Patients undergo fludeoxyglucose F 18 (FDG)-PET/CT imaging at baseline. Patients then receive ABVD chemotherapy comprising doxorubicin hydrochloride IV, bleomycin IV, vinblastine IV, and dacarbazine IV on days 1 and 15. Treatment repeats every 28 days for up to 2 courses in the absence of disease progression or unacceptable toxicity. Between days 22 and 25 of course 2, patients undergo a second FDG-PET/CT scan to assess response. Subsequent therapy is based on FDG-PET/CT scan results.