title: Arterial input function of an optical tracer for dynamic contrast enhanced imaging can be determined from pulse oximetry oxygen saturation measurements.
abstract: In many cases, kinetic modeling requires that the arterial input function (AIF)--the time-dependent arterial concentration of a tracer--be characterized. A straightforward method to measure the AIF of red and near-infrared optical dyes (e.g., indocyanine green) using a pulse oximeter is presented. The method is motivated by the ubiquity of pulse oximeters used in both preclinical and clinical applications, as well as the gap in currently available technologies to measure AIFs in small animals. The method is based on quantifying the interference that is observed in the derived arterial oxygen saturation (SaO₂) following a bolus injection of a light-absorbing dye. In other words, the change in SaO₂ can be converted into dye concentration knowing the chromophore-specific extinction coefficients, the true arterial oxygen saturation, and total hemoglobin concentration. A simple error analysis was performed to highlight potential limitations of the approach, and a validation of the method was conducted in rabbits by comparing the pulse oximetry method with the AIF acquired using a pulse dye densitometer. Considering that determining the AIF is required for performing quantitative tracer kinetics, this method provides a flexible tool for measuring the arterial dye concentration that could be used in a variety of applications.
authors.affiliation: Department of Medical Biophysics, Western University, London, Ontario N6A 5C1, Canada. Imaging Division, Lawson Health Research Institute, London, Ontario N6A 4V2, Canada. jon.t.elliott@gmail.com
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Elliott
authors.forename: Eric A
authors.initials: EA
authors.lastname: Wright
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Tichauer
authors.forename: Mamadou
authors.initials: M
authors.lastname: Diop
authors.forename: Laura B
authors.initials: LB
authors.lastname: Morrison
authors.forename: Brian W
authors.initials: BW
authors.lastname: Pogue
authors.forename: Ting-Yim
authors.initials: TY
authors.lastname: Lee
authors.forename: Keith
authors.initials: K
authors.lastname: St Lawrence
mesh_terms: D000042:Absorption; D000818:Animals; D001158:Arteries / Q000378:metabolism* / Q000502:physiology; D004396:Coloring Agents; D003287:Contrast Media; D061848:Optical Imaging / Q000379:methods*; D055620:Optical Phenomena; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D011817:Rabbits; D015203:Reproducibility of Results
chemical_list: D004396:Coloring Agents; D003287:Contrast Media; D010100:Oxygen