Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8965495 | Ultrasound in Medicine & Biology | 2018 | 16 Pages |
Abstract
A novel histotripsy approach based on fundamental and second harmonic superposition and incorporating hundred-microsecond-long pulses and two-stage pulse protocol is proposed in this study to rapidly generate mechanically homogenized lesions. Two pulse stages were applied: stage 1, pulses with a pulse duration of 500-600 μs and pulse repetition frequency of 100 Hz, and stage 2, multiple periods, each composed of multiple pulses with the same pulse duration and pulse repetition frequency as those in stage 1, but with an off-time of 600 ms between periods. A custom-designed 1.1/2.2-MHz two-element confocal-annular array, with an f-number of 0.69, and lateral and axial full width at half-maximum pressure dimensions of approximately 1.0 and 6.0 mm, was used. The peak positive/negative pressures at the focus were +22/-7 MPa for 1.1 MHz and +56/-14 MPa with shock wave for 2.2 MHz. To investigate the feasibility of this approach, experiments were designed and performed in tissue-mimicking polyacrylamide gel phantoms with bovine serum albumin and in ex vivo porcine tissues. Cavitation and boiling activities were observed through high-speed photography, and the corresponding acoustic emissions were recorded through passive cavitation detection. Ex vivo experimental results revealed that complete tissue homogeneous regions with regular long tear shape and typical dimensions of 5.80 ± 0.19 mm in axial and 2.20 ± 0.26 mm in lateral were successfully generated in porcine kidney samples. The hematoxylin and eosin staining evidenced that the lesions were thoroughly homogenized and sharply demarcated from untreated regions. These results indicated that the histotripsy approach using fundamental and second harmonic superposition combined with hundred-microsecond pulses and two-stage pulse protocol can efficiently obtain a mechanical disruption of soft tissues with spatial precision, and this approach may have the potential to be developed as a useful tool for precise tumor treatment.
Keywords
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Acoustics and Ultrasonics
Authors
Yujiao Li, Rui Wang, Mingzhu Lu, Linglu Zhang, Yanshan Liu, Dan Han, Xuan Wang, Yizhe Geng, Mingxi Wan,