Histotripsy Produced by Hundred-Microsecond-Long Focused Ultrasonic Pulses: A Preliminary Study.
A new strategy is proposed in this study to rapidly generate mechanical homogenized lesions using hundred-microsecond-long pulses. The pulsing scheme was divided into two stages: generating sufficient bubble seed nuclei via acceleration by boiling bubbles and efficiently forming a mechanically homogenized and regularly shaped lesion with a homogenate inside via inertial cavitation. The duty cycle was set at 4.9%/3.9% in stage 1 and 1%/0.88% in stage 2 by changing the pulse duration (PD) and off-time independently. The pulse sequence was 500-μs/400-μs PD with a 100-Hz pulse repetition frequency (PRF) in stage 1, followed by 500-μs/400-μs PD with a 100-Hz PRF and 200-μs PD with a 200-Hz PRF in stage 2. Experiments were conducted on polyacrylamide phantoms with bovine serum albumin and on ex vivo porcine kidney tissues using a single-element 1.06-MHz transducer at an 8-MPa peak negative pressure with shock waves. The lesion evolution and dynamic elastic modulus variation in the phantoms and the histology in the tissue samples were investigated. The results indicate that the two-stage treatment using hundred-microsecond-long pulses can efficiently produce mechanically homogenized lesions with smooth borders, long tear shapes and the total homogenate inside. The time to generate a single mechanically homogenized lesion is shortened from >50 s to 17.1 s.
Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.
Yubo
Y
Guan
Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China. Electronic address: mzlu@mail.xjtu.edu.cn.
Mingzhu
M
Lu
Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.
Yujiao
Y
Li
Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.
Fenfen
F
Liu
Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.
Ya
Y
Gao
Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.
Tengju
T
Dong
Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.
Mingxi
M
Wan
D000818:Animals; D055119:Elastic Modulus; D007668:Kidney / Q000601:surgery*; D023421:Models, Animal; D019047:Phantoms, Imaging; D012709:Serum Albumin; D013552:Swine; D013995:Time; D014159:Transducers; D059708:Ultrasonic Surgical Procedures / Q000379:methods*; D014465:Ultrasonics / Q000379:methods*
D012709:Serum Albumin
Boiling; Histotripsy; Inertial cavitation; Shock wave; Tissue homogenate