I'm just a first year and don't really know what I want to specialize in yet, but I was an electrical engineering major in undergrad and although I decided to go to medical school instead of pursue a PhD in that or biomed, I often think it would be really cool to go into a specialty that sort of straddles the line between medicine and engineering and uses a lot of problem-solving/mathematical concepts. From what I gather now, it seems like my best bets would be nephrology or endocrinology (lots of system modeling and feedback analysis = AWESOME), possibly radiology for the signal/image processing aspect but I can't imagine you would be focusing too much on that in daily practice. Anyone who has actually been exposed to various fields clinically want to offer any suggestions?