Title :
Design and Experimental Evaluations of a Low-Frequency Hemispherical Ultrasound Phased-Array System for Transcranial Blood–Brain Barrier Disruption
Author :
Liu, Hao-Li ; Chen, Heng-Wen ; Kuo, Zhen-Hao ; Huang, Wen-Cheng
Author_Institution :
Dept. of Electr. Eng., Chang-Gung Univ., Taoyuan
Abstract :
The purpose of this paper is to demonstrate a prototype design of a low-frequency multiple-channel hemispherical focused-ultrasound phased-array system for transcranial disruption of the blood-brain barrier (BBB). A 32-channel ultrasound driving system tunable in the frequency range from 200 to 400 kHz was designed for producing a suitable ultrasound output for BBB disruption. The driving system includes a microcontroller/field-programmable gate-array-based control kernel with multiple-channel driving circuits implemented by a high-voltage switching/LC-resonance/impedance-matching circuit module. Three hemispherical phased arrays comprising 22, 31, and 80 elements were fabricated and tested. The pressure distributions at the geometric center and at off-center positions were tested experimentally. The focal performance of the different hemispherical arrays was also evaluated theoretically. The results showed that the developed phased-array system can successfully drive the hemispherical array with multiple-channel ultrasound signals with independent phase control at 8-bit resolution. Good focusing abilities were evident both at the geometric center and at specific off-center target positions. Preliminary animal experiments show that the BBB in rat can be locally disrupted successfully. The system will serve as a reference platform for developing a focused-ultrasound system for clinical use in brain drug delivery applications.
Keywords :
biochemistry; biomedical electronics; biomedical ultrasonics; blood; brain; drug delivery systems; field programmable gate arrays; impedance matching; microcontrollers; ultrasonic focusing; ultrasonic transducer arrays; LC-resonance circuit; brain drug delivery; field-programmable gate-array; focused-ultrasound phased-array system; frequency 200 kHz to 400 kHz; geometric center; high-voltage switching module; impedance-matching circuit module; independent phase control; low-frequency multiple-channel hemispherical system; microcontroller; off-center target position; pressure distributions; transcranial blood-brain barrier disruption; ultrasound driving circuits; Circuit testing; Control systems; Frequency; Kernel; Microcontrollers; Phased arrays; Prototypes; Switching circuits; Tunable circuits and devices; Ultrasonic imaging; Biomedical ultrasonics; Brain; Drug delivery systems; brain; drug delivery systems; Animals; Blood-Brain Barrier; Capillary Permeability; Computer Simulation; Electromagnetic Phenomena; Equipment Design; Equipment Failure Analysis; Male; Phonophoresis; Rats; Therapy, Computer-Assisted; Ultrasonic Therapy;
Journal_Title :
Biomedical Engineering, IEEE Transactions on
DOI :
10.1109/TBME.2008.925697