You will receive two injections of rituximab by vein over about 4 to 6 hours. This is followed by an infusion of Zevalin over about 30 minutes on the same day. Whole body images will be performed immediately and at 4-6, 24, 72, and 144 hours after receiving Zevalin. About 1 week later, you will receive a second infusion of rituximab and Zevalin.