Traditional Posters : Musculoskeletal Imaging
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Articular Cartilage: Quantitative & MRI Analysis

 
Monday May 9th
Exhibition Hall  14:00 - 16:00

1098.   T1 quantification in the cartilage of the knee with a modified IR-FSE technique  
Gyula Kotek1, Marcel J.B. Warntjes2, Piotr Wielopolski1, Jasper van Tiel3, Edwin Oei1, and Gabriel P. Krestin1
1Radiology, Erasmus MC, Rotterdam, Netherlands, 2Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden, 3Orthopedics/Radiology, Erasmus MC, Rotterdam, Netherlands

 
T1 mapping in the cartilage offers a valuable diagnostic tool in degenerative disease of the cartilage. Three dimensional Inversion Recovery Fast Spoiled Gradient Echo (IR-FSPGR) is widely accepted protocol for T1 mapping of the cartilage. In our study we investigated the feasibility and quality of an alternative acquisition technique that is based on 2D Inversion Recovery Fast Spin Echo (IR-FSE).The proposed sequence is a modified version of IR-FSE, where inversion and acquisition is consecutively performed on different slices without Inversion Time (TI) delay.

 
1099.   Consistency of T1lower case Greek rho Measurements: A Phantom Study 
Daniel Ross Thedens1, Noelle F Klocke2, James A Martin2, Thomas E Baer2, and Douglas R Pedersen2
1Radiology, University of Iowa, Iowa City, IA, United States, 2Orthopaedics and Rehabilitation, University of Iowa

 
The purpose of this study was to assess the consistency of T1ρ measurements across multiple acquisition platforms in a phantom study. The phantom consisted of five gels of varying agarose concentration yielding T1ρ relaxation times similar to cartilage. T1ρ measurements were compared from four combinations of scanner and coil, yielding consistent measurements across all platforms and demonstrating the usefulness of the phantom as a validation and quality assurance tool.

 
1100.   Repeatability of Multi-component T2* Mapping on Human Knee Cartilages at 3T 
Yongxian Qian1, Ashley A Williams2, Constance R. Chu2, and Fernando E. Boada1
1Radiology, University of Pittsburgh, Pittsburgh, PA, United States, 2Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States

 
Multi-component T2* relaxations have been observed in human knee cartilages with ultrashort echo time (UTE) acquisitions (min TE=0.6ms), which have potential to reflect disorganization of collagen fibers in early-stage degenerative cartilages. This work demonstrates the repeatability of in vivo multi-component T2* mapping via healthy subject scans on a 3T MRI scanner.

 
1101.   Reproducibility of Magnetic Resonance T1lower case Greek rho and T2 Relaxation Time and Morphological Measurements of Articular Hip Cartilage at 3T 
Alexander Balcar Dillon1, Gabby Blumenkrantz Joseph1, Xiaojuan Li1, Thomas M Link1, and Sharmila Majumdar1
1Radiology and Biomedical Imaging, UCSF, San Francisco, California, United States

 
We evaluated the reproducibility of cartilage thickness, volume, T1lower case Greek rho and T2 relaxation times, and alpha angle measurements in the hip joint using magnetic resonance (MR) imaging at 3 T. The coefficients of variation for these measurements ranged from 0.3-4.7%, indicating their high level of intra-observer reproducibility and the feasibility of monitoring the morphology and biochemical composition (via relaxometry) of articular hip cartilage with these MR techniques.

 
1102.   Texture Analysis of T1ρ Relaxation Times in Knee Osteoarthritis 
Joseph Alan Schooler1, Samuel Paran Yap1, Gabby Blumenkrantz Joseph1, Xiaojuan Li1, Thomas M Link1, and Sharmila Majumdar1
1Musculoskeletal and Quantitative Imaging Research, Department of Radiology and Biomedical Imaging, UCSF, San Francisco, CA, United States

 
Analysis of spatial distribution of T1rho quantitative MR using the gray-level co-occurrence matrix in human articular knee cartilage of knee osteoarthritis patients compared to normal controls.

 
1103.   T1rho MRI of Menisci and Cartilage in Osteoarthritic Patients at 3T 
Ligong Wang1, Gregory Chang1, Jian Xu2, Renata L.R. Vieira1, Svetlana Krasnokutsky3, Steven Abramson3, Michael P. Recht1, and Ravinder R. Regatte1
1Radiology, NYU Langone Medical Center, New York, New York, United States, 2Siemens HealthCare, New York, New York, United States, 3Division of Rheumatology, NYU Langone Medical Center, New York, New York, United States

 
The purpose of this study was to assess T1rho values of cartilage and menisci in patients with osteoarthritis (OA) at 3T. Subjects with varying degrees of OA (K-L Score = 1-4, n = 30) were scanned. Statistically significant differences (P < 0.05) were identified between cartilage T1rho values of moderate-severe OA subjects in the lateral femoral anterior sub-compartment and doubtful-minimal OA subjects in the lateral and medial compartments. There were statistically significant differences in meniscus T1rho values of the medial posterior sub-region of subjects with moderate-severe OA and all sub-regions in the lateral and medial compartments of subjects with doubtful-minimal OA. Meniscus and cartilage T1rho values correlate with conventional MR findings of different degrees of degeneration.

 
1104.   T1lower case Greek rho MRI QUANTIFICATION OF ARTHROSCOPICALLY CONFIRMED CARTILAGE FOCAL LESIONS IN KNEES WITH ACUTE ACL INJURIES 
Riti Gupta1, Daniel Kuo2, Warapat Virayavanich2, Benjamin Ma3, and Xiaojuan Li2
1University of California, Berkeley, Berkeley, CA, United States, 2Radiology and Biomedical Imaging, UCSF, San Francisco, CA, United States, 3Orthopedic Surgery, UCSF, San Francisco, CA, United States

 
Knees with anterior cruciate ligament (ACL) tears have a high risk of developing post-traumatic OA. Quantitative MRI T1lower case Greek rho mapping has been suggested as a promising tool to detect early biochemical changes in cartilage matrix during degeneration. Although many studies in literature show that T1lower case Greek rho could potentially detect cartilage degeneration non-invasively, few studies have correlated quantitative MRI measures with clinical evaluation of cartilage degeneration using arthroscopy. The purpose of this study was to evaluate the capability of MR T1lower case Greek rho to detect cartilage lesions as evaluated by arthroscopy in acutely ACL-injured knees, and to compare with WORMS scoring using clinical standard MRI.

 
1105.   T1lower case Greek rho imaging of articular cartilage after implantation of tibial fracture plate 
Matthew Fenty1, Anup Singh1, Samir Mehta2, Jaimo Ahn2, and Ravinder Reddy1
1CMROI, Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Division of Orthopaedic Trauma and Fracture Surgery, Department of Orthopaedic Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA, United States

 
With traumatic tibial plateau fractures, the integrity of the cartilage may become compromised due to several factors such as vascular damage via fractures to the subchondral bone, abnormal loading conditions, and mechanical blunt force trauma to the cartilage matrix. However, with the insertion of metallic fixation plates, the ability to visualize soft tissue within the affected joint is severely diminished. The objective of this study is to develop a T1lower case Greek rho MRI protocol with B0 distortion compensation to accurately quantify biochemical properties of the articular cartilage post-fixation of the tibia via metallic implant.

 
1106.   A Fractional-Order Model for T2 Relaxation in Normal and Degraded Cartilage 
David A Reiter1, Richard L. Magin2, Weiguo Li2, Maria Pilar Velasco3, Juan Trujillo4, and Richard G. Spencer1
1NIH/NIA, Baltimore, MD, United States, 2University of Illinois at Chicago, 3Universidad Complutense de Madrid, 4Universidad de La Laguna

 
We previously derived a fractional-order relaxation model through incorporating a memory kernel into the Bloch equations. This leads to transverse relaxation decay according to a stretched-exponential (Str-Exp) function. We apply this to cartilage degeneration by fitting Str-Exp functions to decay curves from normal and enzymatically degraded cartilage. We find that the fractional-order parameter, á, is sensitive to, and increases with, proteoglycan loss. We interpret this in terms of a reduction in microstructural tissue complexity. In contrast to multiexponential analysis, Str-Exp fits describe cartilage degradation using a single parameter and may be of particular utility in the setting of limited SNR.

 
1107.   Mapping Cartilage Degradation through Support Vector Machine Probabilistic Classification 
Ping-Chang Lin1, Onyi Irrechukwu1, and Richard G Spencer1
1National Institute on Aging, National Institutes of Health, Baltimore, MD, United States

 
A major limitation of MRI approaches for detection of early osteoarthritis is that individual MRI parameters exhibit substantial overlap between different stages of degradation. To overcome this, we are developing support vector machine (SVM)-based fuzzy classification. We present results obtained on bovine nasal cartilage subjected to pathomimetic enzymatic degradation. SVM analysis was performed on combinations of the parameter set {T1, T2, km, ADC}. Probabilistic maps resulting from the classification procedure represent maps of degradation, with values ranging from zero to unity for assignment to non-degraded status. These maps provide a substantial improvement over univariate MR maps for defining cartilage degradation.

