Acoustic attenuation imaging of tissue bulk properties with a priori information

Abstract

Attenuation of ultrasound waves traversing a medium is not only a result of absorption and scattering within a given tissue, but also of coherent scattering, including diffraction, refraction, and reflection of the acoustic wave at tissue boundaries. This leads to edge enhancement and other artifacts in most reconstruction algorithms, other than 3D wave migration with currently impractical, implementations. The presented approach accounts for energy loss at tissue boundaries by normalizing data based on variable sound speed, and potential density, of the medium using a k-space wave solver. Coupled with a priori knowledge of major sound speed distributions, physical attenuation values within broad ranges, and the assumption of homogeneity within segmented regions, an attenuation image representative of region bulk properties is constructed by solving a penalized weighted least squares optimization problem. This is in contradistinction to absorption or to conventional attenuation coefficient based on overall insertion loss with strong dependence on sound speed and impedance mismatches at tissue boundaries. This imaged property will be referred to as the bulk attenuation coefficient. The algorithm is demonstrated on an opposed array setup, with mean-squared-error improvements from 0.6269 to 0.0424 (dB/cm/MHz) 2 for a cylindrical phantom, and 0.1622 to 0.0256 (dB/cm/MHz) 2 for a windowed phantom.

Acoustic beam anomalies in automated breast imaging

“…[43][44][45] This could strongly reduce shadows at the edges of structures with smooth borders, such as suspensory ligaments, cysts, and fibroadenomas, revealing possible diagnostic information about poorly seen distal borders and providing more information about the attenuation properties of the tissues of the smooth-walled masses themselves, independent of their speed of sound differences with the surrounding material. 16,17 Shadow reduction might be less with the majority of invasive carcinomas, those having very diffuse borders.…”

“…In the past decade, there has been great demand for ultrasound in the United States for breast cancer screening as a supplement of x-ray mammography, since ultrasound can detect unsuspected, mammographically occult cancer, especially in radiographically dense breasts that have a higher risk of developing breast cancer. [2][3][4] Also, several tissue acoustical properties obtained from received ultrasound signals such as speed of sound, [5][6][7][8][9][10][11][12][13] attenuation, [8][9][10]12,[14][15][16][17] density, 18 and elasticity [19][20][21] can be used for characterizing different tissue types as they tend to have different acoustic properties. The ability of ultrasonic imaging to characterize tissues, particularly the differentiation of malignant lesions from benign tissues, shows promise in decreasing the number of breast biopsies needed for adequate diagnosis.…”

A Phantom-free Method to Image the Ultrasound Attenuation Coefficient Slope Using Decorrelated Compounding in Synthetic Transmit Aperture Ultrasound Imaging

“…These fluctuations can arise due to the differences in the acoustic properties and scattering characteristics of the two materials, resulting in variations in the attenuation values along the interface. Additionally, the presence of interfaces can lead to partial reflection and refraction of the ultrasound waves, causing interference patterns and resulting in attenuation variations [35]. One approach to handle this challenge is to estimate the attenuation and tissue backscattering coefficients simultaneously, as shown in B-mode in [26].…”

Numerical investigations on phase-diversity optical digital coherent receiver-based noncontact photoacoustic signal detection

“…By applying the model in Fig. 3, a small displacement on the sample surface induced by the pressure of the PA waves is obtained with a consideration of 10-dB acoustic diffraction propagation loss in the simulation (3.2 dB/cm/MHz acoustic attenuation [22] and 6.5 MHz PA wave [23]). The displacement Δ𝐷 𝑡 can be expressed as [24][25][26][27] Δ𝐷 𝑡 ∝ 𝛥𝑉 𝑡 ∝ 𝑃 𝑡 ∝ 𝛥𝑇 𝑡 , (8) where 𝛥𝑉 𝑡 is the expanded volume, 𝑃 𝑡 is the applied pressure by the PA wave.…”