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Abstract #4134

Optimal Ultrasonic Focusing Through Strongly Aberrating Media Using Radiation Force Magnetic Resonance Guidance

Benoit Larrat1, Mathieu Pernot2, Laurent Marsac3, Benjamin Robert3, Gabriel Montaldo1, Jean-Franois Aubry1, Mathias Fink1, Mickael Tanter2

1ESPCI Paristech - Institut Langevin, CNRS UMR 7587, Paris, France; 2ESPCI Paristech - Institut Langevin, INSERM, Paris, France; 3SuperSonic Imagine, Aix en Provence, France

The non invasive correction of phase aberrations of ultrasonic waves is mandatory in the framework of human transcranial brain High Intensity Focused Ultrasound (HIFU) therapy at relatively high frequency (> 500 kHz). This study proposes an adaptive focusing technique based on the measurement of the acoustic intensity at the focus via MRI. The main objective is here to demonstrate the ability of acoustic radiation force MR imaging to learn experimentally how to correct strong medium aberrations with a few ultrasonic transmissions. Sharp focal spots and optimal acoustic energies are restored through several aberrating layers.