United States
                      Environmental Protection
                      Agency	
                            Office of Research and
                            Development
                            Washington, DC 20460
EPA/620/R-00/005y
April, 2001
      EPA    Coastal   Communications
oao
COMPUTER AIDED TOMOGRAPHY USED
TO DIAGNOSE HEALTH OF ESTUARIES
Background
Computer Aided Tomography (CAT) imaging, usually used by physicians to diagnose problems of
human patients, is helping marine scientists at the National Health and Environmental Effects
                           Research Laboratory's Atlantic Ecology Division (AED), to
                           evaluate the ecological health of animal communities living in
                           coastal estuarine and marine sediments.  This is the first time
                           marine ecologists have used this technology to study
                           environmental pollution problems, as reported in a recent article
                           in the journal, Ecological Applications,
                           [Volume 9(3); 1999; pp. 1050-1058].
                           Approach
                           Traditionally, sediment health is determined by collecting,
                           identifying and counting these sediment dwelling organisms, but
                           this procedure requires  specialized training and is labor-intensive
                           and time-consuming. CAT imaging offers a rapid, cost-effective
                           alternative to this traditional method by quantifying the burrows
                           and tunnels in sediment  cores. Scientists first collect intact mud
cores from an estuary using cylindrical plastic tubes pushed into the sediment. The cores are
tightly sealed at the top and bottom  and transported to South County Hospital, Wakef ield,
Rhode Island, for CAT imaging (see figure above). Under a unique partnership and funding
agreement with EPA, South County Hospital, located approximately seven miles from the AED
(Narragansett, Rhode Island), has made its CAT scan imaging equipment available to EPA. The
CAT imaging data are stored on a magnetic tape and subsequently analyzed on a personal
computer at the AED.  A three-dimensional image of burrows and tunnels
within the core can then be reconstructed with these data (see figure to
the right). In addition, these structures can be quantified and used to
identify, monitor, and assess the effects of human activities on these
sediment habitats.  Because medical CAT imaging scanners are located
throughout the world, this technique could be made widely available for
environmental managers to evaluate the health of sediments.
Further Information
Ken Perez is the principal investigator for this study (email
perez.kenneth@epa.gov: phone: 401-782-3052). Earl Davey is responsible
for the technical work-up on the CAT data (email: davey.earl@epa.gov.
phone: 401-782-3083).  Lenour Durand is the Manager of the Diagnostic
Imaging Department at South County Hospital in Wakef ield, Rhode Island
02880 (phone: 401-782-8030). Visit the Coastal Communications web site
at: http://www.epa.gov/nheerl/whatsnew.

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