title: Intraoperative monitoring of depth-dependent hemoglobin concentration changes during carotid endarterectomy by time-resolved spectroscopy.
abstract: By measuring the adult human head during carotid endarterectomy, we investigate the depth sensitivity of two methods for deriving the absorption coefficient changes (Dmu(a)) from time-resolved reflectance data to absorption changes in inhomogeneous media: (1) the curve-fitting method based on the diffusion equation (DE-fit method) and (2) the time-independent calculation based on the modified Lambert-Beer law (MLB method). Remarkable differences in the determined values of Dmu(a) caused by clamping the external carotid artery and subsequently clamping the common carotid artery were observed between the methods. The DE-fit method was more sensitive to mu(a) changes in cerebral tissues, whereas the MLB method was rather sensitive to mu(a) changes in the extracerebral tissues. Our results indicated that the DE-fit was useful for monitoring the cerebral blood circulation and oxygenation during neurosurgical operations. In addition, the combined evaluation of mu(a) changes with the DE-fit and MLB methods will provide us with more available information about the hemodynamic changes in the depth direction.
authors: Integrated Neuroscience Research Team, Tokyo Institute of Psychiatry, Tokyo, Japan. chies@prit.go.jp
authors: Chie
authors: C
authors: Sato
authors: Takekane
authors: T
authors: Yamaguchi
authors: Mitsuru
authors: M
authors: Seida
authors: Yoshihisa
authors: Y
authors: Ota
authors: Iwae
authors: I
authors: Yu
authors: Yoshinobu
authors: Y
authors: Iguchi
authors: Masahito
authors: M
authors: Nemoto
authors: Yoko
authors: Y
authors: Hoshi
mesh_terms: D000368:Aged; D001921:Brain / Q000098:blood supply / Q000378:metabolism; D016893:Carotid Stenosis / Q000175:diagnosis / Q000378:metabolism* / Q000601:surgery*; D016894:Endarterectomy, Carotid / Q000379:methods*; D006454:Hemoglobins / Q000032:analysis* / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D006454:Hemoglobins