Marco Barbieri¹, Akshay S. Chaudhari^1,2, Catherine J. Moran¹, Garry E. Gold^1,3, Brian A. Hargreaves^1,3,4, and Feliks Kogan^1
1Department of Radiology, Stanford University, Stanford, CA, United States, ²Department of Biomedical Data Science, Stanford University, Stanford, CA, United States, ³Department of Bioengineering, Stanford University, Stanford, CA, United States, ⁴Department of Electrical Engineering, Stanford University, Stanford, CA, United States

Quantitative T₂ mapping is a valuable tool for studying OA changes. qDESS is a rapid sequence that provides accurate T₂ measurements and SNR-efficient morphological imaging. B₀ mapping is an auxiliary scan acquired to correct field inhomogeneity-induced errors using techniques such as WASSR and 2-GRE. This work proposes a method for B₀ mapping that exploits the phase difference between the two echoes acquired with qDESS. The experiments with phantom and in-vivo simultaneous bilateral knee acquisitions showed that the B₀ maps obtained with the qDESS method were in good agreement with those obtained using the WASSR method and the 2-GRE method.

Abdul Wahed Kajabi^1,2,3, Stefan Zbyn^1,3, Cyrus M. Nouraee¹, Kai D. Ludwig^1,3, Casey P. Johnson^1,4, Steen Moeller¹, Mark A. Tompkins⁵, Bradley J. Nelson⁵, Gregory J. Metzger¹, Cathy S. Carlson⁴, and Jutta M. Ellermann^1,3
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, ²Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland, ³Department of Radiology, University of Minnesota, Minneapolis, MN, United States, ⁴Department of Veterinary Clinical Sciences, University of Minnesota, Minneapolis, MN, United States, ⁵Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN, United States

This 3T study evaluates 46 juvenile osteochondritis dissecans (JOCD) lesions of 41 skeletally immature patients using clinical, morphological MRI and diffusion-weighted MRI (DWI). In this study, apparent diffusion coefficient (ADC) values were able to differentiate between healed and not yet healed JOCD lesions, and distinguish between the operative and nonoperative treatment groups. DWI provides noninvasive, quantitative assessment of disease status which may help inform clinical management of JOCD. Further follow-up studies are needed to evaluate the potential of DWI for the prediction of lesion healing in JOCD patients.

Takayuki Sakai^1,2, Masami Yoneyama³, Atsuya Watanabe^4,5, Daichi Murayama¹, Shigehiro Ochi¹, Shuo Zhang⁶, and Tosiaki Miyati^7
1Radiology, Eastern Chiba Medical Center, Tonage, Japan, ²Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan, ³Philips Japan, Tokyo, Japan, ⁴General Medical Services, Chiba University Graduate School of Medicine, Chiba, Japan, ⁵Orthopaedic Surgery, Eastern Chiba Medical Center, Chiba, Japan, ⁶Philips Healthcare, Hamburg, Germany, ⁷Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan

We propose a new sequence called MIXTURE (Multi-Interleaved X-prepared TSE with inTUitive RElaxometry). MIXTURE is a 3D TSE that can set arbitrary echo times using the T2 preparation pulses, and enables several image contrasts (such as PDW, T2W) and T2 mapping by acquiring at least two echo time images.  In this study, we evaluated the clinical feasibility of morphological and pathological MRI with two contrasts images and quantitative MRI with T2 mapping using MIXTURE.

Stephan J. Breda¹, Robert-Jan de Vos², Dirk Poot¹, Gabriel Krestin¹, Juan A. Hernandez-Tamames¹, and Edwin Oei^1
1Radiology & Nuclear Medicine, Erasmus University Medical Center, Rotterdam, Netherlands, ²Orthopaedics, Erasmus Univerity Medical Center, Rotterdam, Netherlands

Patellar tendinopathy (PT) is an overuse injury of the patellar tendon in athletes involving typical degenerative changes to the patellar tendon. The association of MRI-assessed structural changes with symptoms is largely unknown. UTE-MRI was implemented to study longitudinal changes in T2* within the patellar tendon in athletes performing exercise therapy for PT. We found that T2* relaxation times in the degenerative tissue of the patellar tendon were associated with symptom severity and that decreased T2* was associated with clinical improvement.

Harmen Reyngoudt^1,2, Pierre-Yves Baudin^1,2, Ericky C.A. Araujo^1,2, Pierre G. Carlier³, and Benjamin Marty^1,2
1NMR Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, France, ²NMR Laboratory, CEA/DRF/IBFJ/MIRCen, Paris, France, ³CEA, DRF, Service Hospitalier Frédéric Joliot, Orsay, France

Quantitative MRI fat-water separation techniques such as Dixon are often used to evaluate disease progression in muscle of neuromuscular diseases. Although the mean fat fraction (FF) value per region of interest (ROI) is a valuable objective MRI biomarker, it does not reflect the variation of FF within this ROI. In this study we analyzed 6582 muscle ROIs in leg and thigh of 6 different neuromuscular diseases and analyzed, besides the mean FF, other statistical metrics such as median, standard deviation, kurtosis and skewness. The differences in FF distribution might reveal additional information about the individual patient’s disease evolution.

