title: Changes in diffusion path length with old age in diffuse optical tomography.
abstract: Diffuse, optical near infrared imaging is increasingly being used in various neurocognitive contexts where changes in optical signals are interpreted through activation maps. Statistical population comparison of different age or clinical groups rely on the relative homogeneous distribution of measurements across subjects in order to infer changes in brain function. In the context of an increasing use of diffuse optical imaging with older adult populations, changes in tissue properties and anatomy with age adds additional confounds. Few studies investigated these changes with age. Duncan et al. measured the so-called diffusion path length factor (DPF) in a large population but did not explore beyond the age of 51 after which physiological and anatomical changes are expected to occur [Pediatr. Res. 39(5), 889-894 (1996)]. With increasing interest in studying the geriatric population with optical imaging, we studied changes in tissue properties in young and old subjects using both magnetic resonance imaging (MRI)-guided Monte-Carlo simulations and time-domain diffuse optical imaging. Our results, measured in the frontal cortex, show changes in DPF that are smaller than previously measured by Duncan et al. in a younger population. The origin of these changes are studied using simulations and experimental measures.
authors.affiliation: Ecole Polytechnique, Department of Electrical Engineering, C.P. 6079, Succursale Centre-ville, Montréal, Quebec, H3C 3A7, Canada.
authors.forename: Clément
authors.initials: C
authors.lastname: Bonnéry
authors.forename: Paul-Olivier
authors.initials: PO
authors.lastname: Leclerc
authors.forename: Michèle
authors.initials: M
authors.lastname: Desjardins
authors.forename: Rick
authors.initials: R
authors.lastname: Hoge
authors.forename: Louis
authors.initials: L
authors.lastname: Bherer
authors.forename: Philippe
authors.initials: P
authors.lastname: Pouliot
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lesage
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology* / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D004058:Diffusion; D006801:Humans; D007259:Infrared Rays; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D041622:Tomography, Optical / Q000379:methods*; D055815:Young Adult