Imaging of the Zone of Calcified Cartilage (ZCC) Using 3D Ultrashort TE Pulse Sequences
Jiang Du¹, Won C. Bae¹, Sheronda Statum¹, Renie Biswas¹, Michael Carl², Atsushi Takahashi², Christine B. Chung¹, Graeme M. Bydder^1
1Radiology, University of California, San Diego, CA, United States; ²Global Applied Science Laboratory, GE Healthcare Technologies, Menlo Park, CA, United States

The zone of calcified cartilage (ZCC) is a highly modified mineralized region of articular cartilage that forms an important interface between cartilage and bone. It is a region that may change dramatically in osteoarthritis (OA). However, all current clinical sequences show a signal void for the ZCC because of its short T2 and thin structure. Here we present 3D UTE sequences for ZCC imaging using three contrast mechanisms: dual echo acquisition and echo subtraction, single adiabatic inversion recovery (SIR) and dual inversion recovery (DIR). The feasibility of these techniques was tested on five cadaveric patellae on a clinical 3T scanner.

Ultrashort TE Enhanced T₂^* Mapping of Cartilage:   a Pilot Clinical Study
Ashley Williams¹, Yongxian Qian², Constance R. Chu^1
1Cartilage Restoration Laboratory, University of Pittsburgh, Pittsburgh, PA, United States; ²Magnetic Resonance Research Center, University of Pittsburgh, Pittsburgh, PA, United States

This work demonstrates the feasibility of in vivo 3-D UTE-T₂^* mapping of cartilage and examines the sensitivity of UTE-T₂^* to early cartilage degeneration compared to arthroscopic grading as the standard. UTE-T₂^* and standard T₂ knee images were acquired on 10 subjects at 3T. Deep zone UTE-T₂^* values were significantly higher in softened cartilage compared to healthy (arthroscopic grade 1vs0, p<0.01).  Superficial zone UTE-T₂^* showed a trend for higher values in softened tissue compared to healthy (p=0.17). Standard T₂  values showed no differences between healthy and softened cartilage. UTE-T₂^* mapping captures signal from deep cartilage better than standard T₂ .

Change in the DTI Parameters of the Articular Cartilage with Progressive Proteoglycan Depletion
José G. Raya¹, Gerd Melkus², Silvia Adam-Neumair³, Olaf Dietrich⁴, Maximilian F. Reiser, Peter Jakob², Christian Glaser
¹Josef Lissner Laboratory for Biomedial Imaging, , University of Munich, Munich, Germany; ²Deparment of experimental physics V, University of Würzburg, Germany; ³Department of Clinical Radiology, University of Munich, Germany; ⁴Josef Lissner Laboratory for Biomedial Imaging, Department of Clinical Radiology, University of Munich, Germany

DTI has great potential for the early diagnosis of osteoarthritis since it is sensitive to the proteoglycan (PG) content and the integrity of the collagen network. In this work we investigate the effect of progressive PG depletion on the DTI parameters. DTI and T2 of human bone-on-cartilage samples as well as their PG content were measured before and after proteoglycan depletion. ADC showed a linear (r²=0.86, P<0.007) dependence with the PG loss. The diffusion anisotropy (FA and first eigenvector) remained unchanged. Measurements of the T2 relaxation time demonstrated that the collagen structure of the cartilage was unaffected by PG depletion.

Loading and Knee-Alignment Have Significant Influence on Cartilage T2 in Porcine Knee Joints
Toshiyuki Shiomi¹, Takashi Nishii¹, Hisashi Tanaka², Youichi Yamazaki³, Kenya Murase³, Akira Myoui¹, Hideki Yoshikawa¹, Nobuhiko Sugano^1
1Department of Orthopaedic Surgery, Osaka University Medical School, Suita, Osaka, Japan; ²Department of Radiology, Osaka University Medical School, Osaka, Japan; ³Department of Medical Physics and Engineering, Osaka University Medical School, Osaka, Japan

We developed a non-metallic pressure device to be used during MRI under variable loading or knee alignment conditions in excised porcine knee joints, and assessed the influence of loading and knee alignment on T2 mapping of the knee femoral cartilage.

Quantitative Mri Reveals Early Cartilage Degeneration in Acl-Injured Knees - not available
Xiaojuan Li¹, Daniel Kuo, Keerthi Shet, Christoph Stehling, Jonathan Cheng, Thomas Link, Benjamin Ma, Sharmila Majumdar
¹Radiology, University of California, San Francisco, San Francisco, CA, United States

Patients with anterior cruciate ligament (ACL) injuries have a high risk of developing post-traumatic osteoarthritis. The goals of this study were: 1) to longitudinally evaluate cartilage matrix changes using T1ρ and T2 quantification; 2) to study the relationship between meniscal damage and cartilage degeneration. 12 patients with acute ACL-injures and 10 healthy controls were studied. Significantly elevated T1rho were observed at 1-year follow up. T1rho were more sensitive than T2 in detecting early changes in cartilage matrix in ACL-injured knees. Lesions in posterior horn of medial meniscus were correlated with accelerated cartilage degeneration in medial femoral condyle.

