The Visible Human Project has its roots in a 1986 long-range planning
effort of the National Library of Medicine (NLM).
It foresaw a coming era where NLM's bibliographic and factual database services would be
complemented by libraries of digital images, distributed over high
speed computer networks and by high capacity physical media.
Not
surprisingly, it saw an increasing role for electronically
represented images in clinical medicine and biomedical research.
It
encouraged the NLM to consider building and disseminating medical
image libraries much the same way it acquires, indexes, and provides
access to the biomedical literature.
Early in 1989, under the direction of the Board of Regents, an ad hoc
planning panel was convened and made the following recommendation: "NLM
should undertake a first project building a digital image library of
volumetric data representing a complete, normal adult male and female.
This Visible Human Project will include digitized
photographic images for cryosectioning, digital images derived from
computerized tomography and digital magnetic resonance images of cadavers."
Initial Aim
The initial aim of the Visible Human Project is to acquire
transverse CT, MRI and cryosection images of a representative male
and female cadaver at an average of one millimeter intervals.
The corresponding transverse sections in each of the three modalities are
to be registered with one another.
A contract for acquisition of these pixel-based data was awarded
in August 1991 to the University of Colorado at Denver.
Victor M. Spitzer, Ph.D. and David G. Whitlock, M.D., Ph.D.
are the principal investigators.
The Visible Human Male data set consists of MRI, CT and anatomical images.
Axial MRI images of the head and neck and longitudinal
sections of the rest of the body were obtained at 4 mm intervals.
The MRI images are 256 pixel by 256 pixel resolution.
Each pixel has 12 bits of grey tone resolution.
The CT data consists of axial CT scans of the entire body
taken at 1 mm intervals at a resolution of 512
pixels by 512 pixels where each pixel is made up of 12 bits of grey tone.
The axial anatomical images are 2048 pixels by 1216 pixels
where each pixel is defined by 24 bits of color, about 7.5 megabytes.
The anatomical cross-sections are also at 1 mm intervals and coincide
with the CT axial images.
There are 1871 cross-sections for each mode, CT and anatomy.
The complete male data set is 15 gigabytes in size.
The Visible Human Female data set has the same characteristics as the
male cadaver with one exception.
The axial anatomical images were obtained at 0.33 mm intervals
instead of 1.0 mm intervals.
This has resulted in over 5,000 anatomical images.
The data set is about 40 gigabytes.
The spacing in the "Z" direction was reduced to
0.33 mm in order to match the 0.33mm pixel spacing in the "XY" plane.
This will enable developers who are interested in three-dimensional
reconstructions to work with cubic voxels.
Internet Access
Sample full scale images are available via NLM's FTP site:
(nlmpubs.nlm.nih.gov).
Eleven full-color anatomical images and an
explanatory "color24.txt" file can be found on the FTP site in
(visible/bitmaps/color24) as (*.raw).
Please be careful as each of these images is over 7 megabytes in size.
Ten CT scan images and an explanatory "ct.txt" file can be found in
(visible/bitmaps/ct) as (*.fre)
(5 images captured while the cadaver was fresh) and (*.fro)
(5 images captured after the cadaver was frozen).
Six MRI scan images and an explanatory "mri.txt" file
can be found in (visible/bitmaps/mri) as (*.t1).
Scaled down versions of all of these image files can be found on
NLM's FTP site in (visible/gifs) as (*.gif).
On the World Wide Web,
(
http://www.nlm.nih.gov/research/visible/visible_human.html),
the images can be found on the Research Projects page,
in the Visible Human Project section,
as (*.jpg). A license agreement for use of either of the Visible Human Project
data sets is required and it can be retrieved from NLM's Web site.
Phase II - From DataSet to DataBase
Now that the data collection phase of the Visible Human Project is completed,
a second phase has begun - the segmentation, classification, and three-dimensional
rendering of the data set. A new research effort is under way. Its ultimate objective
is to identify all anatomical structures within the Visible Human data set including the
extent of each structure. A contract has been awarded with Engineering Animation, Inc., of Ames,
Iowa, for this work to be performed on the male thorax. Each object in each cross-section will
have to be labeled. The relationship of each object to the other objects in its cross-section
and in the adjacent cross-sections will have to be cataloged The extent of a single object which
spans several cross-sections will have to be noted. In order to accomplish this, information about
building geographic databases and databases associated with computer-aided drafting systems will
be used as starting points for developing this unique interactive anatomical digital atlas.
Long-term Goal
The Visible Human Project data sets are designed to serve as a common reference
point for the study of human anatomy, as a set of common public domain data for
testing medical imaging algorithms, and as a test bed and model for the construction
of image libraries that can be accessed through networks. The data sets are being
applied to a wide range of educational, diagnostic, treatment planning, virtual
reality, artistic, mathematical and industrial uses by over 700 licensees in 26
countries. But key issues remain in the development of methods to link such image
data to text-based data. Standards do not currently exist for such linkages.
Basic research is needed in the description and representation of image based structures,
and to connect image-based structural-anatomical data to text-based functional-physiological data.
This is the larger, long-term goal of the Visible Human Project: to transparently
link the print library of functional-physiological knowledge with the image library
of structural-anatomical knowledge into one unified resource of health information.
For additional information on the Visible Human Project contact:
Visible Human Project
National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894
FAX: (301) 402-4080
Internet: vhp@nlm.nih.gov
For additional information contact:
Office of Public Information,
National Library of Medicine,
8600 Rockville Pike,
Bethesda, Maryland 20894;
Fax: (301) 496-4450; email: publicinfo@nlm.nih.gov
