Tissue characterization using backscatter and attenuation coefficients: theoretical developments and in vivo applications

Abstract

Conventional echographic imaging depicts anatomical structure by displaying the magnitude of backscattered ultrasound echoes. However, ultrasonic radiofrequency data contains a richer information content that can be exploited for constructing images of intrinsic tissue properties. In particular, spectral-based ultrasonic tissue characterization techniques allow imaging parameters such as the backscatter (BSC) and attenuation (AC) coefficients. Even though this type of analysis has been explored for decades, several challenges ranging from technical algorithmic issues to the lack of widely validated, successful clinical applications have limited efforts directed towards these imaging modalities. The formulation of BSC and AC estimation as a 2-D inverse problem in combination with regularization methods is discussed, and this approach is shown to significantly extend the trade-off between estimation precision and spatial resolution. Recent applications of BSC and AC estimation in vivo are also discussed, including the assessment of interstitial fibrosis and tubular atrophy (IFTA) and inflammation in renal allografts, the diagnosis of cervical lymph nodes, and the high frequency characterization of skin.Conventional echographic imaging depicts anatomical structure by displaying the magnitude of backscattered ultrasound echoes. However, ultrasonic radiofrequency data contains a richer information content that can be exploited for constructing images of intrinsic tissue properties. In particular, spectral-based ultrasonic tissue characterization techniques allow imaging parameters such as the backscatter (BSC) and attenuation (AC) coefficients. Even though this type of analysis has been explored for decades, several challenges ranging from technical algorithmic issues to the lack of widely validated, successful clinical applications have limited efforts directed towards these imaging modalities. The formulation of BSC and AC estimation as a 2-D inverse problem in combination with regularization methods is discussed, and this approach is shown to significantly extend the trade-off between estimation precision and spatial resolution. Recent applications of BSC and AC estimation in vivo are also discussed, in...