Even if it's not the same resolution there's still benefits, a bit one that it will likely be WAY less expensive, both upfront and in maintenance, even after building the water tank. It might also replace a fair amount of routine ultrasound usage because of the reduction of operator skill.

Also, there's plenty of people who can't be in MRI machines, and likely a lot safer for everyone else.

MRI is done using X rays which have very very small wavelength compared to sound. And resolution of images i.e. less blurry varies inversely proportional to the wavelength. Yes some algo can make slightly better but I am certain that nothing can beat x rays in clarity for humans