Scott Puckhaber¹, Matthew Fenty², Nancy Major³, and Ravinder Reddy^2
1Duke University School of Medicine, Durham, NC, United States, ²CMROI, Radiology, University of Pennsylvania, Philadelphia, PA, United States, ³Musculoskeletal Imaging, Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA, United States

Glenohumeral arthritis is a disabling condition and may severely affect quality of life and activities of recreation and daily living. With shoulder injuries, either traumatic or from repeated stresses, the integrity of the cartilage may become compromised due to several factors such as abnormal loading conditions and repeated stresses. Osteoarthritic changes to articular cartilage such as loss and breakdown of proteoglycan molecules has been quantified with high sensitivity with T₁ MRI . The aim of this study was to develop a T₁ MRI protocol to accurately quantify biochemical properties of the glenohumeral articular cartilage to monitor the development of cartilage degeneration in vivo.

Chen Lin¹, Scott A Persohn¹, and Boaz Karmazyn^1
1Department of Radiology and Imaging Science, Indiana University School of Medicine, Indianapolis, IN, United States

A pilot study of shows high resolution of T2 and T2* mapping metacarpophalangeal cartilage in children is feasible at 3T despite its small size. The mean T2 value for normal group is 42.6±5.5msec and the mean T2* is 20.9±5.1msec. The profiles of T2 and T2* along the thickness of cartilage are consistent between subject. However, both inter-subject and intra subject variation of T2* is greater than T2, suggesting that T2 values would be a more reliable biomarker for detecting and monitoring the involvement of cartilage in diseases such as Juvenile idiopathic arthritis (JIA).

Nade Sritanyaratana¹, Alexey Samsonov², Samuel A Hurley³, Kevin M Johnson², Pouria Mossahebi¹, Walter F Block^1,3, and Richard Kijowski^2
1Biomedical Engineering, University of Wisconsin - Madison, Madison, WI, United States, ²Radiology, University of Wisconsin - Madison, Madison, WI, United States, ³Medical Physics, University of Wisconsin - Madison, Madison, WI, United States

Longitudinal osteoarthritis (OA) research studies require non-invasive contrast mechanisms to observe disease progression. Since articular cartilage has a high macromolecular concentration consisting primarily of collagen and proteoglycan, quantitative magnetization transfer (qMT) could be sensitive to its macromolecular content and structure. However, given the constraints of cost and patient tolerance, MR examination times in OA research studies are generally limited to only 30 to 45 minutes. As qMT requires the acquisition of multiple MT-weighted images, extremely long scan times are a limitation. We investigate methods for qMT imaging of the entire human patellofemoral joint in less than 30 minutes.

Albert Paul Meier¹, Humberto Rosas¹, Jonathan Tueting², and Richard Kijowski^1
1Department of Radiology, University of Wisconsin, Madison, WI, United States, ²Department of Orthopedics, University of Wisconsin, Madison, WI

The study was performed to compare various two-dimensional and three dimensional MR sequences at 1.5T and 3T for evaluating the articular cartilage in human cadaveric wrist joints. Image quality and diagnostic performance was higher at 3T than at 1.5T. FGRE at 3T was the best sequence for evaluating articular cartilage and had the highest cartilage SNR, highest CNR between cartilage and bone, highest subjective rank for image quality, and highest diagnostic performance for detecting cartilage lesions.

Delphine Périé^1,2, Renaud Grenier¹, Guillaume Gilbert³, and Gilles Beaudoin^4
1Mechanical Engineering, Ecole Polytechnique de Montréal, Montréal, Québec, Canada, ²Research Center, CHU Sainte-Justine, Montréal, Québec, Canada, ³Philips Healthcare, Montréal, Québec, Canada, ⁴Physics and Biomedical Engineering, CHUM Notre Dame, Montréal, Québec, Canada

It is well established that MR parameters obtained by quantitative MRI (qMRI) are linked to the mechanical properties and biochemical composition of cartilages. We hypothesise that a relationship exists between mechanical properties and MR parameters of muscles. A qMRI acquisition and a tensile test were performed on adult rabbit muscles, in a state of rigor or post-rigor mortis. The tension variation between rigor mortis and post-rigor mortis comes from the degradation of myosin and actin. The results indicate that the muscle Young’s modulus, i.e. the passive mechanical behaviour, can be evaluated indirectly from qMRI using magnetization transfer and diffusion tensor acquisitions.

Karupppasamy Subburaj¹, Richard B Souza^1,2, Christoph Stehling³, Brad T Wyman⁴, Marie-Pierre Hellio Le Graverand-Gastineau⁴, Thomas M Link¹, Xiaojuan Li¹, and Sharmila Majumdar^1
1Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States, ²Department of Physical Therapy and Rehabilitation Science, University of California San Francisco, San Francisco, California, United States, ³Department of Clinical Radiology, University of Muenster, Münster, Germany, ⁴Pfizer, Inc., Groton, CT, United States

The purpose of this study was to assess the relationship between MR relaxation times and biomechanical response of articular cartilage to physiological loading (cartilage-on-cartilage contact area and deformation) in OA subjects and controls. The contact area in the medial compartment was significantly higher in OA subjects than controls. The pooled data show that cartilage deformation in medial compartment was significantly higher than the lateral compartment. The T₁ and T₂ relaxation times, contact area and cartilage deformation in OA subjects were higher than normal subjects. These results suggest that the structural degradation affects the load bearing capacity of the cartilage.