 
1108.   Multi-parametric MRI assessment of articular cartilage degeneration 
Elli-Noora Salo1, Mikko J. Nissi1, Timo Liimatainen2, Olli Gröhn3, Silvia Mangia4, Shalom Michaeli4, Jutta Ellermann4, and Miika T. Nieminen5,6
1Department of Physics and Mathematics, University of Eastern Finland, Kuopio, Finland, 2Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Medicine, University of Eastern Finland, Kuopio, Finland, 3Department of Neurobiology, A.I. Virtanen Institute for Molecular Medicine, University of Eastern Finland, Kuopio, Finland, 4Center for Magnetic Resonance Research, University of Minnesota, MN, United States, 5Department of Medical Technology, University of Oulu, Oulu, Finland, 6Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland

 
In the present study, numerous parameters (T1, T2, dGEMRIC, continuous wave T1lower case Greek rho, adiabatic T1lower case Greek rho, adiabatic T2lower case Greek rho, Relaxation Along a Fictitious Field (RAFF) and Magnetization Transfer Ratio (MTR)) were measured in constituent-specific enzymatic treatment models of bovine cartilage as well as in human articular cartilage of varying degree of degeneration. Marked differences are revealed in the sensitivity of various MRI parameters to specific tissue constituents. Particularly, novel rotating-frame techniques may sensitively detect changes in the status of cartilage.

Traditional Posters : Musculoskeletal Imaging
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Ultrashort TE: MSK Applications

 
Tuesday May 10th
Exhibition Hall  13:30 - 15:30

1109.   Bi-component analysis of UTE images: a feasibility study 
Jiang Du1, Eric Diaz1, Michael Carl2, Won Bae1, Christine Chung1, and Graeme Bydder1
1Radiology, University of California, San Diego, San Diego, California, United States, 2GE Healthcare, United States

 
Biological tissues commonly contain distinct water compartments and display multiple T2 relaxation behavior. Current standard techniques are based on multi-component fitting of multiple spin-echo images acquired with CPMG sequences. There are a group of tissues such as menisci, ligaments, tendons and cortical bone which show little or no signal with clinical CPMG or gradient echo sequences. Both free water and water bound to the collagen fibers are typically ‘invisible’. Here we propose a bi-component T2* analysis of images acquired with an ultrashort TE (UTE) sequence with a minimum TE of 8 us to quantify the free and bound water components.

 
1110.   Inverted Double Half RF Pulses: Improved Selective Excitation of Short T2 Components in 3T Joint Imaging 
Habib Al saleh1, Kevin Johnson1, Richard Kijowski2, and Walter F Block1,3
1Medical Physics, University of Wisconsin, School of Medicine & Public Health, Madison, WI, United States, 2Radiology, University of Wisconsin, School of Medicine & Public Health, Madison, WI, United States, 3Biomedical Engineering, University of Wisconsin, Madison, WI, United States

 
Ultra-short TE exhibits a great promise for imaging short T2 species in bone, tendon, ligament and cartilage. However, a considerable effort is spent for suppression of fat and long T2 components to enhance the contrast of short T2 species. An Inverted double half RF is presented for improved suppression of fat and long T2 species at 3T. Application of this method at 3T for musculoskeletal imaging showed promising results.

 
1111.   Comparison of UTE ratios based on magnetization transfer and T2 for quantification of Achilles tendinopathy 
Richard J Hodgson1, Peter Wright2, Andrew J Grainger2, Phillip O'Connor2, Dennis McGonagle3, Phillip Helliwell3, Paul Emery3, and Matthew D Robson4
1LMBRU, University of Leeds, Leeds, Yorkshire, United Kingdom, 2Leeds Teaching Hospitals NHS Trust, 3University of Leeds, 4University of Oxford

 
Ultrashort echo time imaging allows measurement of magnetization transfer ratios and simple ratios of signal intensity which depend on T2. The Achilles tendons of 11 patients with tendinopathy and 13 healthy volunteers were imaged with UTE 140/0.07/30 imaging with and without a MT prepulse, and a similar sequence with an effective echo time of 2ms. MTR and the ratio of the TE=2ms to UTE images were calculated for the Achilles tendon. The T2 dependent ratio was significantly greater in spondyloarthritis patients but the MTR was not. T2-dependent ratios are therefore likely to be better measures of tendinopathy than the MTR.

 
1112.   Dipolar Anisotropy Fiber Imaging Reveals Structure in a Meniscus Specimen 
Nikolaus M. Szeverenyi1, Won C. Bae1, and Graeme M. Bydder1
1Radiology, University of California, San Diego, San Diego, CA, United States

 
We describe a method which exploits unaveraged dipolar effects from a specific set of tissue-to-B0 orientations to produce detailed, high contrast MR images in fibrocartilage. Minimum intensity and coefficient of variation (CV) maps allow visualization of fiber structures previously not appreciated using MRI. This technology is a reduced sampling version of the Dipolar Anisotropy Fiber Imaging (DAFI) technology we have recently introduced. An example of a human knee meniscus specimen is demonstrated.

 
1113.   Ultra-High Resolution UTE Imaging on Human Knee at 3T 
Yongxian Qian1, Ashley A Williams2, Constance R. Chu2, and Fernando E. Boada1,3
1Radiology, University of Pittsburgh, Pittsburgh, PA, United States, 2Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States, 3Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States

 
This work demonstrates technical feasibility of in vivo ultra-high resolution (0.14mm) UTE imaging on human knee by using a home-developed fast 3D UTE sequence.

 
1114.   SUSCEPTIBITLIY WEIGHTED IMAGING OF TENDONS, LIGAMENTS, MENISCI AND CORTICAL BONE USING UTE SEQUENCES 
Michael Carl1, Nikolaus M Szeverenyi2, Jiang Du2, Olivier M Girard2, Won Bae2, and Graeme M Bydder2
1Global Applied Science Laboratory, GE Healthcare, San Diego, CA, United States, 2University of California, San Diego, United States

 
We report our initial experience with susceptibility weighted imaging of short T2 tissues. Adult human subjects and human tissue samples were imaged in a 3T clinical MR system using ultrashort TE sequences. UTE phase contrast is obtained from phase accrued during the RF excitation and readout part of the sequence. The mechanism of the changes may be related to tissue order and reflect the underlying physical chemistry of collagen.

 
1115.   Demonstration of meniscal fiber structure in vivo by radial imaging with minimal phase excitation and adiabatic fat suppression pulses at high field 
Ping-Huei Tsai1, Cheng Li2, Jeremy Magland2, Teng-Yi Huang3, Felix W Wehrli2, and Hsiao-Wen Chung1
1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan, 2Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, 3Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan

 
The meniscus is critical to maintaining proper mechanical functioning of the knee, and plays a vital role in load distribution. Previous studies have emphasized that the menisci¡¦s complex alignment of collagen fibers contributes to the execution of this function. However, assessing the variable orientations of these fibers in vivo is difficult due to their relatively short T2 value and perturbations from spatial variation in magnetic susceptibility. This study used 3D radial imaging with minimal phase excitation and adiabatic fat suppression pulses to obtain adequate SNR to contrast fiber orientations in human menisci. The findings indicated this methodology allows visualization of the fiber structure of the meniscus in vivo.

 
1116.   MRI derived CT substitute 
Adam Johansson1, Joakim Jonsson1, Mikael Karlsson1, and Tufve Nyholm1
1Department of Radiation Sciences, Umeå University, Umeå, Sweden

 
A method using a Gaussian mixture model (GMM) for generating a substitute for a CT image from a set of MR images is presented. The heads of five patients were imaged with CT, a T2 weighted sequence and two dual echo UTE sequences employing both different echo times and flip angles. The method is evaluated using leave-one-out cross-validation. The mean absolute error of the CT number in the substitute CT images compared to the real CT images is found to be 141 Hounsfield units.

 
1117.   Selective Imaging of Bound and Pore Water in Human Cortical Bone 
Robert Adam Horch1,2, Daniel Frank Gochberg2,3, Jeffry S Nyman4,5, and Mark D Does1,2
1Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, 2Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, 3Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States, 4VA Tennessee Valley Healthcare System, 5Department of Orthopaedics & Rehabilitation, Vanderbilt University

 
Modern ultrashort-echo time imaging has enabled human cortical bone MRI in a clinical setting. However, the cortical bone NMR signal contains contributions from both collagen-bound and pore space water, which vary across donors in opposing amounts and thereby degrade the diagnostic utility of the net bone signal. Herein, we present schemes for selectively imaging either bound or pore water, utilizing their differing T1 and T2 characteristics to generate diagnostically useful image contrast. An adiabatic full passage inversion-recovery sequence is shown to have bound water selectivity, and a short-TE fast spin echo sequence is shown to have pore water selectivity.

