I just looked at the Wikipedia page for SAR. I think what you are doing requires a lot more signal processing than an ultrasound. At it's most basic, an ultrasound is really just a 1d graph of signal intensity. You should look at some old ultrasounds, it's pretty obvious how low the resolution is.
I'm sure you know more about signal processing than I do, but trust me when I say a simple diagnostic ultrasound is a pretty rudimentary bit of kit. Most medical imaging is pretty simple actually (not accounting for signal acquisition). Radiologists are trained to read fairly abstract charts, and they want as little processing as possible. Imagine if a CT machine tried lining up images, rather than presenting the raw slices. That might make sense for mapping data, but if you were trying to diagnose a displacement of something, like a broken bone, having the image "fixed" wouldn't do you much good.
That's part of the reason why older ultrasound images of babies are so inscrutable to the casual observer. Since the technician is slowly sweeping a 1d or 2d array by hand, the printed image ends up looking pretty weird if the baby moves. An ultrasound can be 100 db inside the womb[1], so the baby tends to start moving when the ultrasound is performed. The horrible images aren't much of a problem, because the images they give to the parents aren't really used for diagnosis. They use the monitor for that purpose. If there is something the tech wants to explore further, they just look at that area some more.
Based on my limited knowledge of SAR, it seems like the processing is way more important because you are working with data that has been captured in the past.
I'm sure you know more about signal processing than I do, but trust me when I say a simple diagnostic ultrasound is a pretty rudimentary bit of kit. Most medical imaging is pretty simple actually (not accounting for signal acquisition). Radiologists are trained to read fairly abstract charts, and they want as little processing as possible. Imagine if a CT machine tried lining up images, rather than presenting the raw slices. That might make sense for mapping data, but if you were trying to diagnose a displacement of something, like a broken bone, having the image "fixed" wouldn't do you much good.
That's part of the reason why older ultrasound images of babies are so inscrutable to the casual observer. Since the technician is slowly sweeping a 1d or 2d array by hand, the printed image ends up looking pretty weird if the baby moves. An ultrasound can be 100 db inside the womb[1], so the baby tends to start moving when the ultrasound is performed. The horrible images aren't much of a problem, because the images they give to the parents aren't really used for diagnosis. They use the monitor for that purpose. If there is something the tech wants to explore further, they just look at that area some more.
Based on my limited knowledge of SAR, it seems like the processing is way more important because you are working with data that has been captured in the past.
Edit: Edited for clarity, and added source
[1] http://www.popsci.com/scitech/article/2002-01/hey-turn-down-...