title: 3-D real-time motion correction in high-intensity focused ultrasound therapy.
abstract: A method for tracking the 3-D motion of tissues in real-time is combined with a 2-D high-intensity focused ultrasound (US), or HIFU, multichannel system to correct for respiratory motion during HIFU therapy. Motion estimation is based on an accurate ultrasonic speckle-tracking method. A pulse-echo sequence is performed for a subset of the transducers of the phased array. For each of these subapertures, the displacement is estimated by computing the 1-D cross-correlation of the backscattered signals acquired at two different times. The 3-D motion vector is then computed by a triangulation algorithm. This technique is experimentally validated in phantoms moving as fast as 40 mm s(-1), and combined with HIFU sequences. A real-time feedback correction of the HIFU beam is achieved by adjusting the delays of each channel. The sonications "locked on target" are interleaved with very short motion-estimation sequences. Finally, in vitro experiments of "locked on target" HIFU therapy are performed in fresh moving tissues.
authors.affiliation: Laboratoire Ondes et Acoustique, ESPCI, Université Paris VII, Paris, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Pernot
authors.forename: Mickaël
authors.initials: M
authors.lastname: Tanter
authors.forename: Mathias
authors.initials: M
authors.lastname: Fink
mesh_terms: D000465:Algorithms; D000818:Animals; D002417:Cattle; D005246:Feedback; D008099:Liver / Q000000981:diagnostic imaging* / Q000473:pathology; D009038:Motion; D009336:Necrosis; D009369:Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy; D019047:Phantoms, Imaging; D014159:Transducers; D014464:Ultrasonic Therapy / Q000295:instrumentation* / Q000379:methods; D014465:Ultrasonics; D018084:Ultrasonography, Interventional / Q000379:methods