Estimation of ultrasound tissue attenuation along the propagation path by applying multiple filters to the backscattered echoes

Abstract

Quantifying the correlation length of the tissue microstructure has shown potential for diagnosing between benign and malignant tumors. In order to implement these advances in the clinic, the total frequency dependent attenuation along the propagation path must be determined on a patient specific basis. Previously, an algorithm was developed to estimate this attenuation using echoes from multiple sources. In this study, the developed algorithm was extended to echoes from a single source by filtering the echoed signal into multiple frequency bands. This step was needed because it would be challenging to scan exactly the same tissue region using multiple sources in the clinic. Computer simulations were conducted to verify the attenuation could be determined by filtering the echoes from a single source. The simulations utilized a spherically focused single element source (5 cm focal length, f/4, 14 MHz center frequency, 50% bandwidth) exposing a homogeneous tissue region. The simulated tissue had Gaussian scattering structures with effective radii of 5 to 55 ¿m (one size per simulated case) placed at a density of 250/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (~5 scatterers/resolution cell for 14 MHz transducer). The attenuation of the tissue was also varied from 0.1 to 0.9 dB/cm-MHz. The simulations explored the dependence on scatterer size, attenuation, and region of interest (ROI) size. The computer simulations confirmed that the total attenuation along the propagation path can be determined by appropriately applying multiple filters to the backscattered echoes from a single source.