title: A simple method for MR elastography: a gradient-echo type multi-echo sequence.
abstract: To demonstrate the feasibility of a novel MR elastography (MRE) technique based on a conventional gradient-echo type multi-echo MR sequence which does not need additional bipolar magnetic field gradients (motion encoding gradient: MEG), yet is sensitive to vibration. In a gradient-echo type multi-echo MR sequence, several images are produced from each echo of the train with different echo times (TEs). If these echoes are synchronized with the vibration, each readout's gradient lobes achieve a MEG-like effect, and the later generated echo causes a greater MEG-like effect. The sequence was tested for the tissue-mimicking agarose gel phantoms and the psoas major muscles of healthy volunteers. It was confirmed that the readout gradient lobes caused an MEG-like effect and the later TE images had higher sensitivity to vibrations. The magnitude image of later generated echo suffered the T2 decay and the susceptibility artifacts, but the wave image and elastogram of later generated echo were unaffected by these effects. In in vivo experiments, this method was able to measure the mean shear modulus of the psoas major muscle. From the results of phantom experiments and volunteer studies, it was shown that this method has clinical application potential.
authors.affiliation: Department of Radiological Science, Graduate School of Human Health Science, Tokyo Metropolitan University, 7-2-10, Higashiogu, Arakawa-ku, Tokyo, Japan; Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST). Electronic address: t-numano@tmu.ac.jp.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Numano
authors.affiliation: Department of Mechanical Engineering, Tokyo Denki University.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Mizuhara
authors.affiliation: Department of Radiological Science, Graduate School of Human Health Science, Tokyo Metropolitan University, 7-2-10, Higashiogu, Arakawa-ku, Tokyo, Japan; The University of Tokyo Hospital.
authors.forename: Junichi
authors.initials: J
authors.lastname: Hata
authors.affiliation: Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST).
authors.forename: Toshikatsu
authors.initials: T
authors.lastname: Washio
authors.affiliation: Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST).
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Homma
mesh_terms: D016477:Artifacts; D054459:Elasticity Imaging Techniques / Q000379:methods*; D064368:Healthy Volunteers; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D060526:Magnetic Fields; D008297:Male; D009038:Motion; D018482:Muscle, Skeletal / Q000473:pathology*; D019047:Phantoms, Imaging; D012685:Sepharose / Q000737:chemistry; D033081:Shear Strength; D055815:Young Adult
chemical_list: D012685:Sepharose
keywords: MR elastography; Motion encoding gradient; Multi-echo sequence; Pneumatic vibration; Psoas major muscle; Synchronization