Kansas C i t y , Kansas 66103 Measurements o f u l t r a s o n i c b a c k s c a t t e r from s o l i d collagen microspheres i n suspension and f r o m a standard erythrocyte suspension were performed. When normalized t o a standard p a r t i c l e s i z e and concentration, t h e backscatter f r o m the collagen was 29.6 dB above t h a t of t h e erythrocytes. An i n vivo canine experiment using commercial d i a g n o s t i c equipment demonstrated enhanced backscatter from the l i v e r after intravenous i n j e c t i o n o f t h e m icrospheres. Calculations show t h a t the i n vivo enhancement cannot be explained f r o m the earlier s t u d i e s . Possible mechanisms responsible f o r t h i s effect are proposed.
Experimental work using a quantitative C-scan technique to measure in situ enhancement of hepatic backscatter resulting from the administration of gelatin microspheres to dogs is reported. We have found that reproducible enhancement of hepatic backscatter on the order of 2 dB followed the peripheral administration of gelatin within minutes, the magnitude of the effect was not sensitive to the rate of infusion, but was likely to be dose dependent, changes in the overlying tissue attenuation had a pronounced effect on the measurement, and the effect was sustained for up to one half hour or longer.
c e n t r a t i o n . Some of t h e s e s o l u t i o n s w e r e used i n p r e l i m i n a r y i n v i t r o and in vivo c a n i n e experiments and echo enhancement w a s demonstrated. Key words: A c o u s t i c impedance; speed of sound; u l t r a s o n i c c o n t r a s t a g e n t s : u l t r a s o n i c t i s s u e b a c k s c a t t e r T h i s paper d i s c u s s e s methods and p r e l i m i n a r y r e s u l t s of u l t r a s o n i c echo enhancement u s i n g t h e t h i r d t e c h n i q u e . w a s i d e n t i f i e d , and t h e a c o u s t i c p r o p e r t i e s of t h e i r s o l u t i o n s (speed of sound, d e n s i t y and impedance) were determined. One of t h e most promising A group of p o t e n t i a l compounds Supported by N a t i o n a l Cancer I n s t i t u t e C o n t r a c t #NOl-CB-84236
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