Sanam Assili¹, Victor Casula^1,2, Jaakko Ikäheimo¹, Egor Panfilov¹, Ari Väärälä¹, Martijn A. Cloos³, Riccardo Lattanzi⁴, and Miika T. Nieminen^1,2,5
1Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland, ²Medical Research Center, University of Oulu and Oulu University Hospital, Oulu, Finland, ³Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia, ⁴Center for Advanced Imaging Innovation and Research, New York University Grossman School of Medicine, New York, NY, United States, ⁵Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland

Knee osteoarthritis is a degenerative musculoskeletal disorder which is characterized by progressive damage of articular cartilage (AC). Quantitative MRI (qMRI), such as T1 and T2 maps, can be used to assess the AC compositional changes. However, long acquisition time and equipment dependency are the limitations of the current clinical qMRI techniques. In the present study, we validate magnetic resonance fingerprinting (MRF) against conventional T1 and T2 relaxation time mapping methods in cartilage-mimicking phantoms, and apply MRF in vivo for sub-regional analysis of femoral and tibial cartilage in human subjects.

Edward Peake^1,2,3, Stefan Pszczolkowski^1,2,3, Christoph Arthofer^2,3,4, and Dorothee P Auer^1,2,3
1NIHR Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, United Kingdom, ²Radiological Sciences, Division of Clinical Neuroscience, University of Nottingham, Nottingham, United Kingdom, ³Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom, ⁴Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford, United Kingdom

Prediction of future knee replacement in osteoarthritis may support tailored decision making, and provide a surrogate outcome marker for clinical trials of diseases modifying osteoarthritis drugs. Fully automated cartilage segmentation is generated from knee MRI, and feature are extraction to create a radiomic signature for the prediction of knee replacement within 5 -years. The radiomic signature using univariate cox regression predicted surgery with a HR of 7.5 (p = 2e-28, 95% CI 7.1 – 7.9) which was higher than established clinico-demographic multivariate prediction model with HR 5.9 (p = 2e-28, 95%CI 5.6 – 6.2).

Koren Roach¹, Richard Souza¹, Sharmila Majumdar¹, and Valentina Pedoia^1
1UCSF, San Francisco, CA, United States

Hip osteoarthritis coincides with or is preceded by biochemical changes in articular cartilage,^{1, 2} which can be measured on a voxel-wise basis with magnetic resonance T_1ρ and T₂ relaxation times. In this study, we employed principal component analysis to characterize variation in longitudinal changes of hip cartilage T_1ρ relaxation times across healthy subjects and those with early-to-moderate hip osteoarthritis. Our results indicated that over two years, a majority of the variation in T_1ρ relaxation time changes was located in the deep layers of the acetabular cartilage.

Shufang Wei¹, Jiajia Li¹, Xianchang Zhang², Jing An³, and Yinghui Ge^1
1Fuwai Central China Cardiovascular Hospital, Zhengzhou, China, ²MR Collaboration, Siemens Healthcare Ltd, Beijing, China, ³Siemens Shenzhen Magnetic Resonance Ltd, Shenzhen, China

Detecting early articular cartilage damage can help formulate preventive treatment plans for hemophilia arthropathy (HA). Magnetic responance imaging (MRI) T2 mapping has been used extensively to investigate early chondral changes in osteoarthritis; however, it has seldomly been applied to investigate HA. This study acquired T2-mapping results on 30 patients (54 knees) with HA and 15 volunteers (24 knees). Patients with HA had significantly higher knee cartilage T2 values than the healthy controls. The T2 values also increased with the disease severity, suggesting that MRI T2 mapping is a promising method for detecting early stage cartilage damage in patients with hemophilia. 

Seyed Amir Mirmojarabian¹, Victor Casula¹, Olli-Pekka Aro¹, Henning Henschel², Miika T Nieminen^1,3,4, and Timo Liimatainen^1,3
1Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland, ²Department of Medicinal Chemistry, Uppsala University, uppsala, Sweden, ³Medical Research Center, Oulu University Hospital, Oulu, Finland, ⁴Department of Diagnostic Radiology,, Oulu University Hospital, Oulu, Finland

Relaxation along Fictitious Field (RAFF) at various pulse durations was exploited to study the contrast in collagen phantoms and cartilage-mimicking phantoms. RAFF Relaxation times from collagen phantoms agreed with Bloch McConnell simulations. The maximum contrast between collagen phantoms with concentration difference was maximized when pulse duration was ~2.8 ms. Given the optimized pulse duration, our simulation results combined with ex vivo measurements suggest that hydroxyl groups concentration through proton exchange between collagen and free water may have significant role in T_RAFF contrast between intact and degraded cartilage.

