Reverberant optical coherence elastography using 3D-printed randomly distributed scatterers: elasticity mapping of hydrogels in culture dishes.

Significance: Accurate estimation of hydrogel phantom elasticity in 3D cell culture systems provides valuable insights into cellular responses to various mechanical stimuli. Although reverberant wave elastography has been applied to measure hydrogel elasticity in 3D cell cultures using multi-point loading, achieving a high-quality reverberant displacement field remains critical for accurate reverberant wave elastography.

Aim: We develop an innovative approach using 3D-printed randomly distributed scatterers to improve displacement field quality in reverberant wave elastography, inspired by scattering-coded architectured boundaries in object localization.

Approach: Numerical simulations were performed to analyze the reverberant displacement fields under various loading conditions. The results were compared to determine the optimal loading configuration to enhance the reverberation level of the displacement field. Subsequently, both numerical and experimental reverberant wave elastography were carried out to validate the elasticity measurement with 3D-printed randomly distributed scatterers.

Results: The comparison of reverberant displacement patterns under various loading conditions revealed that the displacement pattern under circular loading with 64 scatterers most closely approximated a diffuse wave field, exhibiting both spatial uniformity and directional isotropy. Numerical reverberant wave elastography was subsequently performed, successfully demonstrating its capability for elasticity measurements. Furthermore, the shear wave speeds obtained through optical coherence elastography showed good agreement with shear rheometry measurements.

Conclusions: The developed 3D-printed randomly distributed scatterers successfully enhanced the quality of the reverberant displacement field for reverberant wave elastography. Our approach presents a novel and promising tool for quantifying tissue elasticity in reverberant wave elastography applications.