[1] Univ Calif San Francisco, Dept Surg, San Francisco & San Francisco Vet Affairs Med Ctr, Surg Serv 112, San Francisco, CA 94121 USA
[2] Univ Calif San Francisco, Dept Radiol, San Francisco & San Francisco Vet Affairs Med Ctr, San Francisco, CA 94121 USA
[3] Univ Calif San Francisco, Dept Gastroenterol, San Francisco & San Francisco Vet Affairs Med Ctr, San Francisco, CA 94121 USA
[4] Univ Calif San Francisco, Dept Surg & Hematol Oncol, San Francisco & San Francisco Vet Affairs Med Ctr, San Francisco, CA 94121 USA