Traditional Posters : Musculoskeletal Imaging
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Spine, Intervertebral Disc, Bone

 
Wednesday May 11th
Exhibition Hall  13:30 - 15:30

1118.   In Vivo Sodium MR Imaging of Rabbit Lumbar Disc using Dual-tuned coil at 3T 
Chan Hong Moon1, Lloydine Jacobs2,3, Jung-Hwan Kim1, Bernard Bechara2,3, Tiejun Zhao4, James Kang2,3, and Kyongtae Ty Bae1
1Radiology, University of Pittsburgh, Pittsburgh, PA, United States, 2Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, United States, 3Ferguson Laboratory for Orthopaedic and Spine Research, 4MR Research Support, Siemens Healthcare, Pittsburgh, PA, United States

 
We successfully achieved high-resolution, high-contrast proton and sodium MR imaging and measured sodium concentration of normal rabbit spine discs using an in-house dual-tuned RF coil and ultra-short echo time spiral sequence at 3T human scanner. Further study is necessary to demonstrate difference in sodium concentrations between normal and degenerative disc models in rabbits, thereby validating quantitative sodium imaging biomarker for degenerative disc disease.

 
1119.   MRI-Based Assessment of Vertebral Deformity 
Eual A Phillips1, Chamith S Rajapakse1, Michael J Wald1, Yusuf A Bhagat1, Mary B Leonard2, Felix W Wehrli1, and Mary B Leonard2
1Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Childrens Hospital of Philadelphia, Philadelphia, PA, United States

 
Vertebral fractures are among the most common outcomes of osteoporosis and their presence often indicates an elevated risk for future osteoporotic fractures. The purpose of this study was to evaluate the performance of a custom-built software tool for quantitative morphometry of spine on the basis of mid-line sagittal MR images. Towards this goal, we evaluated the intra-reader reproducibility of computing spinal deformity indices and their associations with age and gender as part of an ongoing translational study.

 
1120.   In Vivo MRI of the Cartilaginous Endplate of the Intervertebral Disc 
Sung M. Moon1,2, Jon H. Yoder1, Dawn M. Elliott1, Felix W. Wehrli2, and Alexander C. Wright2
1Department of Orthopaedic Surgery, School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 2Laboratory for Structural NMR Imaing, Department of Radiology, University of Pennsylvania Medical Center, Philadelphia, PA, United States

 
Cartilaginous endplate of the intervertebral disc is a thin layer of hyaline cartilage, provides a mechanical barrier and a nutritional conduit between the vertebral bone and the disc. With age and degeneration, the CEP becomes thinner, calcifies, and may have reduced porosity. In this study, we have used a 3D FLASH sequence to visualize the CEP, first in specimens and then in volunteers, in order to assess the feasibility of MRI characterization of the CEP for in-vivo studies of disc degeneration.

 
1121.   Quantification of Intervertebral Disc Tears by High-Resolution 3D MRI at 7T 
Sung M. Moon1,2, Jon H. Yoder1, Edward J. Vresilovic3, Dawn M. Elliott1, and Alexander C. Wright2
1Department of Orthopaedic Surgery, School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 2Department of Radiology, University of Pennsylvania Medical Center, Philadelphia, PA, United States, 3Department of Orthopaedics and Rehabilatation, Penn State University, Hershey, PA, United States

 
The intervertebral disc (IVD) undergoes more extensive structural and compositional changes with age and degeneration. With age and degeneration, tears appear within discs due to limiting diffusion of nutrients into the disc, alteration of chemical composition, and injuries. Disc tears are associated with low back pain. However, detection of tears is difficult and quantification of their characteristics is not possible. Radial tears are often visualized under discography, however their location and orientation is difficult to determine. Additionally, discography is an invasive procedure and involves exposure to radiation. Shapes and sizes of tears are intricate, and even multiple histological sections cannot reconstruct the complex 3D tear geometry. As a result, quantitative characteristics of the 3D human AF tear remain largely unknown. The objective of this study is to provide a non-invasive MR tools for 3D visualization, measurement, and the ability to precisely locate disc tear orientation within a disc.

 
1122.   Automated segmentation of lumbar vertebral bodies and intervertebral discs from MRI using statistical shape models 
Ales Neubert1,2, Jurgen Fripp1, Kaikai Shen1, Craig Engstrom2, Raphael Schwarz3, Lars Lauer3, Olivier Salvado1, and Stuart Crozier2
1The Australian E-Health Research Centre, CSIRO, Brisbane, QLD, Australia, 2Department of Biomedical Engineering, University of Queensland, Brisbane, QLD, Australia, 3Siemens Healthcare, Erlangen, Germany

 
Automated segmentation of lumbar spine vertebrae and intervertebral discs is presented. Statistical shape models are built from a training database and applied to segment new cases by matching gray level profiles along normals to shape vertices. Automated initialisation is done by computing 3D spine curve and axial vertebral symmetries. Intensity profile along the spine curve is analysed to detect centres of vertebral bodies where the mean shape is placed. Approach was tested on a set of axial T1w and 3D Space T2w images with mean Dice scores of 0.85 (vertebrae) and 0.83 (discs).

 
1123.   Combined implications of boneprime or minutes structural and material impairment following renal transplantation assessed by lower case Greek muMRI based finite-element modeling 
Chamith S Rajapakse1, Yusuf A Bhagat1, Mary B Leonard2, Jeremy F Magland1, James H Love1, Wenli Sun1, and Felix W Wehrli1
1University of Pennsylvania School of Medicine, Philadelphia, PA, United States, 2The Children's Hospital of Philadelphia, Philadelphia, PA, United States

 
Ordinarily, when generating micro-finite-element (lower case Greek muFE) models on the basis of High-resolution MRI (lower case Greek muMRI), bone tissue is assumed to have a constant modulus because lower case Greek muMRI-based in-vivomeasures of bone mineralization are not yet available. As a consequence, lower case Greek muMRI-based lower case Greek muFE analysis is not sensitive to changes in bone-mineral density (BMD) observed in patient populations such as those who undergo renal transplantation (RTxp). Here, we demonstrate the increased sensitivity achieved when using lower case Greek muMRI-based lower case Greek muFE models of distal tibia with subject-specific tissue modulus which incorporate peripheral quantitative computed tomography (pQCT)-derived BMD measures compared to when a constant modulus is assumed in RTxp recipients.

 
1124.   A longitudinal study of trabecular bone in knees with acute anterior cruciate ligament (ACL) injuries at 3T 
Jin Zuo1, Jenny Folkesson1, Xiaojuan Li1, Samuel Paran Yap1, and Sharmila Majumdar1
1Radiology and Biomedical Imaging, Univ. of California, San Francisco, San Francisco, CA, United States

 
Anterior cruciate ligament (ACL) tear is one of the most common ligament injuries of the knee joint, and is a risk factor for post-traumatic osteoarthritis (OA). Little is known about the changes in the underlying trabecular bone following injury. Previous studies have indicated that the volumetric mineral density decreases due to incomplete mineralization of trabecular bone structure in early stages of OA. The aims of this study are to compare bone structure parameters in knees following ACL tears to those of the contralateral, uninjured “control” knee, and to evaluate these parameter changes at one year follow-up using magnetic resonance imaging.

 
1125.   Comparisons of Bone Density Measurements between Quantitative Computed Tomography and Magnetic Resonance IDEAL Imaging 
Kai-Yu Ho1, Houchun Harry Hu1, Joyce H Keyak2, Patrick M Colletti1, and Christopher M Powers1
1University of Southern California, Los Angeles, California, United States, 2University of California, Irvine, California, United States

 
The purposes of this study are to 1) investigate the relationship between calcium hydroxyapatite (CHA) densities and MR signal intensities, and 2) to correlate the bone density measurements between quantitative computed tomography (QCT) and IDEAL. Our data has demonstrated a linear relationship between CHA density and MR signal intensity, providing the support on current model for estimating CHA equivalent density. With a CHA calibration marker, our study further demonstrated that IDEAL imaging can be used to quantify bone density: the CHA equivalent densities calculated on IDEAL in-phase imaging were significantly correlated with those quantified from QCT on a human patella.

 
1126.   DDIF: A novel contrast for MRI of trabecular bone 
Dionyssios Mintzopoulos1, Jerome L Ackerman1, and Yi-Qiao Song2
1Martinos Center, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 2Schlumberger-Doll Research, Cambridge, MA, United States

 
The novel DDIF (Decay due to Diffusion in the Internal Field) method provides a novel imaging contrast for trabecular bone imaging, related to the surface-to-volume ratio of cancellous bones. We studied fresh specimens of varying trabecular structure and porosity under ex vivo conditions closely resembling in vivo physiological conditions. Significant DDIF effect and significant differences between specimens of different trabecular structure were observed. We conclude that the DDIF contrast is feasible despite the reduction of the diffusion constant and of T1 in such conditions, increasing our confidence that DDIF imaging in vivo may be clinically viable for bone characterization.

