Perfusion flow phantoms with many variably oriented microchannels

Ultrasound perfusion imaging with and without contrast agents continues to be a relevant problem as ultrasound systems and algorithms get more sensitive to slow blood flow. Unfortunately, there have been few phantoms to help develop these techniques. Some have used very small linear tubes, while others have adapted dialysis cartridges. Here we propose a technique based off of conventional gelatin phantoms. We form a gelatin phantom around a polymer resin. Then, the resin structure is dissolved leaving behind a network of small randomly oriented channels. These small channels are connected to a large channel and then connected to a pump to perfuse blood mimicking fluid through the phantom. The average diameter of the microchannels were 33 um with a range of 1-198 um. The presence of perfusion was visually confirmed and speckle SNR was calculated as an initial characterization of the phantoms' acoustic properties. Additionally, we used a previously reported adaptive tissue demodulation technique for imaging perfusion without contrast to also determine whether flow was present and highlight the utility of the phantom. These phantoms are expected to be extremely useful for evaluating slow flow algorithms and in establishing new minimum bounds for flow detection given the newest techniques.