Experimental assessment of phase aberration correction for breast MRgFUS therapy.

Purpose: This study validates that phase aberrations in breast magnetic resonance-guided focussed ultrasound (MRgFUS) therapies can be corrected in a clinically relevant time frame to generate more intense, smaller and more spatially accurate foci.

Materials And Methods: Hybrid angular spectrum (HAS) ultrasound calculations in an magnetic resonance imaging (MRI)-based tissue model, were used to compute phase aberration corrections for improved experimental MRgFUS heating in four heterogeneous breast-mimicking phantoms (n = 18 total locations). Magnetic resonance(MR) temperature imaging was used to evaluate the maximum temperature rise, focus volume and focus accuracy for uncorrected and phase aberration-corrected sonications.

Rapid full-wave phase aberration correction method for transcranial high-intensity focused ultrasound therapies.

Background: Non-invasive high-intensity focused ultrasound (HIFU) can be used to treat a variety of disorders, including those in the brain. However, the differences in acoustic properties between the skull and the surrounding soft tissue cause aberrations in the path of the ultrasonic beam, hindering or preventing treatment.

Methods: We present a method for correcting these aberrations that is fast, full-wave, and allows for corrections at multiple treatment locations.

MR thermometry for focused ultrasound monitoring utilizing model predictive filtering and ultrasound beam modeling.

Background: A major challenge in using magnetic resonance temperature imaging (MRTI) to monitor focused ultrasound (FUS) applications is achieving high spatio-temporal resolution over a large field of view (FOV). This is important to accurately monitor all ultrasound (US) power depositions. Magnetic resonance (MR) subsampling in conjunction with thermal model-based reconstruction of the MRTI utilizing Pennes bioheat transfer equation (PBTE) is one promising approach.

Phase aberration simulation study of MRgFUS breast treatments.

Purpose: This simulation study evaluates the effects of phase aberration in breast MR-guided focused ultrasound (MRgFUS) ablation treatments performed with a phased-array transducer positioned laterally to the breast. A quantification of these effects in terms of thermal dose delivery and the potential benefits of phase correction is demonstrated in four heterogeneous breast numerical models.

Methods: To evaluate the effects of varying breast tissue properties on the quality of the focus, four female volunteers with confirmed benign fibroadenomas were imaged using 3T MRI.

A full-wave phase aberration correction method for transcranial high-intensity focused ultrasound brain therapies.

Transcranial high-intensity focused ultrasound has recently been used to noninvasively treat several types of brain disorders. However, due to the large differences in acoustic properties of skulls and the surrounding soft tissue, it can be a challenge to adequately focus an ultrasonic beam through the skull. We present a novel, fast, full-wave method of correcting the aberrations caused by the skull by phasing the elements of a phased-array transducer to create constructive interference at the target.

Treatment envelope evaluation in transcranial magnetic resonance-guided focused ultrasound utilizing 3D MR thermometry.

Background: Current clinical targets for transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) are all located close to the geometric center of the skull convexity, which minimizes challenges related to focusing the ultrasound through the skull bone. Non-central targets will have to be reached to treat a wider variety of neurological disorders and solid tumors. Treatment envelope studies utilizing two-dimensional (2D) magnetic resonance (MR) thermometry have previously been performed to determine the regions in which therapeutic levels of FUS can currently be delivered.