I think BID talked about it on their website. On my interview tour, which included some upper tiers, I noticed IMGs would only show up at the very worst places (community programs in undesirable areas) and the very best (I ran into 'em at UCSF, Stanford, and Hopkins). I imagine you would probably need a Ph.D. or something to get into such a program though...it's hard enough for American grads!
BID's a tier or so below the other two (for a couple of tier listings search Aunt Minnie for 'tiers'), but is still an excellent program.