 
1127.   Enhanced Algorithm for Desktop PC-Based Micro-Finite Element Modeling of Whole-Section Stiffness from in Vivo MR Images 
Ning Zhang1, Jeremy F Magland1, Chamith S Rajapakse1, Yusuf A Bhagat1, and Felix W Wehrli1
1Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States

 
High resolution MR image based FE simulations have been shown to provide valuable information on changes in bone mechanical properties during aging and in response to intervention. However, the scales of the FE models are currently restricted to computing resources. In this work we describe an optimized algorithm for MR image-based finite-element simulation of trabecular bone, with the objective of running these simulations within the limitations of standard workstations. Simulations based on in-vivo MR images and ex-vivo micro-CT images were performed. Memory usage and CPU times were compared. The optimized algorithm enables simulations of systems with as many as 30 million elements on desktop computers.

 
1128.   Predicting Osteoporosis from T1-weighted MR Images 
Heather Ting Ma1,2, James F. Griffith2, Alvin FW Li2, David K Yeung2, Jason Leung2, Yi-Xiang Wang2, and Ping-Chung Leung2
1Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong, China, People's Republic of, 2The Chinese University of Hong Kong, Hong Kong, China, People's Republic of

 
T1-signal intensity of the marrow cavity is dependent on the type of marrow and the trabecular bone present. Marrow fat increases as bone becomes more osteoporotic. This study investigates whether a simple normalized T1-value of the vertebral body can predict a patient is osteoporotic (according to bone mineral density assessment by dual x-ray absorptiometry). The signal intensity of L3 was normalized by relating it to the signal intensity of prevertebral soft tissue. According to receiver operating characteristics, ratio values of 0.95 and 1.016 respectively gave a successful rate of 84% and 66% for predicting males and females with osteoporosis.

 
1129.   A new method to predict structural parameters of trabecular bone at a standardized SNR level in high-resolution MRI studies of distal tibia 
Wenli Sun1, Chamith S. Rajapakse1, Yusuf A. Bhagat1, Jeremy F. Magland1, and Felix W. Wehrli1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States

 
The structural parameters of trabecular bone depend on SNR but the behavior is predictable. We describe a model that can be used to predict the true structural parameters even in the presence of SNR variation that can result from a longitudinal study.

 
1130.   IDEAL Fat Image in Bone Marrow: Comparison of Metastatic Neoplasm and Benign Marrow Abnormalities 
Shuji Nagata1, Yusuke Uchiyama1, Norimitu Tanaka1, Toshi Abe1, Masafumi Uchida1, Kimberly K Amrami2, and Naofumi Hayabuchi1
1Kurume University Hospital, Kurume, Fukuoka, Japan, 2Radiology, Mayo Clinic, Rochester, MN, United States

 
Fat image of IDEAL is a sensitive method for assessing fat content of bone marrow and can help to predict the likelihood of metastatic or non-metastatic lesions.

 
1131.   Implications of soft-tissue suppression on cortical bone water signal in ultrashort echo-time imaging 
Maximilian James Smith1, Cheng Li1, Yusuf A Bhagat1, Shing Lam1, James H Love1, and Felix W Wehrli1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States

 
The use of soft-tissue suppression in UTE imaging unavoidably suppresses a fraction of the bone water signal. Importantly, bone water suppression may not be uniform throughout the cortex, given that pore size increases from the periosteum to the endosteum and that T2 is likely lengthened in larger pores. We employ in vivo UTE imaging of the mid-tibia with and without soft-tissue suppression to determine the degree of bone water suppression within different regions of cortex. Suppression of cortical bone water varied with location in the cortex and appears to be age-dependent, potentially confounding measures of bone water concentration.

 
1132.   Perfusion of the Femoral Head following Fracture Using Dynamic Contrast Enhanced MRI 
Jonathan P Dyke1, Carolyn Hettrich2, Keith Hentel1, Sreevathsa Boraiah3, and Dean Lorich4
1Radiology, Weill Cornell Medical College, New York, NY, United States, 2Orthopedics, Vanderbilt University Medical Center, Nashville, TN, United States, 3Orthopedics, Westchester Medical Center, Hawthorne, NY, United States, 4Orthopedic Trauma, Hospital for Special Surgery, New York, NY, United States

 
Assessment of bone perfusion at the time of injury following femoral neck fracture is important in determining the prognostic success of implanting joint sparing fixation hardware or total hip arthroplasty. Dynamic Contrast Enhanced (DCE) MRI was used to assess perfusion of the femoral head following minimally displaced subcapital fractures of the femoral neck. A statistically significant decrease in uptake (Akep) was seen in the injured versus contralateral side. This indicates the potential utility of this method to assess bone perfusion at the time of injury aiding the clinician in predicting the risk of possible avascular necrosis.

 
1133.   USPIO-enhanced Capital Greek DeltaR2* MR-Relaxometry for in-vivo Monitoring of Fracture Healing 
Thorsten Persigehl1,2, Britta Wieskötter3, Stefanie Remmele4, Hannah Tiggemann3, Janine Ring1, Jochen Keupp4, Walter Heindel1, Christoph Bremer1, Richard Stange3, and Volker Vieth1
1Department of Clinical Radiology, University Hospital Muenster, Münster, NRW, Germany, 2Department of Radiology, Columbia University Medical Center, New York, NY, United States,3Department of Trauma, Hand and Reconstructive Surgery, University Hospital Muenster, Münster, NRW, Germany, 4Philips Research Hamburg, Hamburg, HH, Germany

 
Angiogenesis is an essential progress in bone fracture healing. The aim of this study was to evaluate USPIO-enhanced susceptibly-corrected ∆R2* MR-relaxometry in a bone fracture rat model. USPIO-enhanced ∆R2* MR-relaxometry was performed on day 0, 7, 14, 21, and 28 after surgery and confirmed by histological microvessel density analysis. Thus, we concluded that ∆R2* MR-relaxometry allows an in-vivo monitoring of angiogenic changes in fracture healing and may facilitate experimental studies in bone repair, investigation of its underlying mechanisms, and possible novel molecular therapies.

 
1134.   Perfusion measurements of subchondral bone in patellofemoral joint of rats with experimental OA model 
Ping-Huei Tsai1, Cheng-Chieh Cheng1, Ming-Huang Lin2, Chien-Yuan Lin2, Herng-Sheng Lee3, Hsiao-Wen Chung1, and Guo-Shu Huang4
1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan, 2Functional and Micro-Magnetic Resonance Imaging Center, Institute of Biomedical Science, Academia Sinica, Taipei, Taiwan, 3Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, 4Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan

 
Osteoarthritis (OA) is a disease related to the degeneration of knee cartilage and pathological changes of subchondral bone, which can lead to inflammation and pain. Several studies have demonstrated the importance of early detection of OA using quantitative measurements of MR T2 values of knee cartilage. In addition, perfusion change of bone would result in bone remodeling and cartilage degeneration. Therefore, the purpose of this study is using DCE-MRI to measure bone perfusion of rat patellofemoral joint with experimental OA. Our preliminary finding indicated the feasibility of using DCE-MRI to investigate bone perfusion during the progression of OA, which may contribute to early detection of OA.

 
1135.   3D Geodesic Topological Analysis of Trabecular Bone Micro-Architecture of the Proximal Femur 
Julio Carballido-Gamio1, Jenny Folkesson2, Thomas Baum2, Thomas M Link2, Sharmila Majumdar2, and Roland Krug2
1Grupo Tecnológico Santa Fe, Mexico, DF, Mexico, 2Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States

 
The purpose of this work was twofold: 1) to develop a technique to perform 3D Geodesic Topological Analysis (GTA) of trabecular bone micro-architecture; 2) to demonstrate 3D GTA on high-spatial resolution MR images of the proximal femur. 3D GTA was validated using digital phantoms. Skeletonization results showed the medial location of the skeleton and preservation of shape and topology. 3D GTA correctly assigned each voxel to its closest connected junction enabling volume, spacing and orientation measures of trabecular bone. Also based on minimum geodesic distances, voxels in the trabecular bone network were correctly classified as plates or rods.

Traditional Posters : Musculoskeletal Imaging
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
MSK, MRS & MRI I

 
Thursday May 12th
Exhibition Hall  13:30 - 15:30

1136.   Is free carnitine visible in 1H-MR spectra of skeletal muscle? 
Andreas Boss1, Roland Kreis1, Pierre Saillen1, Chris Boesch1, and Peter Vermathen1
1Department of Clinical Research, University of Bern, Bern, Switzerland

 
The exercise-induced production of intramyocellular acetylcarnitine is mirrored by decreased free carnitine. In 1H MR-spectra of muscle it was observed that trimethylammonium, supposedly with contributions from both, acetylcarnitine and carnitine, was increased after exercise. We applied spectroscopic imaging in 8 runners (calf) and 8 cyclists (thigh) and found that the change of trimethylammonium was significantly correlated with the exercise-induced production of acetylcarnitine in calf (R2=0.55, p<0.001) and thigh (R2=0.27, p<0.001). The present results suggest that the increase of trimethylammonium resulted at least partly from acetylcarnitine production and, hence, that free carnitine is largely invisible in 1H MR-spectra of the muscle.

