Application of Zernike polynomials towards accelerated adaptive focusing of transcranial high intensity focused ultrasound

Kaye, Elena; Hertzberg, Y.; Marx, Michael; Werner, Beat; Levoy, Marc; Pauly, Kim Butts

doi:10.1118/1.4752085

Cited by 30 publications

(37 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, recently proposed techniques for phase correction have been shown to result in higher intensity at the focus at the expense of longer time for correction compared to the current clinically used techniques. [37][38][39] For the acoustic parameters used as inputs to the simulation, we build on equations used previously for simulating acoustic beam propagation in the skull 12,25,34 and extend these equations for use in a large dataset. We model each voxel in the skull as a mixture of bone and water and calculate the bone fraction of each voxel of the skull.…”

Section: Discussionmentioning

confidence: 99%

Predicting variation in subject thermal response during transcranial magnetic resonance guided focused ultrasound surgery: Comparison in seventeen subject datasets

et al. 2016

Self Cite

View full text Add to dashboard Cite

Purpose: In transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) treatments, the acoustic and spatial heterogeneity of the skull cause reflection, absorption, and scattering of the acoustic beams. These effects depend on skull-specific parameters and can lead to patient-specific thermal responses to the same transducer power. In this work, the authors develop a simulation tool to help predict these different experimental responses using 3D heterogeneous tissue models based on the subject CT images. The authors then validate and compare the predicted skull efficiencies to an experimental metric based on the subject thermal responses during tcMRgFUS treatments in a dataset of seventeen human subjects. Methods: Seventeen human head CT scans were used to create tissue acoustic models, simulating the effects of reflection, absorption, and scattering of the acoustic beam as it propagates through a heterogeneous skull. The hybrid angular spectrum technique was used to model the acoustic beam propagation of the InSightec ExAblate 4000 head transducer for each subject, yielding maps of the specific absorption rate (SAR). The simulation assumed the transducer was geometrically focused to the thalamus of each subject, and the focal SAR at the target was used as a measure of the simulated skull efficiency. Experimental skull efficiency for each subject was calculated using the thermal temperature maps from the tcMRgFUS treatments. Axial temperature images (with no artifacts) were reconstructed with a single baseline, corrected using a referenceless algorithm. The experimental skull efficiency was calculated by dividing the reconstructed temperature rise 8.8 s after sonication by the applied acoustic power. Results: The simulated skull efficiency using individual-specific heterogeneous models predicts well (R 2 = 0.84) the experimental energy efficiency. Conclusions: This paper presents a simulation model to predict the variation in thermal responses measured in clinical ctMRGFYS treatments while being computationally feasible. C 2016 American Association of Physicists in Medicine. [http://dx

show abstract

Section: Discussionmentioning

confidence: 99%

Predicting variation in subject thermal response during transcranial magnetic resonance guided focused ultrasound surgery: Comparison in seventeen subject datasets

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…MR acoustic radiation force imaging (MR-ARFI) [63] is a recently developed technique that utilises MRI through motion-sensitive encoding MR gradients, similar to those used in MR elastography [64,65], to measure the micron-scale static tissue displacement induced by FUS waves as phase shifts in the resulting MR image [66,67]. Since this tissue displacement is proportional to the local acoustic intensity, i.e.…”

Section: Mr-arfi Techniquesmentioning

confidence: 99%

A review of numerical and experimental compensation techniques for skull-induced phase aberrations in transcranial focused ultrasound

Kyriakou

Neufeld

Werner

et al. 2013

International Journal of Hyperthermia

Self Cite

116

View full text Add to dashboard Cite

The development of phased array transducers and their integration with magnetic resonance (MR) guidance and thermal monitoring has established transcranial MR-guided focused ultrasound (tcMRgFUS) as an attractive non-invasive modality for neurosurgical interventions. The presence of the skull, however, compromises the efficiency of transcranial FUS (tcFUS) therapy, as its heterogeneous nature and acoustic characteristics induce significant phase aberrations and energy attenuation, especially at the higher acoustic frequencies employed in tcFUS thermal therapy. These aberrations may distort and shift the acoustic focus as well as induce heating at the patient's scalp and skull bone. Phased array transducers feature hundreds of elements that can be driven individually, each with its own phase and amplitude. This feature allows for compensation of skull-induced aberrations by calculation and application of appropriate phase and amplitude corrections. In this paper, we illustrate the importance of precise refocusing and provide a comprehensive review of the wide variety of numerical and experimental techniques that have been used to estimate these corrections.

show abstract

“…Clinical studies using focused ultrasound phased arrays to treat a range of diseases, including liver and kidney cancer [5], uterine fibroids [6], neuropathic pain [7], and essential tremor [8], [9], among others, have demonstrated the promise of focused ultrasound as a non-invasive treatment modality. As the use of focused ultrasound phased arrays continues to grow, increasing efforts have been expended in optimizing treatments and postulating methods for improved patient outcomes, including the use of quantitative temperature images to predict the optimal power for focused ultrasound surgery [10], the application of Zernike polynomials to adaptive focusing [11], optimizing thermal dose distribution using numerical models [12], investigating standing wave formation in transcranial focused ultrasound [13], and a study on the effect of near- and far-field heating on patient safety in uterine fibroid treatments [14]. In addition, new techniques have been introduced to control the acoustic field emitted from a phased array [15], [16].…”

Section: Introductionmentioning

confidence: 99%

A Tikhonov Regularization Scheme for Focus Rotations With Focused Ultrasound-Phased Arrays

Hughes

Hynynen

2016

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

View full text Add to dashboard Cite

Phased arrays have a wide range of applications in focused ultrasound therapy. By using an array of individually-driven transducer elements, it is possible to steer a focus through space electronically and compensate for acoustically heterogeneous media with phase delays. In this paper, the concept of focusing an ultrasound phased array is expanded to include a method to control the orientation of the focus using a Tikhonov regularization scheme. It is then shown that the Tikhonov regularization parameter used to solve the ill-posed focus rotation problem plays an important role in the balance between quality focusing and array efficiency. Finally, the technique is applied to the synthesis of multiple foci, showing that this method allows for multiple independent spatial rotations.

show abstract

Application of Zernike polynomials towards accelerated adaptive focusing of transcranial high intensity focused ultrasound

Cited by 30 publications

References 38 publications

Predicting variation in subject thermal response during transcranial magnetic resonance guided focused ultrasound surgery: Comparison in seventeen subject datasets

Predicting variation in subject thermal response during transcranial magnetic resonance guided focused ultrasound surgery: Comparison in seventeen subject datasets

A review of numerical and experimental compensation techniques for skull-induced phase aberrations in transcranial focused ultrasound

A Tikhonov Regularization Scheme for Focus Rotations With Focused Ultrasound-Phased Arrays

Contact Info

Product

Resources

About