MR Guidance, Monitoring and Control of Brain Focused Ultrasound Therapy: In Vivo Demonstration in Rats at 7T

Benoit Larrat¹, Mathieu Pernot¹, Elvis Dervishi², Danielle Seilhean², Yannick Marie², Anne-Laure Boch², Jean-Franois Aubry¹, Mathias Fink¹, Mickael Tanter¹

A complete therapeutic workflow is developed to induce necrosis in the rat brain using a focused ultrasonic transducer under the guidance and monitoring of a 7T MR system. Three sequences are combined to monitor the procedure at different steps. Before the treatment, acoustic radiation force imaging shows the ability to accurately locate the focal spot in vivo. Furthermore, the MR signal is shown to provide a reliable quantification of the maximum acoustic pressure in situ. Then, the heating step is followed up via MR-thermometry. Finally, MR-Elastography.is evaluated as a tool to assess necrosis. 15 rats with and without injected tumors are treated. Induced lesions are confirmed at histology.