Mitigating high frame rate demands in shear wave elastography using radial basis function-based reconstruction: An experimental phantom study.

Abstract

Background: Shear wave elastography (SWE) is a technique that quantifies tissue stiffness by assessing the speed of shear waves propagating after being excited by acoustic radiation force. SWE allows the quantification of elastic tissue properties and serves as an adjunct to conventional ultrasound techniques, aiding in tissue characterization. To capture this transient propagation of the shear wave, the ultrasound device must be able to reach very high frame rates.

Methodology: In this paper, our aim is to relax the high frame rate requirement for SWE imaging. To this end, we propose lower frame rate SWE imaging followed by employing a 2-dimensional (2D) radial basis functions (RBF)-based interpolation. More specifically, the process involves obtaining low frame rate data and then temporal upsampling to reach a synthetic high frame rate data by inserting the 'UpS-1' image frames with missing values between two successive image frames (UpS: Upsampling rate). Finally, we apply the proposed interpolation technique to reconstruct the missing values within the incomplete high frame rate data.

Results and conclusion: The results obtained from employing the proposed model on two experimental datasets indicate that we can relax the frame rate requirement of SWE imaging by a factor of 4 while maintaining shear wave speed (SWS), group velocity, and phase velocity estimates closely align with the high frame rate SWE model so that the error is less than 3%. Furthermore, analysis of the structural similarity index (SSIM) and root mean squared error (RMSE) on the 2D-SWS maps highlights the efficacy of the suggested technique in enhancing local SWS estimates, even at a downsampling (DS) factor of 4. For DS≤4, the SSIM values between the 2D-SWS maps produced by the proposed technique and those generated by the original high frame rate data consistently remain above 0.94. Additionally, the RMSE values is below 0.37 m/s, indicating promising performance of the proposed technique in reconstruction of SWS values.