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Keywords: MSK, Quantitative Imaging

T2 mapping reflects biochemical composition of tissues such as cartilage, tendon, ligament, meniscus without requirement for a contrast injection or special MRI imaging hardware, and there are numerous available techniques for post-processing of T2 images. However, scan time and signal-to-noise ratio are critical factors in clinical implementation. With the development of parallel imaging in combination of deep-learning based reconstruction algorithm, high-resolution and reproducible T2 mapping was potentially achieved to identify cartilage injury or degeneration in spite that T2 relaxation time cannot directly refer to previous studies but showed high consistency with the same acceleration factor for T2 mapping.

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Constantin von Deuster^1,2 and Daniel Nanz^2,3
1Advanced Clinical Imaging Technology, Siemens Healthineers International AG, Zurich, Switzerland, ²Swiss Center for Musculoskeletal Imaging, Balgrist Campus AG, Zurich, Switzerland, ³University of Zurich, Zurich, Switzerland

Keywords: MSK, Contrast Mechanisms, Driven Equilibrium

Fluid-sensitive Turbo-Spin-Echo (TSE) imaging in combination with Short-Tau Inversion Recovery for fat suppression (STIR) is commonly employed in musculoskeletal MRI. A Driven Equilibrium (DE) module following the imaging train can be used to reduce the Repetition Time (TR) without significant SNR loss. However, due to the STIR preparation, a conventional DE element rotates the fluid magnetization onto the negative z-axis instead of the positive z-axis, which delays longitudinal relaxation and attenuates the fluid signal. We implemented a modified DE module that increased fluid-signal intensity in STIR-TSE images of the spine.

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Keywords: Neurography, Neurography

Geometric image combination (GIC) and deep learning (DL) reconstructions were together applied to improve nerve visualization in lumbosacral plexus MR neurography (MRN) using the 3D dual echo steady-state free precession (DESS) sequence. Qualitative comparisons were made against standard image reconstruction of the 2nd echo of the DESS sequence. While standard-of-care (SOC) reconstructions of 3D DESS images provided effective vascular suppression and good nerve conspicuity, the DL-GIC reconstructed images demonstrated similar or improved nerve conspicuity.

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Laura Carretero Gómez^1,2, Maggie Fung³, Bruno Nunes⁴, Valentina Pedoia⁵, Sharmila Majumdar⁵, Akshay Chaudhari ⁶, Arjun Divyang Desai^6,7, Anthony Andrea Gatti⁶, Feliks Kogan⁶, and Mario Padron^8
1GE Healthcare, Munich, Germany, ²LAIMBIO, Rey Juan Carlos University, Madrid, Spain, ³GE Healthcare, New York, NY, United States, ⁴GE Healthcare, San Ramon, CA, United States, ⁵University of California, San Francisco, San Francisco, CA, United States, ⁶Radiology, Stanford University, Stanford, CA, United States, ⁷Electrical Engineering, Stanford University, Stanford, CA, United States, ⁸Clinica CEMTRO, Madrid, Spain

Keywords: Cartilage, Quantitative Imaging

The clinical translation of MRI Quantitative Imaging is still hampered by the high variability and suboptimal reproducibility of the cartilage biomarkers. The purpose of this work is to validate the consistency of a novel accelerated DL reconstructed T2 mapping technique compared to conventional reconstructed acquisition, on knee patient population. To access both femoral cartilage T2 maps, we propose a semi-automatic workflow through AI-based cartilage segmentation and regional quantification using DOSMA framework. Relaxometry analysis showed no difference between both T2 mapping techniques, implying a great step into an extensive clinical adoption.

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Won Bae^1,2, Vadim Malis¹, Asako Yamamoto³, Yoshimori Kassai⁴, Jun Isogai⁵, Katsumi Nakamura⁶, John Lane⁷, and Mitsue Miyazaki^1
1Radiology, University of California, San Diego, La Jolla, CA, United States, ²VA San Diego Healthcare System, San Diego, CA, United States, ³Radiology, Teikyo University, Tokyo, Japan, ⁴Canon Medical Systems Corp, Otawara, Japan, ⁵Radiology, Asahi General Hospital, Chiba, Japan, ⁶Kyoritsu Tobata Hospital, Kitakyusyu, Japan, ⁷University of California, San Diego, La Jolla, CA, United States

Keywords: MSK, Arterial spin labelling, Bilateral feet perfusion, ASL, Feet and Toes

Non-contrast MR perfusion techniques were developed to assess micro-vascularity of the foot in humans. Using flow-out spin labeling with 3D SSFSE acquisition at multiple Tis, we obtained perfusion signal into distal feet and toes. Signal vs. TI data was fit to determine perfusion metrics including peak height (PH), apparent blood volume (aBV) and apparent blood flow (aBF). Compared to 1-tag, when 4-tag pulses were used PH, aBV, and aBF were significantly greater, suggesting increased signal afforded by the 4-tag pulses. This will be useful for subjects with low blood flow, such as those with peripheral artery disease.