MRI of Bioregenerative Approaches in Cartilage Repair: Differentiation of Repair Tissue After Matrix-Associated Autologous Chondrocyte Transplantation Using a Hyaloronic Acid-Based or a Collagen-Based Scaffold with Advanced Morphological Scoring and Bioch
Goetz Hannes Welsch^1,2, Tallal Charles Mamisch³, Lukas Zak⁴, Matthias Blanke², Alexander Olk², Stefan Marlovits⁴, Siegfried Trattnig^1
1MR Center, Department of Radiology, Medical University of Vienna, Vienna, Austria; ²Department of Trauma and Orthpaedic Surgery, University Hospital of Erlangen, Erlangen, Germany; ³Department of Orthopaedic Surgery, University of Basel, Basel, Switzerland; ⁴Center for Joints and Cartilage, Department of Trauma Surgery, Medical University of Vienna, Vienna, Austria

Aim of the study was to compare cartilage repair tissue at the femoral condyle noninvasively after matrix-associated autologous chondrocyte transplantation (MACT) using Hyalograft® C (HC), a hyaloronic acid-based scaffold, to cartilage repair tissue after MACT using CaReS®, a collagen-based scaffold, with morphological and biochemical MRI. Differences in the surface of the repair tissue using morphological MRI and higher T2 values for the cartilage repair tissue depicted by biochemical T2 maps indicate differences in the composition of the repair tissue that was based on a collagen scaffold (CaReS®), compared to the hyaloronic acid-based scaffold (HC), even two years post-implantation.

In Vivo Quantification of Cartilage Regeneration in an Equine Model at 3T Following Gene Therapy
Daniel James Clark¹, Guang Jia¹, Maria Isabel Menendez², Seongjin Choi¹, Craig James Miller, Steffen Sammet¹, David C. Flanigan³, Alicia Louise Bertone², Michael V. Knopp^1
1Radiology, College of Medicine, The Ohio State University, Columbus, OH, United States; ²Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, United States; ³Orthopedics, OSU Sports Medicine Center, The Ohio State University, Columbus, OH, United States

Currently, there is no established human sized model for cartilage regeneration.  This study is the first to assess the time course of healing in vivo using quantitative MRI in live ponies with cartilage thicknesses comparable to humans in a 3T clinical scanner. We use several innovative, quantitative methods including delayed contrast-enhanced MRI of cartilage (dGEMRIC), dynamic contrast-enhanced MRI (DCE-MRI), and T₂ mapping.  The results of this study strongly suggest that in vivo quantitative MRI can be used to monitor cartilage healing and characterize the physiological state of repaired tissue.

High Resolution Cartilage and Whole Organ Knee Joint Assessment: 3D Radial Fat-Suppressed Alternating TR SSFP
Jessica Leigh Klaers¹, Ethan K. Brodsky^1,2, Walter F. Block^1,3, Richard Kijowski^2
1Medical Physics, University of Wisconsin - Madison, Madison, WI, United States; ²Radiology, University of Wisconsin - Madison, Madison, WI, United States; ³Biomedical Engineering, University of Wisconsin - Madison, Madison, WI, United States

Effective cartilage imaging and whole organ joint assessment requires both high isotropic resolution and fat suppression or separation.  We present a single pass, 3D radial fat-suppressed Alternating TR (FS ATR) SSFP acquisition which provides ultra-high isotropic resolution of 0.33 mm (voxel volume of 1/27 mm3) throughout the entire knee joint and contrast the method against a two pass, 3D radial Linear Combination SSFP (LC-SSFP) method.  3D radial FS-ATR offers complete visualization of the articular cartilage surface, further enhancing the ability to appreciate submillimeter cartilage defects which is useful for longitudinal research studies of cartilage degeneration and simultaneous whole organ assessment.

Diffusivity and Kinetics of Gadopentetate in Articular Cartilage in Vitro
Elli-Noora Salo¹, Mikko J. Nissi^1,2, Katariina Aino Maria Kulmala¹, Juha Töyräs^1,3, Miika T. Nieminen^4,5
1Department of Physics, University of Kuopio, Kuopio, Finland; ²Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland; ³Diagnostic Imaging Centre, Kuopio University Hospital, Kuopio, Finland; ⁴Department of Medical Technology, University of Oulu, Oulu, Finland; ⁵Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland

In the dGEMRIC method, full equilibrium of gadopentetate is required to quantify the proteoglycan content of articular cartilage. In this study, the diffusivity and kinetics of gadopentetate was studied by limiting equilibration only through the articular surface or deep cartilage. The distribution of gadopentetate in bovine cartilage samples was followed for 18 hours with repeated T₁ mapping at 9.4 T. The results showed that full equilibration takes longer than previously assumed. Diffusion was faster through the articular surface. With equilibration through the articular surface, the superficial cartilage reached near-equilibrium relatively quickly, possibly allowing early visualization of superficial degenerative changes.

The in Vivo Transport of Anionic Contrast Agent Into Human Femoral Knee Cartilage
Eveliina Lammentausta¹, Carl Johan Tiderius², Leif E. Dahlberg^2
1Department of Clinical Sciences, Malmö, Joint and Soft Tissue Unit, University of Lund, Malmö, Sweden; ²Department of Orthopaedics, Malmö University Hospital, Malmö, Sweden

The aim of the study was to investigate the distribution of Gd-DTPA^2- into human knee cartilage in vivo at areas of different loading conditions. T1 relaxation time was measured before and regularly after triple does (0.3mM/kg) injection of Gd-DTPA^2- for five healthy volunteers. Contrast agent transport was analyzed for three regions in femur and one in tibia, for deep and superficial cartilage separately. Different transport patterns were observed between weight-bearing and non-weight-bearing regions. The transport into deep cartilage was remarkably slower indicating transport only through cartilage surface.