As far as I know, JHU BME has sent out (most) rotation offers. But the RA offers are sent saperately from the POIs, maybe some of the POIs haven't sent out their offer. Most international students will receive the RA offer but not rotation offer.
ps. To the folks who received the rotation offer in IMAGING TRACK and get any better offers: Pleaseeeeee reject it (no need to do that asap, just before April). I am a current student at JHU BME, and it is my top choice. I want this offer sooooo bad. Please ?