Esha Baidya Kayal¹, Nikhil Sharma¹, Raju Sharma², Sameer Bakhshi³, Devasenathipathy Kandasamy², and Amit Mehndiratta^1,4
1Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India, ²Radio diagnosis, All India Institute of Medical Sciences Delhi, New Delhi, India, ³Department of Medical Oncology, Dr. B.R. Ambedkar Institute-Rotary Cancer Hospital (IRCH), All India Institute of Medical Sciences Delhi, New Delhi, India, ⁴Department of Biomedical Engineering, All India Institute of Medical Sciences Delhi, New Delhi, India

The spin relaxation time (T1) of the water protons, an intrinsic property of tissue, can be a useful marker of therapeutic response in osteosarcoma. T1 values were estimated in whole tumor volume before and after completion of chemotherapy and histogram analysis was performed to characterize tumor T1 and its changes in the course of chemotherapy. Results showed mean and skewness of T1 relaxation time in tumor may be useful as non-invasive imaging markers of chemotherapeutic response in osteosarcoma.

Guangtao Fan¹, Yudan Li¹, Fenglin Xue², Yilong Huang¹, Yanlin Li³, Guoliang Wang³, Tianfu Qi¹, Lisha Nie⁴, and Bo He^1
1Department of Imaging, the First Affiliated Hospital of Kunming Medical University, Kunming, China, ²Department of Pathology, the First Affiliated Hospital of Kunming Medical University, Kunming, China, ³Department of Sports Medicine, the First Affiliated Hospital of Kunming Medical University, Kunming, China, ⁴GE Healthcare, Kunming, China

The study aims to explore the clinical application value of MRI to quantitatively assess the anterior cruciate ligament mucoid degeneration (ACL-MD).The results indicated MRI Values of T1, T2 and T2*(relaxation time) show potential for diagnosis of ACL-MD and T2* may deliberately has the highest diagnostic efficacy.

Jikai Shen¹, Qi Zhao¹, Yi Qi¹, Gary Cofer¹, G. Allan Johnson¹, and Nian Wang^2
1Duke University, Durham, NC, United States, ²Radiology and Imaging Sciences, Indiana University, Indianapolis, IN, United States

Recently, diffusion MRI and tractography in musculoskeletal system has used to investigate the tissue microstructure, local collagen fiber alignment, and the 3D collagen network. To the best of our knowledge, nondestructively probing the local collagen fiber direction and 3D collagen fiber architecture is still limited. The water diffusion properties derived from DTI were quantified at different areas of meniscus using the proposed automatic segmentation method. Combining tractography and automatic segmentation, we were able to observe the structural connections among different areas of the meniscus.

Fang Liu¹, Georges El Fakhri¹, Martin Torriani¹, Richard Kijowski², and Miho Tanaka^3
1Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States, ²New York University School of Medicine, New York, NY, United States, ³Orthopaedic Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States

The purpose of this work was to develop and evaluate a model-guided self-supervised deep learning MRI reconstruction framework called REference-free LAtent map eXtraction (RELAX) for rapid quantitative relaxometry of the whole knee joint. This approach incorporated end-to-end CNN mapping to perform image-to-parameter domain transform. A concept of cyclic loss was utilized to enforce data fidelity and eliminate the explicit need for full-sampled training references. This approach was demonstrated in accelerated T1/T2 mapping of the whole knee joint and proven to outperform state-of-the-art reconstruction methods. The result suggests that RELAX allows accelerated relaxometry without training with reference data.

Dimitri MARTEL¹, Benjamin LEPORQ², Stephen HONIG³, and Gregory CHANG^1
1Radiology, NYU Langone Health, New york, NY, United States, ²Université de Lyon; CREATIS CNRS UMR 5220, Inserm U1206, INSA-Lyon, UCBL Lyon 1, Villeurbanne, France, ³Osteoporosis Center, Hospital for Joint Diseases, NYU Langone Health, New york, NY, United States

Osteoporosis (OP) is a disease associated with low bone mass and deterioration of bone microarchitecture leading to bone fragility and increased fracture risk, especially in the proximal femur. Therefore, we have developed a chemical-shift encoded acquisition performed with a spiral k-space sampling to acquire ultrashort echo-time and longer echo time in the echo train. This study aims to determine if uTE acquisition can be performed for fat/water separation and if additional information can be provided through cortical bone imaging.