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Poster Sessions

TRADITIONAL POSTER

Give the Dog a Bone

Hall B Monday 14:00-16:00

784. Preliminary In-Vivo Bone Quantification Results Using MR and PQCT

Victor Rakesh Lazar¹, Gary P. Liney², David J. Manton¹, Peter Gibbs¹, Martin Lowry¹, Celia L. Gregson³, Joern Rittweger⁴, Sue Steel⁵, Chris Langton⁶, J H. Tobias³, Lindsay W. Turnbull<sup>1

1</sup>Centre for MR Investigations, University of Hull, Hull, North Humberside, United Kingdom; ²Radiotherapy Physics, University of Hull, Hull, North Humberside, United Kingdom; ³Academic Rheumatology, University of Bristol, Bristol, United Kingdom; ⁴Excercise and Sports Medicine, Manchester Metropolitan University, Manchester, United Kingdom; ⁵Centre for Metabolic Bone Disease, Hull Royal Infirmary, Hull, North Humberside, United Kingdom; ⁶School of Physical and Chemical Sciences, Queensland University of Technology, Australia

Bone quantification is commonly measured using DEXA and pQCT. Research in MRI and MRS have shown promising potential in the quantification of bones. Our work was based on using these ideas in a clinical setting on individual patients. The work was involved in a High Bone Mass (HBM) study program to identify individuals affected with a genetic condition of LRP–5. pQCT data was collected from 169 individuals from the HBM study. 43 people were selected for MRI and MRS acquisition from the total pQCT population. Preliminary results from these investigations have been explained in this abstract.

785. Software Tools for MR and PQCT Bone Quantification

Victor Rakesh Lazar¹, Gary P. Liney², David J. Manton¹, Peter Gibbs¹, Martin Lowry¹, Celia L. Gregson³, Joern Rittweger⁴, Sue Steel⁵, Chris Langton⁶, J H. Tobias³, Lindsay W. Turnbull<sup>1

1</sup>Centre for MR Investigations, University of Hull, Hull, North Humberside, United Kingdom; ²Radiotherapy Physics, University of Hull, Hull, North Humberside, United Kingdom; ³Academic Rheumatology, University of Bristol, Bristol, United Kingdom; ⁴Excercise and Sports Medicine, Manchester Metropolitan University, Manchester, United Kingdom; ⁵Centre for Metabolic Bone Disease, Hull Royal Infirmary, Hull, United Kingdom; ⁶School of Physical and Chemical Sciences, Queensland University of Technology, Australia

Peripheral Quantitative Computed Tomography (pQCT) and Dual Energy X-Ray Absorptiometry (DEXA) are the current gold standards for the measurement of bone density and structure, in the research and clinical setting respectively. However, Magnetic Resonance Imaging (MRI) and unsuppressed 1H Magnetic Resonance Spectroscopy (MRS) can also offer several advantages including the ability to quantify bone marrow content and structure. In-house software was developed to process and evaluate cortical and trabecular bone structure, marrow composition and vertebrae segmentation using data from MRI/MRS and structural details from pQCT.

786. Characterization of Bone Explants by Magnetic Resonance Microscopy

Ingrid E. Chesnick¹, Carol B. Fowler¹, Francis A. Avallone², Kimberlee Potter<sup>1

1</sup>Department of Biophysics, Armed Forces Institute of Pathology Annex, Rockville, MD, United States; ²Department of Genitourinary Pathology, Armed Forces Institute of Pathology, Washington, DC, United States

MRI studies of tissue engineered constructs prior to implantation clearly demonstrate the utility of the MRI technique for monitoring the bone formation process. However, in our studies of osteoblast-seeded scaffolds, implanted on the chorioallantoic membrane of a chick embryo, we have found that the presence of angiogenic vessels and fibrous tissue around the implant can confound MRI findings of bone deposition. On-going studies support the use of targeted contrast agents for studying mineral deposition and blood vessel infiltration in tissue engineered scaffolds post-implantation.

