Local harmonic motion imaging guidance and monitoring for thermal surgery

Our goal is to develop a new imaging guidance and monitoring technique using ultrasound local harmonic motion (LHM) for thermal surgery. Local harmonic motion is induced by radiating the tissues with an amplitude modulated single-frequency ultrasound beam. Upon exposure, the tissues oscillate at the modulation frequency of the beam and, as the treatment progresses, the amplitude of the oscillation decreases. A separate ultrasound beam tracks the actual movement of the tissues in the focal zone. This technique could make monitoring of minimally invasive thermal and ultrasound therapies much less expensive than the current use of magnetic resonance imaging.

We have validated LHM in simulation (Heikkilä and Hynynen 2010) and in early in vivo testing (Curiel et al. 2009) in which LHM corresponded with magnetic resonance imaging displacement tracking (Huang et al. 2009). We are continuing to investigate the following:

• LHM performance in different types of tissues and near tissue-bone interfaces
• LHM with phased-array transducers through simulations.

Selected Publications:

1. Curiel L, Chopra R, and Hynynen K, "In vivo monitoring of focused ultrasound surgery using local harmonic motion," Ultrasound Med Biol. 2009 Jan;35(1):65-78. Epub 2008 Sep 21.
2. Curiel L, Huang Y, Vykhodtseva N, and Hynynen K, "Focused ultrasound treatment of VX2 tumors controlled by local harmonic motion," Phys Med Biol. 2009 Jun 7;54(11):3405-19. Epub 2009 May 13.
3. Huang Y, Curiel L, Kukic A, Plewes D, Chopra R, and Hynynen K, "MR acoustic radiation force imaging: in vivo comparison to ultrasound motion tracking," Med Phys. 2009 Jun;36(6):2016-20.
4. Heikkilä J, Curiel L, and Hynynen K, "Local Harmonic Motion Monitoring of Focused Ultrasound Surgery-A Simulation Model," IEEE Trans Biomed Eng. 2010 Jan;57(1):185-93. Epub 2009 Oct 9.