title: Temperature estimation using ultrasonic spatial compound imaging.
abstract: The feasibility of temperature estimation during high-intensity focused ultrasound therapy using pulse-echo diagnostic ultrasound data has been demonstrated. This method is based upon the measurement of thermally-induced modifications in backscattered RF echoes due to thermal expansion and local changes in the speed of sound. It has been shown that strong ripple artifacts due to the thermo-acoustic lens effect severely corrupt the temperature estimates behind the heated region. We propose here a new imaging technique that improves the temperature estimation behind the heated region and reduces the variance of the temperature estimates in the entire image. We replaced the conventional beamforming on transmit with multiple steered plane wave insonifications using several subapertures. A two-dimensional temperature map is estimated from axial displacement maps between consecutive RF images of identically steered plane wave insonifications. Temperature estimation is then improved by averaging the two-dimensional maps from the multiple steered plane wave insonifications. Experiments were conducted in a tissue-mimicking gelatin-based phantom and in fresh bovine liver.
authors.affiliation: Laboratoire Ondes et Acoustique, ESPCI, Université Paris VII, U.M.R. C.N.R.S. 7587, 10 rue Vauquelin, 75005 Paris, France. mathieu.pernot@loa.espci.fr
authors.forename: Matlieu
authors.initials: M
authors.lastname: Pernot
authors.forename: Mickael
authors.initials: M
authors.lastname: Tanter
authors.forename: Jeremy
authors.initials: J
authors.lastname: Bercoff
authors.forename: Kendall R
authors.initials: KR
authors.lastname: Waters
authors.forename: Mathias
authors.initials: M
authors.lastname: Fink
mesh_terms: D000818:Animals; D016477:Artifacts; D001831:Body Temperature / Q000502:physiology* / Q000528:radiation effects; D002417:Cattle; D003238:Connective Tissue / Q000000981:diagnostic imaging / Q000502:physiology; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D066298:In Vitro Techniques; D008099:Liver / Q000000981:diagnostic imaging* / Q000502:physiology*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013817:Thermography / Q000295:instrumentation / Q000379:methods*; D014464:Ultrasonic Therapy / Q000379:methods*; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods*