Benjamin Schmitt¹, Stefan Zbyn^2,3, David Stelzeneder², Vladimir Jellus⁴, Dominik Paul⁴, Lars Lauer⁴, Peter Bachert¹, and Siegfried Trattnig^2
1Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany, ²Radiology, Medical University of Vienna, Vienna, Austria, ³Orthopedics, Medical University of Vienna, ⁴Siemens Healthcare, Erlangen, Germany

A new imaging method based on GRE that allows for acquisition of volumetric gagCEST image datasets in clinically relevant scan times is introduced. Reliability and glycosaminoglycan (GAG)-specificity are evaluated by comparison of results from the new technique to results obtained with sodium imaging in a patient study at 7 Tesla. All patients had cartilage repair surgery in the knee prior to examination, and a strong correlation be-tween gagCEST results, and sodium imaging was found. Cartilage repair regions could be equally well deline-ated from healthy cartilage with both imaging techniques.

Sarah Pownder¹, Matthew F Koff¹, Lisa Fortier², Emme Castiglione³, Ryan Saska³, Gino Bradica³, Kira Novakofski², and Hollis G Potter^1
1Department of Radiolgy and Imaging - MRI, Hospital for Special Surgery, New York, NY, United States, ²College of Veterinary Medicine, Cornell University, Ithaca, NY, United States, ³Kensey Nash Corporation

Evaluation of cartilage repair by MRI is largely based on subjective impressions of gray scale images. Quantitative MRI sequences such as T1ñ and T2 mapping measure tissue relaxation to assess the proteoglycan content and collagen organization, respectively. This study evaluated cartilage repair in an equine model using morphologic and quantitative MRI. The repair sites demonstrated regions of variable signal intensity, and the quantitative data indicated peripheral incorporation with native tissue, and diminished proteoglycan content and collagen orientation in the center of the repair. This study demonstrates the feasibility of MR evaluation of a preclinical model of cartilage repair at clinically relevant field strengths.

Ernesto Staroswiecki^1,2, Kristin Lee Granlund^1,2, Marcus Tedrow Alley¹, Garry Evan Gold¹, and Brian Andrew Hargreaves^1
1Radiology, Stanford University, Stanford, CA, United States, ²Electrical Engineering, Stanford University, Stanford, CA, United States

While ADC and T₂ maps have been suggested as methods to obtain biochemical information generating them in cartilage is usually slow or limited by SAR, SNR, or distortion. In this work we present modifications to 3D DESS that enable manipulation of diffusion weighting of the sequence. We then acquire two datasets with this sequence with different weightings to generate two high-resolution images with different contrast and, by fitting to the signal equations, T₂ and ADC maps. We show the accuracy of this method with a phantom study and demonstrate maps in vivo that are free of evident artifacts or distortion.

Jose G Raya¹, Annie Horng², Olaf Dietrich², Svetlana Krasnokutsky³, Luis S Beltran³, Maximilian F Reiser², Michael Recht³, Michael Recht³, and Christian Glaser^3
1Radiology, New York University Langone Medical Center, New York, NY, United States, ²University of Munich, ³New York University Langone Medical Center

In this work we assess the value of in vivo DTI of the articular cartilage for the early diagnosis of osteoarthritis (OA) at 7T using a 28Ch knee coil and a line scan diffusion sequence. DTI and T2 maps were obtained from 16 volunteers and 8 OA patients with early morphologic cartilage degeneration. Discrimination of the volunteer and patient were possible with mean ADC and FA (P<0.005) but not with T2. A cutoff of 1.2×10-3mm2 in average ADC and 0.4 in average FA resulted in a specificity of 100% and a sensitivity of 87.5% (positive predictive value=100%, negative predictive value=94.1%).

Lauren Michelle Shapiro¹, Deborah M Lee¹, Karthryn J Stevens¹, Weitian Chen², Anja C Brau², Brian A Hargreaves³, and Garry Evan Gold^1,4
1Department of Radiology, Stanford University, Stanford, CA, United States, ²Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States, ³Department of Radiology, Stanford University, Stanford University, CA, United States, ⁴Department of Bioengineering, Stanford University, Stanford, CA, United States

Musculoskeletal MRI studies usually comprise of 2D-FSE sequences acquired in orthogonal planes. 3D-FSE enables isotropic voxel acquisition allowing reformations and decreased overall exam time. Thinner slice thickness in 3D-FSE also results in less partial volume artifact. We compare the clinical performance of 3D-FSE to 2D-FSE in evaluating the symptomatic upper extremity at 3.0T using arthroscopy as a reference standard. 3D-FSE showed similar performance to 2D-FSE in pathology identification in the upper extremity. The thinner slices of 3D-FSE, and the ability to reformat images in arbitrary planes, enabled optimal visualization of smaller and oblique pathology.

