ELECTRONIC POSTER - ismrm

optical microscopy measurements. Pore distribution images suggests a potential for using this new contrast mechanism and our
modeling framework to map a useful feature of local material microstructure.
Methodology for MR Elastography
Hall B Monday 14:00-16:00 Computer 18
14:00 3400. Non-Invasive Measurement of Vitreous Humor Stiffness in the Mouse Using MR
Elastography
Erik Holt Clayton 1 , Qing Wang 1 , Sheng Kwei Song 2 , Philip V. Bayly 1,3
1 Mechanical Aerospace & Structural Engineering, Washington University in St. Louis, Saint Louis, MO, United
States; 2 Radiology/Radiological Sciences, Washington University in St. Louis, Saint Louis, MO, United States;
3 Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO, United States
MR elastography (MRE) shows great promise for estimating the stiffness of various biological tissues. In this study, the shear
modulus of the mouse eye vitreous humor was determined with MRE. A novel corneal actuation system was devised to non-invasively
impart propagating shear waves into the vitreous. Spatial-temporal images of the corresponding wave field were acquired at 4.7T
using a custom spin echo pulse sequence. Viscoelastic material parameters were extracted from the displacement field by a leastsquares
inversion method. Results show that MRE of the mouse vitreous is feasible, and suggest that MRE may be applicable to
diagnosis of ocular disease.
14:30 3401. Development of a Method for Imaging Tissue Elasticity Using Tagged Magnetic
Resonance Imaging
Ryosuke Nasada 1 , Tomoki Takeuchi 1 , Junfeng Zhang 1 , Takashi Tokuno 2 , Mitsunori
Tada 3 , Youichi Yamazaki 1 , Kenya Murase 1
1 Department of Medical Physics and Engineering, Graduate School of Medicine, Osaka University , Suita,
Osaka, Japan; 2 Course of Precision Engineering, School of Science and Engineering, Chuo University, Tokyo,
Japan; 3 Digital Human Research Center, National Institute of Advanced Industrial Science and Technology,
Tokyo, Japan
This study was undertaken to develop a method for generating the maps of Youngfs elastic modulus using tagged MRI. The maps
were generated using the strain obtained by harmonic phase analysis and stress distribution. The accuracy of our method was
investigated using silicone phantoms of different hardness. There was a good correlation between the strain obtained by our method
and that measured using a material testing machine (r=0.99). The difference in hardness in phantoms was clearly demonstrated. Our
method will be useful for evaluating the tissue elasticity, because it allows us to automatically generate the maps of elastic modulus.
15:00 3402. Is a Velocity Encoding of 5 Cm/sec Sufficient to Quantify Brain Motion?
Guillaume Calmon 1,2 , Marc Labrousse, 1,3 , Gabriela Hossu 4 , Jacques Felblinger 1,4 , Marc
Braun 1,5
1 IADI, Nancy, France; 2 GE Healthcare, Buc, France; 3 CHU Reims, France; 4 INSERM CIT801, CIC-IT, Nancy,
France; 5 Nancy Université, Nancy, France
Brain motion during cardiac cycle, linked to the one of cerebro-spinal fluid (CSF), presents interesting challenges and can have an
interest to analyze brain “elastography”. In this study, we measured brain speed and motion in volunteers at the level of thalamus and
brain stem. A velocity encoding of 5 cm/sec was sufficient to obtain brain values consistent with literature. Absolute brain tissue
speeds were measured between 0.0002 and 0.17 cm/sec in thalami ROIs and between 0.0014 and 0.48 cm/sec in brain stem ROIs.
There was a decreased of motion with cardiac frequency and with age in certain territories.
15:30 3403. Gas Content Dependence in Magnetic Resonance Elastography of the Lungs
Marlies Friese 1,2 , Roberta Santarelli 2 , Lionel Martin 2 , Luc Darrasse 2 , Ralph Sinkus 3 ,
Xavier Maître 2
1 Center for Magnetic Resonance, The University of Queensland, Brisbane, Queensland, Australia; 2 Imagerie par
Résonance Magnétique et MultiModalités (UMR8081), Univ Paris-Sud, CNRS, Orsay, France; 3 Institut
Langevin (UMR 7587), ESPCI, Univ Denis Diderot, CNRS, Paris, France
Magnetic resonance elastography is performed in a pig lung inflated with three different gases, helium-4 (4He), air and sulphur
hexafluoride (SF6), in a phantom designed for voxel-by-voxel comparison. Proton MRI morphology and computed l, Gd and Gl
maps were compared on a voxel-by-voxel basis by computing mean differences between corresponding voxels. Voxel-by-voxel
comparison of Morphology data and l values shows good agreement between air/4He, Air/Air and Air/SF6 measurements while Gd
and Gl values agree less well. Global values of Gl, Gd and l are in excellent agreement for the different gases, showing gas density
does not affect MRE measurement.