|Cartilage Imaging: Methods|
gagCEST & NOE: Assessment of Glycosaminoglycan
Concentration in Vivo
Wen Ling1, Ravinder R. Regatte2, Gil Navon1, Alexej Jerschow2
1Tel Aviv University, Israel; 2New York University, New York, New York, USA
Glycosaminogycan (GAG) plays numerous vital functions in the human body. GAG concentration [GAG] in vivo is a sensitive biomarker indicative of both osteoarthritis (OA) and intervertebral disk (IVD) degenerative diseases. Currently existing techniques for GAG monitoring, such as, dGEMRIC (delayed gadolinium-enhanced MRI contrast), T1?, and 23Na MRI have some practical limitations. By exploiting the exchangeable protons of GAG we demonstrate that one can directly map the localized GAG concentration in vivo (gagCEST). The gagCEST approach is exploited on both human articular cartilage and animal IVD. Moreover, we also report the observation of the Nuclear Overhauser effect (NOE) from macromolecules in tissue, which contributes significantly to CEST/MT contrast mechanism in MRI and may lead to further diagnostic abilities.
In Vivo Measurement of 23Na T2* in Human Articular
Cartilage at 3T and 7T
Ernesto Staroswiecki1, 2, Neal Kepler Bangerter1, Paul Thomas Gurney1, Garry Evan Gold1, Samantha Jane Holdsworth1, Thomas Grafendorfer2, Brian Andrew Hargreaves1
1Stanford University, Stanford, USA; 2GE Healthcare, Waukesha, USA
Quantification of sodium in cartilage correlates positively with proteoglycan content, making sodium MRI very attractive for tracking early degenerative changes associated with osteoarthritis. However, the challenges associated with in-vivo sodium imaging, including extremely rapid T2 relaxation decay, low concentration, and low gyromagnetic ratio, have hindered its adoption. Short-TE gradient-spoiled sequences with efficient k-space trajectories can improve image quality. Accurate characterization of sodium T2* in the tissue of interest improves sequence parameter optimization and may be a marker of underlying physiologic structure. In this work we present in-vivo measurements of sodium T2* in human articular cartilage at 3T and 7T.
T1ρ Relaxation Time of Lateral Meniscus
and Its Relationship with T1ρ of Adjacent Cartilage in Knees with Acute
ACL Injuries at 3T
Radu Ioan Bolbos1, Benjamin C. Ma1, Thomas M. Link1, Sharmila Majumdar1, Xiaojuan Li1
1University of California San Francisco, San Francisco, USA
Meniscus injury and cartilage degenerations preceded by damage of the collagen-proteoglycan (PG) matrix are present in acute knee injuries such as ACL tear. Previous studies have suggested potential associated degenerative processes of proteoglycans in meniscus and cartilage. T1 ρ relaxation time mapping techniques were used to assess lateral meniscus and adjacent cartilage in 16 patients with ACL tears. T1 ρ elevation in posterior horn of meniscus was significantly correlated with cartilage T1 ρ elevation in posterior compartment of LT, which demonstrated a strong injury-related relationship between meniscus and cartilage biochemical changes.
Detection of Proteoglycan Content in Human
Osteoarthritic Cartilage Samples with Magnetic Resonance T1rho Imaging
Jonathan Cheng1, Ehsan Saadat1, Radu Ioan Bolbos1, Bjoern Jobke1, Sarmad Muneeb Siddiqui1, 2, Michael D. Ries1, Thomas M. Link1, Xiaojuan Li1, Sharmila Majumdar1
1University of California, San Francisco, San Francisco, California , USA; 2University of California, Berkeley, Berkeley, California , USA
We demonstrated that MR T1rho imaging is capable of quantifying proteoglycan (PG) content in human osteoarthritic articular cartilage. Human cartilage samples were harvested from total knee arthroplasty surgeries and imaged with T1rho ex vivo. Later, biopsy punches were taken from the samples and proteoglycan content was determined biochemically. T1rho relaxation times and PG content were significantly negatively correlated, showing a potential for T1rho to predict PG content in vivo.