Jiajia Li¹, Shufang Wei¹, Xianchang Zhang², Jing An³, and Yinghui Ge^1
1Fuwai Central China Cardiovascular Hospital, Zhengzhou, China, ²MR Collaboration, Siemens Healthcare Ltd., Beijing, China, Beijing, China, ³Siemens Shenzhen Magnetic Resonance Ltd, Shenzhen, China

Early detection and therapy of articular cartilage damage are key to the management of hemophilia arthropathy (HA). Magnetic resonance (MR) T2* mapping has been used to detect iron deposits in the brain and liver but rarely in HA. We compared T2*mapping results of 15 HA patients (18 knees) and 10 volunteers (18 knees). We found that the average T2* values of the medial femoral condyle and medial tibial plateau cartilage in HA patients were significantly lower than in the normal group, suggesting the importance of T2* mapping in the quantitative assessment of iron deposition for early cartilage damage diagnosis in HA patients.

Saeed Jerban¹, Yajun Ma¹, Amir Masoud Afsahi¹, Douglas G Chang², Zhao Wei¹, Meghan Shen¹, Mei Wu¹, Alecio Lombardi^1,3, Nicole Le⁴, Jiang Du¹, and Eric Y Chang^1,3
1Radiology, University of California, San Digeo, La Jolla, CA, United States, ²Orthopaedic Surgery, University of California, San Digeo, La Jolla, CA, United States, ³Radiology Service, VA San Diego Healthcare System, San Diego, CA, United States, ⁴Radiology, VA San Diego Healthcare System, La Jolla, CA, United States

Bone and tendon comprise a highly interactive mechanical unit. Investigating tendons quality during osteoporosis and osteopenia progress is of great interests. Clinical MRI sequences are not often capable of directly visualizing tendon because of the tissue’s short T2.  Ultrashort echo time (UTE) MRI combined with magnetization transfer (MT) modeling (UTE-MT) has demonstrated promise as a quantitative technique that is resistant to the magic angle effect. Lower leg tendons in osteopenia and osteoporosis patients were compared with healthy subjects via UTE-MT. Macromolecular fraction (MMF) obtained from UTE-MT modeling showed a significant reduction in osteopenia and osteoporosis patients compared with healthy subjects.

Hyungseok Jang¹, Yajun Ma¹, Michael Carl², Saeed Jerban¹, Eric Y Chang^1,3, and Jiang Du^1
1University of California, San Diego, San Diego, CA, United States, ²GE Healthcare, San Diego, CA, United States, ³Veterans Affairs San Diego Healthcare System, San Diego, CA, United States

In this study, we explored the feasibility of applying single-point Dixon (spDixon)-based fat suppression to a novel ultrashort echo time-based double echo steady state (UTE-DESS) sequence for highly efficient morphological musculoskeletal (MSK) imaging. Compared to the two-point Dixon-based approach used with conventional UTE-DESS MSK imaging which requires two echoes for fat-water separation, we demonstrated a new technique which requires only a single image in, removing the need for additional data acquisitions. The feasibility and efficacy of our approach were demonstrated in human knee joints.

Lauren Watkins^1,2, Andrew Schmidt¹, Elka Rubin¹, Marco Barbieri¹, Arjun Desai^1,3, Valentina Mazzoli¹, Marianne Black¹, Garry Gold^1,2, Brian Hargreaves^1,2,3, Akshay Chaudhari^1,4, and Feliks Kogan^1
1Radiology, Stanford University, Stanford, CA, United States, ²Bioengineering, Stanford University, Stanford, CA, United States, ³Electrical Engineering, Stanford University, Stanford, CA, United States, ⁴Biomedical Data Science, Stanford University, Stanford, CA, United States

Subtle variations in T2 relaxation times may be related to the risk of early osteoarthritis and progression. It is important to estimate T2 variability in healthy individuals as a basis for cross-sectional and longitudinal comparisons. We examine short-term T2 variability in femoral articular cartilage of healthy volunteers over 5 days and 5 weeks and consider the impacts of physical activity. Over both periods, mean T2 change, variance, and CV_RMS were small and comparable between knees and cartilage subregions. There was a moderate positive correlation between T2 changes and weekly rated perceived exertion over 5 weeks

Hannah Mantebea¹, Syeda Batool¹, Mouhamad Hammami¹, and Yang Xia^1
1Physics, Oakland University, Rochester, MI, United States

This study aims to quantity the structural morphology of sesamoid fibrocartilage in rabbits, using µMRI at 19.5-µm resolution and polarized light microscopy at 1-µm resolution. We show that the sesamoid fibrocartilage has one thin surface layer (~ 10 µm) of parallel-arranged fibers followed immediately by the majority of random fibers (~ 390 µm). T2 anisotropy was not observed in fibrocartilage. The collagen fibers in the surface layer are dense and in parallel with the surface, which allows it to withstand stress from the quadriceps tendon during flexion, while at the same time to reduce pressure load from the femur.

