Feasibility study of the application of magnetic resonance elastography (MRE) to measure oral posture related changes in stiffness of zygomaticus major muscle

Emi Hojo; Kevin J Glaser; Ayako Harada-Hayashi; Yuan Le; Jun Chen; Thomas C Hulshizer; Phillip J Rossman; Sachiko Noyori; Neil Roberts

doi:10.1016/j.mri.2024.05.005

Feasibility study of the application of magnetic resonance elastography (MRE) to measure oral posture related changes in stiffness of zygomaticus major muscle

Magn Reson Imaging. 2024 May 7:111:196-201. doi: 10.1016/j.mri.2024.05.005. Online ahead of print.

Authors

Emi Hojo¹, Kevin J Glaser², Ayako Harada-Hayashi³, Yuan Le², Jun Chen⁴, Thomas C Hulshizer², Phillip J Rossman², Sachiko Noyori³, Neil Roberts⁵

Affiliations

¹ Centre for Reproductive Health (CRH), Institute for Regeneration and Repair (IRR), 4-5 Little France Drive, Edinburgh EH16 4UU, UK; Department of Radiology, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
² Department of Radiology, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
³ Rohto Pharmaceutical Company, 1-8-1, Tatsumi-nishi, Ikunoku, Osaka 544-8666, Japan.
⁴ Department of Radiology, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA; Department of Radiology, Nanjing Drum Tower Hospital, 321 Zhongshan Rd, Gulou, Nanjing, Jiangsu 210008, China; Resoundant, Inc., 421 1st Ave SW, Rochester, MN, USA.
⁵ Centre for Reproductive Health (CRH), Institute for Regeneration and Repair (IRR), 4-5 Little France Drive, Edinburgh EH16 4UU, UK. Electronic address: neil.roberts@ed.ac.uk.

PMID: 38723783
DOI: 10.1016/j.mri.2024.05.005

Abstract

Purpose: Development of a technique for measuring the mechanical properties of zygomaticus major (ZM) may aid advances in clinical treatments for correcting abnormal oral posture. The objective of this work was to demonstrate the feasibility of measuring the stiffness of ZM using an MR elastography technique that incorporates a custom local driver and a phase-gradient (PG) inversion.

Methods: 2D MRE investigations were performed for 3 healthy subjects using a vibration frequency of 90 Hz to test the prediction that the stiffness of ZM would be greater in the mouth-open compared to the mouth-closed position. MRE wave images were acquired along the long axis of ZM and processed using a 2D spatial-temporal directional filter applied in the direction of wave propagation along the long axis of the muscle. Stiffness measurements were obtained by applying the PG technique to a 1D-profile drawn in the phase image of the first harmonic of the wave images and a one-tailed paired t-test was used to compare the ZM stiffness between the two mouth postures (p < 0.05).

Results: The mean stiffness and standard deviation (SD) of ZM across the three participants in the mouth-closed and mouth-open postures was 6.75 kPa (SD 3.36 kPa) and 15.5 kPa (SD 5.15 kPa), respectively. Changes of ZM stiffness were significantly greater in the mouth-open than the mouth-closed posture (p = 0.038).

Conclusion: The feasibility of using the PG MRE technique to measure stiffness changes in a small muscle such as ZM for different mouth postures has been demonstrated. Further investigations are required in a larger cohort of participants to investigate the sensitivity and reproducibility of the technique for potential clinical application as well as in health and beauty related studies.

Keywords: Health and well-being; Magnetic resonance elastography (MRE); Muscle stiffness; Oral posture; Phase-gradient (PG) technique; Zygomaticus major (ZM).