 
1137.   1H-MRS detects differences of carnosine profile in skeletal muscle of rats fed with high-fat and placebo diets 
Yew S. K. Terry1, Arunima Pola1, Bhaskaran David Prakash1, Mehdy Ghaeminia1, and S S Velan1
1Laboratory of Molecular Imaging, Singapore Bioimaging Consortium, Singapore, Singapore, Singapore

 
Carnosine is a dipeptide found in high concentrations in the skeletal muscle. In this study, F344 rats on high fat diet [n=4] and placebo diet [n=2] were scanned over a period of 12 weeks using a Bruker 7T ClinScan MRI/MRS scanner. Over a period of 17 weeks, the supplementation of high fat diet containing histidine (0.5%) apart from other amino acids caused a slight upregulation of carnosine content in the rats compared to their control, fed CE2. Histidine supplementation upregulates carnosine content in the rat’s EDL skeletal muscle and provides additional information on diet induced changes to metabolism.

 
1138.   Mitochondrial energy metabolism in skeletal muscle in a murine cancer cachexia model 
Cibely Cristine Fontes De Oliveira1, Dionyssios Mintzopoulos2,3, Caterina Constantinou2,4, Valeria Righi2,3, Nikolaos Psychogios3,5, Michael N Mindrinos6, Yong-Ming Yu7, Alexander A Shestov8, Ronald G Tompkins7, Francois Lepine9, Laurence G Rahme10, Josep M Argiles1, and Aria A Tzika2,3
1Cancer Research Group, Departament de Bioquımica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain, 2NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School, Boston, MA, United States, 3Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 4Molecular Surgery Laboratory, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School, Boston, MA, United States, 5Dept. of Surgery, Massachusetts General Hospital, Boston, Massachusetts, United States, 6Department of Biochemistry, School of Medicine, Stanford University, Stanford, CA, United States, 7Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School, Boston, MA, United States, 8Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, United States, 9Institut National de la Recherche Scientifique-Institut Armand-Frappier, Quebec, QC, Canada, 10Molecular Surgery Laboratory, Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School, Boston, MA, United States

 
We employed in vivo P31 NMR on intact mice and mass spectrometry in skeletal muscle samples, in a mouse cancer (Lewis lung carcinoma) cachexia model. ATP synthesis rate by P31 NMR and TCA cycle flux by mass spectrometry were significantly reduced by 47% and 25% respectively in cancer-bearing mice (P<0.03; t-test). The ratio of ATP synthesis rate to the TCA cycle flux, which provides an index of mitochondrial coupling, was 30% less in cancer-bearing mice (P<0.05; t-test). Our results were cross-validated with genomic analysis, showing aberrant expression levels in key regulatory genes and by electron microscopy showing abnormal giant mitochondria.

 
1139.   Direct comparison of parameters of skeletal muscle energy metabolism 
Albrecht Ingo Schmid1,2, Vera Schrauwen-Hinderling3, Martin Andreas4,5, Michael Wolzt4, Ewald Moser1,2, and Michael Roden6,7
1MR Center of Excellence, Medical University of Vienna, Wien, Wien, Austria, 2Centre of Medical Physics and Biomedical Engineering, Medical University of Vienna, Wien, Austria, 3Department of Radiology and Human Biology, Maastricht University Medical Center, Wien, Netherlands, 4Department of Clinical Pharmacology, Medical University of Vienna, Wien, Austria, 5Department of Surgery, Medical University of Vienna, Wien, Austria, 6Institute for Clinical Diabetology, German Diabetes Center, Department of Metabolic Diseases, Heinrich-Heine University, Düsseldorf, Germany, 7Karl-Landsteiner Institute of Endocrinology and Metabolism, Wien, Austria

 
Saturation transfer and PCr kinetics in ischemia and recovery were used to measure skeletal muscle ATP production in eight male healthy subjects. Saturation transfer rates were 0.21±.04mM/s compared to Q=0.0079±0.0015mM/s derived from ischemia-induced PCr decrease, both measures of resting state ATP demand. Despite the large difference in absolute values, there was, however, a strong, significant correlation between saturation transfer, PCr decrease and recovery, despite the fact that PCr recovery measures mitochondrial, oxidative capacity. This interesting fact is to be considered when evaluating recent publications on skeletal muscle energy metabolism, especially those using the saturation transfer technique.

 
1140.   Measuring energy diffusion: phosphocreatine in human skeletal muscle 
Refaat E Gabr1, AbdelMonem M El-Sharkawy1, Michael Schär2, Robert G Weiss1,3, and Paul A Bottomley1
1Division of MR Research, Johns Hopkins University, Baltimore, MD, United States, 2Philips Healthcare, Cleveland, OH, United States, 3Division of Cardiology, Johns Hopkins University, Baltimore, MD, United States

 
Phosphocreatine (PCr) is central to muscle energetics where it putatively serves as a temporal-spatial buffer, transferring high-energy phosphate between the mitochondria and myofibrils by means of diffusion in the cytosol. We report the first measurements of PCr diffusion (DPCr) in human calf muscle using localized 31P MRS as a function of diffusion time and orientation in eight healthy subjects. We find a DPCr of 0.3-0.8x10-3 mm2/s that is both anisotropic and shows evidence of restricted diffusion. Nevertheless, diffusion appears sufficiently fast to traverse the expected distances between mitochondria and myofibrils within the half-life of PCr in the creatine kinase reaction.

 
1141.   In vivo assessment of the effects of pioglitazone on muscle oxidative capacity and intramyocellular lipid content in diabetic rats using 31P and 1H MRS 
Bart Wessels1, Jolita Ciapaite1, Klaas Nicolay1, and Jeanine Prompers1
1Biomedical NMR, Eindhoven University of Technology, Eindhoven, Netherlands

 
The aim of this study was to investigate if the pioglitazone’s insulin-sensitizing effect is accompanied by improved in vivo skeletal muscle mitochondrial function and reduced intramyocellular lipid (IMCL) levels in a rat model of type 2 diabetes using 31P and 1H magnetic resonance spectroscopy (MRS), respectively. Two weeks of treatment with pioglitazone lowered fasting plasma glucose levels in Zucker diabetic fatty rats, which were paralleled by a decrease in IMCL and an increase in vivo muscle oxidative capacity. Our results suggest that the insulin-sensitizing effect of pioglitazone is brought about by improved in muscle mitochondrial function and partial normalized IMCL.

 
1142.   Effects of maltodextrin on liver and muscle glycogen synthesis during short-term recovery and on post-recovery cycling performance 
Fiona Elizabeth Smith1, Eva Detko2, Peter E Thelwall3, John O'Hara2, Rodney King4, and Michael I Trenell5
1Newcastle Magnetic Resonance Centre, Newcastle University, Newcastle upon Tyne, Tyneside, United Kingdom, 2Carnegie Research Centre, Leeds Metropoliton University, Leeds, United Kingdom, 3Newcastle Magnetic Resonance Centre, Newcastle University, Newcastle Upon Tyne, Tyneside, United Kingdom, 4Carnegie Research Centre, Leeds Metropoliton University, Leeds,5MRC Centre for Brain Ageing and Vitality, Newcastle University, Newcastle upon Tyne, United Kingdom

 
Athletes are advised to consume sufficient amounts of sugar (carbohydrate) and fluid post exercise in order to speed up recovery. Co-ingestion of protein may also be efficacious. In this study, the effect of different drink combinations on recovery from exhausting exercise and subsequent exercise performance were investigated by directly measuring change in muscle and liver glycogen concentration using 13C –NMR spectroscopy at 3T

 
1143.   Morphological and metabolic characterization of a new model of spinal cord injury without reloading using 1H MRI and 31P NMR spectroscopy 
Celine Baligand1, Ravneet S Vohra2, Fan Ye2, Jonathon Keener3, Wootaek Lim2, Sean Charles Forbes2, Prithvi K Shah2, Prodip Bose3,4, Glenn A Walter1, Floyd Thompson3,4, and Krista H. E. Vandenborne2
1Physiology and Functional Genomics, University of Florida, Gainesville, Florida, United States, 2Physical Therapy, University of Florida, Gainesville, Florida, United States, 3North Florida/South Georgia Veterans Health System of Florida, Gainesville, Florida, United States, 4Departments of Physiological Science and Neurology, University of Florida, Gainesville, Florida, United States

 
MRI and dynamic 31P spectroscopy were used to characterize morphology and function in a new rat model of muscle atrophy with incomplete spinal cord injury (SCI) combined to cast immobilization (IMM). We demonstrated that IMM prevented muscle recovery due to reloading, and show slower phosphocreatine recovery after exercise in SCI animals.

 
1144.   ‘Functional muscle-bone unit’ in osteoporotic patients 
Heather Ting Ma1,2, James F. Griffith2, Li Xu3, and Ping-Chung Leung2
1Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong, China, People's Republic of, 2The Chinese University of Hong Kong, Hong Kong, China, People's Republic of,3Beijing Jishuitan Hospital, Beijing, China, People's Republic of

 
Bone is an architecturally adaptive tissue which responds to mechanical loading and the concept “functional muscle-bone unit” has been proposed to reflect this muscle-bone interaction. This study utilizes the functional muscle-bone unit to evaluate the interaction between lumbar bone strength and muscle mass in young normal subjects and elderly females of varying bone mineral density (BMD). It shows that as bone becomes osteoporotic there is relative muscle mass acting on it per unit bone mass. This may be contributory to the occurrence of non-traumatic vertebral fractures in elderly subjects with reduced BMD.

