Particulate Radiographic Contrast Material for Quantitative Representation of Blood-Flow Patterns

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Abstract
A theoretical evaluation was undertaken concerning the relationship between harmonic motions of liquid and of macrospheres suspended in the liquid. For Re ≤ 1 the solution was: where a and b are amplitudes for fluid and particle, ρb and ρp the relative densities, ω the angular frequency, ω0 a characteristic constant depending upon particle size, liquid viscosity and the densities, while ϕ is the phase difference between liquid and particle motion. With certain restrictions an identical solution form was obtained for Re > 1,000. When these results were applied to the use of radiopaque particles of relative density 1.3 to 1.4 and radius 1 to 2 mm for registration of blood-flow pulsations, the quantitative difference in frequency characteristics of the two solutions was so slight as to suggest a general solution independent of Re. For Fourier-composite blood-flow pulsations of frequency 1 to 2 cps the relative particle amplitudes were calculated to 90 to 100%, and the phasic time delay to 1 to 5 msec. More than 99% of the DC velocity component was recovered by a particle of initial velocity zero in 0.2 to 0.6 sec following its introduction into the blood stream.

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