787. Performance of 7T µMRI-Based Virtual Bone Biopsy for Structural and Mechanical Analysis at the Distal Tibia

Yusuf Abu Tayeb Bhagat¹, Chamith S. Rajapakse¹, James H. Love¹, Michael J. Wald¹, Jeremy F. Magland¹, Alexander C. Wright¹, Hee Kwon Song¹, Felix W. Wehrli<sup>1

1</sup>Laboratory for Structural NMR Imaging, University of Pennsylvania, Philadelphia, PA, United States

The detection of subtle microstructural trabecular bone (TB) alterations such as the conversion of plates to rods requires adequate signal-to-noise ratio (SNR), which governs achievable spatial resolution and scan time. Increased SNR may enhance detection sensitivity for microstructural changes in treatment studies. Here, the reproducibility of TB quantitative parameters was investigated using a new 3D fast-spin-echo technique at 7.0T. The imaging and analysis protocol is shown to provide highly reproducible measures of scale, topology and mechanical parameters related to TB microstructure. Performance improvements relative to earlier work are attributed to enhanced SNR, motion control and correction, and improved registration techniques.

788. Studying the Effect of Different Biomaterials on Healing Process in Bone Injury Model Using Microscopic MRI and Micro CT

May Abdel Hamid Taha¹, Sarah L. Manske², Erika Kristensen³, Jaymi T. Taiani⁴, Roman Krawetz⁵, Ying Wu, Steven K. Boyd⁶, John Robert Matyas⁷, Derrick E. Rancourt⁵, Jeffery F. Dunn<sup>1

1</sup>Radiology, University of Calgary, Calgary, Alberta, Canada; ²Kinesiology; ³Mechanical and Manufacturing Engineering; ⁴ Medical Sciences; ⁵Departments of Oncology, Biochemistry & Molecular Biology and Medical Genetics; ⁶Mechanical and Manufacturing Engineering; ⁷Comparative Biology and Experimental Medicine in Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada

The objective of this study was to investigate the effect of different biomaterials on bone healing in vivo in a mouse model of bone injury. These materials; matrigel, purecol gel and hydroxyapatite (HA) are potential matrices to support stem cells. Optimized in vivo MR microscopy and micro computed tomography were used to assess fracture repair. In addition, MRI images and µCT scans were compared at the same time point, to show the difference between them in revealing the actual stage of healing.

789. Traditional Bone Structural Parameters on Different Resolutions in Magnetic Resonance Imaging

June-Goo Lee^1,2, Gyunggoo Cho¹, Youngkyu Song¹, Jong Hyo Kim², Namkug Kim<sup>3

1</sup>Division of Proteome Research/Bio-Magnetic Resonance Research Center, Korea Basic Science Institute, Cheongwon-Gun, Chungcheongbuk-Do, Korea, Republic of; ²Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea, Republic of; ³Department of Radiology, Asan Medical Center, University of Ulsan, Seoul, Korea, Republic of

Our study focused on the development of robust image processing algorithm on low resolution μ-MR bone image

790. Advanced Image Analysis Techniques of New High-Resolution Images of the Proximal Femur in the Presence of Red and Yellow Bone Marrow Using Local Bone Enhancement Fuzzy Clustering

Jenny Folkesson¹, Julio Carballido-Gamio¹, Dimitrios C. Karampinos¹, Patrick Koon², Suchandrima Banerjee², Eric Han², Thomas M. Link¹, Sharmila Majumdar¹, Roland Krug<sup>1

1</sup>Radiology and Biomedical Imaging, University of California, San Francisco, CA, United States; ²Applied Science Laboratory, GE Heathcare, Menlo Park, CA, United States

With the advent of new MR hardware and pulse sequences it is now possible to image the small trabecular structure of deeper seated regions like the proximal femur with high spatial resolution in a clinically feasible scan time. We employ a novel partial membership bone segmentation technique (BE-FCM) technique that enhances bone segmentation compared to an established dual thresholding method in the presence of signal variations due to different marrow types. We demonstrate that the new image acquisition and analysis framework enables trabecular bone analysis in the deeply situated femoral head, something which has been previously unfeasible in vivo.

