The linked text database of 1500 anatomical structure names integrated in the Visible Human Explorer is a prototype of a wider application of such database linkages. With such linked data sets, the Visible Human Project images may become either the initiators or the result of a user's search. Image access is direct and interactive. There is no need to previously plan and choose images to load and wait during a lengthy image loading stage before the pixel location can be found. In a simple case, upon entering "spinal cord", the system automatically prepares a list of sequential image filenames containing the spinal cord. This list in turn drives the animation of only those images. Note that animated images do not need to be stored sequentially on the disk to maintain display speed from hard disk. By linking the database to the images through a lookup table, the database can be easily expanded, contracted or replaced completely. All that needs to be changed is the table and storage disks as appropriate.
In the other direction, the user may click on an individual voxel, individual image, or range of images and be returned information pertinent to the input, the associated muscle name, the mechanical resistance, and the CT density and so on or to a related series of images. In an educational setting, clicking of the CT, X-ray, or colour photograph image of the healthy body of the Visible Human Project can link to a large set of X-rays of real patients with various conditions.
Beyond the Visible Human Project data sets, a doctor may wish to scan a large number of X-rays or other images looking for something similar to the one he has in hand from a patient. He is looking for something similar to the one he has and in turn information on the treatment of that case. He cannot search the other way because the X-ray database has not been indexed to that level, or it is partially indexed and the keyword search returns 300 images. At this point, a customized version of the Visible Human Explorer can take over the list of those 300 images and let him quickly browse them to find the matching image(s).
The 45 gigabytes of raw Visible Human Project data has now become simply a minor storage problem, a few hard disks. Local, immediate access to it is not a challenge. It is an example of the imagery that is coming continuously every day. The University of Michigan Medical School, for example, produces greater than 2 terabytes of microscopic 2-D and 3-D research microscopic digital imagery per year. This led to the consideration of a distribution network linked to a central storage facility.