Dimitri Martel¹, Benjamin Leporq², Anmol Monga¹, Stephen Honig³, and Gregory Chang^1
1Radiology, NYU Langone, New York, NY, United States, ²Université de Lyon; CREATIS CNRS UMR 5220, Inserm U1206, INSA-Lyon, Villeurbanne, France, ³Osteoporosis Center, Hospital for Joint Diseases, NYU Langone, New York, NY, United States

Keywords: Bone, Fat

Chemical Shift Encoded (CSE) MRI method has been used to highlight subregional differences in the femoral bone marrow in terms of fatty acids composition in proximal femur, suggesting an important role of the marrow in bone quality. This method requires a certain number of echoes (3 for fat/water separation and >8 for fatty acids mapping). Deep Learning (DL) has been recently applied to accelerate, improve the quality and efficiency for fat/water separation in CSE-MRI. Our aim was to develop a DL-CSE method and evaluate it for fatty acids composition mapping; using different echo numbers. 

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Eléonore Vermeulen¹, Pierre-Yves Baudin¹, Marc Lapert², and Benjamin Marty^1
1NMR Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, France, ²Siemens Healthcare SAS, Saint-Denis, France

Keywords: Muscle, Quantitative Imaging

Intramuscular fat fraction (FF) is a frequently used biomarker of neuromuscular disease severity while water-T2 has been identified as a biomarker of disease activity. In this feasibility study, we explored the possibility to exploit RF phase-modulated 3D gradient-echo imaging to obtain multi-parametric mapping adapted to the study of skeletal muscles. Monte Carlo simulations were conducted to evaluate the robustness to noise of this proposed approach. An in vivo proof of concept on healthy volunteers was performed.

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Kevin D Harkins^1,2,3, Nicholson S Chadwick¹, and Mark D Does^2,3
1Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, ²Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, United States, ³Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

Keywords: MSK, Pulse Sequence Design

The adoption of 2D UTE for general musculoskeletal imaging has been slowed by technical limitations—especially gradient errors that cause slice profile distortions. In this work, a library of predistorted gradient waveforms were used to interpolate slice select gradient waveforms for oblique oriented half-pulse 2D UTE. Example multi-echo and multi-slice acquired 2D UTE images are shown in the tibia, ankle, & knee. Positive contrast in collagen rich tissues like bone and tendon could provide a new source of information to potentially diagnose MSK injuries.

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Masami Yoneyama¹, Minako Azuma², Masahiro Enzaki³, Guruprasad Krishnamoorthy^4,5, Ryan Robison⁴, Iain Ball⁶, Hiroshi Hamano¹, and Marc Van Cauteren^7
1Philips Japan, Tokyo, Japan, ²Department of Radiology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan, ³Division of Radiology, Miyazaki University Hospital, Miyazaki, Japan, ⁴Philips Healthcare, Rochester, MN, United States, ⁵Department of Radiology, Mayo Clinic College of Medicine and Science, Rochester, MN, United States, ⁶Philips Australia & New Zealand, North Ryde, Australia, ⁷Philips Healthcare, Best, Netherlands

Keywords: Bone, Bone

MR bone imaging has gained more attention for detecting and assessing bone pathology. In this study, we proposed a new technique consisting of broadband inversion recovery preparation with FLORET UTE with Fibonacci interleaved trajectory ordering (FLORET BoneVIEW) to obtain 3D isotropic bone images within a clinically feasible scan time. FLORET BoneVIEW has great potential to help a more accurate assessment of bone pathology as an alternative to CT bone imaging.
 