791. Bone Marrow Fat Fraction Mapping in the Proximal Femur in Vivo Using IDEAL Gradient Echo Imaging

Dimitrios C. Karampinos¹, Huanzhou Yu², Ann Shimakawa², Eric T. Han², Thomas M. Link¹, Sharmila Majumdar¹, Roland Krug<sup>1

1</sup>Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States; ²Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States

There is some evidence that osteoporosis is associated with increased marrow fat content as well as an accelerated conversion from red marrow to yellow (fatty) marrow with age. In this work, we investigated the marrow fat composition in the proximal femur in vivo using IDEAL gradient echo imaging. 3-point IDEAL FGRE hip images of six healthy subjects were acquired and water-fat separation was performed using multi-peak IDEAL. The average fat fraction and standard deviation were determined in three different regions of interest (femoral head, greater trochanter and neck). Significant differences in marrow fat content were identified between the three regions for all subjects.

792. 1H MRS to Detect Biochemical Degenaration of the Vertebral Bone Marrow in Gaucher Disease

Simona Ortori¹, Michela Tosetti², Marzio Perri³, Margherita Marchetti¹, Gabriele Caproni¹, Laura Biagi², Mirco Cosottini⁴, Virna Zampa¹, Giuliano Mariani³, Carlo Bartolozzi<sup>1

1</sup>Divisione di Radiologia Diagnostica ed Interventistica, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy; ²MR Laboratory, Stella Maris Scientific Institute, Pisa, Italy; ³Divisione di Medicina Nucleare, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy; ⁴Dipartimento di Neuroscienze, Università di Pisa, Pisa, Italy

Gaucher disease is the most prevalent inherited, lysosomial storage disease and results in a deficient level of activity of β-glucocerebrosidase, a membrane-bound lysosomal enzyme. This deficiency leads to accumulation of the lipid glucocerebroside in the lysosomes of monocytes and macrophages, called Gaucher cells. The symptoms and pathology of Gaucher disease result from the accumulation of Gaucher cells in various organ system, including vertebral bodies. To evaluate the biochemical process underlying the infiltration of Gaucher cells, 1H-MRS has been acquired on vertebral bone marrow in patients affected by Gaucher disease, highlighting a significant reduction of fat content of any age range

793. Characterization of Trabecular Orientation in Chicken Femur by Multi-Directional SPENT (Sub-Pixel Enhancement of Non-Uniform Tissue)

Bailiang Chen¹, Bernard Siow², David Carmichael^1,3, Freddy Odille², Roger Ordidge¹, Andrew Todd-Pokropek<sup>1

1</sup>Medical Physics and Bioengineering, University College London, London, United Kingdom; ²Centre for Medical Image Computing, University College London, London, United Kingdom; ³Institute of Neurology , University College London, London, United Kingdom

The recently proposed SPENT sequence can provide direction specific information based on the sub-voxel structural uniformity of a sample. Analogous to diffusion tensor imaging, given a voxel with a local anisotropic structure (e.g. trabecular bone), it is possible to characterize the orientation of sub-pixel micro-structure by applying SPENT with multiple directions. A 6-direction SPENT series was applied to a chicken femur head in order to characterize its trabecular bone orientation by reconstructing a 2D tensor in each voxel. Both tensor statistics and eigensystems were computed and showed good qualitative agreement with data from a subsequent micro-CT acquisitions.

794. The Effect of Freezing on Measurements of Trabecular Bone Structure Based on NMR Spectroscopy

Viktoria Prantner¹, Hanna Isaksson¹, Johanna Närväinen², Eveliina Lammentausta³, Olli HJ Gröhn^2,4, Jukka S. Jurvelin<sup>1

1</sup>Department of Physics, University of Kuopio, Kuopio, Finland; ²A.I. Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland; ³Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland; ⁴Biomedical Imaging Unit, University of Kuopio, Kuopio, Finland

NMR is a potential tool for the assessment of trabecular bone structure. Since trabecular bone provides a negligible NMR signal, the indirect evaluation of the trabecular bone structure is based on the analysis of water and fat components in the bone marrow. Earlier studies have revealed that freezing affects the bone marrow structure, suggesting there may be changes in the molecular structure. The aim of the current study is to investigate the effect of freezing on trabecular bone and bone marrow, as assessed by NMR spectroscopy.