 
1145.   Ischemia-reperfusion injury in rat skeletal muscle assessed with T2-weighted and dynamic contrast-enhanced MRI 
Sandra Loerakker1, Cees W.J. Oomens1, Emmy Manders1, Tim Schakel2, Dan L Bader1,3, Frank P.T. Baaijens1, Klaas Nicolay2, and Gustav J Strijkers2
1Soft Tissue Biomechanics and Engineering, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands, 2Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands, 3Department of Engineering and IRC in Biomedical Materials, Queen Mary, University of London, London, United Kingdom

 
Pressure ulcers are localized areas of soft tissue breakdown due to mechanical loading. Ischemia-reperfusion injury may play an important role in the etiology of pressure ulcers. Here we investigated the local interrelation between post-ischemic perfusion and muscle damage in the hindlimbs of rats, using DCE-MRI to investigate muscle perfusion and quantitative T2 MRI to assess muscle damage. DCE-MRI revealed the presence of no-reflow areas in the hindlimb subjected to ischemia and reperfusion, associated with a post-ischemic increase in T2 and additional muscle damage. The influence of reperfusion is heterogeneous, which must be considered when designing appropriate pressure relief strategies.

 
1146.   Interethnic differences in fat metabolism of overweight Chinese, Malays and Indians by MRI and MRS approaches 
Suresh Anand Sadananthan1,2, Melvin Khee-Shing Leow1,3, Chin Meng Khoo4, Yung Seng Lee1,4, E Shyong Tai1,4, and Sambasivam Sendhil Velan1,5
1Singapore Institute for Clinical Sciences, A*STAR, Singapore, 2Dept. of Obstetrics & Gynaecology, National University of Singapore, Singapore, 3Dept. of Endocrinology, Tan Tock Seng Hospital, Singapore, 4Dept. of Medicine, National University of Singapore, Singapore, 5Singapore BioImaging Consortium, A*STAR, Singapore

 
The study of fat distribution is important to understand the pathophysiology of obesity-related disorders, diabetes mellitus and cardiovascular diseases. In this study, we determined the relationship between insulin sensitivity and abdominal fat (obtained by MRI), hepatic fat and intramyocellular fat (IMCL) (obtained by MRS) accumulation. We also examined whether there are ethnic differences in these fat depots in a multi-ethnic cohort of overweight adults consisting of Chinese, Malays and Indians. We observed that IMCL, abdominal and hepatic fat had significant negative correlation with ISI. IMCL and subcutaneous fat showed significant differences among the ethnic groups while hepatic fat and visceral fat had no differences.

 
1147.   Probing tissue microstructure using oscillating diffusion gradients in the human calf 
Damien Joseph McHugh1,2, Penny L. Hubbard1,2, Sha Zhao1,2, David M Higgins3, Geoff J Parker1,2, and Josephine H Naish1,2
1Imaging Sciences and Biomedical Engineering, University of Manchester, Manchester, United Kingdom, 2The University of Manchester Biomedical Imaging Institute, Manchester, United Kingdom, 3Philips Healthcare, Guildford, United Kingdom

 
We present preliminary results of using trapezoidal oscillating gradients to reach short diffusion times and measure the apparent diffusion coefficient (ADC) in human calf muscle as a function of effective diffusion time. Oscillating gradients of various frequencies were used to look for evidence of restricted diffusion within muscle fibres, probing length scales between 6 and 14 μm. Results show a similar trend to pre-clinical studies, with ADC increasing as shorter diffusion times are reached and the barriers to diffusion are reduced. This indicates a sensitivity to microstructure and the potential for the clinical use of oscillating gradients.

 
1148.   EVALUATION OF B1 RECEIVE NON-UNIFORMITY CORRECTION TECHNIQUES FOR QUANTITATIVE MUSCULOSKELETAL NMR IMAGING. 
Noura Azzabou1,2, Paulo Loureiro de Sousa1,2, and Pierre G. Carlier1,2
1NMR Laboratory, Institute of Myology, Paris, Paris, France, 2NMR Laboratory, CEA, I2BM, MIRCen, IdM, Paris, Paris, France

 
We focused here on B1 receive non-uniformity artifacts correction. We presented the techniques that can be used in the context of quantitative musculoskeletal NMR imaging. To estimate the inhomogeneity function, these approaches rely on the assumption of the signal uniformity inside the subcutaneous fat region. They include normalized convolution based techniques and those that approximate functions through cosine basis or Legendre polynomial sum. The comparison between them was achieved on data acquired using 3pt Dixon sequence and different types of coils. Experimental results showed that techniques based on Legendre polynomial or cosine basis provided better correction quality.

 
1149.   Correlation between BMLs and Quadriceps Arthogenous Muscle Inhibition 
Charles Edward Hutchinson1,2, David Felson3, and Michael Callaghan3
1Radiology, University of Warwick, Coventry, Warkwickshire, United Kingdom, 2Cancer and Enabling Science, University of Manchester, Manchester, Lancashire, United Kingdom, 3University of Manchester

 
BMLs visualised on MRI are implicated in knee pain. In patients with knee OA, quadriceps weakness is a common clinical feature which is an important determinant of disability and is due to arthrogenous muscle inhibition (AMI). AMI has been associated with swelling of the joint and pain. Given the centrality of BMLs to OA pathology and their neural innervation, we hypothesised that subjects with patellofemoral joint (PFJ) OA and BMLs may also have AMI of the quadriceps. This study correlates the number, size and signal intensity of BMLs in PFJ OA and the percentage of quadriceps AMI, knee pain scores.

 
1150.   Gene transfer of arginine kinase to skeletal muscle using adeno-associated virus 
Sean C Forbes1, Larry T Bish2, Elizabeth R Barton3, Fan Ye1, Celine Baligand4, H L Sweeney2, and Glenn A Walter4
1Department of Physical Therapy, University of Florida, Gainesville, Florida, United States, 2Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania, 3Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, Pennsylvania, 4Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida

 
In this study we tested the feasibility of using 31P-MRS to monitor gene therapy by a commonly used nonpathogenic adeno-associated virus (AAV) delivery system. Muscle specific expression of the marker gene, arginine kinase (AK), was achieved using an AAV type 2/8 virus and the gene product (phosphoarginine) was monitored using 31P-MRS. The results indicate that AK was expressed within 8 weeks of delivery in muscle regions localized to the injection site. Therefore, delivery of AK gene via AAV may be effective as a reporter gene to noninvasively monitor the regional and global transfer of genes for therapeutic interventions.

 
1151.   In vivo high-resolution magic angle spinning proton NMR spectroscopy of Drosophila melanogaster flies as a model system to investigate mitochondrial dysfunction in trauma 
Nikolaos Psychogios1,2, Yiorgos Apidianakis3, Valeria Righi1,2, Hazel Szeto4, Ronald G Tompkins5, Laurence G Rahme3,5, and Aria A Tzika1,2
1NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School, Boston, MA, United States, 2Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 3Molecular Surgery Laboratory, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School, Boston, MA, United States, 4Department of Pharmacology, Joan and Sanford I. Weill Medical College of Cornell University, New Yor, Joan and Sanford I. Weill Medical College of Cornell University, New York, NY, United States, 5Department of Surgery, Massachusetts General Hospital and Shriners Burn Institute, Harvard Medical School, Boston, MA, United States

 
Using high-resolution MAS proton NMR spectroscopy in vivo, we evaluated in a Drosophila melanogaster fly trauma model the effects of a novel (Szeto-Schiller) SS-31 peptide known to be targeted to mammalian mitochondria. In old flies, our results showed that SS-31 peptide reduced both insulin resistance and apoptosis biomarkers. We thus provide evidence for the hypothesis that trauma in aging is linked to insulin signaling and thus mitochondrial dysfunction. Our approach advances the development of novel in vivo non-destructive research approaches in the model host D. melanogaster, and suggests biomarkers for investigation of biomedical paradigms that may contribute to the development of novel therapeutics.

Traditional Posters : Musculoskeletal Imaging
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
MSK, MRS & MRI II

 
Monday May 9th
Exhibition Hall  14:00 - 16:00

1152.   Reduced FOV spinal muscle DWI with single-shot interleaved multi-slice inner volume stimulated echo DW-EPI 
Dimitrios C Karampinos1, Suchandrima Banerjee2, Kevin F. King3, Roland Krug1, Thomas M. Link1, and Sharmila Majumdar1
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, United States, 3Global Applied Science Laboratory, GE Healthcare, Waukesha, WI, United States

 
Diffusion-weighted imaging (DWI) of spinal muscles is challenging due to the large susceptibility-induced geometric distortions and the significant fat-induced chemical shift artifacts in single-shot EPI scans without parallel imaging. Reduced FOV imaging is an alternative approach to parallel imaging for reducing distortions as well as for excluding artifact prone regions of the FOV. In the present work, a stimulated echo prepared DW-EPI sequence enabling interleaved multi-slice inner volume imaging is developed. The proposed technique benefits from the reduced distortions of reduced-FOV DWI and the SNR advantages of stimulated echo preparation. The sequence trade-offs are characterized and in vivo results are shown in DWI of lumbar spine muscles.

