Lung damage assessment from exposure to pulsed-wave ultrasound inthe rabbit, mouse, and pig

摘要

The principal motivation of the study was to assess experimentallynthe question: “Is the MI (Mechanical Index) an equivalent ornbetter indicator of nonthermal bioeffect risk than ISPPA.3n(derated spatial peak, pulse average intensity)?”. To evaluatenthis question, the experimental design consisted of a reproduciblenbiological effect in order to provide a quantitative assessment of theneffect. The specific biological effect used was lung damage and thenspecies chosen was the rabbit. This work was initiated, in part, by anstudy in which lung hemorrhage was observed in 7-week old C3H mice forndiagnostic-type, pulsed-wave ultrasound exposures, and, therefore, 6- ton7-week old C3H mice were used in this study as positive controls.nForty-seven adult New Zealand White male rabbits were exposed to a widenrange of ultrasound amplitude conditions at center frequencies of 3 andn6 MHz with all temporal exposure variables held constant. A calibrated,ncommercial diagnostic ultrasound system was used as the ultrasoundnsource with output levels exceeding, in some cases, permissible FDAnlevels. The MI was shown to be at least an equivalent, and in somencases, a better indicator of rabbit lung damage than either thenISPPA.3 or pr.3 (derated peak rarefactionalnpressure), thus answering the posed question positively. Further, innsitu exposure conditions were estimated at the lung pleural surfacen(PS); the estimated in situ ISPPA.PS and pr.PSnexposure conditions tracked lung damage no better thannISPPA.3 and pr.3, respectively, whereas thenestimated in situ MIPS exposure condition was a slightlynpoorer predictor of lung damage than MI. Finally, the lungs of six adultncrossbred pigs were exposed at the highest amplitude exposure levelsnpermitted by a diagnostic ultrasound system (to prevent probe damage) atnboth frequencies; no lung damage was observed which suggests thenpossibility of a species dependency biological effect