title: Multiwavelength time-resolved detection of fluorescence during the inflow of indocyanine green into the adult's brain.
abstract: Optical technique based on diffuse reflectance measurement combined with indocyanine green (ICG) bolus tracking is extensively tested as a method for clinical assessment of brain perfusion in adults at the bedside. Methodology of multiwavelength and time-resolved detection of fluorescence light excited in the ICG is presented and advantages of measurements at multiple wavelengths are discussed. Measurements were carried out: 1. on a physical homogeneous phantom to study the concentration dependence of the fluorescence signal, 2. on the phantom to simulate the dynamic inflow of ICG at different depths, and 3. in vivo on surface of the human head. Pattern of inflow and washout of ICG in the head of healthy volunteers after intravenous injection of the dye was observed for the first time with time-resolved instrumentation at multiple emission wavelengths. The multiwavelength detection of fluorescence signal confirms that at longer emission wavelengths, probability of reabsorption of the fluorescence light by the dye itself is reduced. Considering different light penetration depths at different wavelengths, and the pronounced reabsorption at longer wavelengths, the time-resolved multiwavelength technique may be useful in signal decomposition, leading to evaluation of extra- and intracerebral components of the measured signals.
authors.affiliation: Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Trojdena 4, 02-109 Warsaw, Poland. anna.gerega@ibib.waw.pl
authors.forename: Anna
authors.initials: A
authors.lastname: Gerega
authors.forename: Daniel
authors.initials: D
authors.lastname: Milej
authors.forename: Wojciech
authors.initials: W
authors.lastname: Weigl
authors.forename: Marcin
authors.initials: M
authors.lastname: Botwicz
authors.forename: Norbert
authors.initials: N
authors.lastname: Zolek
authors.forename: Michal
authors.initials: M
authors.lastname: Kacprzak
authors.forename: Wojciech
authors.initials: W
authors.lastname: Wierzejski
authors.forename: Beata
authors.initials: B
authors.lastname: Toczylowska
authors.forename: Ewa
authors.initials: E
authors.lastname: Mayzner-Zawadzka
authors.forename: Roman
authors.initials: R
authors.lastname: Maniewski
authors.forename: Adam
authors.initials: A
authors.lastname: Liebert
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000166:cytology* / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007208:Indocyanine Green / Q000493:pharmacokinetics*; D008297:Male; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D055420:Perfusion Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D007208:Indocyanine Green