| Popis: |
Currently, there are few simple-to-construct in vitro, wall-less phantoms that have accurate acoustic properties while mimicking the complex normal and neoplastic geometries and flow of the vascular network. The purpose of this study was to develop agar-based tissue-mimicking phantoms (TMP) to model such flow networks and to quantify the mean intensity and slope measurements of the ultrasound flow. Three types of vascular networks were developed; (1) single vessel, (2) multi-vessel with artery bifurcations and (3) multi-vessel with artery bifurcations and structural abnormalities typical of disease (tumor) vascular networks. Bolus injections of ultrasound contrast agents (UCAs) were performed under varying flow conditions relevant to our ongoing work in developing techniques to simultaneously quantify both the total volume and flow measurements within a tumor phantomThe correlation coefficient between the mean slope measurements and the least squares fitted line was all higher than 0.95, indicating a good linear relationship between the mean slope and the flow-rates. For all single-vessel flow phantom data, the mean proportional difference of the slope measurements and flow-rate was 0.695 ± 0.18 (mean ± SD). It was found that the correlation coefficient between the mean slope measurements and the least squares fitted line is 0.90, indicating a good linear correlation between the single-vessel and Multi-vessel flow phantoms. However, the parameters obtained from tumor region 1, 2 and 3 did not show any significant flow pattern and correlation after contrast injection of UCAs. Finally, the slope measurements of intensity at the tumor regions inflow and outflow demonstrated the nonlinear and undefined relationship between the measured intensity and varied flow rates. Ideally, most information could be obtained when intensities at both the input and the output of the tumor periphery are measured. For further studies, alternative modeling of the problem is required as in physiology, microvasculature flow system has multiple input vessels and multiple output vessels. Developing new time-intensity-based techniques is the focus of future research. |
