Modulation of transcranial focusing thermal deposition in nonlinear HIFU brain surgery by numerical simulation

Abstract

As the skull induces strong aberrations in phase and amplitude during transcranial treatment of brain surgery, high-intensity focused ultrasound suffers degradation in beam shape and deposits significant heat in the skull which may cause thermal damage to the bone and surrounding tissue. The goal of this study is to optimize the transcranial pressure and thermal fields to reduce thermal damage to the skull and simultaneously concentrate more energy in the focal region and make its size controllable during transcranial brain tumor treatment by modulating the excitation signals of the transducer array (including the phase and amplitude) and superposing the signals used to reduce peak pressure in the skull. A 3D numerical model was developed based on the reconstructed images from high-resolution CT scans of a human skull and a 64-element phased array to simulate acoustic propagation and thermal behavior calculated by the finite-difference time domain method. The simulation showed that more energy was focused at the setting target with little temperature elevation in the skull after correcting phase and amplitude and reducing peak pressure in the skull; through modulating the input intensity of arrays, the volume of focal regions located off-axis could be made equal to the volume achieved with on-axis focusing.

The Effects of the Structural and Acoustic Parameters of the Skull Model on Transcranial Focused Ultrasound

“…Based on the self-programming simulation, we have already accurately reproduced the tFUS propagation through the skull [ 24 , 25 ]. Throughout the paper, the nonlinear Westervelt equation is used to describe acoustic fields in the simulation [ 26 , 27 ].…”

Modeling sequence and quasi-uniform assumption in computational neurostimulation

“…To accurately predict brain current flow produced during stimulation, one needs to specify the (1) relevant aspects of the stimulation device, and (2) relevant tissue properties; below we consider the relevant features each case. In this review, we focus on electrical stimulation, but in any form of energy application where the physics are well defined, then defining device and tissue properties should lead to straightforward prediction of energy dissipation in the body (Cho et al, 2010;Deng et al, 2014;Ding et al, 2015;Jagdeo et al, 2012;Lee et al, 2015;Wu et al, 2012).…”

The Influence of Transcranial Magnetoacoustic Stimulation Parameters on the Basal Ganglia-Thalamus Neural Network in Parkinson’s Disease

“…Based on the time reversal (TR) method ( Ding et al, 2015 ), place the pulse wave virtual point sound source S 0 ( t ) at the target focus F, as shown in Figure 2 ,…”

“…In mouse or rat animal experiments, because the mouse skull is very thin, it has little effect on the ultrasound transcranial focused sound pressure field, whereas the human skull is approximately 2.33–19.08 mm thick and has heterogeneity, which will distort the ultrasound transcranial focused sound pressure field. Unfavorable phenomena such as phase distortion and defocusing occur, which cause distortion of the focus position and the shape of the TMAS induced current ( Ding et al, 2015 ). In 2006, Yand et al recorded the frequency of EEG in adult mice at 24–42°C for 60 min, and found that brain tissue damage is reversible when the temperature is less than 40°C ( Yang and Qi, 2006 ).…”