Ashley A. Williams^1,2, Karyn E. Chappell^1,2, and Constance R. Chu^1,2
1Orthopaedic Surgery, Stanford University, Stanford, CA, United States, ²Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, United States

This study evaluated deep cartilage and meniscus UTE-T2* against spatially targeted arthroscopic assessments in patients with degenerative meniscus tears to further inform interpretation and utility of in vivo UTE-T2* for different degrees of pathology. While arthroscopic evaluation confirmed that UTE-T2* was elevated in menisci with degenerative fraying and tears, increasing intra-operative cartilage grade was not associated with strictly increasing cartilage UTE-T2*. Instead, in osteoarthritic disease states where the articular surface of cartilage is disrupted, this report suggests that mono-exponential deep cartilage UTE-T2* may not be a reliable indicator of tissue pathology.

Stefan Zbyn^1,2, Cassiano Santiago¹, Casey P. Johnson^1,3, Kai D. Ludwig^1,2, Lin Zhang⁴, Shelly Marette², Marc A. Tompkins⁵, Bradley J. Nelson⁵, Takashi Takahashi², Gregory J. Metzger¹, Cathy S. Carlson³, and Jutta M. Ellermann^1,2
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, ²Department of Radiology, University of Minnesota, Minneapolis, MN, United States, ³Department of Veterinary Clinical Sciences, University of Minnesota, St. Paul, MN, United States, ⁴Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, United States, ⁵Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN, United States

Clinical MRI of patients with juvenile osteochondritis dissecans (JOCD) relies on morphological, spin echo imaging with long echo times that cannot unambiguously distinguish between the cartilaginous, fibrous and osseous tissues within lesions. This 3T study evaluates 34 JOCD lesions from 25 patients using morphological MRI and T₂* mapping. JOCD progression was associated with a significant T₂* decrease in progeny and interface. Additionally, significantly lower T₂* in stage IV progeny and parent bone of stable lesions suggests increased bone density compared to the healthy, control bone. T₂* mapping provides quantitative evidence of disease progression which may help inform clinical JOCD management.

Nian Wang¹, Anthony J. Mirando², Yi Qi³, Matthew J. Hilton², and Charles E. Spritzer^3
1Radiology and Imaging Sciences, Indiana University, Indianapolis, IN, United States, ²Department of Orthopaedic Surgery, Duke University, Durham, NC, United States, ³Department of Radiology, Duke University, Durham, NC, United States

Nondestructively probing the 3D collagen fiber architecture of articular cartilage is still challenging for both clinical and preclinical studies. Diffusion tensor imaging (DTI) is able to resolve the collagen fiber directions by quantifying the unique water diffusion properties in soft tissues. Applying DTI and tractography in cartilage is limited but may provide noninvasive imaging biomarkers for Osteoarthritis (OA). In this study we imaged rat knees after 8 weeks destabilization of the medial meniscus (DMM) surgery using a modified 3D diffusion-weighted spin-echo pulse sequence at both high spatial resolution and high angular resolution.

Claudia Iriondo¹, Jinhee Lee¹, Sharmila Majumdar¹, and Valentina Pedoia^1
1University of California, San Francisco, San Francisco, CA, United States

We derive cartilage and meniscus point clouds from 40,796 high resolution knee MR images and train point cloud networks to extract osteoarthritis shape features. We demonstrate the utility of these learned features by assessing their relative contributions in a Cox Proportional Hazard Regression model with existing clinical risk factors predicting incident radiographic osteoarthritis. Shape biomarkers for tibiofemoral joint cartilage and menisci had significantly increased hazard ratios. The best performing shape biomarker– tibial and femoral cartilage shape– combined with clinical risk factors achieved a concordance index of 0.759. Our findings suggest point cloud learned shape features are promising OA biomarkers.

Hui Tan¹, Bin Wang², Wulin Kang¹, Qiuju Fan¹, Nan Yu¹, Shaoyu Wang³, Esther Raithel⁴, Yue Li², and Tuona Di^2
1The affiliated hospital of Shaanxi University of Chinese Medicine, Xianyang, China, ²Shaanxi University of Chinese Medicine, Xianyang, China, ³Siemens Healthineers, Shanghai, China, ⁴Siemens Healthcare, Erlangen, Germany

This study aimed to quantitative measurements of the cartilage volume , thickness and T2 relaxation times in patients with symptomatic mild to moderate KOA by using T2 mapping in 3 T MR. The prototypic software were used to evaluate 17 mild  KOA and 14 moderate KOA patients. Both biochemical imaging and morphologic examinations were sensitive  to study the mild to moderate KOA. Compared with the mild, the moderate OA patients exhibited decreased CV and CT with the growth of K-L grade, and the T2 value increased with the growth of K-L grade. 

