Transcranial High-Intensity Focused Ultrasound Therapies with ArrayFire

John Melonakos ArrayFire, Case Studies Leave a Comment

Researchers from the University of Utah recently used ArrayFire to publish results on a full-wave phase aberration correction method for transcranial high-intensity ultrasound therapies. From the Journal of Therapeutic Ultrasound, the following abstract summarizes the research:

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

The paper presents a method for correcting these aberrations that is fast, full-wave, and allows for corrections at multiple treatment locations. The method is simulation-based: an acoustic model is built based on high-resolution CT scans, and simulations are performed using the hybrid angular spectrum (HAS) method to determine the phases needed for correction.

Results

Computation of corrections for clinically applicable resolutions can be achieved in approximately 15 min. For fast computation that would be required in a clinical setting, each element’s pressure pattern is computed in parallel on an NVIDIA Tesla GPU with ArrayFire.

Experimental results with a plastic model designed to mimic the aberrations caused by the skull show that the method can recover 95 % of the peak pressure obtained using hydrophone-based time-reversal methods. Testing using an ex vivo human skull flap resulted in recovering up to 70 % of the peak pressure at the focus and 61 % when steering (representing, respectively, a 1.52- and 1.19-fold increase in the peak pressure over the uncorrected case). Additionally, combining the phase correction method with rapid HAS simulations allows evaluation of such treatment metrics as the effect of misregistration on resulting pressure levels.

The Aberrator Model Recovers the Peak Pressure at the Focus

Conclusions

The method presented here is able to rapidly compute phases required to improve ultrasound focusing through the skull at multiple treatment locations. Combining phase correction with rapid simulation techniques allows for the evaluation of various treatment metrics such as the effect of steering on pressure levels. Since the method computes 3D pressure patterns, it may also be suitable for predicting off-focus hot spots during treatments—a primary concern for transcranial HIFU. Additionally, the plastic-skull method presented here may be a useful tool in evaluating the effectiveness of phase correction methods.


ArrayFire is used in many different ultrasound applications, both through our open source library as well as through our consulting services. If you would like to learn more, email us at sales@arrayfire.com.

Thank you to these researchers for their work!

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