 
1153.   In Vivo Measurement of Membrane Permeability and Fiber size in Calf Muscle Using Time-dependent DWI 
Els Fieremans1, Dmitry S Novikov1, Eric E Sigmund1, Kecheng Liu2, Jens H Jensen1, and Joseph A Helpern1,3
1Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, United States, 2Siemens Medical Systems, United States, 3Center for Advanced Brain Imaging, Nathan S. Kline Institute, Orangeburg, NY, United States

 
The diffusivity measured in tissue in vivo depends on the diffusion time and is sensitive to tissue microstructure. Here we measure the time-dependent diffusion in the human calf muscle of healthy subjects. Based on our recent modeling of diffusion restricted by permeable membranes, we derive estimates of the free diffusion coefficient, membrane permeability, surface-to-volume ratio and mean fiber diameter. The obtained fiber diameter values agree very well with histological findings. Hence, we demonstrate here for the first time a non-invasive method to create parametric maps of cell membrane permeability and cell size.

 
1154.   Reconstruction of 3-D Fabric Structure and Fiber Nets in Skeletal Muscle via In Vivo DTI 
Armen Alex Gharibans1, Curtis Laurence Johnson1, Danchin Daniel Chen1, and John G Georgiadis1
1Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States

 
Driven by the hypothesis that the transverse eigenvalue asymmetry in diffusion tensor imaging of skeletal muscle is correlated with gross muscle organization, we reconstruct and superimpose the tracts corresponding to the primary and secondary eigenvectors from DTI axial slices of the calf and thigh of a group of healthy, lean volunteers at rest. The reconstruction of organized nets consisting of crossing primary and secondary tracts provides quantitative evidence of the presence of a woven fabric in the middle part of the gastrocnemius and vastus lateralis muscles.

 
1155.   IMAGING REGENERATION IN DYSTROPHIC MUSCLE USING T2 AND DIFFUSION MRI 
Nathan David Bryant1, Ravneet Vohra2, Sunita Mathur3, Krista Vandenborne4, and Glenn A. Walter5
1Radiology, Vanderbilt University, Nashville, TN, United States, 2Physical Therapy, University of Florida, 3Department of Physical Therapy, University of Toronto, Canada, 4Department of Physical Therapy, University of Florida, 5The Department of Physiology and Functional Genomic, University of Florida

 
Dystrophic muscle is especially prone to injury during eccentric contractions. During cyclic bouts of damage and recovery, the muscle tissue undergoes various stages of remodeling. T2 and diffusion weighted MRI were used to observe changes associated with damage and repair in muscle tissue. This study set out to image eccentric damage in dystrophic muscle caused by downhill (-14°) treadmill running for 15 - 20 minutes. The greatest difference was seen in λ3 and FA. A combined analysis of T2 and diffusion parameters appears to be a promising approach for monitoring recovery from damage in longitudinal studies of dystrophic skeletal muscle.

 
1156.   A novel bootstrap approach for reducing noise-induced error in DTI-based measurements of muscle architecture 
Amanda K. Wake1,2, and Bruce M. Damon1,2
1Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, 2Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center

 
A novel approach of identifying and using the best subset of diffusion directions for the calculation of the diffusion tensor and associated diffusion parameters was demonstrated using simulated images and was implemented in real DT-MR data sets.

 
1157.   Use of probabilistic diffusion tractography to improve visualization in skeletal muscle tractography 
Yoshikazu Okamoto1, Kiichi Tadano2, Tomohiko Masumoto1, Yuji Hirano1, Tomonori Isobe2, and Manabu Minami1
1University of Tsukuba Hospital, Tsukuba, Ibaraki, Japan, 2University of Tsukuba, Tsukuba, Ibaraki, Japan

 
The purpose of this study is to elucidate whether the probabilistic diffusion tractography (PDT) method is useful for visualizing skeletal muscle tractography, especially for gtangledh muscle fibers.And in conclusion, we successfully tracked skeletal muscle using the PDT method. PDT appears to be especially useful for demonstrating tangled muscle fibers, like SOL. Scan parameters using more MPG directions can produce better visualization.

 
1158.   Muscle Architecture Measurements from DT-MRI Fiber Tracking: Tract Smoothing and Voxel Size Considerations 
Bruce M. Damon1,2
1Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States, 2Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States

 
Diffusion tensor (DT)-MRI muscle fiber tracking can be used to determine muscle architectural parameters in vivo, but the data are noise-sensitive. The purpose of this study was to determine whether or not the accuracy and precision of DT-MRI-derived muscle architectural parameters could be improved by varying voxel dimensions and by fiber tract smoothing. Simulated datasets, based on previously published in vivo ultrasound images, were generated and analyzed in Matlab. Smaller voxel volumes, high signal-to-noise ratios, and 2nd order polynomial fitting of the initially reconstructed fiber tracts were all found to be useful ways to improve DT-MRI-based muscle architectural measurements.

 
1159.   MRI and MRS in the assessment of dietary-induced and age-related changes of the muscle in an animal model for sarcopenic obesity 
Claudia Fellner1, Christine Hechtl2, Marianne Vorbuchner3, Roland Büttner2, Christian Stroszczynski1, Okka W. Hamer1, and Cornelius Bollheimer2
1Institute of Radiology, University Medical Center Regensburg, Regensburg, Germany, 2Department of Internal Medicine I, University Medical Center Regensburg, Regensburg, Germany,3Siemens Healthcare, Erlangen, Germany

 
To assess dietary-induced and age-related changes of the muscle, 7 high fat fed rats (HFR) and 14 control animals (CR) fed with standard diet underwent MRI and MRS at the age of 16 and 21 months. Maximum cross sectional area of the M. quadriceps was smaller in HFR compared with CR and decreased with increasing age. HFR yielded increased lipid content and prolonged T2 relaxation times compared with control animals. Although all effects aggravated with increasing age, dietary-induced differences were most pronounced at the age of 16 month. The results of our pilot study support the hypothesis of sarcopenic obesity.

 
1160.   Quantification of Myocellular Lipids via 1H-MR Spectroscopy in Elderly Women: Effect of Adiposity and Physical Activity 
Danchin Daniel Chen1, Diego Hernando2, Curtis Laurence Johnson1, Armen Alex Gharibans1, Dolores D Guest3, Christie Ward4, Bhibha Das3, Ellen M Evans4, and John G Georgiadis1,5
1Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 2Department of Radiology, University of Wisconsin, Madison, WI, United States,3Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 4Department of Kinesiology, University of Georgia, Athens, GA, United States, 5Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States

 
Single-voxel 1H-MR spectroscopy was utilized in a cross-sectional study of elderly women (n=41) blocked on adiposity (obese vs. lean), with the lean group (n=17) further blocked on physical fitness (sedentary vs. physically active). The lipid distribution in the vastus medialis of lean/sedentary individuals was found to be similar to that of obese individuals, while lean/active individuals had a lower concentration of lipids (p<0.005) with a higher percentage stored as IMCL (p<0.1) than the obese and the lean/sedentary individuals.

 
1161.   Using Long Echo Times in Proton Magnetic Resonance Spectroscopy in the Vastus Lateralis Muscle 
Lucas Lindeboom1, M. Eline Kooi1, Matthijs Hesselink2, Patrick Schrauwen3, Joachim Wildberger1, and Vera Schrauwen-Hinderling1,3
1Radiology, Maastricht University Medical Center, Maastricht, Netherlands, 2Human Movement Sciences, Maastricht University Medical Center, Maastricht, Netherlands, 3Human Biology, Maastricht University Medical Center, Maastricht, Netherlands

 
Using long echo times in Proton Magnetic Resonance Spectroscopy can provide new insight into skeletal muscle metabolism. Spectra with excellent separation of methylene and methyl peaks of IMCL and EMCL can be acquired in the vastus lateralis muscle. The use of carnitine as an internal concentration reference is more reliable, due to the diminished contamination of this peak at long TE. In vivo detection of acetylcarnitine is facilitated by the relative suppression of broad peaks from short T2 metabolites. Acetylcarnitine can possibly be seen as a marker for mitochondrial imbalance between acyl-CoA load and tricarboxylic acid cycle activity.

 
1162.   Modeling the hyperemic response in skeletal muscle fMRI 
Kiril Schewzow1,2, Martin Andreas2,3, Ewald Moser1,4, Michael Wolzt2, and Albrecht Ingo Schmid1,4
1MR Center of Excellence, Medical University of Vienna, Wien, Austria, 2Dpt. of Clinical Pharmacology, Medical University of Vienna, Wien, Austria, 3Dpt. of Surgery, Medical University of Vienna, Wien, Austria, 4Centre of Medical Physics and Biomedical Engineering, Medical University of Vienna, Wien, Austria

 
Ischemia and reperfusion in skeletal muscle were studied by BOLD-MRI. In this work, we fitted the EPI time courses of the hyperemic response to ischemia, using similar a function as in DCE-MRI. Several parameters which describe hyperemia were determined from the fit results. Significant differences between muscle groups and the impact of post-occlusive stenosis could be shown.

