My assumptions is, if you are in F1 visa, you are fairly young and your brother is too. It is kind a difficult for someone of an young age who could potentially stay and work here to get a visa. I know someone who tried to have her brother in for her wedding ceremony but they denied his visa. I, myself (it was few years back though) tried to have my brother come over for my graduation and they didn't let him. That might not happen now, thats just my experience. Well, good luck to you and your brother!