title: Optical tracking of acoustic radiation force impulse-induced dynamics in a tissue-mimicking phantom.
abstract: Optical tracking was utilized to investigate the acoustic radiation force impulse (ARFI)-induced response, generated by a 5-MHz piston transducer, in a translucent tissue-mimicking phantom. Suspended 10-microm microspheres were tracked axially and laterally at multiple locations throughout the field of view of an optical microscope with 0.5-microm displacement resolution, in both dimensions, and at frame rates of up to 36 kHz. Induced dynamics were successfully captured before, during, and after the ARFI excitation at depths of up to 4.8 mm from the phantom's proximal boundary. Results are presented for tracked axial and lateral displacements resulting from on-axis and off-axis (i.e., shear wave) acquisitions; these results are compared to matched finite element method modeling and independent ultrasonically based empirical results and yielded reasonable agreement in most cases. A shear wave reflection, generated by the proximal boundary, consistently produced an artifact in tracked displacement data later in time (i.e., after the initial ARFI-induced displacement peak). This tracking method provides high-frame-rate, two-dimensional tracking data and thus could prove useful in the investigation of complex ARFI-induced dynamics in controlled experimental settings.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA. rrb@duke.edu
authors.forename: Richard R
authors.initials: RR
authors.lastname: Bouchard
authors.forename: Mark L
authors.initials: ML
authors.lastname: Palmeri
authors.forename: Gianmarco F
authors.initials: GF
authors.lastname: Pinton
authors.forename: Gregg E
authors.initials: GE
authors.lastname: Trahey
authors.forename: Jason E
authors.initials: JE
authors.lastname: Streeter
authors.forename: Paul A
authors.initials: PA
authors.lastname: Dayton
mesh_terms: D016477:Artifacts; D004547:Elastic Tissue / Q000000981:diagnostic imaging*; D004548:Elasticity; D005780:Gelatin; D033401:Microscopy, Acoustic / Q000295:instrumentation*; D008863:Microspheres; D008954:Models, Biological; D019047:Phantoms, Imaging; D014159:Transducers; D014465:Ultrasonics
chemical_list: D005780:Gelatin