 
1163.   Fourier Analysis of Muscle BOLD Data After Exercise 
Andrew D. Davis1, and Michael D. Noseworthy2,3
1Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada, 2Electrical and Computer Engineering, School of Biomedical Engineering, and Department of Radiology, McMaster University, Hamilton, Ontario, Canada, 3Brain Body Institute, St. Joseph's Healthcare, Hamilton, Ontario, Canada

 
BOLD data was acquired while plantar flexion exercise was performed using an in-house built MRI compatible ergometer. An intense exercise protocol of 2.5 minutes plantar flexion at 0.5 Hz at 50% of the subject’s MVC was performed. Immediately following the exercise, 10 minutes of BOLD data was acquired. Region of interest (ROI) analysis was performed on the data to segment the muscle groups of the lower leg, with both broadly inclusive ROIs that touched arteries, and more carefully drawn ROIs which excluded them. FT and time-series analysis was done. Next, an exercise protocol was performed to determine the effects of applying SAT bands just outside the FOV No physiological signals were present from the carefully drawn ROIs. The peaks only showed when the ROIs included the arteries. Time course plots for the Sat bands test revealed no obvious effects on the BOLD signal course due to the SAT bands. SAT bands do no not seem to affect BOLD signal recovery characteristics: base-peak height of recovery curves agree within the uncertainty for each muscle. The FT technique seems to be sensitive to arterial inflow, but not strangulation of the microvasculature in the tissue. Since SAT bands above and below imaging plane don’t seem to affect BOLD data results from tissue oxygenation, but do dampen arterial inflow effects, they should probably be used for all BOLD muscle scanning in the leg in future studies.

 
1164.   Muscle functional MRI of exercise-induced rotator cuff 
Noriyuki Tawara1, Osamu Nitta2, Hironobu Kuruma2, Mamoru Niitsu3, Naoyuki Tamura4, Hideyuki Takahashi4, Atsuto Hoshikawa1, Kakuko Nakamura1, Toru Okuwaki1, and Akiyoshi Itoh5
1Department of Sports Medicine, Japan Institute of Sports Sciences, Tokyo, Japan, 2Department of Physical Therapy, Faculty of Health Sciences, Tokyo Metropolitan University, Tokyo, Japan,3Department of Radiology, Saitama Medical University, Saitama, Japan, 4Department of Sports Sciences, Japan Institute of Sports Sciences, Tokyo, Japan, 5Graduate Course of Computer Sciences, College of Sciences and Technology, Nihon University, Chiba, Japan

 
Strengthening of the rotator cuff muscles in one of the most integral parts of a rehabilitation program for athletes with shoulder problems who are involved in throwing sports. MRI can evaluate muscle activity; T2 of exercised muscle increases compared to that of rested muscle. However, it is difficult for efficient use as the evaluation by the rehabilitation. This study evaluated the detectability of the rotator cuffsf muscle activity induced by acute exercises. In this study, we presented the detectability of rotator cuffsf activities. T2 calculating from SE-EPI images indicated high detectability for muscle activity in the region of shoulder.

 
1165.   Correlation study between 31P magnetic resonance spectroscopy and electromyogram on muscle fatigue 
Kang-soo Kim1, Do-beom Son2, Heung-ho Choi1, Choong-ki Eun3, and Chi-Woong Mun1,4
1Biomedical Engineering, Inje University, Gimhae, Gyoungnam, Korea, Republic of, 2Radiology, Haeundae Paik Hospital, Busan, Gyoungnam, Korea, Republic of, 3Medicine, Radiology, Haeundae Paik Hospital, Busan, Gyoungnam, Korea, Republic of, 4UHRC, Inje University, Gimhae, Gyoungnam, Korea, Republic of

 
The purpose of this study is to investigate the the electrophysiological signal and energy phosphate metabolism measured by EMG and 31P-MRS, respectively, to examine the relationship of muscle fatigue during isometric calf-muscle exercise in human. Four healthy, male volunteers participated in this study. The subjects performed the static ankle plantar flexion exercise at 45 degree with 30% MVC according to the exercise protocol. The correlation coefficient(r) was 0.866 and they had statistically significant (P<0.001) between EMG and 31P-MRS. If it is possible to estimate muscle fatigue using the MDF and PCr/Pi, it will be widely used in various fields.

 
1166.   Muscle Boundary Estimation Using Interpolated Image Masks 
Amanda K Wake1,2, Wyatt M. Rose2,3, Bruce M. Damon1, and Amanda K Wake1
1Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States, 2Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, 3Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

 
Some muscle modeling techniques require exact knowledge of a muscles boundaries. However, hand-digitizing regions of interest of many slices is time consuming. The purpose of this study was to determine whether or not defining regions of interest and interpolating the masks in the intervening slices could produce accurate estimates of the muscle boundaries. The data presented will show that this approach is feasible and produces muscle boundaries that are not significantly different from hand-digitized masks.

 
1167.   Parametric MRI for Muscle Degeneration and Regeneration 
Donghoon Lee1, Shu Feng1, Daniel Chen1, and Martin Kushmerick1
1University of Washington, Seattle, WA, United States

 
We report our efforts on MRI monitoring for the process of muscle damage and recovery over time, which was correlated with histology. Myotoxin was injected on mouse hind-limb muscle of one leg to damage the muscle and continuously monitor the processes of muscle damage and repair using multi-parametric MRI and histology. Acute damage and necrosis is evident with 1 – 2 days post injection, followed by macrophage infiltration then by onset of regeneration followed by recovery by the third week. Our results show parametric MRI can be a systematic monitoring tool in distinguishing underlying muscle pathology as a function of time.

 
1168.   Detection of changes in quadrupolar peaks by FFC-MRI in skeletal muscle 
Lionel M Broche1, Henning Wackerhage2, and David J Lurie1
1ABIC, University of Aberdeen, Aberdeen, Aberdeenshire, United Kingdom, 2School of Medical Sciences, University of Aberdeen, Aberdeen, Aberdeenshire, United Kingdom

 
Field-cycling MRI is a novel technique that involves changing the main magnetic field in an MRI scanner during the pulse sequence. Among others, it allows the measurement of interactions between water protons and 14N quadrupolar moments from proteins in tissues in vivo. In this study we used the linearity between the quadrupolar signal and the protein concentration to determine the physiological changes that occur during muscle swelling. The study was performed in the soleus and gastrocnemius region on 12 volunteers with controlled swelling. Data show good agreement with the values reported in the literature from standard biopsy procedure.

 
1169.   The Reliability of Repeated Measures of the Time Constant for Post-Exercise Phosphocreatine Recovery Using a Weighted Intraclass Correlation Coefficient 
Howard Smithline1,2, Long Ngo3,4, Elyse Linson1, and Robert Greenman4,5
1Emergency Medicine, Baystate Medical Center, Springfield, MA, United States, 2Tufts University Medical School, Boston, MA, United States, 3General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Boston, MA, United States, 4Harvard Medical School, Boston, MA, United States, 5Radiology, Beth Israel Deaconess Medical Center, Boston, MA, United States

 
The time constant (tau) of post-exercise phosphocreatine (PCr) recovery curve, reflects oxidative metabolism. Tau-PCr calculated from repeated low-intensity exercise may be more reliable than a single low-intensity or high-intensity exercise. Five volunteers performed three low-intensity and one high-intensity plantar flexion protocol on two days. 31P spectra were acquired every 10 seconds. Monoexponential curves were fitted to normalized PCr yielding tau and its SE. Weighted (inverse variance) intraclass correlation coefficients (ICC) were calculated. ICC increased from 0.39 to 0.92 by using repeated measures for low-intensity exercise. The ICC for the high-intensity exercise was 0.82. Repeated measures of tau-PCr increase reliability.

 
1170.   3Tesla gradient-echo 3-point Dixon imaging for robust water-only imaging of the extra-ocular muscles 
Christopher David James Sinclair1,2, Robert D S Pitceathly1, Indran Davagnanam2, Michael G Hanna1, Mary M Reilly1, Tarek A Yousry1,2, Xavier Golay2, and John S Thornton1,2
1MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, United Kingdom, 2Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, United Kingdom

 
We evaluated 3 point Dixon gradient-echo imaging of the extra-ocular muscles at 3T as a method of fat suppression by comparing it to short tau inversion recovery (STIR) and spectral fat saturation. The 3 sequences were prescribed to have identical geometrical coverage and an imaging time of 3m44s. Seven healthy adult subjects were imaged. The 3-point Dixon method delivered the statistically highest contrast ratio between the muscle and surrounding fat indicating efficient elimination of the fat signal and clear delineation of muscle boundaries. This method offers the additional potential advantage of quantifying intra-muscular fat-fraction in the extra-ocular muscles.