Implementation and repeatability of preclinical continuous vibration shear wave elastography.

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Cancer Research

Background:

• Tissue biomechanical properties are crucial in preclinical cancer research, reflecting treatment response.
• Small tumor size poses challenges for preclinical shear wave elastography (SWE) measurements.
• Assessing viscoelastic properties of tumors requires precise measurement techniques.

Purpose of the Study:

• To evaluate the repeatability of 3D shear wave speed (SWS) measurements using continuous harmonic vibrations.
• To investigate the impact of different conditions (frequency, orientation, anesthesia) on SWS repeatability in an in vivo preclinical tumor model.
• To establish the feasibility of SWE for in vivo preclinical tumor analysis.

Main Methods:

• Subcutaneous MDA-MB-231 tumors in athymic nude mice were imaged using a research ultrasound scanner with a 18 MHz linear probe.
• Shear waves were induced using external contactors at 500, 700, and 1000 Hz, with measurements taken from top and side orientations.
• Repeatability was assessed over three days using 3D tumor volume registration and normalized cross-correlation analysis of SWS data.

Main Results:

• Significant differences in mean SWS were observed between tumors and vibration frequencies (p<0.001).
• Mean SWS was unaffected by anesthesia type or tumor orientation.
• Improved day-to-day SWS repeatability was achieved with same-tumor, same-orientation measurements, particularly side orientation at 500 Hz.

Conclusions:

• 3D SWE with continuous vibration is a repeatable and feasible technique for in vivo preclinical research.
• Optimizing measurement conditions, such as orientation and frequency, enhances the repeatability of SWS data.
• The study validates SWE as a valuable tool for characterizing tumor biomechanics in preclinical settings.