795. Performance of Two Spin-Echo Sequences for Quantitative Structure Analysis of Trabecular Bone

Michael Jeffrey Wald¹, Jeremy Francis Magland¹, X. Edward Guo², Felix Werner Wehrli<sup>1

1</sup>Laboratory for Structural NMR Imaging, University of Pennsylvania Medical Center, Philadelphia, PA, United States; ²Bone Bioengineering Laboratory, Columbia University, New York, United States

The performance of two spin-echo based pulse sequences for imaging trabecular bone microstructure are evaluated at 1.5T in seven fixed, cadaveric distal tibia specimens. SNR efficiency and sensitivity of image-derived trabecular bone structural parameters to variations in bone quality as assessed by µCT were investigated. Inter- pulse sequence correlations suggest similar structural sensitivity, while comparisons to µCT reveal good sensitivity but large deviations in absolute values between modalities.

796. Ultra-Short TE (UTE) Imaging of Skull and a Quantitative Comparison of Skull Images Obtained from MRI and CT

Liya Wang¹, Xiaodong Zhong², Longjiang Zhang³, Diana Tiwari¹, Hui Mao<sup>1

1</sup>Department of Radiology and Emory Center for Systems Imaging, Emory University School of Medicine, Atlanta, GA, United States; ²MR R&D Collaborations, Siemens healthcare, Atlanta, GA, United States; ³Department of Radiology, Jinlin Hospital and Nanjing University College of Clinical Medicine, Nanjing, Jiangsu, China

This study provided a quantitative evaluation of skull images obtained using UTE MRI and a direct comparison to those from CT. The skull thickness measured from UTE images showed good agreement with those obtained from CT images in different slices. There is also a good correlation between the thickness measurements obtained from CT and UTE images. Signal intensity based evaluation showed that there is no statistical difference between UTE and CT images in outer, inner layer and diploe of the skull. The comparison of bone UTE MRI and CT of skull suggests that UTE images match closely with CT images.

797. MR Imaging Detects Impaired Angiogenesis and Trabecular Bone Formation During Endochondral Bone Growth Mediated Through PKBalpha/Akt1 in Gene Dosage Dependent Manner

Katrien Vandoorne¹, Jeremy Magland², Vicki Plaks¹, Inbal E. Biton³, Amnon Sharir^4,5, Elazar Zelzer⁴, Felix Wehrli⁶, Brian A. Hemmings⁷, Alon Harmelin³, Michal Neeman<sup>1

1</sup>Biological Regulation, Weizmann Institute, Rehovot, Israel; ²Department of Radiology, University of Pennsylvania Health System, Philadelphia, PA, United States; ³Veterinary Resources, Weizmann Institute, Rehovot, Israel; ⁴Molecular Genetics, Weizmann Institute, Rehovot, Israel; ⁵The Laboratory of Musculoskeletal Biomechanics and Applied Anatomy, Koret School of Veterinary Medi, Hebrew University of Jerusalem, Rehovot, Israel; ⁶Department of Radiology, University of Pennsylvania Health System, Philadelphia, PA, Israel; ⁷Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland

Since infiltration of the newly formed blood vessels is required for endochondral bone formation, and PKBalpha/Akt1 mediates intracellular signaling of angiogenesis, we postulated that a vascular deficiency at the site of the long bones could contribute indirectly to impaired bone development in PKBalpha/Akt1 deficient mice. Our study demonstrated using macromolecular DCE-MRI in vivo and ex vivo µCT and µMRI, vascular and bone developmental defects in PKBalpha/Akt1 null mice, and remarkably also in heterozygous mice, lacking a single copy of the gene.

798. Water and Fat Suppressed Proton Projection MRI (WASPI) Study on Bone Specimens After Proton-Deuteron Exchange

Haihui Cao^1,2, Jerome L. Ackerman, ^2,3, Guangping Dai, ^2,3, Mirko Hrovat⁴, Melvin J. Glimcher, ^2,5, Yaotang Wu, <sup>2,5

1</sup>Department of Orthopedic Surgery, Children's Hospital , Boston, MA, United States; ²Harvard Medical School, Boston, MA, United States; ³Department of Radiology, Massachusetts General Hospital, Boston, MA, United States; ⁴Mirtech, Inc, Brockton, MA, United States; ⁵Department of Orthopedic Surgery, Children's Hospital, Boston, MA, United States

Questions have arisen as to the nature of the molecular species giving rise to the short-T2 proton signal in Water- and fat-suppressed proton projection MRI (WASPI), a noninvasive means to image bone. In this study we use deuterium exchange to identify the source of proton signal in WASPI.

