Bone, Tendon & Menisci: State of the Art

Monday 22 April 2013

Yusuf A. Bhagat¹, Cheng Li¹, Shing Chun Benny Lam¹, Alan C. Seifert¹, Mahdieh Bashoor Zadeh¹, and Felix W. Wehrli^1
1Laboratory for Structural NMR Imaging, University of Pennsylvania, Philadelphia, PA, United States

The pore water fraction of cortical bone water is known to increase with age. Here, 3T-based ultra-short echo-time (UTE) MRI of the mid-diaphyseal tibia was used to evaluate the potential of the suppression ratio (SR, unsuppressed to soft-tissue suppressed UTE signal) as a surrogate parameter for porosity in 39 healthy women (24-81 years) and in 13 cortical bone specimens from human donors (27-97 years). SR was strongly associated with age and correlated with micro-CT-derived porosity. SR may serve as an in vivo biomarker of porosity in lieu of more involved methods such as bi-component T2* analysis.

Won C. Bae¹, Reni Biswas¹, Shantanu Patil², Christine Chung¹, Darryl D. D'Lima², Graeme M. Bydder³, and Jiang Du^1
1Radiology, University of California, San Diego, San Diego, CA, United States, ²Molecular and Experimental Medicine, Scripps Translational Science Institute, La Jolla, CA, United States, ³Radiology, University of California San Diego, San Diego, CA, United States

Bone water occurs at various locations and in different binding states, including water bound to organic matrix and free water residing in the microscopic pores of cortical bone. Cortical bone is typically regarded as “MR invisible” with conventional clinical MR sequences. In this study, we aimed to investigate bone water imaging with UTE and clinical FSE sequences, and to correlate the structure seen with FSE imaging with that seen with uCT imaging.

Silvia Capuani^1
1Physics Department, Sapienza University, Rome, Italy, Italy

A porous system model suitable to investigate the structural properties of the cancellous bone by using diffusion techniques is shown. To validate the model, the calcaneus and the femoral neck of healthy, osteopenic and osteoporotic subjects, as classified by the bone mineral density (BMD) were investigated by measuring the apparent diffusion coefficient (ADC), together with the marrow fat content (Mfc) and assessing associations between BMD, Mfc and ADC. In calcaneus cancellous bone, a microstructure deterioration with a pore enlargement due to osteoporosis, increases ADC. Diffusion assessment obtained in large populations, might increase our pathophysiological understanding of osteoporosis.

Dimitrios C. Karampinos^1,2, Gerd Melkus¹, Thomas Baum², Jan S. Bauer², Ernst J. Rummeny², and Roland Krug^1
1Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California, United States, ²Department of Diagnostic and Interventional Radiology, Technical University of Munich, Munich, Germany

Single-voxel MR spectroscopy has been the technique of choice for measuring fat content in localized bone marrow regions. However, there is a growing interest on applying quantitative water-fat imaging techniques to measure bone marrow fat content with high spatial resolution. Bone marrow fat content measurements in the presence of trabecular bone are hindered by strong susceptibility effects and short T₂*. The present study describes our preliminary findings in comparing bone marrow fat fraction measurements in the presence of trabecular bone using water-fat imaging and single-voxel MRS. A good agreement was found between the two techniques after accounting for the effect of short T₂* species.

Ja-Young Choi¹, Reni Biswas², Mike Im¹, Won C. Bae¹, Sheronda Statum¹, Eric Chang², Jiang Du², Graeme M. Bydder³, Darryl D. D'Lima⁴, and Christine Chung^2
1Radiology, UC San Diego Medical Center, San Diego, California, United States, ²Radiology, University of California, San Diego, San Diego, California, United States,³Radiology, University of California San Diego, San Diego, California, United States, ⁴Molecular and Experimental Medicine, Scripps Translational Science Institute, La Jolla, California, United States

In this study, variation of lamellar layer thickness in normal human menisci was evident on 2D UTE images, and femoral lamellar layers were found to be significantly thicker than tibial ones. Moreover, the thickness significantly correlated with surface indentation stiffness.

