| Abstrakt: |
To determine the ability of Doppler color flow mapping to accurately and reproducibly assess the flow volume and kinetic energy of in vitro fluid jets, a Doppler color flow mapping system was interfaced with an image processing computer. An aliasing correction algorithm was used to extend the upper limit of measurable velocity to 184 cm/s. Images were analyzed for jet area (equal to the total number of image pixels) and jet energy (equal to the sum of all pixel velocities squared), both integrated over all frames of the injection and in single maximal frames. The Doppler flow mapping area and energy measurements were compared with known flow volume and delivered kinetic energy, and the effects of four experimental variables (orifice area, gain setting, chamber compliance and chamber size) were evaluated. Jet area correlated nonlinearly with flow volume and was markedly affected by each of these experimental variables, increasing by 40 to 150% from the smallest to the largest orifice size, 15 to 94% with the highest versus the lowest gain setting, 1 to 54% with greater chamber compliance and 7 to 70% in the large versus the small chamber. In contrast, jet energy correlated linearly with delivered kinetic energy up to 350,000 ergs, at which point velocities started to exceed the extended velocity range and second wrap aliasing occurred. The relation was not affected by orifice area, gain or compliance, and was only minimally affected by chamber size.(ABSTRACT TRUNCATED AT 250 WORDS) |
