[1] Univ Penn, Perelman Sch Med, Dept Radiol, Hosp Univ Penn, 1 Silverstein,3400 Spruce St, Philadelphia, PA 19104 USA
[2] Univ Pittsburgh, Sch Med, Dept Radiol, Radiol Adm, PUH Suite E204,200 Lothrop St, Pittsburgh, PA 15213 USA
[3] Univ Pittsburgh, Sch Med, Dept Otolaryngol, Radiol Adm, PUH Suite E204,200 Lothrop St, Pittsburgh, PA 15213 USA
[4] Univ Penn, Perelman Sch Med, Hosp Univ Penn, Dept Radiol, 219 Dulles Bldg,3400 Spruce St, Philadelphia, PA 19104 USA