Changes in tissue oxyhaemoglobin concentration measured using multichannel near infrared spectroscopy during internal carotid angiography

摘要

OBJECTIVE—To develop an in vivo model fortesting spatially resolved spectroscopy and quantified near infraredspectroscopy (NIRS) cerebral blood flow measurements.
METHOD—Multiple detector NIRS has been used tostudy changes in tissue oxyhaemoglobin (O2Hb) concentrationduring selective internal carotid angiography. A significant reductionin O2Hb occurred in tissue interrogated by detectorssituated between 0.7 and 4.1cm from the NIRS light source.
RESULTS—The time course of O2Hbconcentration change was consistent with displacement of oxygenatedblood by the radiocontrast medium from vascular beds of differing flowand NIR light attenuation. Increasing changes in O2Hbconcentration per unit photon path length—predicted to occur atgreater emitter-detector separations if those changes had occurredpredominantly in cerebral tissue—were found in the first four secondsafter injection of radiocontrast medium. However, later changes(6-10 s) were larger and were not proportional to emitter-detector separation.
CONCLUSION—The findings indicate that simpleassumptions regarding the distribution of the internal carotid arteryblood supply to cerebral and extracerebral tissues, the photon pathlength through those tissues, and their relative contributions toattenuation of NIR light may not be justified.