title: A new broadband near-infrared spectroscopy system for in-vivo measurements of cerebral cytochrome-c-oxidase changes in neonatal brain injury.
abstract: We present a novel lens-based broadband near-infrared spectroscopy system to simultaneously measure cerebral changes in tissue oxygenation and haemodynamics via estimation of the changes in haemoglobin concentration; in addition to oxygen utilization via the measurement of the oxidation state of cytochrome-c-oxidase (CCO). We demonstrate the use of the system in a cohort of 6 newborn infants with neonatal encephalopathy in the Neonatal Intensive Care Unit for continuous measurement periods of up to 5 days. NIRS data was collected from above the frontal lobe on the left and right hemispheres simultaneously with systemic data to allow multimodal data analysis. This allowed us to study the NIRS variables in response to global pathophysiological events and we focused our analysis to spontaneous oxygen desaturations. We identified changes from the NIRS variables during 236 oxygen desaturations from over 212 hours of data with a change from the baseline to nadir of -12 ± 3%. There was a consistent negative change in the Δ[HbD] (= oxygenated - deoxygenated haemoglobin) and Δ[oxCCO] measurements, mean decreases were 3.0 ± 1.7μM and 0.22 ± 0.11μM, and a positive change in the Δ[HbT] (= oxygenated + deoxygenated haemoglobin) measurements across all subjects, mean increase was 0.85 ± 0.58μM. We have shown with a feasibility study that the relationship between haemoglobin oxygenation changes and CCO oxidation changes during these desaturation events was significantly associated with a magnetic resonance spectroscopy (MRS)-measured biomarker of injury severity (r = 0.91, p<0.01).
authors.affiliation: Department of Medical Physics and Bioengineering, Malet Place Engineering Building, University College London, UK.
authors.forename: Gemma
authors.initials: G
authors.lastname: Bale
authors.affiliation: Institute for Women's Health, University College London and Neonatal Unit, University College London Hospitals Trust, London, UK.
authors.forename: Subhabrata
authors.initials: S
authors.lastname: Mitra
authors.affiliation: Institute for Women's Health, University College London and Neonatal Unit, University College London Hospitals Trust, London, UK.
authors.forename: Judith
authors.initials: J
authors.lastname: Meek
authors.affiliation: Institute for Women's Health, University College London and Neonatal Unit, University College London Hospitals Trust, London, UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: Robertson
authors.affiliation: Department of Medical Physics and Bioengineering, Malet Place Engineering Building, University College London, UK.
authors.forename: Ilias
authors.initials: I
authors.lastname: Tachtsidis
keywords: (170.3890) Medical optics instrumentation; (170.6510) Spectroscopy, tissue diagnostics