System and method for focusing of high intensity focused ultrasound based on magnetic resonance—acoustic radiation force imaging feedback

摘要

A system and method for focusing ultrasound into a target tissue is disclosed. The method calculates a pressure field for an array of transducer elements to generate an unaberrated pressure field matrix and causes the transducer elements to apply focused ultrasound to generate a respective aberrated pressure field at a focus location in a target tissue and surrounding volume. MR-ARFI images are acquired of the focus location and surrounding volume, a magnitude of the aberrated pressure field is measured that is generated by the applied focused ultrasound at respective focus locations in the target tissue and surrounding volume based on the MR-ARFI images, an aberration for the transducer elements is determined from the pressure field matrix and the MR-ARFI images of the focus location and the surrounding volume using a magnitude least-squares method, and a corrective phase/amplitude adjustment is applied to the transducer elements based on the determined aberrations.

主权项

1. A system for focusing ultrasound into a target tissue of a subject, the system comprising:
a phased array of ultrasound transducer elements configured to generate an ultrasound focus in the target tissue; a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet, and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images; and a computer operatively connected to the phased array of ultrasound transducer elements and the MRI system, the computer programmed to:
calculate a pressure field for each transducer element in the phased array of ultrasound transducer elements to generate an unaberrated pressure field matrix;cause the phased array of ultrasound transducer elements to apply focused ultrasound to the target tissue, wherein application of focused ultrasound by each transducer element of the phased array of ultrasound transducer elements generates a respective aberrated pressure field at a focus location in the target tissue and in a volume surrounding the focus location;cause the MRI system to acquire magnetic resonance acoustic radiation force impulse (MR-ARFI) images of the focus location and the surrounding volume;based on the MR-ARFI images, measure a magnitude of the aberrated pressure field generated by the applied focused ultrasound from each transducer element of the phased array of ultrasound transducer elements at its respective focus location in the target tissue and in the volume surrounding the focus location;determine an aberration for each transducer element of the phased array of ultrasound transducer elements from the pressure field matrix and the MR-ARFI images of the focus location and the surrounding volume using a magnitude least-squares method; andapply at least one of corrective phase adjustment and a corrective amplitude adjustment to each transducer element in the phased array of ultrasound transducer elements based on the determined aberration for each respective element.