Jasper van Tiel^1,2, Esther Bron^1,3, Koen Bos², Stefan Klein^1,3, Max Reijman², Jan Verhaar², Gabriel Krestin¹, Harrie Weinans^2,4, Gyula Kotek¹, and Edwin Oei^1
1Radiology, Erasmus MC, Rotterdam, Zuid-Holland, Netherlands, ²Orthopedic Surgery, Erasmus MC, Rotterdam, Zuid-Holland, Netherlands, ³Medical Informatics, Erasmus MC, Rotterdam, Zuid-Holland, Netherlands, ⁴Biomechanical Engineering, Delft University of Technology, Delft, Zuid-Holland, Netherlands

We investigated the relation between delayed contrast-enhancement of an ionic contrast agent in the meniscus and adjacent cartilage in early stage knee osteoarthritis patients. We observed a moderate to strong relation between contrast uptake into both structures after a 1.5 hour delay. This finding is in agreement with the outcomes of previous research in which semi-quantitative whole joint assessment on MR images showed a relation between meniscal damage and cartilage loss. However, our results also raise a question about the specificity of delayed gadolinium-enhanced MRI of cartilage for sGAG content in (osteoarthritic) cartilage.

Yang Xia^1,2 and Nian Wang^1
1Physics, Oakland University, Rochester, Michigan, United States, ²Center for Biomedical Research, Oakland University, Rochester, Michigan, United States

To study the anisotropic characteristics of multi-component T1ρ and T2 relaxation times in tendon, T2 and T1ρ were measured by NMR spectroscopy at different orientations and by microscopic MRI at the magic angle. Up to three T2 and T1ρ components were resolved in tendon. Both the values and the fractions of T2 in tendon showed significant orientational dependence. T1ρ strongly depended on both the specimen orientation and the spin-lock strength. The imaging resolution (35 – 280 µm) had little influence in the T2 experiments. The transitions between mono- and multi-component result call for the caution in interpreting the relaxation results.

Daniel H. Cortes¹, Jeremy F. Magland², Alexander C. Wright², and Dawn M. Elliott^1
1Biomedical Engineering, University of Delaware, Newark, DE, United States, ²Radiology, University of Pennsylvania, Philadelphia, PA, United States

Intervertebral disc degeneration is characterized by a progressive cascade of biochemical and mechanical changes that affect its function. The structural changes characteristic of advanced degeneration are considered permanent due to the slow matrix turnover performed by disc cells. Therefore, early diagnosis of disc degeneration is critical for the success of any molecular or biological treatment. It is known that the shear modulus of the tissues in the disc changes significantly even for mild degeneration, and therefore it has potential for the diagnosis of early changes in the degeneration cascade. The objectives of the this study are: 1) to develop MRE methods to measure the shear modulus of the NP of intervertebral disc segments, 2) to quantify the effect of disc degeneration on the shear modulus measured using MRE, and 3) to compare the shear modulus to other MR-based biomarkers of disc degeneration.

Ephraim I. Ben-Abraham¹, Jun Chen¹, and Richard Leroy Ehman^1
1Mayo Clinic, Rochester, Minnesota, United States

Low back pain (LBP) is a very costly and prevalent health disorder in the U.S. One of the most common causes of LBP is degenerative disc disease (DDD). There are many techniques to characterize disc degeneration; however there is no way to directly assess the material properties of the intervertebral disc within the intact spine. Shear stiffness may be a more sensitive measure for DDD than current methods. In this study, we investigate the feasibility of using MRE to detect shear wave propagation in the intervertebral disc, and compare the experimental results with a finite element model of disc MRE.

L. Tugan Muftuler^1,2, Hon J. Yu³, Vance O. Gardner⁴, and Dennis J. Maiman^1
1Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States, ²Center for Imaging Research, Medical College of Wisconsin, Milwaukee, WI, United States, ³Department of Radiology, University of California, Irvine, CA, United States, ⁴Orthopaedic Education and Research Institute of Southern California, Orange, CA, United States

The IVD is avascular; nutrition is supplied via diffusion from the capillary beds of the cartilaginous vertebral body endplates. We are investigating perfusion characteristics in these capillary beds, disruption of which might cause poor nutrient delivery and lead to disc degeneration. We anticipated that the DCEMRI signal would be different in the endplate capillaries from those in bone marrow in adjacent vertebral bodies because of the different mechanisms of nutrient delivery to these two different systems. Our findings show slow wash-out in the endplates, which might be needed to maintain higher concentrations to sustain diffusion into the discs.