期刊
ULTRASOUND IN MEDICINE AND BIOLOGY
卷 39, 期 3, 页码 475-489出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.ultrasmedbio.2012.10.004
关键词
Perfluorocarbon droplets; Ultrasound contrast agents; Cancer detection
资金
- Ontario Institute of Cancer Research
- Terry Fox Foundation
- Ontario Research Fund-Research Excellence Program
- National Cancer Institute of Canada
Because many tumors possess blood vessels permeable to particles with diameters of 200 nm, it is possible that submicron perfluorocarbon droplets could constitute a novel extravascular ultrasound contrast agent capable of selectively enhancing tumors. Under exposure to bursts of ultrasound of sufficient rarefactional pressure, droplets can undergo vaporization to form echogenic microbubbles. In this study, phase-change thresholds of 220-nm-diameter droplets composed of perfluoropentane were studied in polyacrylamide gel phantoms maintained at temperatures of 21-37 degrees C, exposed to high-pressure bursts of ultrasound with frequencies ranging from 5-15 MHz and durations of 1 mu s to 1 ms. The thresholds were found to depend inversely and significantly (p < 0.001) on ultrasound frequency, pulse duration, and droplet temperature, ranging from 9.4 +/- 0.8 MPa at 29 degrees C for a 1-mu s burst at 5 MHz to 3.2 +/- 0.5 MPa at 37 degrees C for a 1-ms burst at 15 MHz. The diameters of microbubbles formed from droplets decreased significantly as phantom stiffness increased (p < 0.0001), and were independent of pulse duration, although substantially more droplets were converted to microbubbles for 1-ms pulse durations compared with briefer exposures. In vivo experiments in a mouse tumor model demonstrated that intravenously injected droplets can be converted into highly echogenic microbubbles 1 h after administration. (E-mail: williams@sri.utoronto.ca) (C) 2013 World Federation for Ultrasound in Medicine & Biology.
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