Onyi Irrechukwu¹, Sarah von-Thaer¹, Eliot Frank², David Reiter¹, Alan Grodzinsky², and Richard Spencer^1
1National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States, ²Massachusetts Institute of Technology, Cambridge, Massachusetts, United States

The objective of this study was to correlate the components and fractions determined from multiexponential analysis of cartilage transverse relaxation with tissue mechanical properties. Analysis was performed on bulk T2 relaxation data obtained from bovine nasal cartilage explants. Identical explants were mechanically tested in unconfined compression to determine matrix dynamic and equilibrium moduli. Four relaxation components, interpreted in terms of tissue water compartments, were detected in all explants. Compressive moduli were positively correlated with fractions representing macromolecules and negatively correlated with macromolecular component T2 values. This is consistent with increased stiffness resulting from increasing macromolecular concentration and decreasing water mobility.

Kathryn E Keenan^1,2, Thor Besier¹, R Lane Smith^1,2, Gary S Beaupre^1,2, and Garry E Gold^1
1Stanford University, Stanford, CA, United States, ²Bone & Joint RR&D Center, VAHCS, Palo Alto, CA, United States

Cartilage material properties have been related to MR parameters, but initial elastic modulus, which is useful in subject-specific finite element models of walking, has not been studied. Initial elastic modulus (E₀) of human patellar cartilage was regressed with T1 and T2 relaxation times. T1 did not individually correlate with E₀, nor did T2. However, sGAG and collagen were individually correlated with E₀. T1 was related to sGAG, while T2 was not related to collagen. T1 and T2 were significantly correlated in this study.

Delphine Périé^1,2, Maximilien Recuerda^1,3, Guillaume Gilbert⁴, and Gilles Beaudoin^5
1Mechanical Engineering, Ecole Polytechnique de Montréal, Montréal, Québec, Canada, ²Research Center, CHU Sainte-Justine, Montréal, Québec, Canada, ³Reserach Center, CHU Sainte-Justine, Montréal, Québec, Canada, ⁴Philips Healthcare, Montréal, Québec, Canada, ⁵Physics and Biomedical Engineering, CHUM Notre Dame, Montréal, Québec, Canada

We hypothesed that the compressive modulus and hydraulic permeability of the intervertebral disc can be explained by a combination of MRI parameters. Mechanical properties from unconfined compression tests, confined compression tests and direct measurements of permeability, and MRI properties from quantitative T1, T2, ADC, FA and MT acquisitions were evaluated on in-situ and digested bovine isolated discs. Relationships were found between axial or radial hydraulic permeability and quantitative MRI parameters. The changes induced by the trypsin treatment were detected by both mechanical tests and quantitative MRI. Thus the relationships found between permeability and MRI parameters are valid for both groups.

Hon J Yu¹, Shadfar Bahri¹, Lutfi Tugan Muftuler¹, Orhan Nalcioglu¹, and Vance Gardner^2
1Center for Functional Onco-Imaging, University of California, Irvine, CA, United States, ²Orthopaedic Education and Research Institute of Southern California, Orange, CA, United States

Measurements of apparent diffusion coefficient (ADC) and T1rho-relaxation time were investigated as a combined means for in-vivo assessment of the degenerative states in lumbar discs. Visual classification of disc degeneration based on morphological change such as Pfirrmann grades, currently only-accepted means to assess disc-degeneration in vivo, is fundamentally inadequate as a quantitative means for assessment of disc degeneration or for validating other quantitative measurements in correlation with disc degeneration. The results indicate a strong positive linear correlation between the ADC and T1rho-relaxation time values in association with disc degeneration, demonstrating the potential values of ADC and T1rho as a combined means for in-vivo assessment of disc-degeneration.

Delphine Périé^1,2, Yann-Guirec Manach¹, Guillaume Gilbert³, and Gilles Beaudoin^4
1Mechanical Engineering, Ecole Polytechnique de Montréal, Montréal, Québec, Canada, ²Research Center, CHU Sainte-Justine, Montréal, Québec, Canada, ³Philips Healthcare, Montréal, Québec, Canada, ⁴Physics and Biomedical Engineering, CHUM Notre Dame, Montréal, Québec, Canada

The present question focuses on the influence of mechanical loading during MRI acquisition on the relaxation times, magnetization transfer and diffusion parameters within the intervertebral disc. Quantitative MR measurements were carried out on isolated bovine discs submitted to 0%, 5%, 10%, 20% and 40% deformation. No significant differences were observed between the loading cases for all MR parmeters. Even if the disc conditions changed between the different MR sequences, loading and relaxation of disc tissues did not affect the MRI parameters. Quantitative MRI of isolated discs is not sensitive to the compressive state when changing from 0% to 40% deformation.

Chan Hong Moon¹, Jung-Hwan Kim¹, Xiang He¹, Tiejun Zhao², and Kyongtae Ty Bae^1
1Radiology, University of Pittsburgh, Pittsburgh, PA, United States, ²MR Research Support, Siemens Healthcare, Pittsburgh, PA, United States

We obtained consistent T2, T1rho, and sodium concentration in intervertebral discs from normal subjects using spin-lock, and ultra-short echo-time spiral sequence with a dual-tuned multi-channel RF torso coil at 3T human scanner. These MR-based measures of intervertebral discs may play an important role as imaging biomarkers for early diagnosis of degenerative disc disease..