NY, United States, ²University of Queensland, Brisbane, Brisbane, Australia

Conventional quantitative cartilage MRI (e.g., T₁, T₂, and T_1ρ) approaches measure one single parameter at a time. Magnetic resonance fingerprinting (MRF) is a flexible, non-invasive measurement technique that simultaneously quantifies multiple MR parameters. In this work, we proposed a 3D-MRF sequence for the simultaneous volumetric acquisition of submillimetric proton density (PD) image and T₁, T₂, T_1ρ, and B₁⁺ maps of the knee cartilage in clinically feasible scan time (~11 minutes).

Sophia Kronthaler¹, Georg C. Feuerriegel¹, Christof Boehm¹, Alexandra S. Gersing¹, Benedikt J. Schwaiger², Marcus R. Makowski¹, Kilian Weiss³, and Dimitrios C. Karampinos^1
1Department of Diagnostic and Interventional Radiology, School of Medicine, Technical University of Munich, Munich, Germany, ²Department of Neuroradiology, Technical University of Munich, Munich, Germany, ³Philips GmbH Market DACH, Hamburg, Germany

In patients with vertebral fractures or degenerative changes often CT and MR imaging are performed, with CT aiming at the characterization of osseous changes and the MR focusing on soft tissue components. Previous work presented a single UTE-Dixon (sUTE-Dixon) approach which enabled the simultaneous assessment of vertebral fractures and edema of the thoracolumbar spine from a single ultrashort-echo time (UTE) image. This work investigates the robustness of the sUTE-Dixon methodology in various skeletal anatomies.

Elka Rubin¹, Joanna L Langner², Marianne S Black², Arjun D Desai², James MacKay³, Carly Jones⁴, Kimberly E Hall², Marc R Safran², Feliks Kogan², and Garry E Gold^2
1Radiology, Stanford University, Stanford, CA, United States, ²Stanford University, Stanford, CA, United States, ³University of Easy Anglia, Norwich, United Kingdom, ⁴University of British Columbia, Vancouver, BC, Canada

Water polo players and synchronized swimmers have previously been found to have an increased prevalence of femoroacetabular impingement morphology compared to the general population. In this study, we used MRI to identify regional patterns in the microstructure of the hip cartilage and joint of high-level female water polo players and synchronized swimmers. Compared to healthy controls, the water-treading athletes had significantly higher T₂ relaxation times in the right hip and a significantly higher prevalence of cam morphology in both hips. This study suggests that microstructural and morphological differences are present in these athletes’ hip cartilage compared to controls.

Rajiv G. Menon¹, Azadeh Sharafi¹, and Ravinder R Regatte^1
1Center for Biomedical Imaging, Grossman school of Medicine, NYU Langone Health, New York, NY, United States

Low back pain that have etiologies related to degenerative intervertebral(IVD) disc changes are difficult to diagnose and treat. Quantitative characterization of the lumbar spine IVD can potentially be useful in detecting early changes to the IVD. In this study a 3D-MR fingerprinting technique was employed that is capable of simultaneously quantifying four different parameters in a clinically feasible time. Five healthy subjects underwent lumbar spine 3D-MRF scans. The results demonstrate that 3D-MRF can simultaneously measure and generate T₁, T₂, T_1ρ, and B₁₊ volumetric maps of lumbar spine  in a single scan within clinically feasible scan time of about 10 minutes.

Alfredo Liubomir Lopez Kolkovsky^1,2, Beatrice Matot^1,2, Yves Fromes^1,2, Eric Giacomini¹, Pierre G Carlier³, Harmen Reyngoudt^1,2, and Benjamin Marty^1,2
1NMR Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, France, ²NMR Laboratory, CEA/DRF/IBFJ/MIRCen, Paris, France, ³University Paris-Saclay, CEA/DRF/SHFJ, Orsay, France

Evaluating quadriceps function is key in the context of sarcopenia. A pneumatic ergometer was built to allow performing knee extensions in supine position. An increasing-load, 13-min-long, isotonic exercise was successfully performed by volunteers during interleaved ¹H MRI/¹H MRS/³¹P MRS acquisitions in the quadriceps. Work, pedal displacement and velocity values per stroke and the maximum voluntary torque were measured with the ergometer. End-of-exercise [PCr] decreased (69±10%) and T₂* increased (up to 10.5±7.2% in Rectus Femoris) relative to baseline. Simultaneous vascular, metabolic and physical effort evaluations during an incremental physical test could be a powerful method to investigate muscle quality in aging.

Kevin Koch¹, Mohammad Zarenia¹, V. Emre Arpinar¹, and Rajeev Mannem^1
1Radiology, Medical College of Wisconsin, Milwaukee, WI, United States

4D-dynamic MRI were collected and utilized to track unconstrained movement of individual wrist carpal bones in 31 asymptomatic volunteer subjects.  Rotational and translational trajectories of the scaphoid, lunate, and capitate bones were collected and processed using a novel multi-subject profile registration and analysis engine. Morphological images were analyzed by an expert radiologist to identify asymptomatic abnormalities within the cohort. Statistical parametric mapping of each profile was performed to identify normative variances of each profile metric and correlation with identified abnormalities. The study presents methodological approaches and normative baseline profile metrics of value to future studies of symptomatic wrists.       

Kenneth T Gao^1,2, Emily Xie¹, Vincent Chen¹, Francesco Caliva¹, Claudia Iriondo¹, Richard B Souza¹, Sharmila Majumdar¹, and Valentina Pedoia^1
1Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, ²University of California, Berkeley-University of California San Francisco Graduate Program in Bioengineering, Berkeley, CA, United States

While meniscal morphology is central to its capacity for weight distribution and stabilization in the knee joint, the relationship between the geometric shape of the meniscus and osteoarthritis is relatively unexplored. With 4,791 subjects from the Osteoarthritis Initiative, this study utilizes an automatic statistical shape modeling technique to identify variations in meniscus morphology as precursors to future development of osteoarthritis. Seven of the 20 shape features extracted were found to be significantly associated with osteoarthritis incidence. These features were further characterized with local changes in cartilage thickness across 8 years.

Lena V. Gast¹, Oliver Chaudry², Wolfgang Kemmler^1,3, Michael Uder¹, Armin M. Nagel^1,4, and Klaus Engelke^2,3
1Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany, ²Department of Medicine 3, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany, ³Institute of Medical Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany, ⁴Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

In addition to fat fraction (FF), muscular T2 could provide information on disease progression and potential training effects in osteosarcopenia, a combination of osteoporosis and sarcopenia. However, muscular T2 is highly dependent on the amount of muscle fat infiltration, which is usually increased in these patients. Thus, we aimed to assess T2 in thigh muscle tissue of elderly men with osteosarcopenia, comparing vendor-provided T2 maps with custom-fitted approaches also considering fat infiltration. We found highly elevated T2 values in the vendor-provided T2 maps compared to tri-exponentially fitted T2, which might lead to misinterpretation of muscle T2.