[1] Univ Penn, Perelman Sch Med, Philadelphia, PA 19104 USA
[2] Hosp Univ Penn, Dept Radiol, Philadelphia, PA 19104 USA
[3] Temple Univ, Lewis Katz Sch Med, Philadelphia, PA 19122 USA
[4] Univ Connecticut, Dept Med, Hartford, CT USA
[5] Hosp Univ Penn, Dept Radiat Oncol, Philadelphia, PA 19104 USA
[6] Oslo Univ Hosp, Div Radiol & Nucl Med, Oslo, Norway
[7] Univ Oslo, Fac Med, Inst Clin Med, Oslo, Norway