The Visible Human

With funding from the National Library of Medicine, PSC scientists for the past three years have worked to develop software and networking to make better use of some unique data, the NLM's Visible Human Data Set. Compiled from painstaking preparation of two cadavers, a man and woman, with cross-sectional slices converted into digital form for computer access, the Visible Human is a powerful resource for education and training in human anatomy and for planning of surgery and radiation therapy.

Its effectiveness has been limited, however, because viewing technologies have allowed access only by 2D cross-sections from top, front or side views. The spinal column, for instance, isn't a straight line, so a single horizontal cross-section can't display more than a section of the spinal cord in one view. Similarly, looking at the heart from only a frontal or side view doesn't show how close it is to the spinal cord.

In collaboration with University of Michigan researchers, PSC has developed innovate software tools for interactive viewing that overcome these limitations. The Visible Human Browser, released in October, allows users to zoom in or out on the data and to select views from any angle or surface they choose. The software then reconstructs the corresponding image in real time.

Other browser capabilities to be incorporated in the future include advanced visualization features, as exemplified in this image. With a technique called "ray casting," the skin and fatty tissue become translucent. At the same time, muscular tissue is more opaque. As a result, veins in the legs, normally hard to see, stand out, a view that faciliates segmenting arterial tissue from surrounding tissue.