The clinical core is intended to consolidate the provision to the individual project leaders of a number of clinical resources. First, clinical data for each of the individual projects will be collected by means of a single technical protocol, in which a series of ultrasound B- scan image frames will be recorded digitally at the amplified but undemodulated ('raw RF') level by means of a specially modified commercial scanner. This scanner will be used for transabdominal studies of the liver, transrectal examination of the prostate and real-time breast imaging. Its normal function in the production of images for clinical diagnosis will be unaffected. Second, the clinical core will provide correlative and follow-up information for all patients participating in the study. Biopsy puncture, histological analysis and, in many cases, correlative imaging using CT or MRI, will be carried by, or under the direct supervision of co-investigators in the core. The core will also evaluate the effect of injecting intravenous contrast agents in woodchucks and rabbits according to already established protocols. Data will be coded and stored on a database maintained in the clinical core, allowing retrospective analysis of signals by the technical groups as analysis techniques are refined during the program. For those methods in which image processing or the production of novel images are involved, viewing panels will be prepared by the clinical core which will enable state-of-the-art conventional ultrasound images to be compared with those under investigation. The core will include facilities for statistical advice and computer-based analysis. Finally, the clinical core will act as a conduit through which clinical guidance from senior specialists at Thomas Jefferson University Hospital will be available to the science and engineering projects at all phases of development, including the design of signal analysis methods themselves. A clinical ultrasound physicist will form part of the core's facilities.