Room: Exhibit Hall | Forum 1
Purpose: Phantoms are used in ultrasound imaging to provide a stable, controlled test-bed system for evaluating new techniques. There are no commercially-available perfusion phantoms for ultrasound liver imaging. The aim of this study was to build a perfusion phantom that generated time-intensity curves(TICs) mimicking those produced in healthy and diseased liver tissue and to evaluate a newly-developed subharmonic imaging technique.
Methods: The phantom consisted of three types of perfusion cores, consisting of 10 pores-per-inch sponge, with different amounts of 10% PVAc tissue mimicking material, representing healthy, diseased and necrotic tissue. The perfusion cores were constructed to generate tissue representative TICs at different depths. The complex perfusion core was encapsulated in silicone and placed in a water tank with an acoustic window. The phantom was imaged using a liver contrast-enhanced ultrasound pre-set on the Aixplorer system(Supersonic Imagine, France) and a newly-developed subharmonic imaging technique. TICs from â€˜Nativeâ€™ and â€˜alteredâ€™ UCA were investigated by injecting boluses for imaging. The techniques were evaluated in terms of their ability to accurately measure the TICs generated by the different perfusions cores within the perfusion phantom, representing different type of liver tissue.
Results: The mean signal in a selected region within the phantom was sampled over each frame of the acquisitions and the TICs plotted to track the change in intensity with UCA flow and perfusion. TICs mimicking the perfusion in different types of liver tissues were successfully generated using the phantom. An improvement due to the newly developed SHI technique was demonstrated, in terms of quantification of signals at depth. The new SHI technique had less shadowing artifacts present as well as better suppression of â€˜tissueâ€™ signals generated by the PVAc TMM.
Conclusion: The phantom generated TICs representing healthy and diseased tissue. The phantom successfully evaluated the clinical implementation of a newly-developed subharmonic imaging technique.
Funding Support, Disclosures, and Conflict of Interest: The authors acknowledge funding from the Irish Research Council.