1. From the Veterans Affairs Medical Center, Nuclear Medicine Service and Departments of Radiology and Urology, University of Iowa, Iowa City, Iowa, Department of Urology, George Washington University Medical Center, Washington, D. C., Department of Nuclear Medicine, Sutter General Hospital, Sacramento, California, Departments of Nuclear Medicine and Urology, Lahey Hitchcock Medical Center, Burlington, Massachusetts, and CYTOGEN Corporation, Princeton, New Jersey