title: Computed ultrasound tomography in echo mode for imaging speed of sound using pulse-echo sonography: proof of principle.
abstract: The limitations of diagnostic echo ultrasound have motivated research into novel modalities that complement ultrasound in a multimodal device. One promising candidate is speed of sound imaging, which has been found to reveal structural changes in diseased tissue. Transmission ultrasound tomography shows speed of sound spatially resolved, but is limited to the acoustically transparent breast. We present a novel method by which speed-of-sound imaging is possible using classic pulse-echo equipment, facilitating new clinical applications and the combination with state-of-the art diagnostic ultrasound. Pulse-echo images are reconstructed while scanning the tissue under various angles using transmit beam steering. Differences in average sound speed along different transmit directions are reflected in the local echo phase, which allows a 2-D reconstruction of the sound speed. In the present proof-of-principle study, we describe a contrast resolution of 0.6% of average sound speed and a spatial resolution of 1 mm (laterally) × 3 mm (axially), suitable for diagnostic applications.
authors.affiliation: Institute of Applied Physics, University of Bern, Bern, Switzerland. Electronic address: Michael.Jaeger@iap.unibe.ch.
authors.forename: Michael
authors.initials: M
authors.lastname: Jaeger
authors.affiliation: Institute of Applied Physics, University of Bern, Bern, Switzerland.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Held
authors.affiliation: Institute of Applied Physics, University of Bern, Bern, Switzerland.
authors.forename: Sara
authors.initials: S
authors.lastname: Peeters
authors.affiliation: Institute of Applied Physics, University of Bern, Bern, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Preisser
authors.affiliation: Institute of Applied Physics, University of Bern, Bern, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Grünig
authors.affiliation: Institute of Applied Physics, University of Bern, Bern, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Frenz
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014054:Tomography / Q000295:instrumentation / Q000379:methods*; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods*
keywords: Aberration correction; Diagnostic imaging; Multimodal imaging; Speed of sound; Ultrasound tomography