Ultrafast 2‐Dimensional Image Monitoring and Array‐Based Passive Cavitation Detection for Ultrasound Contrast Agent Destruction in a Variably Sized Region

• Published in: Journal of ultrasound in medicine Vol. 33; no. 11; pp. 1957 - 1970
• Main Authors: Xu, Shanshan, Hu, Hong, Jiang, Hujie, Xu, Zhi'an, Wan, Mingxi
• Format: Journal Article
• Language: English
• Published: England American Institute of Ultrasound in Medicine 01.11.2014
• Subjects: Contrast Media - chemistry; Contrast Media - radiation effects; diagnostic ultrasound scanner; Dose-Response Relationship, Radiation; Equipment Design; Equipment Failure Analysis; Gases - chemistry; Gases - radiation effects; High-Energy Shock Waves; High-Intensity Focused Ultrasound Ablation - instrumentation; microbubble destruction; passive cavitation detection; Phantoms, Imaging; Phospholipids - chemistry; Phospholipids - radiation effects; Radiation Dosage; Reproducibility of Results; Sensitivity and Specificity; Sulfur Hexafluoride - chemistry; Sulfur Hexafluoride - radiation effects; Systems Integration; ultrafast 2-dimensional imaging; Ultrasonography, Interventional - instrumentation; variably sized focal region; variably sized focal region; diagnostic ultrasound scanner; passive cavitation detection; ultrafast 2-dimensional imaging; microbubble destruction
• ISSN: 0278-4297; 1550-9613
• DOI: 10.7863/ultra.33.11.1957

Objectives A combined approach was proposed, based on programmable ultrasound equipment, to simultaneously monitor surviving microbubbles and detect cavitation activity during microbubble destruction in a variably sized region for use in ultrasound contrast agent (UCA)‐enhanced therapeutic ultrasound applications. Methods A variably sized focal region wherein the acoustic pressure was above the UCA fragmentation threshold was synthesized at frequencies of 3, 4, 5, and 6 MHz with a linear broadband imaging probe. The UCAs’ temporal and spatial distribution during the microbubbles’ destruction was monitored in a 2‐dimensional imaging plane at 5 MHz and a frame rate of 400 Hz, and simultaneously, broadband noise emissions during the microbubbles’ fragmentation were extracted by using the backscattered signals produced by the focused release bursts (ie, destruction pulses) themselves. Afterward, the temporal evolution of broadband noise emission, the surviving microbubbles in a region of interest (ROI), and the destruction area in a static UCA suspension were computed. Then the inertial cavitation dose, destruction rate of microbubbles in the ROI, and area of the destruction region were determined. Results It was found that an increasing pulse length and a decreasing transmit aperture and excitation frequency were correlated with an increased inertial cavitation dose, microbubble destruction rate, and destruction area. Furthermore, it was obvious that the microbubble destruction rate was significantly correlated with the inertial cavitation dose (P < .05). In addition, the intensity decrease in the ROI was significantly correlated with the destruction area (P < .05). Conclusions By the proposed strategy, microbubbles could be destroyed in a variably sized region, and destruction efficiency as well as the corresponding inertial cavitation dose could be regulated by manipulating the transmission parameters.