Jose M Raya¹, Alejandra M Duarte¹, Dalibel M Bravo¹, Elisa M Ramos¹, Chongda M Zahng¹, Mary M Cowman², Thorsten M Kirsch¹, Mark Wilne³, Len Lyut³, and Amparo M Ruiz^1
1New York University Langone Health, New York, NY, United States, ²New York University Tandon School of Engineering, New York, NY, United States, ³University of Western Ontario, Ontario, ON, Canada

The objective of this work is to develop and validate a molecular imaging approach to image inflammation in articular cartilage. We targeted hyaluronan (HA)-mediated inflammation, which is a common inflammatory pathway activated in cartilage, with contrast agents designed using a 15-mer peptide that modulates HA-cell interactions. We identify optimal imaging times and demonstrate that contrast agent accumulates in areas of macroscopic damage. In vivo, MRI detected accumulation of the contrast agent in cartilage of PTOA joints but not in controls. Cartilage in all but one ACL-injured joint showed T₁-changes indicative of inflammation, demonstrating that HA-mediated inflammation is a common finding.

Marcelo Victor Wust Zibetti¹, Azadeh Sharafi¹, and Ravinder Regatte^1
1Radiology, NYU Langone Health, New York, NY, United States

in evaluating the performance of optimized SP for accelerating T1rho mapping of the knee cartilage. In this study, we investigate the improvements in accelerating the T1rho mapping of knee joint  by learning the SP in a data-driven manner. It was observed that the optimal learned SP depends on the selected spatial-temporal (k-t) data and the chosen reconstruction. Our preliminary results show that the learned SP improved the quality of the accelerated T1rho mapping of knee cartilage over Poisson disk for several different kinds of CS reconstructions.

Peiqi Ma¹, Yushan Yuan¹, Zongxi Zhang¹, Bin Peng¹, Jian Xu¹, and Xiuzheng Yue^2
1Fuyang People's Hospital，Anhui Province，China, Fuyang, China, ²Philips Healthcare, Beijing, China, Beijing, China

The compressed SENSE(CS-SENSE) technique, which is the combination of the parallel imaging technique SENSE with compressed sensing, has now been widely used in acceleration of MR examinations of various anatomies and anatomical contrasts. The purpose of this study was to explore the possibility of CS-SENSE in 3D knee joint imaging and its diagnostic value for meniscus injury types.

Elka B Rubin¹, Joanna L Langner², Marianne S Black², Arjun D Desai², James W 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, ³Radiology, Cambridge University, Cambridge, United Kingdom, ⁴Centre for Hip Health and Mobility, University of British Columbia, Vancouver, BC, Canada

Water polo players and synchronized swimmers have been found to have an increased prevalence of femoroacetabular impingement morphology compared to the general population. In this study, we used quantitative MRI to identify regional patterns in the composition of hip cartilage of Division 1 female water polo players and synchronized swimmers. Variations in T₂ relaxation times showed regional hip cartilage differences between the water polo players and synchronized swimmers and within the sub-regions of the synchronized swimmer’s hip cartilage. This study suggests that microstructural differences are present in the various regions of these athletes’ hip cartilage.

Elena Voronkova^1,2, Petr Menshchikov^3,4, Ilya Melnikov¹, Andrei Manzhurtsev^1,4, Maxim Ublinskii^1,4, Denis Vorobyev¹, Dmitriy Kupriyanov³, and Tolib Akhadov^1
1Clinical and Research Institute of Emergency Pediatric Surgery and Trauma, Moscow, Russian Federation, ²National Research Nuclear University MEPhI, Moscow, Russian Federation, ³Philips Healthcare, Moscow, Russian Federation, ⁴Emanuel Institute of Biochemical Physics of RAS, Moscow, Russian Federation

In this work, the values of the transverse relaxation times (T2) were measured for the first time in the deep, intermediate, and superficial layers of the patellar cartilage at different stages of chondromalacia as compared to control. The T2 values in the intermediate layer of cartilage show the best sensitivity to the grade of injury and have statistically significant differences for the groups of normal, mild, and severe cartilage damage. The T2-mapping technique is a potential tool for studying structural changes in cartilage and T2 values can be considered as a non-invasive biomarker for the assessment of the cartilage condition.