799. Quantification of Bound and Mobile Water in Human Cortical Bone by 1H and 2H Magnetic Resonance

Henry H. Ong¹, Alexander C. Wright¹, Felix W. Wehrli<sup>1

1</sup>Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, PA, United States

Magnetic resonance is a powerful tool for non-destructive study of bone water, which can provide insight into bone micro- and nanostructure. However, the MR signal of bone is comprised of several proton populations including collagen-associated water, and water within the pore space (Haversian and lacuno-canalicular system). We hypothesize that water in pores is predominantly free and water in the bone matrix is predominantly associated with collagen. Using 2H exchange and inversion recovery experiments, we estimated porosity in human cortical bone and found it to agree with micro-CT based volumetric measurements with a significant fraction being collagen-associated.

800. MR Spin Behavior During RF Pulses: T2 Vs. T2' Relaxation

Michael Carl¹, Nikolaus Szeverenyi², Mark Bydder², Eric Han¹, Graeme Bydder<sup>2

1</sup>GE Healthcare, Waukesha, WI, United States; ²University of California, San Diego

We investigated the behavior of the MR magnetization vector during RF pulses in the presence of rapid transverse relaxation caused by either amplitude loss or spin dephasing. We found that different tissues with the same T2* may generate different responses to RF pulses, dependent on whether the relaxation is dominated by a homogeneously or inhomogeneously broadened linewidth and RF optimization may hence require explicit knowledge of the intrinsic T2 and T2* of the tissue.

801. Multi-Modality Imaging of Bone Marrow Edema-Like Lesions and Associated Cartilage in Osteoarthritic Patients

Daniel Kuo¹, Joseph Schooler¹, Janet Goldenstein¹, Sarmad Siddiqui¹, Swetha Shanbhag¹, Jean-Baptiste Pialat¹, Andrew Burghardt¹, Sharmila Majumdar¹, Michael Ries², Galateia Kazakia¹, Xiaojuan Li<sup>1

1</sup>Musculoskeletal Quantitative Imaging Research (MQIR), Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States; ²Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, United States

Osteoarthritis (OA) is a complex disease that affects both cartilage and bone. Bone marrow edema-like lesions (BMEL) are important in studying OA, but knowledge about them is limited. In this study, we take a multi-modality imaging approach, examining MR T1ñ and T2 values of BMEL-associated cartilage plus structure and composition of BMEL tissue using high resolution peripheral quantitative computed tomography (HR-pQCT) imaging and Fourier transform infrared (FTIR) spectroscopy. Our results indicate that regions of BMEL are associated with more advanced cartilage degeneration and that there is a localized imbalance in bone formation and mineralization specific to BMEL regions.

802. Perfusion Abnormalities of Bone Marrow Edema-Like Lesions in Knees with Anterior Cruciate Ligament Injury Using Dynamic Contrast-Enhanced MRI

Jin Zuo¹, Sharmila Majumdar¹, Xiaojuan Li<sup>1

1</sup>Radiology and Biomedical Imaging, Univ. of California, San Francisco, San Francisco, CA, United States

Anterior cruciate ligament (ACL) tear is a common knee injury, and is a risk factor of post-traumatic osteoarthritis (OA). The disease is frequently associated with bone marrow edema-like (BMEL) lesions which exhibit as an area of high signal intensity in T2-weighted, fat-saturated fast spin echo MR images. BMEL is also commonly seen in OA and has been associated with disease progression and pain in OA. However, the knowledge on the pathophyisiology and significance of BMEL in ACL-injured knees is very limited. Dynamic contrast enhanced MRI (DCE-MRI) can probe bone marrow and subchondral bone perfusion as well as fluid dynamics. Impaired perfusion in bone may lead to cartilage degeneration. A recent study showed bone marrow abnormalities were associated with BME in OA. The aim of this study is to apply DCE MRI to evaluate bone marrow perfusion in patients with ACL tears, and to compare the perfusion patterns between BMEL region and normal appearing bone marrow region.

