Image-Guided Acoustic Therapy

Abstract

The potential role of therapeutic ultrasound in medicine is promising. Currently, medical devices are being developed that utilize high-intensity focused ultrasound as a noninvasive method to treat tumors and to stop bleeding (hemostasis). The primary advantage of ultrasound that lends the technique so readily to use in noninvasive therapy is its ability to penetrate deep into the body and deliver to a specific site thermal or mechanical energy with submillimeter accuracy. Realizing the full potential of acoustic therapy, however, requires precise targeting and monitoring. Fortunately, several imaging modalities can be utilized for this purpose, thus leading to the concept of image-guided acoustic therapy. This article presents a review of high-intensity focused ultrasound therapy, including its mechanisms of action, the imaging modalities used for guidance and monitoring, some current applications, and the requirements and technology associated with this exciting and promising field.

Controllable in vivo hyperthermia effect induced by pulsed high intensity focused ultrasound with low duty cycles

“…15 In the blood vessel domain, the blood flow field is composed by a fully developed parabolic flow, whose flow velocityũ in x direction isũ ¼ 2U 0 ½1 À ðr=r 0 Þ 2 , where U 0 is the average velocity, r is the radial distance from the flow axis, and r 0 is the vessel radius. The flow velocity in y and z direction is zero.…”

Thermal Therapy, Part IV: Electromagnetic and Thermal Dosimetry

“…However, high costs are associated with MRI and it requires a special environment that can hinder patient accessibility. 201 Magnetic resonance imaging is based on the principles of nuclear magnetic resonance (NMR), a spectroscopic technique used by scientists to obtain microscopic chemical and physical information about molecules. The technique was called MRI rather than NMR imaging (NMRI) because of the negative connotations associated with the word nuclear in the late 1970s.…”

“…It requires a special environment that can hinder patient accessibility and minimal use of metal parts in the therapy assembly is necessary to prevent distortion of the MRI trends. 201 Major current topics of study include the improvement of image quality in fast imaging, improvement of the accuracy of functional MRI (fMRI). Clinical applications of diffusion/perfusion imaging and the development of ultra-high magnetic fi eld devices with magnetic fi eld intensities above 10 T. 34 …”

Magnetic resonance imaging and model prediction for thermal ablation of tissue

“…We approximate this critical temperature as T C Ϸ 43°C (21). The probability function between P U ϭ 0 and P U ϭ 1 over a short distance interval provides a boundary between undamaged and damaged tissue associated with insufficient perfusion.…”

“…Simulation with this model requires a numerical solution of the partial differential equations based on the method of lines (21). The format and boundary conditions for the numerical solution are shown in Appendix B.…”