Plantar Soft Tissue Characterization Using Reverberant Shear Wave Elastography: A Proof-of-Concept Study

S.E. Romero, R. Naemi, G. Flores, D. Allan, J. Ormachea, E. Gutierrez, F.L. Casado, B. Castaneda

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1 Citation (Scopus)

Abstract

Plantar soft tissue stiffness provides relevant information on biomechanical characteristics of the foot. Therefore, appropriate monitoring of foot elasticity could be useful for diagnosis, treatment or health care of people with complex pathologies such as a diabetic foot. In this work, the reliability of reverberant shear wave elastography (RSWE) applied to plantar soft tissue was investigated. Shear wave speed (SWS) measurements were estimated at the plantar soft tissue at the first metatarsal head, the third metatarsal head and the heel from both feet in five healthy volunteers. Experiments were repeated for a test–retest analysis with and without the use of gel pad using a mechanical excitation frequency range between 400 and 600 Hz. Statistical analysis was performed to evaluate the reliability of the SWS estimations. In addition, the results were compared against those obtained with a commercially available shear wave-based elastography technique, supersonic imaging (SSI). The results indicate a low coefficient of variation for test–retest experiments with gel pad (median: 5.59%) and without gel pad (median: 5.83%). Additionally, the values of the SWS measurements increase at higher frequencies (median values: 2.11 m/s at 400 Hz, 2.16 m/s at 450 Hz, 2.24 m/s at 500 Hz, 2.21 m/s at 550 Hz and 2.31 m/s at 600 Hz), consistent with previous reports at lower frequencies. The SWSs at the plantar soft tissue at the first metatarsal head, third metatarsal head and heel were found be significantly (p<0.05) different, with median values of 2.42, 2.16 and 2.03 m/s, respectively which indicates the ability of the method to differentiate between shear wave speeds at different anatomical locations. The results indicated better elastographic signal-to-noise ratios with RSWE compared to SSI because of the artifacts presented in the SWS generation. These preliminary results indicate that the RSWE approach can be used to estimate the plantar soft tissue elasticity, which may have great potential to better evaluate changes in biomechanical characteristics of the foot.

Original languageEnglish
Pages (from-to)35-46
Number of pages12
JournalUltrasound in Medicine and Biology
Volume48
Issue number1
Early online date23 Oct 2021
DOIs
Publication statusPublished online - 23 Oct 2021

Bibliographical note

Funding Information:
This work was funded by the Binational UK–PERU Newton–Paulet Fund administered by the Fondo Nacional de Desarrollo Cientifico y Tecnologico-PERU under Grant 232-2018-FONDECYT from the Peruvian government. In particular, Stefano Romero was under the doctoral scholarship program in Computer Science (174-2020-FONDECYT-PUCP). In addition, Benjamin Castaneda was supported by the PUCP Research Award Period.

Funding Information:
We are grateful to Elastance Imaging for the loan of the vibration sources equipment. We also thank Dr. Kevin J. Parker for his technical suggestions and advice regarding the reverberant shear wave elastography approach. This work was funded by the Binational UK?PERU Newton?Paulet Fund administered by the Fondo Nacional de Desarrollo Cientifico y Tecnologico-PERU under Grant 232-2018-FONDECYT from the Peruvian government. In particular, Stefano Romero was under the doctoral scholarship program in Computer Science (174-2020-FONDECYT-PUCP). In addition, Benjamin Castaneda was supported by the PUCP Research Award Period. The authors declare that they have no conflicts of interest.

Publisher Copyright:
© 2021 World Federation for Ultrasound in Medicine & Biology

Keywords

  • Elastography
  • Plantar soft tissue
  • Reverberant shear wave field
  • Shear wave
  • Ultrasound

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