title: A consistent tissue attenuation coefficient estimator using bubble harmonic echoes.
abstract: The ultrasonic property of soft tissue can be quantified by its attenuation coefficient α. Traditionally the backscattering signal of tissue is used to estimate α. To improve precision, a large number of spatially independent samples of tissue echoes are required for averaging. In this paper, we propose a new estimation method, which makes use of microbubbles to provide temporally independent samples for averaging. It is easier for temporal sampling to maintain ergodicity and provide a large number of independent samples for statistical averaging. A stochastic model for the harmonic signals of an ideal bubble attenuated by tissue is derived based on Kuc's and Miller's works. An estimator of α is then presented. This estimator is consistent and could be biased because of the unknown squarelaw relation between the second and fundamental harmonics for non-ideal bubble oscillation. In experimental works, we design a simplified phantom for demonstrating the performance of the proposed estimator. It is shown that both first and second harmonics can estimate α consistently. However, the interference of the tissue backscattering signal may cause additional estimation error using the first harmonic.
authors.affiliation: National Taiwan University, Graduate Institute of Communication Engineering, Taipei, Taiwan.
authors.forename: Sheng-Kai
authors.initials: SK
authors.lastname: Tsao
authors.forename: Jenho
authors.initials: J
authors.lastname: Tsao
mesh_terms: D000465:Algorithms; D003287:Contrast Media; D045423:Microbubbles; D008954:Models, Biological; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted; D013269:Stochastic Processes; D014463:Ultrasonography / Q000379:methods*
chemical_list: D003287:Contrast Media