title: A new technique for MR elastography of the supraspinatus muscle: A gradient-echo type multi-echo sequence.
abstract: Magnetic resonance elastography (MRE) can measure tissue stiffness quantitatively and noninvasively. Supraspinatus muscle injury is a significant problem among throwing athletes. The purpose of this study was to develop an MRE technique for application to the supraspinatus muscle by using a conventional magnetic resonance imaging (MRI). MRE acquisitions were performed with a gradient-echo type multi-echo MR sequence at 100Hz pneumatic vibration. A custom-designed vibration pad was used as a pneumatic transducer in order to adapt to individual shoulder shapes. In a gradient-echo type multi-echo MR sequence, without motion encoding gradient (MEG) that synchronizes with vibrations, bipolar readout gradient lobes achieved a similar function to MEG (MEG-like effect). In other words, a dedicated MRE sequence (built-in MEG) is not always necessary for MRE. In this study, 7 healthy volunteers underwent MRE. We investigated the effects of direction of the MEG-like effect and selected imaging planes on the patterns of wave propagation (wave image). The results indicated that wave images showed clear wave propagation on a condition that the direction of the MEG-like effect was nearly perpendicular to the long axis of the supraspinatus muscle, and that the imaging plane was superior to the proximal supraspinatus muscle. This limited condition might be ascribed to specific features of fibers in the supraspinatus muscle and wave reflection from the boundaries of the supraspinous fossa. The mean stiffness of the supraspinatus muscle was 10.6±3.17kPa. Our results demonstrated that using MRE, our method can be applied to the supraspinatus muscle by using conventional MRI.
authors.affiliation: Department of Radiological Science, Graduate School of Human Health Science, Tokyo Metropolitan University, 7-2-10, Higashiogu, Arakawa-ku, Tokyo, Japan.
authors.forename: Daiki
authors.initials: D
authors.lastname: Ito
authors.affiliation: Department of Radiological Science, Graduate School of Human Health Science, Tokyo Metropolitan University, 7-2-10, Higashiogu, Arakawa-ku, Tokyo, Japan. 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 Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama.
authors.forename: Koichi
authors.initials: K
authors.lastname: Takamoto
authors.affiliation: Department of Radiological Science, Graduate School of Human Health Science, Tokyo Metropolitan University, 7-2-10, Higashiogu, Arakawa-ku, Tokyo, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Onishi
authors.affiliation: Department of Neurophysiotherapy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama; System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama.
authors.forename: Hisao
authors.initials: H
authors.lastname: Nishijo
mesh_terms: D000328:Adult; D054459:Elasticity Imaging Techniques / Q000379:methods*; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012016:Reference Values; D017006:Rotator Cuff / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: MR elastography; Muscle; Muscle fiber; Shoulder; Stiffness; Supraspinatus