Abstract

We have developed an optical Imaging system, Dual Wavelength Phased Array system (DWLPA) that can be used for testing neonate’s brain function. A phased array system consists of 16 sets of phase cancellation optodes, 0 and 180 degree laser sources with a detector in middle. For this purpose, 9 sets of lasers each with 780 and 830 nms (20 mwatt) and 4 detectors, (PMT-T08 Hamamatsu) are placed on a probe, 4×9 cm. These optodes make 16 combinations of triangle; each has a function of phase cancellation. Thus all the probe areas were filled with 16 triangles and can be seen as sensitive to heterogeneity. The optodes separation is 2.5 cm for each array, and data information is taken by a detector in the middle when each two sources at 1 and 180 degree ignite at once. The actual images are made by subtracting from resting state to active state of cortex when physicians test for neurological examinations, hearing, touching, and visual display. The subtraction can cancel outcome of artifacts caused by inconsistent hair, probe pressure to the head, and slightly dislocated probe angles. The results show that like adults, we saw functions of cortices. The significant is that these blood volume changes by the stimulation can be detected much earlier stage of life than the development of EEG (electrical encephalogram) and Evoked potential. Thus the usefulness of this optical technology can be very beneficial. It implies that neonates already develop circulatory response from the metabolic needs of neurons in the area. We conclude that this technology, namely PA imaging system has a superior S/N ratio by the fact flat it has 180 degree shift for 2.5 cm resolution. These methods can be used clinically to detect infant’s neurological dysfunction before EEG and other test can be used.

© 1998 Optical Society of America