Estimation of the surface mechanical properties of soft tissues mimicking phantoms using impact analyses: a comparative study

TL;DR

This study compares an impact-based analysis method (IBAM) with other techniques for non-invasively assessing the mechanical properties of soft tissue phantoms, showing IBAM's superior sensitivity and potential for clinical applications.

Contribution

The paper introduces and evaluates IBAM, a novel impact-based technique, demonstrating its improved sensitivity over existing methods for soft tissue mechanical property assessment.

Findings

IBAM outperforms other methods in stiffness discrimination.

IBAM shows 2.5 to 4.5 times better sensitivity to tissue variations.

Cutometer's measurement depth is severely limited.

Abstract

Background: Palpation is the most widely used approach to empirically assess the mechanical properties of superficial tissues. While elastography is used for volume measurements, it remains difficult to assess skin properties with non-invasive methods. This study aimed to compare the performances of an impact-based analysis method (IBAM) consisting in studying the dynamic response of a punch in contact with the tissue with other approaches available on the market. Materials and Methods: IBAM consists in analyzing the time dependent force signal induced when a hammer instrumented with a force sensor impacts a cylindrical punch placed in contact with soft tissue. Sensitivities to stiffness changes and to spatial variations were compared between IBAM and four other mechanical surface characterization techniques: IndentoPro (macroindentation), Cutometer (suction), MyotonPro (damped oscillation) and Shore Durometer (durometry) using soft tissue phantoms based on polyurethane gel. Results: For stiffness discrimination in homogeneous phantoms, IBAM was slightly better than IndentoPro and MyotonPro (by 20 % and 35 % respectively), and outperformed the Shore Durometer and Cutometer by a factor of 2 to 4. Furthermore, for stiffness and thickness variations in bilayer phantoms, the axial sensitivity of IBAM was between 2.5 and 4.5 times better than that of MyotonPro and IndentoPro. In addition, the Cutometer appeared to be severely limited by its measurement depth. Conclusion: IBAM seems to be a promising technique for characterizing the mechanical properties of soft tissue phantoms at relatively low depth after future ex vivo and in vivo validation studies with biological tissues (with both animal and in human experiments). This work could pave the way to the development of a decision support system in the field of dermatology and cosmetics.