803. The Influence of Running on Patellar Water Content and Bone Marrow Edema in Females with and Without Patellofemoral Pain

Kai-Yu Ho¹, Houchun H. Hu², Krishna S. Nayak², Patrick M. Colletti³, Christopher M. Powers<sup>1

1</sup>Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, United States; ²Department of Electrical Engineering, University of Southern California, Los Angeles, CA, United States; ³Department of Radiology, University of Southern California, Los Angeles, CA, United States

The purpose of this study was to investigate the influence of running on patellar water content and bone marrow edema (BME) in individuals with and without patellofemoral pain (PFP). Using the IDEAL protocol, two subjects with PFP and 2 pain-free controls were evaluated. Each subject underwent a pre-running MR scan, a 40-min moderate effort running, and a post-running MR scan. Our data showed that in persons with PFP, content and volume of local BME increases post-running. Additionally, the PFP subjects demonstrated increased water content of the bone marrow region post-running while the controls showed no changes in water content.

804. Using ¹⁸F NaF PET/CT to Image Increased Bone Activity in Patellofemoral Pain: Correlation with MRI

Christine Elizabeth Draper¹, Michael Fredericson¹, Thor F. Besier¹, Gary S. Beaupre², Scott L. Delp¹, Andrew Quon¹, Garry E. Gold<sup>1

1</sup>Stanford University, Stanford, CA, United States; ²VA Palo Alto Health Care System, Palo Alto, CA, United States

Articular cartilage deterioration is associated with the development of osteoarthritis. Cartilage health depends upon the integrity of the underlying subchondral bone and there may be abnormalities in bone metabolic activity that accompany structural defects in bone and cartilage. 18F NaF PET/CT enables bone metabolic activity to be visualized. We compared metabolic abnormalities detected using PET/CT with structural defects seen using MRI. We found that regions of increased bone metabolic activity do not always correlate with cartilage damage or bone marrow edema, indicating that 18F NaF PET/CT may image bone abnormalities prior to the development of structural damage seen using MRI.

805. Improved Fat-Suppression for Unspoiled GRASS Imaging of the Knee Using Multi-Peak IDEAL Chemical Shift Fat-Water Separation

Richard Kijowski¹, Catherine Debra Hines², Huanzhou Yu³, Scott Brian Reeder<sup>1,2

1</sup>Radiology, University of Wisconsin, Madison, WI, United States; ²Medical Physics, University of Wisconsin, Madison, WI, United States; ³GE Healthcare, Applied Science Laboratory, Menlo Park, CA, United States

This study was performed to demonstrate improvements in the quality of fat-suppression for unspoiled GRASS imaging of the knee using multi-peak fat spectral modeling and IDEAL fat-water separation. An IDEAL-GRASS sequence was performed at 3.0T on the knees of 10 asymptomatic volunteers. The IDEAL-GRASS images were reconstructed using a single-peak method and a multi-peak method that more accurately models the NMR spectrum of fat. Multi-peak IDEAL-GRASS had significantly greater (p<0.001) suppression of bone marrow signal and significantly higher (p<0.001) CNR between cartilage and bone marrow than single-peak IDEAL-GRASS.

806. Tissue Repair Differentiation Using T2 Multicomponents: Investigation in Tissue-Engineered Bone Regeneration

Marine Beaumont¹, Marc G. DuVal², Yasir Loai³, Walid A. Farhat³, George K. Sándor², Hai-Ling Margaret Cheng<sup>1,4

1</sup>The Research Institute and Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada; ²Department of Oral and Maxillofacial Surgery, University of Toronto, Toronto, Ontario, Canada; ³Division of Urology, The Hospital for Sick Children, Toronto, Ontario, Canada; ⁴Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada

Tissue repair plays a key role in successful tissue regeneration and involves various simultaneous processes. In bone regeneration, bone growth in a defect occurs only in the absence of early fibrous scar formation or collapse of surrounding tissues into the defect. In this study, a tissue-engineered construct is inserted into a defect in the rabbit calvarium to provide a 3-dimensional resorbable scaffold that maintains a space for bone growth. Multicomponent T2 measurements are performed to characterize and differentiate tissue repair from normal construct resorption.