In Vivo Quantification of the Nonlinear Shear Modulus in Breast Lesions: Feasibility Study

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Acoustics

Background:

• Early breast cancer detection is crucial for prognosis and treatment effectiveness.
• Existing methods rely on tissue mechanical properties, but novel techniques are needed.
• Nonlinear shear modulus (NLSM) is a potential biomarker for tissue characterization.

Purpose of the Study:

• To implement and validate a technique for measuring in vivo nonlinear shear modulus (NLSM).
• To assess the utility of NLSM for differentiating breast lesions from healthy tissue.
• To explore the application of acoustoelasticity theory in quasi-incompressible media for breast cancer diagnosis.

Main Methods:

• Combined static elastography and supersonic shear imaging to measure strain and shear modulus maps under compression.
• Utilized acoustoelasticity theory in quasi-incompressible media to calculate NLSM (μ(NL)).
• Developed nonlinear phantoms with biological tissue inclusions and conducted in vivo breast tissue acquisitions.

Main Results:

• Phantoms demonstrated clear differentiation of liver inclusions (mean μ(NL) -114.1 kPa) from gelatin (mean μ(NL) -34.7 kPa).
• In vivo measurements showed distinct NLSM values for healthy tissue (-95 kPa), benign lesions (-619 kPa), and malignant lesions (-806 kPa).
• The shear modulus values for phantoms were similar (3.7 kPa liver vs. 3.4 kPa gelatin), highlighting NLSM's unique diagnostic capability.

Conclusions:

• The implemented technique successfully measures in vivo NLSM.
• NLSM shows significant potential as a new diagnostic parameter for breast cancer detection.
• Acoustoelasticity in quasi-incompressible media offers a promising approach for improved breast lesion characterization.