Journal of Ultrasound in Medicine, Vol 20, Issue 3 235-240, Copyright © 2001 by American Institute of Ultrasound in Medicine
Overlaying ultrasonographic images on direct vision
G. D. Stetten and V. S. Chib
Department of Bioengineering, University of Pittsburgh, Pennsylvania 15261, USA.
The objective of this technical advance is to permit in situ visualization
of ultrasonographic images so that direct hand-eye coordination can be used
during invasive procedures. A method is presented that merges the visual
outer surface of a patient with a simultaneous ultrasonographic scan of the
patient's interior. The method combines a flat-panel monitor with a
half-silvered mirror such that the image on the monitor is reflected
precisely at the proper location within the patient. The ultrasonographic
image is superimposed in real time on the patient, merging with the
operator's hands and any invasive tools in the field of view. Instead of
looking away from the patient at an ultrasonographic monitor, the operator
sees through skin and underlying tissue as if it were translucent. Two
working prototypes have been constructed, demonstrating independence of
viewer location and requiring no special apparatus to be worn by the
operator. This method could enable needles and scalpels to be manipulated
with direct hand-eye coordination under ultrasonographic guidance. Invasive
tools would be visible up to where they enter the skin, permitting natural
visual extrapolation into the ultrasonographic slice. Biopsy needles would
no longer be restricted to lie in the plane of the ultrasonographic scan
but could instead intersect it. These advances could lead to increased
safety, ease, and reliability in certain invasive procedures.
