An amazing portable US is soon coming from Butterfly Network. The transducer plus DSP is on a very large integrated circuit, and it can do breathtaking stuff for a device of this size and cost, like real time Doppler US (show blood flow in the image).
I'm looking forward to the introduction of this device, but it should be noted that color Doppler is also available on the VScan handheld. I think MEMS sensors are going to revolutionize the industry by making the probe an inexpensive part.
https://www.butterflynetwork.com