Richard Kijowski¹, Jessica Klaers², Kenneth Lee¹, Humberto Rosas¹, Larry Hernandez², and Walter Block^2,3
1Radiology, University of Wisconsin, Madison, Wisconsin, United States, ²Medical Physics, University of Wisconsin, Madison, Wisconsin, United States, ³Biomedical Engineering, University of Wisconsin, Madison, Wisconsin, United States

The study was performed to compare SNR, CNR, and subjective criteria of image quality of VIPR-ATR and currently used three-dimensional MR sequences for evaluating the articular cartilage of the knee joint. VIPR-ATR produced multi-planar images of the knee joint with 0.4 mm isotropic resolution in 5 minutes and 0.3 mm isotropic resolution in 8 minutes which were well suited for evaluating articular cartilage. VIPR-ATR had high cartilage SNR and high CNR between cartilage and adjacent joint structure. On subjective analysis, VIPR-ATR had the highest rank for tissue contrast, clarity of articular surface, cartilage lesion conspicuity, and overall image quality.

Riccardo Lattanzi^1,2, Christian Glaser^1,2, Artem V Mikheev², Catherine Petchprapa², David J Mossa², Soterios Gyftopoulos², Henry Rusinek², Michael Recht², and Daniel Kim^1,2
1Center for Biomedical Imaging, New York University Langone Medical Center, New York, NY, United States, ²Radiology, New York University Langone Medical Center, New York, NY, United States

Early detection of cartilage degeneration in the hip with dGEMRIC may help prevent osteoarthritis in patients with femoroacetabular impingement. We propose a new high-resolution 2D T₁-mapping saturation-recovery (SR) pulse sequence with FSE readout for dGEMRIC at 3T in radial imaging planes. Our sequence was validated in a phantom and in 10 hips against a rigorous multi-point SR pulse sequence. T₁ measurements by the two sequences were strongly correlated (R² > 0.95) and in excellent agreement (mean difference = -8.7ms; ± 95% limits of agreement = 64.5 and -81.9ms, respectively). T₁ measurements were insensitive to B₁⁺ variation as large as 20%.

Wen Ling¹, Elizabeth Arendt², Denis Clohisy², Silvia Mangia¹, Shalom Michaeli¹, Michael Garwood¹, and Jutta Elllermann^1
1Center for Magnetic Resonance Research, Univ. of Minnesota, Minneapolis, MN, United States, ²Dept. of Orthopedic Surgery, Univ. of Minnesota, Minneapolis, MN, United States

Bovine patellar cartilage plugs with trypsin treatment (n=4) were used to compare various contrast mechanisms, including T2, T1ρ by adiabatic HS1 and HS4 modulation, RAFF (relaxation along a fictitious field), and MT (magnetic transfer). Each of the plugs was scanned twice: before and after trypsin treatments. The control group (n=4) were through the same process except without trypsin treatment. Our results not only depict that adiabatic T1ρ gives rise to high sensitivity to proteoglycan induced change in cartilage, but also indicate it is a robust and artifact-free method.

Xiaojuan Li¹, Joseph Schooler¹, Fei Liang¹, Keerthi Shet Vishnudas¹, Weitian Chen², Suchandrima Banerjee², and Sharmila Majumdar^1
1Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, ²Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA

Magnetic resonance (MR) T1ρ and T2 relaxation time quantification can detect biochemical changes within cartilage collagen/proteoglycan matrix, and may provide complementary information associated with cartilage degeneration during osteoarthritis (OA). These techniques, however, normally need a long acquisition time. Furthermore, few studies have explored the potential diurnal variation in cartilage. The goals of this study were three fold: 1) To develop a sequence that combines T1ρ and T2 quantification; 2) To examine intra-day and inter-day reproducibility of the T1ρ and T2 quantification; 3) To examine the potential diurnal variation of T1ρ and T2 quantification in cartilage in young healthy adults.

Melissa Ann Vogelsong^1,2, George Pappas³, Ernesto Staroswiecki^1,4, Neal K Bangerter⁵, Eric Han⁶, Brian A Hargreaves¹, Hillary J Braun¹, Marc R Safran³, and Garry E Gold^1
1Radiology, Stanford University, Stanford, CA, United States, ²UCSF School of Medicine, San Francisco, CA, United States, ³Orthopaedic Surgery, Stanford University,⁴Electrical Engineering, Stanford University, ⁵Electrical Engineering, Brigham Young University, ⁶GE Global Applied Sciences Laboratory, Menlo Park, CA

Advances in imaging of cartilage biochemistry allow a more nuanced look at the effects of exercise on articular cartilage. T₂ mapping reflects collagen structure and water content, while T_1ρ and sodium MRI reflect proteoglycan content. We imaged 21 knees of collegiate basketball players before and after one season and assessed knee health using conventional proton, T₂ mapping, T_1ρ and sodium MRI. Rates of morphological pathologies remained relatively stable while T_1ρ decreased in all patellar and tibiofemoral regions, T₂ increased in the medial femur, lateral femur and medial tibia, and sodium signal decreased in the patella, suggesting that basketball may have varying effects on different cartilage regions.