Imager that combines near-infrared diffusive light and ultrasound

We introduce an imaging technique that combines complementary features of u ltrasound and near-infrared diffusive light imaging. We achieve the combine d technology experimentally by mounting an ultrasound array together with m ultiple laser source and optical detector fibers upon a hand-held probe. Th e technique is demonstrated with tissue phantoms wherein both acoustic and optical sensors image the volume underneath the probe. Coregistration of ac oustic and optical images is achieved with an accuracy of 0.27 +/- 0.20 cm, approximately half of the image pixel size of our prototype. Accurate dete rmination of target optical absorption is also achieved by use of image seg mentation on the ultrasound reconstruction. The combined technique may prov ide improved breast-cancer detection sensitivity and specificity. (C) 1999 Optical Society of America.