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Oliver Kraff¹, Jenni Schulz², Markus W May^1,3, Tom WJ Scheenen^1,2, Thomas B Meurs⁴, Sebastian Schmitter⁵, Jens M Theysohn⁶, and Harald H Quick^1,3
1Erwin L Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany, ²Medical Imaging, Radboud UMC, Nijmegen, Netherlands, ³High-Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany, ⁴Tesla Dynamic Coils, Zaltbommel, Netherlands, ⁵Physikalisch-Technische Bundesanstalt (PTB), Braunschweig und Berlin, Germany, ⁶Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany

Keywords: Joints, RF Pulse Design & Fields, UHF

First experiences with direct signal control with variable excitation and refocusing (DiSCoVER) for T2-weighted TSE imaging in 7 Tesla musculoskeletal (MSK) applications of hip, shoulder, and ankle are presented. Images were compared to static RF shimming aiming at a homogeneous excitation by using the MR system’s framework as well as optimizing for a B₁⁺-efficient shim in an offline calculation. DiSCoVER yielded satisfying results within the ROI defined for signal optimization but showed more pronounced signal dropouts outside the ROI compared to static RF shimming. Workflow improvements were particularly noted for DiSCoVER as it calculates pTx scale factors under SAR constraints.

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Yingying Lin¹, Yin Chung Ho², Shirley Chui Wai Chan³, Kam Ho Lee⁴, and Peng Cao^3
1the university of HongKong, Hongkong, Hong Kong, ²Chiron Medical, HongKong, Hong Kong, ³the university of HongKong, HongKong, Hong Kong, ⁴Queen Mary Hospital, HongKong, Hong Kong

Keywords: Joints, Joints, deep learning, MRI, Ankylosing spondylitis

Our work proposed a work pipeline to automatic score the inflammatory lesion based on the SPARCC scoring system. This pipeline included the reference vessel intensity set-up, template-based registration, and lesion detection with scoring. With this pipeline, a time-saving and objective scoring method based on SPARCC scoring system could be achieved and widely applied to AS patient management. Our result showed reasonable performance for score-2 and score-3 lesions demonstrating the deep learning initial capacity of performing the SPARCC scoring. 

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Keywords: Bone, Bone

$$$B_1^+$$$ field inhomogeneity is a source of metal artifacts in patients with orthopedic hardware. Local $$$B_1^+$$$ shimming can potentially decrease these artifacts and improve visualization of the bone-metal interface. Our proposed turbo-spin echo-based $$$B_1^+$$$ mapping technique enables accurate estimation of the $$$B_1^+$$$ field near the metal hardware. After optimization for in-vivo applications, the technique was successfully employed on a clinical 3.0 T parallel-transmit system aiming at $$$B_1^+$$$ shimming near the orthopedic hardware. Our results demonstrate significant improvement in visualization of the bone-metal interface compared to standard 1.5 and 3.0 T acquisitions. 

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Saeed Jerban^1,2,3, Yajun Ma^1,2, Dina Moazamian¹, Jiyo Athertya¹, Sophia Dwek¹, Hyungseok Jang^1,2, Gina Woods⁴, Christine B Chung^1,2, Eric Y Chang^1,2, and Jiang Du^1,2
1Department of Radiology, University of California, San Diego, La Jolla, CA, USA, San Diego, CA, United States, ²Radiology Service, Veterans Affairs San Diego Healthcare System, San Diego, La Jolla, CA, USA, San Diego, CA, United States, ³Department of Orthopedic Surgery, University of California, San Diego, La Jolla, CA, USA, San Diego, CA, United States, ⁴Department of Medicine, University of California, San Diego, La Jolla, CA, USA, San Diego, CA, United States

Keywords: Bone, Bone, Tibia

The porosity index (PI) and the suppression ratio (SR) are two rapid MRI-based techniques developed using ultrashort echo time (UTE) sequences to evaluate the cortical bone microstructure. We have investigated the performance of PI and SR in detecting tibial bone quality differences between osteoporosis (OPo) patients, osteopenia (OPe) patients, and healthy volunteers with normal bone (Normal). We also investigated the correlations of PI and SR with DEXA T-score performed at the hip in patients. PI and SR were significantly higher in the OPo group compared with the Normal and OPe groups. DEXA T-score was significantly correlated with PI and SR.

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Keywords: Cartilage, Cartilage, supervised learning

We propose a self-supervised learning method that derives T1 map from a reduced number of variable flip angle images without requiring ground truth maps, aimed at minimizing data acquisition efforts for obtaining training and testing data.

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Laurel Hales¹, Arjun Desai¹, Valentina Mazzoli ¹, Akshay Chaudhari¹, and Feliks Kogan^1
1Radiology, Stanford University, Stanford, CA, United States

Keywords: Joints, Image Reconstruction, kinematic

We demonstrated the potential applying a noise removal machine learning network trained on images without motion, on a set of similar real-time images acquired with motion.