Local Flip Angle Correction for Improved Volume
T1-Quantification in 3D DGEMRIC Using the Look-Locker Technique
Carl Siversson1, Carl-Johan Tiderius1, Leif Dahlberg1, Jonas Svensson1
1Lund University, Malmo, Sweden
In 3D Look-Locker delayed Gadolinium enhanced MRI of cartilage (dGEMRIC) local flip angle variations may cause erroneous T1 values. The aim of this work was to evaluate the extent of this effect and try to correct for it in in vivo data. This was achieved by calculating and compensating for the local flip angle as it varies in the slice encoding direction, thus extending the number of slices usable for the dGEMRIC measurement.
|14:30||328.||Fast 3D T1 Mapping with Variable Flip Angle Method
for DGEMRIC: Preliminary Validation
Wei Li1, Nitya Krishnan2, Pottumarthi V. Prasad1
1Evanston Hospital and Northwestern University Feinberg School of Medicine, Evanston, Illinois, USA; 2Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
The purpose of this study was to validate the accuracy of VFA approach for dGEMRIC in both phantoms and in vivo compared to standard 2D IR-TSE technique. Two separate phantom tests, one for estimating the optimal flip-angle combination and the other for evaluating the spread in T1 values across slices were performed. Four OA patients and 4 healthy human subjects were imaged sagittally using 2D IR-TSE and 3D VFA sequences. Our preliminary results indicate that VFA method is able to provide adequate accuracy of T1 for dGEMRIC, with major advantages of entire joint coverage and shorter acquisition times.
Multiparametric MRI Characterization of
Degradation in Bovine Nasal Cartilage
Ping-Chang Lin1, Kenneth W. Fishbein1, Richard G. Spencer1
1National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
Mono-parametric characterization of cartilage with MRI has met with limited success; there is a large degree of overlap in mean parameter values for e.g. normal and OA cartilage. We extend MRI analysis of cartilage by delineating the relationship between pairs of MR parameters pre- and post-enzymatic degradation. Results are visualized as clusters of parameter values in two-dimensional space, with axes consisting of T1, T2, and MT rate taken pairwise. We find that parameter clusters exhibit motion in parameter space defined by translation, rotation, and changes in shape and size, with differences seen between trypsin and collagenase digestion.
Multiparametric Characterization of Healthy and
Diseased Articular Cartilage at 17.6T: Early Results
Jose G. Raya1, Gerd Melkus2, Olaf Dietrich1, Daniel Ludwig Weber2, Lucianna Filidoro1, Maimilian Felix Reiser1, Peter Michael Jakob2, Christian Glaser1
1Ludwig Maximilian University of Munich, Munich, Germany; 2University of Würzburg, Würzburg, Germany
Articular cartilage is a highly structured tissue and plays an important role in the pathogenesis of osteoarthritis. The purpose of this work was to establish a protocol for multiparametric (T2, T1, ADC and FA) examination of healthy and diseased articular cartilage at 17.6T. Three differentiated zones (radial, transitional and tangential) could be identified in healthy cartilage, whereas no transitional zone was present in diseased cartilage. ADC and T2 were increased and FA reduced on diseased cartilage. Lesions appeared larger in the ADC and FA maps than in T2 maps indicating a higher sensitivity of DTI to loss of cartilage integrity.
Accelerated T2 Mapping of Articular Cartilage Using
Joshua Jay Jacobson1, Rafael O'Halloran1, Alexey A. Samsonov1, Richard Kijowski1, Sean B. Fain1, Walter F. Block1
1University of Wisconsin Madison, Madison, Wisconsin, USA
T2 mapping can be used to quantify early changes consistent with cartilage degradation before changes can be detected in morphological scans. However, the lengthy scan times approaching 10 minutes limit their utilization. We recognize that recent methods to exploit temporal correlations in time-resolved imaging (HYPR) can be applied to parametric imaging, by simply replacing the temporal dimension with a parametric dimension. We present a method to utilize an iterative constrained reconstruction algorithm with an undersampled acquisition to reduce scan time by a factor of four.
Ultrashort TE Spectroscopic Imaging (UTESI) of the
Short T2 Tissues in the Musculoskeletal System
Jiang Du1, Atsushi Takahashi2, Christine B. Chung1, Graeme M. Bydder1
1University of California, San Diego, San Diego, California , USA; 2GE Healthcare Technologies, Menlo Park, California , USA
The human musculoskeletal (MSK) system contains a variety of tissues with short T2 components such as the deep layers of articular cartilage, menisci, ligaments, tendons, entheses and cortical bone. The 2D UTE sequences allow these previously “MR invisible” tissues to be directly imaged and quantified. Here we present a UTE spectroscopic imaging (UTESI) technique for high resolution imaging and quantification, and apply it to six types of short T2 tissues in the MSK on a clinical 3T scanner