Appeal No. 2000-0827
Application 08/466,104
Under the heading "Techniques For Measuring Ultrasound
Contrast-Enhancement Phenomena" ( id. at 6), the specification
discusses three main contrast-enhancing effects: backscatter ( id.
at 7-11); beam attenuation (id. at 11-13); and speed of sound
differential (id. at 13). Of these three effects, "the marked
increase in backscatter caused by free gas microbubbles is the
most dramatic effect and contrast-enhancing agents that take
advantage of this phenomenon would be the most desirable if the
obstacle of their limited stability in solution could be
overcome." Id. at 13, ll. 24-29.
Appellant has determined that the persistence of gas
microbubbles in a solution can be ascertained by calculating the
Q coefficient or value for the gas in accordance with
Equation (7) at page 25 of the specification, which appears in
slightly modified form in originally filed claim 1:
1. Contrast media for ultrasound image-
enhancement comprising microbubbles of a biocompatible
gas having a Q coefficient greater than 5 where
Q = 4.0 x 10-7 x D/CsD
and D is the density of the gas (Kgm -3), Cs is the water
solubility of the gas (M) and D is the diffusivity of
the gas in solution (cm3sec-1).
The Q coefficient is directly proportional to the persistence of
the microbubbles. For example, if the Q coefficient for gas X is
10,000, a microbubble of gas X will survive 10,000 times longer
in solution than will a microbubble of air ( id. at 26, ll. 1-4).
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