K. Hongo et al., NONINVASIVE CEREBRAL OPTICAL SPECTROSCOPY - DEPTH-RESOLVED MEASUREMENTS OF CEREBRAL HEMODYNAMICS USING INDOCYANINE GREEN, Neurological research, 17(2), 1995, pp. 89-93
To investigate the feasibility of a newly developed, near-infrared opt
ical spectroscopy device, we analysed measurements of the infrared tra
cer indocyanine green (ICG) using sensors with a single near infrared
light source and multiple light detectors. Two mi of ICC dye, 1.0 mg m
l(-1) in concentration, were injected into the internal carotid artery
during cerebral angiography in 14 adult patients. The resultant washo
ut curves were measured bilaterally using sensors with 4 detectors spa
ced at 10, 20, 30 and 40 mm from the infrared light source on the righ
t side, and 15, 25, 35 and 45 mm from the source for the left side, re
spectively. Washout curves were analysed to determine the relative amp
litude of the ICC absorption signal and deduce each detector's penetra
tion distance. When ICC was injected into the internal carotid artery,
relative absorption increased with detector distance from the light s
ource. No substantial difference in attenuation was observed in any of
the detectors during external carotid injection of ICC. The resultant
information related depth of penetration of the light with source-det
ector separation distances. The feasibility of the system for measurin
g cerebral oxygen saturation and haemodynamics noninvasively or monito
ring at bedside is discussed.